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Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com>
jgalar
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Oct 28, 2019
The following crash was reported when short-lived applications are traced in a live session with per-pid buffering channels. From the original report: ``` Thread 1 (Thread 0x7f72b67fc700 (LWP 1912155)): #0 0x00005650b3f6ccbd in commit_one_metadata_packet (stream=0x7f729c010bf0) at ust-consumer.c:2537 #1 0x00005650b3f6cf58 in lttng_ustconsumer_sync_metadata (ctx=0x5650b588ce60, metadata=0x7f729c010bf0) at ust-consumer.c:2608 #2 0x00005650b3f4dba3 in do_sync_metadata (metadata=0x7f729c010bf0, ctx=0x5650b588ce60) at consumer-stream.c:471 #3 0x00005650b3f4dd3c in consumer_stream_sync_metadata (ctx=0x5650b588ce60, session_id=0) at consumer-stream.c:548 #4 0x00005650b3f6de78 in lttng_ustconsumer_read_subbuffer (stream=0x7f729c0058e0, ctx=0x5650b588ce60) at ust-consumer.c:2917 #5 0x00005650b3f45196 in lttng_consumer_read_subbuffer (stream=0x7f729c0058e0, ctx=0x5650b588ce60) at consumer.c:3524 #6 0x00005650b3f42da7 in consumer_thread_data_poll (data=0x5650b588ce60) at consumer.c:2894 #7 0x00007f72bdc476db in start_thread (arg=0x7f72b67fc700) at pthread_create.c:463 #8 0x00007f72bd97088f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 The segfault happen on the access to 'stream->chan->metadata_cache->lock' chan value here is zero. ``` The problem is easily reproducible if a sleep(1) is added just after the call to lttng_ustconsumer_request_metadata(), before the metadata stream lock is re-acquired. During the execution of the "request_metadata", an application can close. This will cause the session daemon to push any remaining metadata to the consumer daemon and to close the metadata channel. Closing the metadata channel closes the metadata stream's wait_fd, which is an internal pipe. The closure of the metadata pipe is detected by the metadata_poll thread, which will ensure that all metadata has been consumed before issuing the deletion of the metadata stream and channel. During the deletion, the channel's "stream" attribute the stream's "chan" attribute are set to NULL as both are logically deleted and should not longer be used. Meanwhile, the thread executing commit_one_metadata_packet() re-acquires the metadata stream lock and trips on the now-NULL "chan" member. The fix consists in checking if the metadata stream is logically deleted after its lock is re-acquired. It is correct for the sync_metadata operation to then complete successfully as the metadata is synced: the metadata guarantees this before deleting the stream/channel. Since the metadata stream's lifetime is protected by its lock, there may be other sites that need such a check. The lock and deletion check could be combined into a single consumer_stream_lock() helper in follow-up fixes. Reported-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
jgalar
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Oct 29, 2019
The following crash was reported when short-lived applications are traced in a live session with per-pid buffering channels. From the original report: ``` Thread 1 (Thread 0x7f72b67fc700 (LWP 1912155)): #0 0x00005650b3f6ccbd in commit_one_metadata_packet (stream=0x7f729c010bf0) at ust-consumer.c:2537 #1 0x00005650b3f6cf58 in lttng_ustconsumer_sync_metadata (ctx=0x5650b588ce60, metadata=0x7f729c010bf0) at ust-consumer.c:2608 #2 0x00005650b3f4dba3 in do_sync_metadata (metadata=0x7f729c010bf0, ctx=0x5650b588ce60) at consumer-stream.c:471 #3 0x00005650b3f4dd3c in consumer_stream_sync_metadata (ctx=0x5650b588ce60, session_id=0) at consumer-stream.c:548 #4 0x00005650b3f6de78 in lttng_ustconsumer_read_subbuffer (stream=0x7f729c0058e0, ctx=0x5650b588ce60) at ust-consumer.c:2917 #5 0x00005650b3f45196 in lttng_consumer_read_subbuffer (stream=0x7f729c0058e0, ctx=0x5650b588ce60) at consumer.c:3524 #6 0x00005650b3f42da7 in consumer_thread_data_poll (data=0x5650b588ce60) at consumer.c:2894 #7 0x00007f72bdc476db in start_thread (arg=0x7f72b67fc700) at pthread_create.c:463 #8 0x00007f72bd97088f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 The segfault happen on the access to 'stream->chan->metadata_cache->lock' chan value here is zero. ``` The problem is easily reproducible if a sleep(1) is added just after the call to lttng_ustconsumer_request_metadata(), before the metadata stream lock is re-acquired. During the execution of the "request_metadata", an application can close. This will cause the session daemon to push any remaining metadata to the consumer daemon and to close the metadata channel. Closing the metadata channel closes the metadata stream's wait_fd, which is an internal pipe. The closure of the metadata pipe is detected by the metadata_poll thread, which will ensure that all metadata has been consumed before issuing the deletion of the metadata stream and channel. During the deletion, the channel's "stream" attribute the stream's "chan" attribute are set to NULL as both are logically deleted and should not longer be used. Meanwhile, the thread executing commit_one_metadata_packet() re-acquires the metadata stream lock and trips on the now-NULL "chan" member. The fix consists in checking if the metadata stream is logically deleted after its lock is re-acquired. It is correct for the sync_metadata operation to then complete successfully as the metadata is synced: the metadata guarantees this before deleting the stream/channel. Since the metadata stream's lifetime is protected by its lock, there may be other sites that need such a check. The lock and deletion check could be combined into a single consumer_stream_lock() helper in follow-up fixes. Reported-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
jgalar
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Nov 5, 2019
The following crash was reported when short-lived applications are traced in a live session with per-pid buffering channels. From the original report: ``` Thread 1 (Thread 0x7f72b67fc700 (LWP 1912155)): #0 0x00005650b3f6ccbd in commit_one_metadata_packet (stream=0x7f729c010bf0) at ust-consumer.c:2537 #1 0x00005650b3f6cf58 in lttng_ustconsumer_sync_metadata (ctx=0x5650b588ce60, metadata=0x7f729c010bf0) at ust-consumer.c:2608 #2 0x00005650b3f4dba3 in do_sync_metadata (metadata=0x7f729c010bf0, ctx=0x5650b588ce60) at consumer-stream.c:471 #3 0x00005650b3f4dd3c in consumer_stream_sync_metadata (ctx=0x5650b588ce60, session_id=0) at consumer-stream.c:548 #4 0x00005650b3f6de78 in lttng_ustconsumer_read_subbuffer (stream=0x7f729c0058e0, ctx=0x5650b588ce60) at ust-consumer.c:2917 #5 0x00005650b3f45196 in lttng_consumer_read_subbuffer (stream=0x7f729c0058e0, ctx=0x5650b588ce60) at consumer.c:3524 #6 0x00005650b3f42da7 in consumer_thread_data_poll (data=0x5650b588ce60) at consumer.c:2894 #7 0x00007f72bdc476db in start_thread (arg=0x7f72b67fc700) at pthread_create.c:463 #8 0x00007f72bd97088f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 The segfault happen on the access to 'stream->chan->metadata_cache->lock' chan value here is zero. ``` The problem is easily reproducible if a sleep(1) is added just after the call to lttng_ustconsumer_request_metadata(), before the metadata stream lock is re-acquired. During the execution of the "request_metadata", an application can close. This will cause the session daemon to push any remaining metadata to the consumer daemon and to close the metadata channel. Closing the metadata channel closes the metadata stream's wait_fd, which is an internal pipe. The closure of the metadata pipe is detected by the metadata_poll thread, which will ensure that all metadata has been consumed before issuing the deletion of the metadata stream and channel. During the deletion, the channel's "stream" attribute the stream's "chan" attribute are set to NULL as both are logically deleted and should not longer be used. Meanwhile, the thread executing commit_one_metadata_packet() re-acquires the metadata stream lock and trips on the now-NULL "chan" member. The fix consists in checking if the metadata stream is logically deleted after its lock is re-acquired. It is correct for the sync_metadata operation to then complete successfully as the metadata is synced: the metadata guarantees this before deleting the stream/channel. Since the metadata stream's lifetime is protected by its lock, there may be other sites that need such a check. The lock and deletion check could be combined into a single consumer_stream_lock() helper in follow-up fixes. Reported-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
jgalar
added a commit
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Apr 15, 2020
Observed issue
==============
A NULL pointer dereference occurs during the creation of
a session that is associated with a peer older than 2.11.
The resulting backtrace follows:
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000564af45b755b in lttng_trace_chunk_set_as_owner (chunk=0x7f8ca8004730, session_output_directory=0x7f8ca8004680) at trace-chunk.c:1033
1033 if (chunk->path[0] != '\0') {
[Current thread is 1 (Thread 0x7f8cb808d700 (LWP 7300))]
#0 0x0000564af45b755b in lttng_trace_chunk_set_as_owner (chunk=0x7f8ca8004730, session_output_directory=0x7f8ca8004680) at trace-chunk.c:1033
#1 0x0000564af45a6a78 in session_set_anonymous_chunk (session=0x7f8ca8001380) at session.c:229
#2 session_create (session_name=<optimized out>, hostname=<optimized out>, base_path=<optimized out>, live_timer=<optimized out>, snapshot=<optimized out>,
sessiond_uuid=<optimized out>, id_sessiond=<optimized out>, current_chunk_id=<optimized out>, creation_time=<optimized out>, major=<optimized out>,
minor=<optimized out>, session_name_contains_creation_time=<optimized out>) at session.c:416
#3 0x0000564af459207e in relay_create_session (conn=0x7f8ca0000f60, payload=<optimized out>, recv_hdr=<optimized out>) at main.c:1428
#4 0x0000564af4594f12 in relay_process_control_command (payload=0x7f8cb808c940, header=0x7f8ca0001000, conn=0x7f8ca0000f60) at main.c:3218
#5 relay_process_control_receive_payload (conn=0x7f8ca0000f60) at main.c:3361
#6 0x0000564af45980b0 in relay_process_control (conn=0x7f8ca0000f60) at main.c:3478
#7 relay_thread_worker (data=<optimized out>) at main.c:3927
#8 0x00007f8cbba9a46f in start_thread () from /usr/lib/libpthread.so.0
lttng#9 0x00007f8cbb9ca3d3 in clone () from /usr/lib/libc.so.6
Cause
=====
lttng_trace_chunk_set_as_owner() correctly handles the case
where a trace chunk has no output path, but expects the path
to be an empty string rather than being NULL.
This is not correct as an anonymous chunk, created in backward
compatibility mode when interacting with older peers, has no
path; the path is transmitted as part of the streams' attributes
upon their creation.
Solution
========
Simply check for a NULL pointer in the same place where the empty
chunk path string is created. The rest of the code in trace-chunk.c
doesn't assume that the chunk's path is non-NULL.
Note
====
The problem was introduced during the 2.12 release cycle (clear
feature); this doesn't need to be backported.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Iaeb41e1648d61fbbe78d70b21191fd6d720900df
jgalar
added a commit
that referenced
this pull request
Apr 15, 2020
Observed issue
==============
A NULL pointer dereference occurs during the creation of
a session that is associated with a peer older than 2.11.
The resulting backtrace follows:
Program terminated with signal SIGSEGV, Segmentation fault.
#0 0x0000564af45b755b in lttng_trace_chunk_set_as_owner (chunk=0x7f8ca8004730, session_output_directory=0x7f8ca8004680) at trace-chunk.c:1033
1033 if (chunk->path[0] != '\0') {
[Current thread is 1 (Thread 0x7f8cb808d700 (LWP 7300))]
#0 0x0000564af45b755b in lttng_trace_chunk_set_as_owner (chunk=0x7f8ca8004730, session_output_directory=0x7f8ca8004680) at trace-chunk.c:1033
#1 0x0000564af45a6a78 in session_set_anonymous_chunk (session=0x7f8ca8001380) at session.c:229
#2 session_create (session_name=<optimized out>, hostname=<optimized out>, base_path=<optimized out>, live_timer=<optimized out>, snapshot=<optimized out>,
sessiond_uuid=<optimized out>, id_sessiond=<optimized out>, current_chunk_id=<optimized out>, creation_time=<optimized out>, major=<optimized out>,
minor=<optimized out>, session_name_contains_creation_time=<optimized out>) at session.c:416
#3 0x0000564af459207e in relay_create_session (conn=0x7f8ca0000f60, payload=<optimized out>, recv_hdr=<optimized out>) at main.c:1428
#4 0x0000564af4594f12 in relay_process_control_command (payload=0x7f8cb808c940, header=0x7f8ca0001000, conn=0x7f8ca0000f60) at main.c:3218
#5 relay_process_control_receive_payload (conn=0x7f8ca0000f60) at main.c:3361
#6 0x0000564af45980b0 in relay_process_control (conn=0x7f8ca0000f60) at main.c:3478
#7 relay_thread_worker (data=<optimized out>) at main.c:3927
#8 0x00007f8cbba9a46f in start_thread () from /usr/lib/libpthread.so.0
lttng#9 0x00007f8cbb9ca3d3 in clone () from /usr/lib/libc.so.6
Cause
=====
lttng_trace_chunk_set_as_owner() correctly handles the case
where a trace chunk has no output path, but expects the path
to be an empty string rather than being NULL.
This is not correct as an anonymous chunk, created in backward
compatibility mode when interacting with older peers, has no
path; the path is transmitted as part of the streams' attributes
upon their creation.
Solution
========
Simply check for a NULL pointer in the same place where the empty
chunk path string is created. The rest of the code in trace-chunk.c
doesn't assume that the chunk's path is non-NULL.
Note
====
The problem was introduced during the 2.12 release cycle (clear
feature); this doesn't need to be backported.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Iaeb41e1648d61fbbe78d70b21191fd6d720900df
jgalar
added a commit
that referenced
this pull request
Apr 22, 2020
Observed issue -------------- While running the out-of-tree java agent tests [1], the session daemon and agent often end up in a deadlock. Attaching gdb to the session daemon, we can see that two threads are blocked in an intriguing state. Thread 13 (Thread 0x7f89027fc700 (LWP 9636)): #0 0x00007f891e81a4cf in __lll_lock_wait () from /usr/lib/libpthread.so.0 #1 0x00007f891e812e03 in pthread_mutex_lock () from /usr/lib/libpthread.so.0 #2 0x000055637f1fbd92 in session_lock_list () at session.c:156 #3 0x000055637f25dc47 in update_agent_app (app=0x7f88ec003480) at agent-thread.c:56 #4 0x000055637f25ec0a in thread_agent_management (data=0x556380cd2400) at agent-thread.c:426 #5 0x000055637f22fb3a in launch_thread (data=0x556380cd24a0) at thread.c:65 #6 0x00007f891e81046f in start_thread () from /usr/lib/libpthread.so.0 #7 0x00007f891e7203d3 in clone () from /usr/lib/libc.so.6 Thread 8 (Thread 0x7f8919309700 (LWP 9631)): #0 0x00007f891e81b44d in recvmsg () from /usr/lib/libpthread.so.0 #1 0x000055637f267847 in lttcomm_recvmsg_inet_sock (sock=0x7f88ec0033c0, buf=0x7f89192f5d5c, len=4, flags=0) at inet.c:367 #2 0x000055637f2146c6 in recv_reply (sock=0x7f88ec0033c0, buf=0x7f89192f5d5c, size=4) at agent.c:275 #3 0x000055637f215202 in app_context_op (app=0x7f88ec003400, ctx=0x7f8908020900, cmd=AGENT_CMD_APP_CTX_DISABLE) at agent.c:552 #4 0x000055637f215c2d in disable_context (ctx=0x7f8908020900, domain=LTTNG_DOMAIN_JUL) at agent.c:841 #5 0x000055637f217480 in agent_destroy (agt=0x7f890801dc20) at agent.c:1326 #6 0x000055637f243448 in trace_ust_destroy_session (session=0x7f8908004010) at trace-ust.c:1408 #7 0x000055637f1fd775 in session_release (ref=0x7f8908001e70) at session.c:873 #8 0x000055637f1fb9ac in urcu_ref_put (ref=0x7f8908001e70, release=0x55637f1fd62a <session_release>) at /usr/include/urcu/ref.h:68 lttng#9 0x000055637f1fdad2 in session_put (session=0x7f8908000d10) at session.c:942 lttng#10 0x000055637f2369e6 in process_client_msg (cmd_ctx=0x7f890800e6e0, sock=0x7f8919308560, sock_error=0x7f8919308564) at client.c:2102 lttng#11 0x000055637f2375ab in thread_manage_clients (data=0x556380cd1840) at client.c:2347 lttng#12 0x000055637f22fb3a in launch_thread (data=0x556380cd18b0) at thread.c:65 lttng#13 0x00007f891e81046f in start_thread () from /usr/lib/libpthread.so.0 lttng#14 0x00007f891e7203d3 in clone () from /usr/lib/libc.so.6 T8 is holding session list lock while the cmd_destroy_session command is being processed. More specifically, it is attempting to destroy an "agent_context" by communicating with an "agent" application. Meanwhile, T13 is still registering that same "agent" application. Cause ----- The deadlock itself is pretty simple to understand. The "agent thread" (T13) has the responsability of accepting new agent application connections. When such a connection occurs, the thread creates a new `agent_app` instance and sends the current sessions' configuration (i.e. their event rules and contexts) to the agent application. When that "update" is complete, a "registration done" message is sent to the new agent application. From the stacktrace above, we can see that T13 is attempting to update the agent application with its initial configuration, but it is blocked on the acquisition of the session list lock. The application's agent is also blocked since it is waiting for the "registration done" message before allowing tracing to proceed (not shown here, but seen in the test logs). Meanwhile, T8 is holding the session list lock while destroying a session. This is expected as all client commands are executed with this lock held. It is, amongst other reasons, used to serialize changes to the sessions' configuration and configuration updates sent to the tracers (i.e. because new apps appear or to keep existing tracers in sync with the users' session configuration). The question becomes: why is T8 tearing down an application that is not yet registered? First, inspecting `agent_app` immediately shows that this structure has no built-in synchronization mechanism. Therefore, the fact that two threads are accessing it at the same time raises a big red flag. Speculating on the intentions of the original design, my intuition is that the "agent_management" thread's role is limited to instantiating an `agent_app` and synchronizing it with the various sessions' configuration. Once that synchronization is performed, the agent application should be published and never accessed again by the "agent thread". Configuration updates (i.e. new event rules, contexts) are then sent synchronously as they are requested by a client in the context of the client thread. Those updates are performed while holding the session list lock. Hence, there is only one thread that should manipulate the agent application at any given time making an explicit `agent_app` lock unnecessary. Overall, this would echo what is done when a 'user space tracer' application registers to the session daemon (see dispatch.c:368). Evidently this isn't what is happening here. The agent thread creates the `agent_app`, publishes it, and then performs an "agent app update" (sending the configuration) while holding the session list lock. This means that there is a window where an agent application is visible to the other threads, yet has not been properly registered. Solution -------- The acquisition of the session list lock is moved outside of update_agent_app() to allow the "agent thread" to hold the session list lock during the "configuration update" phase of the agent application registration. Essentially, the sequence of operation changes from: - Agent tcp connection established - call handle_registration() - agent version check - allocation of agent_app instance - new agent_add is published through the global agent_apps_ht_by_sock hashtable *** it is now reachable by all other threads without any form of exclusivity synchronization. *** - update_agent_app - acquire session list lock - iterate over sessions - send configuration - release session list lock - send registration done to: - Agent tcp connection established - call accept_agent_registration() - agent version check - allocation of agent_app instance - acquire session list lock - update_agent_app - iterate over sessions - send configuration - send registration done - new agent_add is published through the global agent_apps_ht_by_sock hashtable - release session list lock Links ----- [1] https://github.com/lttng/lttng-ust-java-tests Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ia34c5ad81ed3936acbca756b425423e0cb8dbddf
jgalar
added a commit
that referenced
this pull request
Apr 29, 2020
Observed issue -------------- While running the out-of-tree java agent tests [1], the session daemon and agent often end up in a deadlock. Attaching gdb to the session daemon, we can see that two threads are blocked in an intriguing state. Thread 13 (Thread 0x7f89027fc700 (LWP 9636)): #0 0x00007f891e81a4cf in __lll_lock_wait () from /usr/lib/libpthread.so.0 #1 0x00007f891e812e03 in pthread_mutex_lock () from /usr/lib/libpthread.so.0 #2 0x000055637f1fbd92 in session_lock_list () at session.c:156 #3 0x000055637f25dc47 in update_agent_app (app=0x7f88ec003480) at agent-thread.c:56 #4 0x000055637f25ec0a in thread_agent_management (data=0x556380cd2400) at agent-thread.c:426 #5 0x000055637f22fb3a in launch_thread (data=0x556380cd24a0) at thread.c:65 #6 0x00007f891e81046f in start_thread () from /usr/lib/libpthread.so.0 #7 0x00007f891e7203d3 in clone () from /usr/lib/libc.so.6 Thread 8 (Thread 0x7f8919309700 (LWP 9631)): #0 0x00007f891e81b44d in recvmsg () from /usr/lib/libpthread.so.0 #1 0x000055637f267847 in lttcomm_recvmsg_inet_sock (sock=0x7f88ec0033c0, buf=0x7f89192f5d5c, len=4, flags=0) at inet.c:367 #2 0x000055637f2146c6 in recv_reply (sock=0x7f88ec0033c0, buf=0x7f89192f5d5c, size=4) at agent.c:275 #3 0x000055637f215202 in app_context_op (app=0x7f88ec003400, ctx=0x7f8908020900, cmd=AGENT_CMD_APP_CTX_DISABLE) at agent.c:552 #4 0x000055637f215c2d in disable_context (ctx=0x7f8908020900, domain=LTTNG_DOMAIN_JUL) at agent.c:841 #5 0x000055637f217480 in agent_destroy (agt=0x7f890801dc20) at agent.c:1326 #6 0x000055637f243448 in trace_ust_destroy_session (session=0x7f8908004010) at trace-ust.c:1408 #7 0x000055637f1fd775 in session_release (ref=0x7f8908001e70) at session.c:873 #8 0x000055637f1fb9ac in urcu_ref_put (ref=0x7f8908001e70, release=0x55637f1fd62a <session_release>) at /usr/include/urcu/ref.h:68 lttng#9 0x000055637f1fdad2 in session_put (session=0x7f8908000d10) at session.c:942 lttng#10 0x000055637f2369e6 in process_client_msg (cmd_ctx=0x7f890800e6e0, sock=0x7f8919308560, sock_error=0x7f8919308564) at client.c:2102 lttng#11 0x000055637f2375ab in thread_manage_clients (data=0x556380cd1840) at client.c:2347 lttng#12 0x000055637f22fb3a in launch_thread (data=0x556380cd18b0) at thread.c:65 lttng#13 0x00007f891e81046f in start_thread () from /usr/lib/libpthread.so.0 lttng#14 0x00007f891e7203d3 in clone () from /usr/lib/libc.so.6 T8 is holding session list lock while the cmd_destroy_session command is being processed. More specifically, it is attempting to destroy an "agent_context" by communicating with an "agent" application. Meanwhile, T13 is still registering that same "agent" application. Cause ----- The deadlock itself is pretty simple to understand. The "agent thread" (T13) has the responsability of accepting new agent application connections. When such a connection occurs, the thread creates a new `agent_app` instance and sends the current sessions' configuration (i.e. their event rules and contexts) to the agent application. When that "update" is complete, a "registration done" message is sent to the new agent application. From the stacktrace above, we can see that T13 is attempting to update the agent application with its initial configuration, but it is blocked on the acquisition of the session list lock. The application's agent is also blocked since it is waiting for the "registration done" message before allowing tracing to proceed (not shown here, but seen in the test logs). Meanwhile, T8 is holding the session list lock while destroying a session. This is expected as all client commands are executed with this lock held. It is, amongst other reasons, used to serialize changes to the sessions' configuration and configuration updates sent to the tracers (i.e. because new apps appear or to keep existing tracers in sync with the users' session configuration). The question becomes: why is T8 tearing down an application that is not yet registered? First, inspecting `agent_app` immediately shows that this structure has no built-in synchronization mechanism. Therefore, the fact that two threads are accessing it at the same time raises a big red flag. Speculating on the intentions of the original design, my intuition is that the "agent_management" thread's role is limited to instantiating an `agent_app` and synchronizing it with the various sessions' configuration. Once that synchronization is performed, the agent application should be published and never accessed again by the "agent thread". Configuration updates (i.e. new event rules, contexts) are then sent synchronously as they are requested by a client in the context of the client thread. Those updates are performed while holding the session list lock. Hence, there is only one thread that should manipulate the agent application at any given time making an explicit `agent_app` lock unnecessary. Overall, this would echo what is done when a 'user space tracer' application registers to the session daemon (see dispatch.c:368). Evidently this isn't what is happening here. The agent thread creates the `agent_app`, publishes it, and then performs an "agent app update" (sending the configuration) while holding the session list lock. This means that there is a window where an agent application is visible to the other threads, yet has not been properly registered. Solution -------- The acquisition of the session list lock is moved outside of update_agent_app() to allow the "agent thread" to hold the session list lock during the "configuration update" phase of the agent application registration. Essentially, the sequence of operation changes from: - Agent tcp connection established - call handle_registration() - agent version check - allocation of agent_app instance - new agent_add is published through the global agent_apps_ht_by_sock hashtable *** it is now reachable by all other threads without any form of exclusivity synchronization. *** - update_agent_app - acquire session list lock - iterate over sessions - send configuration - release session list lock - send registration done to: - Agent tcp connection established - call accept_agent_registration() - agent version check - allocation of agent_app instance - acquire session list lock - update_agent_app - iterate over sessions - send configuration - send registration done - new agent_add is published through the global agent_apps_ht_by_sock hashtable - release session list lock Links ----- [1] https://github.com/lttng/lttng-ust-java-tests Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ia34c5ad81ed3936acbca756b425423e0cb8dbddf
jgalar
pushed a commit
that referenced
this pull request
May 26, 2020
Observed issue ============== Core dump: #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x0000003eb4025548 in __GI_abort () at abort.c:79 #2 0x0000003eb402542f in __assert_fail_base (fmt=0x3eb4184ae0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x4cdee0 "(trace_chunk->timestamp_close).is_set", file=0x4cde78 "../../../lttng-tools-2.11.3/src/common/trace-chunk.c", line=903, function=0x4cf4a0 <__PRETTY_FUNCTION__.6756> "lttng_trace_chunk_move_to_completed") at assert.c:92 #3 0x0000003eb4033af2 in __GI___assert_fail (assertion=assertion@entry=0x4cdee0 "(trace_chunk->timestamp_close).is_set", file=file@entry=0x4cde78 "../../../lttng-tools-2.11.3/src/common/trace-chunk.c", line=line@entry=903, function=function@entry=0x4cf4a0 <__PRETTY_FUNCTION__.6756> "lttng_trace_chunk_move_to_completed") at assert.c:101 #4 0x000000000047f37e in lttng_trace_chunk_move_to_completed (trace_chunk=0x7fcb5c00e570) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:903 #5 0x0000000000480755 in lttng_trace_chunk_release (ref=0x7fcb5c00e598) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1117 #6 urcu_ref_put (release=<optimized out>, ref=0x7fcb5c00e598) at /usr/include/urcu/ref.h:68 #7 lttng_trace_chunk_put (chunk=0x7fcb5c00e570) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1150 #8 0x0000000000429c22 in cmd_rotate_session (session=0x7fcb5c003ff0, rotate_return=rotate_return@entry=0x7fcb6b7ed470, quiet_rotation=quiet_rotation@entry=false) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/cmd.c:5037 lttng#9 0x00000000004451d7 in process_client_msg (cmd_ctx=0x7fcb5c00e760, sock=sock@entry=0x7fcb6b7fd4c0, sock_error=sock_error@entry=0x7fcb6b7fd4c4) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/client.c:1852 lttng#10 0x00000000004474c6 in thread_manage_clients (data=<optimized out>) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/client.c:2199 lttng#11 0x00000000004422f2 in launch_thread (data=0x4f97a0) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/thread.c:75 lttng#12 0x0000003eb4408ed4 in start_thread (arg=<optimized out>) at pthread_create.c:479 lttng#13 0x0000003eb40f8e6f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Reproduction: Disable ntp/any time management mechanism. lttng create lttng enable-event -u 'lttng_ust_tracef:*' lttng start lttng rotate date --set="$(date --date='-1 hour')" lttng rotate auto-20200515-142503 Waiting for rotation to complete Error: Failed to query the state of the rotation. Logs: DEBUG1 - 12:25:28.570037987 [2660/2717]: Setting trace chunk close command to "move to completed chunk folder" (in lttng_trace_chunk_set_close_command() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1073) Error: Failed to set trace chunk close timestamp: close timestamp is before creation timestamp Error: Failed to set the close timestamp of the current trace chunk of session "auto-20200515-142503" lttng-sessiond: ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:903: lttng_trace_chunk_move_to_completed: Assertion `(trace_chunk->timestamp_close).is_set' failed. ... Aborted (core dumped) root@X10SDV-8C-TLN4F:~# DEBUG1 - 12:25:29.534263017 [2739/2739]: Releasing trace chunk registry to all trace chunks (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1414) DEBUG1 - 12:25:29.534317468 [2739/2739]: Releasing reference to trace chunk: session_id = 0chunk_id = 2, name = "20200515T122528+0000-2", status = closed (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1435) DEBUG1 - 12:25:29.534365653 [2739/2739]: Releasing reference to trace chunk: session_id = 0chunk_id = 1, name = "20200515T142520+0000-1", status = closed (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1435) DEBUG1 - 12:25:29.534400638 [2739/2739]: Released reference to 2 trace chunks in lttng_trace_chunk_registry_put_each_chunk() (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1447) Error: 2 trace chunks are leaked by lttng-consumerd. This can be caused by an internal error of the session daemon. Cause ===== The trace_chunk->timestamp_close is not set since the result from time() is smaller than the creation timestamp. The close timestamp is smaller because the calendar system time is modified by an administrator. time() offers no monotonicity guarantee and hence is exposed to time modification of the system. The begin and close timestamps are strictly used in the name generation of the chunk/archives. Given the current usage of these timestamps validating monotonicity should not be a fatal error. Name uniqueness is provided by the chunk name suffix (auto increment). Solution ======== Do not enforce monotonicity for the begin and close timestamps but warn on unexpected return (begin > close). Known drawbacks ========= None. Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ic4b17285d150358d1569d6821c451c243e64e9a1
jgalar
pushed a commit
that referenced
this pull request
May 28, 2020
Observed issue ============== Core dump: #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x0000003eb4025548 in __GI_abort () at abort.c:79 #2 0x0000003eb402542f in __assert_fail_base (fmt=0x3eb4184ae0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x4cdee0 "(trace_chunk->timestamp_close).is_set", file=0x4cde78 "../../../lttng-tools-2.11.3/src/common/trace-chunk.c", line=903, function=0x4cf4a0 <__PRETTY_FUNCTION__.6756> "lttng_trace_chunk_move_to_completed") at assert.c:92 #3 0x0000003eb4033af2 in __GI___assert_fail (assertion=assertion@entry=0x4cdee0 "(trace_chunk->timestamp_close).is_set", file=file@entry=0x4cde78 "../../../lttng-tools-2.11.3/src/common/trace-chunk.c", line=line@entry=903, function=function@entry=0x4cf4a0 <__PRETTY_FUNCTION__.6756> "lttng_trace_chunk_move_to_completed") at assert.c:101 #4 0x000000000047f37e in lttng_trace_chunk_move_to_completed (trace_chunk=0x7fcb5c00e570) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:903 #5 0x0000000000480755 in lttng_trace_chunk_release (ref=0x7fcb5c00e598) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1117 #6 urcu_ref_put (release=<optimized out>, ref=0x7fcb5c00e598) at /usr/include/urcu/ref.h:68 #7 lttng_trace_chunk_put (chunk=0x7fcb5c00e570) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1150 #8 0x0000000000429c22 in cmd_rotate_session (session=0x7fcb5c003ff0, rotate_return=rotate_return@entry=0x7fcb6b7ed470, quiet_rotation=quiet_rotation@entry=false) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/cmd.c:5037 lttng#9 0x00000000004451d7 in process_client_msg (cmd_ctx=0x7fcb5c00e760, sock=sock@entry=0x7fcb6b7fd4c0, sock_error=sock_error@entry=0x7fcb6b7fd4c4) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/client.c:1852 lttng#10 0x00000000004474c6 in thread_manage_clients (data=<optimized out>) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/client.c:2199 lttng#11 0x00000000004422f2 in launch_thread (data=0x4f97a0) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/thread.c:75 lttng#12 0x0000003eb4408ed4 in start_thread (arg=<optimized out>) at pthread_create.c:479 lttng#13 0x0000003eb40f8e6f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Reproduction: Disable ntp/any time management mechanism. lttng create lttng enable-event -u 'lttng_ust_tracef:*' lttng start lttng rotate date --set="$(date --date='-1 hour')" lttng rotate auto-20200515-142503 Waiting for rotation to complete Error: Failed to query the state of the rotation. Logs: DEBUG1 - 12:25:28.570037987 [2660/2717]: Setting trace chunk close command to "move to completed chunk folder" (in lttng_trace_chunk_set_close_command() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1073) Error: Failed to set trace chunk close timestamp: close timestamp is before creation timestamp Error: Failed to set the close timestamp of the current trace chunk of session "auto-20200515-142503" lttng-sessiond: ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:903: lttng_trace_chunk_move_to_completed: Assertion `(trace_chunk->timestamp_close).is_set' failed. ... Aborted (core dumped) root@X10SDV-8C-TLN4F:~# DEBUG1 - 12:25:29.534263017 [2739/2739]: Releasing trace chunk registry to all trace chunks (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1414) DEBUG1 - 12:25:29.534317468 [2739/2739]: Releasing reference to trace chunk: session_id = 0chunk_id = 2, name = "20200515T122528+0000-2", status = closed (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1435) DEBUG1 - 12:25:29.534365653 [2739/2739]: Releasing reference to trace chunk: session_id = 0chunk_id = 1, name = "20200515T142520+0000-1", status = closed (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1435) DEBUG1 - 12:25:29.534400638 [2739/2739]: Released reference to 2 trace chunks in lttng_trace_chunk_registry_put_each_chunk() (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1447) Error: 2 trace chunks are leaked by lttng-consumerd. This can be caused by an internal error of the session daemon. Cause ===== The trace_chunk->timestamp_close is not set since the result from time() is smaller than the creation timestamp. The close timestamp is smaller because the calendar system time is modified by an administrator. time() offers no monotonicity guarantee and hence is exposed to time modification of the system. The begin and close timestamps are strictly used in the name generation of the chunk/archives. Given the current usage of these timestamps validating monotonicity should not be a fatal error. Name uniqueness is provided by the chunk name suffix (auto increment). Solution ======== Do not enforce monotonicity for the begin and close timestamps but warn on unexpected return (begin > close). Known drawbacks ========= None. Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ic4b17285d150358d1569d6821c451c243e64e9a1
jgalar
added a commit
that referenced
this pull request
May 28, 2020
Observed issue -------------- While running the out-of-tree java agent tests [1], the session daemon and agent often end up in a deadlock. Attaching gdb to the session daemon, we can see that two threads are blocked in an intriguing state. Thread 13 (Thread 0x7f89027fc700 (LWP 9636)): #0 0x00007f891e81a4cf in __lll_lock_wait () from /usr/lib/libpthread.so.0 #1 0x00007f891e812e03 in pthread_mutex_lock () from /usr/lib/libpthread.so.0 #2 0x000055637f1fbd92 in session_lock_list () at session.c:156 #3 0x000055637f25dc47 in update_agent_app (app=0x7f88ec003480) at agent-thread.c:56 #4 0x000055637f25ec0a in thread_agent_management (data=0x556380cd2400) at agent-thread.c:426 #5 0x000055637f22fb3a in launch_thread (data=0x556380cd24a0) at thread.c:65 #6 0x00007f891e81046f in start_thread () from /usr/lib/libpthread.so.0 #7 0x00007f891e7203d3 in clone () from /usr/lib/libc.so.6 Thread 8 (Thread 0x7f8919309700 (LWP 9631)): #0 0x00007f891e81b44d in recvmsg () from /usr/lib/libpthread.so.0 #1 0x000055637f267847 in lttcomm_recvmsg_inet_sock (sock=0x7f88ec0033c0, buf=0x7f89192f5d5c, len=4, flags=0) at inet.c:367 #2 0x000055637f2146c6 in recv_reply (sock=0x7f88ec0033c0, buf=0x7f89192f5d5c, size=4) at agent.c:275 #3 0x000055637f215202 in app_context_op (app=0x7f88ec003400, ctx=0x7f8908020900, cmd=AGENT_CMD_APP_CTX_DISABLE) at agent.c:552 #4 0x000055637f215c2d in disable_context (ctx=0x7f8908020900, domain=LTTNG_DOMAIN_JUL) at agent.c:841 #5 0x000055637f217480 in agent_destroy (agt=0x7f890801dc20) at agent.c:1326 #6 0x000055637f243448 in trace_ust_destroy_session (session=0x7f8908004010) at trace-ust.c:1408 #7 0x000055637f1fd775 in session_release (ref=0x7f8908001e70) at session.c:873 #8 0x000055637f1fb9ac in urcu_ref_put (ref=0x7f8908001e70, release=0x55637f1fd62a <session_release>) at /usr/include/urcu/ref.h:68 lttng#9 0x000055637f1fdad2 in session_put (session=0x7f8908000d10) at session.c:942 lttng#10 0x000055637f2369e6 in process_client_msg (cmd_ctx=0x7f890800e6e0, sock=0x7f8919308560, sock_error=0x7f8919308564) at client.c:2102 lttng#11 0x000055637f2375ab in thread_manage_clients (data=0x556380cd1840) at client.c:2347 lttng#12 0x000055637f22fb3a in launch_thread (data=0x556380cd18b0) at thread.c:65 lttng#13 0x00007f891e81046f in start_thread () from /usr/lib/libpthread.so.0 lttng#14 0x00007f891e7203d3 in clone () from /usr/lib/libc.so.6 T8 is holding session list lock while the cmd_destroy_session command is being processed. More specifically, it is attempting to destroy an "agent_context" by communicating with an "agent" application. Meanwhile, T13 is still registering that same "agent" application. Cause ----- The deadlock itself is pretty simple to understand. The "agent thread" (T13) has the responsability of accepting new agent application connections. When such a connection occurs, the thread creates a new `agent_app` instance and sends the current sessions' configuration (i.e. their event rules and contexts) to the agent application. When that "update" is complete, a "registration done" message is sent to the new agent application. From the stacktrace above, we can see that T13 is attempting to update the agent application with its initial configuration, but it is blocked on the acquisition of the session list lock. The application's agent is also blocked since it is waiting for the "registration done" message before allowing tracing to proceed (not shown here, but seen in the test logs). Meanwhile, T8 is holding the session list lock while destroying a session. This is expected as all client commands are executed with this lock held. It is, amongst other reasons, used to serialize changes to the sessions' configuration and configuration updates sent to the tracers (i.e. because new apps appear or to keep existing tracers in sync with the users' session configuration). The question becomes: why is T8 tearing down an application that is not yet registered? First, inspecting `agent_app` immediately shows that this structure has no built-in synchronization mechanism. Therefore, the fact that two threads are accessing it at the same time raises a big red flag. Speculating on the intentions of the original design, my intuition is that the "agent_management" thread's role is limited to instantiating an `agent_app` and synchronizing it with the various sessions' configuration. Once that synchronization is performed, the agent application should be published and never accessed again by the "agent thread". Configuration updates (i.e. new event rules, contexts) are then sent synchronously as they are requested by a client in the context of the client thread. Those updates are performed while holding the session list lock. Hence, there is only one thread that should manipulate the agent application at any given time making an explicit `agent_app` lock unnecessary. Overall, this would echo what is done when a 'user space tracer' application registers to the session daemon (see dispatch.c:368). Evidently this isn't what is happening here. The agent thread creates the `agent_app`, publishes it, and then performs an "agent app update" (sending the configuration) while holding the session list lock. This means that there is a window where an agent application is visible to the other threads, yet has not been properly registered. Solution -------- The acquisition of the session list lock is moved outside of update_agent_app() to allow the "agent thread" to hold the session list lock during the "configuration update" phase of the agent application registration. Essentially, the sequence of operation changes from: - Agent tcp connection established - call handle_registration() - agent version check - allocation of agent_app instance - new agent_add is published through the global agent_apps_ht_by_sock hashtable *** it is now reachable by all other threads without any form of exclusivity synchronization. *** - update_agent_app - acquire session list lock - iterate over sessions - send configuration - release session list lock - send registration done to: - Agent tcp connection established - call accept_agent_registration() - agent version check - allocation of agent_app instance - acquire session list lock - update_agent_app - iterate over sessions - send configuration - send registration done - new agent_add is published through the global agent_apps_ht_by_sock hashtable - release session list lock Links ----- [1] https://github.com/lttng/lttng-ust-java-tests Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ia34c5ad81ed3936acbca756b425423e0cb8dbddf
jgalar
added a commit
that referenced
this pull request
May 28, 2020
Observed issue -------------- While running the out-of-tree java agent tests [1], the session daemon and agent often end up in a deadlock. Attaching gdb to the session daemon, we can see that two threads are blocked in an intriguing state. Thread 13 (Thread 0x7f89027fc700 (LWP 9636)): #0 0x00007f891e81a4cf in __lll_lock_wait () from /usr/lib/libpthread.so.0 #1 0x00007f891e812e03 in pthread_mutex_lock () from /usr/lib/libpthread.so.0 #2 0x000055637f1fbd92 in session_lock_list () at session.c:156 #3 0x000055637f25dc47 in update_agent_app (app=0x7f88ec003480) at agent-thread.c:56 #4 0x000055637f25ec0a in thread_agent_management (data=0x556380cd2400) at agent-thread.c:426 #5 0x000055637f22fb3a in launch_thread (data=0x556380cd24a0) at thread.c:65 #6 0x00007f891e81046f in start_thread () from /usr/lib/libpthread.so.0 #7 0x00007f891e7203d3 in clone () from /usr/lib/libc.so.6 Thread 8 (Thread 0x7f8919309700 (LWP 9631)): #0 0x00007f891e81b44d in recvmsg () from /usr/lib/libpthread.so.0 #1 0x000055637f267847 in lttcomm_recvmsg_inet_sock (sock=0x7f88ec0033c0, buf=0x7f89192f5d5c, len=4, flags=0) at inet.c:367 #2 0x000055637f2146c6 in recv_reply (sock=0x7f88ec0033c0, buf=0x7f89192f5d5c, size=4) at agent.c:275 #3 0x000055637f215202 in app_context_op (app=0x7f88ec003400, ctx=0x7f8908020900, cmd=AGENT_CMD_APP_CTX_DISABLE) at agent.c:552 #4 0x000055637f215c2d in disable_context (ctx=0x7f8908020900, domain=LTTNG_DOMAIN_JUL) at agent.c:841 #5 0x000055637f217480 in agent_destroy (agt=0x7f890801dc20) at agent.c:1326 #6 0x000055637f243448 in trace_ust_destroy_session (session=0x7f8908004010) at trace-ust.c:1408 #7 0x000055637f1fd775 in session_release (ref=0x7f8908001e70) at session.c:873 #8 0x000055637f1fb9ac in urcu_ref_put (ref=0x7f8908001e70, release=0x55637f1fd62a <session_release>) at /usr/include/urcu/ref.h:68 lttng#9 0x000055637f1fdad2 in session_put (session=0x7f8908000d10) at session.c:942 lttng#10 0x000055637f2369e6 in process_client_msg (cmd_ctx=0x7f890800e6e0, sock=0x7f8919308560, sock_error=0x7f8919308564) at client.c:2102 lttng#11 0x000055637f2375ab in thread_manage_clients (data=0x556380cd1840) at client.c:2347 lttng#12 0x000055637f22fb3a in launch_thread (data=0x556380cd18b0) at thread.c:65 lttng#13 0x00007f891e81046f in start_thread () from /usr/lib/libpthread.so.0 lttng#14 0x00007f891e7203d3 in clone () from /usr/lib/libc.so.6 T8 is holding session list lock while the cmd_destroy_session command is being processed. More specifically, it is attempting to destroy an "agent_context" by communicating with an "agent" application. Meanwhile, T13 is still registering that same "agent" application. Cause ----- The deadlock itself is pretty simple to understand. The "agent thread" (T13) has the responsability of accepting new agent application connections. When such a connection occurs, the thread creates a new `agent_app` instance and sends the current sessions' configuration (i.e. their event rules and contexts) to the agent application. When that "update" is complete, a "registration done" message is sent to the new agent application. From the stacktrace above, we can see that T13 is attempting to update the agent application with its initial configuration, but it is blocked on the acquisition of the session list lock. The application's agent is also blocked since it is waiting for the "registration done" message before allowing tracing to proceed (not shown here, but seen in the test logs). Meanwhile, T8 is holding the session list lock while destroying a session. This is expected as all client commands are executed with this lock held. It is, amongst other reasons, used to serialize changes to the sessions' configuration and configuration updates sent to the tracers (i.e. because new apps appear or to keep existing tracers in sync with the users' session configuration). The question becomes: why is T8 tearing down an application that is not yet registered? First, inspecting `agent_app` immediately shows that this structure has no built-in synchronization mechanism. Therefore, the fact that two threads are accessing it at the same time raises a big red flag. Speculating on the intentions of the original design, my intuition is that the "agent_management" thread's role is limited to instantiating an `agent_app` and synchronizing it with the various sessions' configuration. Once that synchronization is performed, the agent application should be published and never accessed again by the "agent thread". Configuration updates (i.e. new event rules, contexts) are then sent synchronously as they are requested by a client in the context of the client thread. Those updates are performed while holding the session list lock. Hence, there is only one thread that should manipulate the agent application at any given time making an explicit `agent_app` lock unnecessary. Overall, this would echo what is done when a 'user space tracer' application registers to the session daemon (see dispatch.c:368). Evidently this isn't what is happening here. The agent thread creates the `agent_app`, publishes it, and then performs an "agent app update" (sending the configuration) while holding the session list lock. This means that there is a window where an agent application is visible to the other threads, yet has not been properly registered. Solution -------- The acquisition of the session list lock is moved outside of update_agent_app() to allow the "agent thread" to hold the session list lock during the "configuration update" phase of the agent application registration. Essentially, the sequence of operation changes from: - Agent tcp connection established - call handle_registration() - agent version check - allocation of agent_app instance - new agent_add is published through the global agent_apps_ht_by_sock hashtable *** it is now reachable by all other threads without any form of exclusivity synchronization. *** - update_agent_app - acquire session list lock - iterate over sessions - send configuration - release session list lock - send registration done to: - Agent tcp connection established - call accept_agent_registration() - agent version check - allocation of agent_app instance - acquire session list lock - update_agent_app - iterate over sessions - send configuration - send registration done - new agent_add is published through the global agent_apps_ht_by_sock hashtable - release session list lock Links ----- [1] https://github.com/lttng/lttng-ust-java-tests Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ia34c5ad81ed3936acbca756b425423e0cb8dbddf
jgalar
pushed a commit
that referenced
this pull request
Jun 19, 2020
Observed issue ============== Core dump: #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x0000003eb4025548 in __GI_abort () at abort.c:79 #2 0x0000003eb402542f in __assert_fail_base (fmt=0x3eb4184ae0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x4cdee0 "(trace_chunk->timestamp_close).is_set", file=0x4cde78 "../../../lttng-tools-2.11.3/src/common/trace-chunk.c", line=903, function=0x4cf4a0 <__PRETTY_FUNCTION__.6756> "lttng_trace_chunk_move_to_completed") at assert.c:92 #3 0x0000003eb4033af2 in __GI___assert_fail (assertion=assertion@entry=0x4cdee0 "(trace_chunk->timestamp_close).is_set", file=file@entry=0x4cde78 "../../../lttng-tools-2.11.3/src/common/trace-chunk.c", line=line@entry=903, function=function@entry=0x4cf4a0 <__PRETTY_FUNCTION__.6756> "lttng_trace_chunk_move_to_completed") at assert.c:101 #4 0x000000000047f37e in lttng_trace_chunk_move_to_completed (trace_chunk=0x7fcb5c00e570) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:903 #5 0x0000000000480755 in lttng_trace_chunk_release (ref=0x7fcb5c00e598) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1117 #6 urcu_ref_put (release=<optimized out>, ref=0x7fcb5c00e598) at /usr/include/urcu/ref.h:68 #7 lttng_trace_chunk_put (chunk=0x7fcb5c00e570) at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1150 #8 0x0000000000429c22 in cmd_rotate_session (session=0x7fcb5c003ff0, rotate_return=rotate_return@entry=0x7fcb6b7ed470, quiet_rotation=quiet_rotation@entry=false) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/cmd.c:5037 lttng#9 0x00000000004451d7 in process_client_msg (cmd_ctx=0x7fcb5c00e760, sock=sock@entry=0x7fcb6b7fd4c0, sock_error=sock_error@entry=0x7fcb6b7fd4c4) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/client.c:1852 lttng#10 0x00000000004474c6 in thread_manage_clients (data=<optimized out>) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/client.c:2199 lttng#11 0x00000000004422f2 in launch_thread (data=0x4f97a0) at ../../../../lttng-tools-2.11.3/src/bin/lttng-sessiond/thread.c:75 lttng#12 0x0000003eb4408ed4 in start_thread (arg=<optimized out>) at pthread_create.c:479 lttng#13 0x0000003eb40f8e6f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Reproduction: Disable ntp/any time management mechanism. lttng create lttng enable-event -u 'lttng_ust_tracef:*' lttng start lttng rotate date --set="$(date --date='-1 hour')" lttng rotate auto-20200515-142503 Waiting for rotation to complete Error: Failed to query the state of the rotation. Logs: DEBUG1 - 12:25:28.570037987 [2660/2717]: Setting trace chunk close command to "move to completed chunk folder" (in lttng_trace_chunk_set_close_command() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1073) Error: Failed to set trace chunk close timestamp: close timestamp is before creation timestamp Error: Failed to set the close timestamp of the current trace chunk of session "auto-20200515-142503" lttng-sessiond: ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:903: lttng_trace_chunk_move_to_completed: Assertion `(trace_chunk->timestamp_close).is_set' failed. ... Aborted (core dumped) root@X10SDV-8C-TLN4F:~# DEBUG1 - 12:25:29.534263017 [2739/2739]: Releasing trace chunk registry to all trace chunks (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1414) DEBUG1 - 12:25:29.534317468 [2739/2739]: Releasing reference to trace chunk: session_id = 0chunk_id = 2, name = "20200515T122528+0000-2", status = closed (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1435) DEBUG1 - 12:25:29.534365653 [2739/2739]: Releasing reference to trace chunk: session_id = 0chunk_id = 1, name = "20200515T142520+0000-1", status = closed (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1435) DEBUG1 - 12:25:29.534400638 [2739/2739]: Released reference to 2 trace chunks in lttng_trace_chunk_registry_put_each_chunk() (in lttng_trace_chunk_registry_put_each_chunk() at ../../../lttng-tools-2.11.3/src/common/trace-chunk.c:1447) Error: 2 trace chunks are leaked by lttng-consumerd. This can be caused by an internal error of the session daemon. Cause ===== The trace_chunk->timestamp_close is not set since the result from time() is smaller than the creation timestamp. The close timestamp is smaller because the calendar system time is modified by an administrator. time() offers no monotonicity guarantee and hence is exposed to time modification of the system. The begin and close timestamps are strictly used in the name generation of the chunk/archives. Given the current usage of these timestamps validating monotonicity should not be a fatal error. Name uniqueness is provided by the chunk name suffix (auto increment). Solution ======== Do not enforce monotonicity for the begin and close timestamps but warn on unexpected return (begin > close). Known drawbacks ========= None. Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ic4b17285d150358d1569d6821c451c243e64e9a1
jgalar
pushed a commit
that referenced
this pull request
Aug 13, 2020
Observed issue ============== Deadlock between the notification thread and the action executor thread. Thread 5 holds cmd_queue.lock and request the client lock. Thread 6 holds the client lock and request the cmd_queue lock. Thread 5 have little value in holding the queue lock considering it effectively to a "pop" of the cmd_queue. Thread 9 is waiting on the cmd_queue lock but does not hold any other locks and thus not part of the deadlock but is a casualties of this deadlock and leave a client "hanging". Other threads are all in their respective waiting state. Thread 9 (Thread 0x7f76f2ffd700 (LWP 240467)): #0 __lll_lock_wait (futex=futex@entry=0x1ad1308, private=0) at lowlevellock.c:52 [1070/1123] #1 0x00007f77052c80a3 in __GI___pthread_mutex_lock (mutex=0x1ad1308) at ../nptl/pthread_mutex_lock.c:80 #2 0x00000000004611dd in run_command_wait (handle=0x1ad12f0, cmd=0x7f76f2fe31e0) at notification-thread-commands.c:31 #3 0x000000000046143a in notification_thread_command_unregister_trigger (handle=0x1ad12f0, trigger=0x7f76e4000ef0) at notification-thread-commands.c:148 #4 0x00000000004444af in cmd_unregister_trigger (cmd_ctx=0x7f76e4000d40, sock=68, notification_thread=0x1ad12f0) at cmd.c:4618 #5 0x0000000000483d23 in process_client_msg (cmd_ctx=0x7f76e4000d40, sock=0x7f76f2ffcba4, sock_error=0x7f76f2ffcb90) at client.c:2001 #6 0x000000000047f00b in thread_manage_clients (data=0x1ad1a80) at client.c:2402 #7 0x000000000047b303 in launch_thread (data=0x1ad1af0) at thread.c:66 #8 0x00007f77052c5609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#9 0x00007f77051cc103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 6 (Thread 0x7f7700fcf700 (LWP 240464)): #0 __lll_lock_wait (futex=futex@entry=0x1ad1308, private=0) at lowlevellock.c:52 #1 0x00007f77052c80a3 in __GI___pthread_mutex_lock (mutex=0x1ad1308) at ../nptl/pthread_mutex_lock.c:80 #2 0x0000000000461bf2 in run_command_no_wait (handle=0x1ad12f0, in_cmd=0x7f7700fce340) at notification-thread-commands.c:87 #3 0x0000000000461b93 in notification_thread_client_communication_update (handle=0x1ad12f0, id=1, transmission_status=CLIENT_TRANSMISSION_STATUS_QUEUED) at notification-thread-commands.c:400 #4 0x0000000000497658 in client_handle_transmission_status (client=0x7f76f8004e30, status=CLIENT_TRANSMISSION_STATUS_QUEUED, user_data=0x7f76f8004a00) at action-executor.c:154 #5 0x0000000000467be7 in notification_client_list_send_evaluation (client_list=0x7f76f8004fe0, condition=0x7f76e40041a0, evaluation=0x7f76cc000cc0, trigger_creds=0x7f76e4004288, source_object_creds=0x0, client_report=0x4971a0 <client_ha ndle_transmission_status>, user_data=0x7f76f8004a00) at notification-thread-events.c:4007 #6 0x00000000004956bb in action_executor_notify_handler (executor=0x7f76f8004a00, work_item=0x7f76f80062d0, action=0x7f76e4004210) at action-executor.c:199 #7 0x00000000004953fd in action_executor_generic_handler (executor=0x7f76f8004a00, work_item=0x7f76f80062d0, action=0x7f76e4004210) at action-executor.c:493 #8 0x0000000000495101 in action_work_item_execute (executor=0x7f76f8004a00, work_item=0x7f76f80062d0) at action-executor.c:506 lttng#9 0x0000000000493ff5 in action_executor_thread (_data=0x7f76f8004a00) at action-executor.c:559 lttng#10 0x000000000047b303 in launch_thread (data=0x7f76f8004aa0) at thread.c:66 lttng#11 0x00007f77052c5609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#12 0x00007f77051cc103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 5 (Thread 0x7f77017d0700 (LWP 240463)): #0 __lll_lock_wait (futex=futex@entry=0x7f76f8004e30, private=0) at lowlevellock.c:52 #1 0x00007f77052c80a3 in __GI___pthread_mutex_lock (mutex=0x7f76f8004e30) at ../nptl/pthread_mutex_lock.c:80 #2 0x0000000000463080 in handle_notification_thread_command (handle=0x1ad12f0, state=0x7f77017cfb00) at notification-thread-events.c:2936 #3 0x000000000045e881 in thread_notification (data=0x1ad12f0) at notification-thread.c:705 #4 0x000000000047b303 in launch_thread (data=0x1ad1420) at thread.c:66 #5 0x00007f77052c5609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #6 0x00007f77051cc103 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Cause ===== The action executor holds the client lock across the communication to prevent simultaneous update to the client state. The notification thread holds the cmd_queue lock across operation for no apparent reason (TODO make sure there is no internal add to the queue. if so we should reacquire the lock only when necessery.) Solution ======== Reduce the windows for which the cmd_queue lock is held by the notification thread to only the "pop" action on the queue. As soon as we have the lock, get the cmd, remove it from the list and release the lock. This prevent inverted lock acquisition base on the pattern of the action executor thread. Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I91d30c134bc1a128c96058f0e0cdd325808c91bc
jgalar
added a commit
that referenced
this pull request
Nov 27, 2020
Observed issue
==============
The clear tests occasionally fail with the following babeltrace error
when a live session is stopped following a "clear". Unfortunately, this
problem only seems to occur on certain machines. In my case, I only
managed to reproduce this on the CI's workers.
10-07 12:39:48.333 7679 7679 E PLUGIN/SRC.CTF.LTTNG-LIVE/VIEWER lttng_live_get_stream_bytes@viewer-connection.c:1610 [lttng-live] Received get_data_packet response: error
10-07 12:39:48.333 7679 7679 E PLUGIN/CTF/MSG-ITER request_medium_bytes@msg-iter.c:563 [lttng-live] User function failed: status=ERROR
10-07 12:39:48.333 7679 7679 E PLUGIN/CTF/MSG-ITER ctf_msg_iter_get_next_message@msg-iter.c:2899 [lttng-live] Cannot handle state: msg-it-addr=0x5603c28e2830, state=DSCOPE_TRACE_PACKET_HEADER_BEGIN
10-07 12:39:48.333 7679 7679 E PLUGIN/SRC.CTF.LTTNG-LIVE lttng_live_iterator_next_handle_one_active_data_stream@lttng-live.c:845 [lttng-live] CTF message iterator failed to get next message: msg-iter=0x5603c28e2830, msg-iter-status=ERROR
10-07 12:39:48.333 7679 7679 E PLUGIN/SRC.CTF.LTTNG-LIVE lttng_live_msg_iter_next@lttng-live.c:1665 [lttng-live] Error preparing the next batch of messages: live-iter-status=LTTNG_LIVE_ITERATOR_STATUS_ERROR
10-07 12:39:48.333 7679 7679 W LIB/MSG-ITER bt_message_iterator_next@iterator.c:864 Component input port message iterator's "next" method failed: iter-addr=0x5603c28cb0f0, iter-upstream-comp-name="lttng-live", iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=SOURCE, iter-upstream-comp-class-name="lttng-live", iter-upstream-comp-class-partial-descr="Connect to an LTTng relay daemon", iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR
10-07 12:39:48.333 7679 7679 E PLUGIN/FLT.UTILS.MUXER muxer_upstream_msg_iter_next@muxer.c:454 [muxer] Upstream iterator's next method returned an error: status=ERROR
10-07 12:39:48.333 7679 7679 E PLUGIN/FLT.UTILS.MUXER validate_muxer_upstream_msg_iters@muxer.c:991 [muxer] Cannot validate muxer's upstream message iterator wrapper: muxer-msg-iter-addr=0x5603c28dbe70, muxer-upstream-msg-iter-wrap-addr=0x5603c28cd0f0
10-07 12:39:48.333 7679 7679 E PLUGIN/FLT.UTILS.MUXER muxer_msg_iter_next@muxer.c:1415 [muxer] Cannot get next message: comp-addr=0x5603c28dc960, muxer-comp-addr=0x5603c28db0a0, muxer-msg-iter-addr=0x5603c28dbe70, msg-iter-addr=0x5603c28caf80, status=ERROR
10-07 12:39:48.333 7679 7679 W LIB/MSG-ITER bt_message_iterator_next@iterator.c:864 Component input port message iterator's "next" method failed: iter-addr=0x5603c28caf80, iter-upstream-comp-name="muxer", iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=FILTER, iter-upstream-comp-class-name="muxer", iter-upstream-comp-class-partial-descr="Sort messages from multiple inpu", iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR
10-07 12:39:48.333 7679 7679 W LIB/GRAPH consume_graph_sink@graph.c:473 Component's "consume" method failed: status=ERROR, comp-addr=0x5603c28dcb60, comp-name="pretty", comp-log-level=WARNING, comp-class-type=SINK, comp-class-name="pretty", comp-class-partial-descr="Pretty-print messages (`text` fo", comp-class-is-frozen=0, comp-class-so-handle-addr=0x5603c28c8140, comp-class-so-handle-path="/home/jenkins/jgalar-debug/build/usr/lib/babeltrace2/plugins/babeltrace-plugin-text.so", comp-input-port-count=1, comp-output-port-count=0
10-07 12:39:48.333 7679 7679 E CLI cmd_run@babeltrace2.c:2548 Graph failed to complete successfully
10-07 12:39:48.333 7679 7679 E PLUGIN/SRC.CTF.LTTNG-LIVE/VIEWER lttng_live_session_detach@viewer-connection.c:1227 [lttng-live] Unknown detach return code 0
ERROR: [Babeltrace CLI] (babeltrace2.c:2548)
Graph failed to complete successfully
CAUSED BY [libbabeltrace2] (graph.c:473)
Component's "consume" method failed: status=ERROR, comp-addr=0x5603c28dcb60,
comp-name="pretty", comp-log-level=WARNING, comp-class-type=SINK,
comp-class-name="pretty", comp-class-partial-descr="Pretty-print messages
(`text` fo", comp-class-is-frozen=0, comp-class-so-handle-addr=0x5603c28c8140,
comp-class-so-handle-path="/home/jenkins/jgalar-debug/build/usr/lib/babeltrace2/plugins/babeltrace-plugin-text.so",
comp-input-port-count=1, comp-output-port-count=0
CAUSED BY [libbabeltrace2] (iterator.c:864)
Component input port message iterator's "next" method failed:
iter-addr=0x5603c28caf80, iter-upstream-comp-name="muxer",
iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=FILTER,
iter-upstream-comp-class-name="muxer",
iter-upstream-comp-class-partial-descr="Sort messages from multiple inpu",
iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR
CAUSED BY [muxer: 'filter.utils.muxer'] (muxer.c:991)
Cannot validate muxer's upstream message iterator wrapper:
muxer-msg-iter-addr=0x5603c28dbe70,
muxer-upstream-msg-iter-wrap-addr=0x5603c28cd0f0
CAUSED BY [muxer: 'filter.utils.muxer'] (muxer.c:454)
Upstream iterator's next method returned an error: status=ERROR
CAUSED BY [libbabeltrace2] (iterator.c:864)
Component input port message iterator's "next" method failed:
iter-addr=0x5603c28cb0f0, iter-upstream-comp-name="lttng-live",
iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=SOURCE,
iter-upstream-comp-class-name="lttng-live",
iter-upstream-comp-class-partial-descr="Connect to an LTTng relay daemon",
iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR
CAUSED BY [lttng-live: 'source.ctf.lttng-live'] (lttng-live.c:1665)
Error preparing the next batch of messages:
live-iter-status=LTTNG_LIVE_ITERATOR_STATUS_ERROR
CAUSED BY [lttng-live: 'source.ctf.lttng-live'] (lttng-live.c:845)
CTF message iterator failed to get next message: msg-iter=0x5603c28e2830,
msg-iter-status=ERROR
CAUSED BY [lttng-live: 'source.ctf.lttng-live'] (msg-iter.c:2899)
Cannot handle state: msg-it-addr=0x5603c28e2830,
state=DSCOPE_TRACE_PACKET_HEADER_BEGIN
CAUSED BY [lttng-live: 'source.ctf.lttng-live'] (msg-iter.c:563)
User function failed: status=ERROR
CAUSED BY [lttng-live: 'source.ctf.lttng-live'] (viewer-connection.c:1610)
Received get_data_packet response: error
This occurs immediately following a 'stop' on the session. As the error
indicates, a request to obtain a data packet fails with a generic
error reply.
Moreover, the following LTTNG_VIEWER_DETACH_SESSION appears to fail
with an invalid status code. This is addressed in a different commit.
Reproducing the test's failure without redirecting the relay daemon's
allows us to see the following errors after the first stop:
PERROR - 14:33:44.929675253 [25108/25115]: Failed to open fs handle to ust/uid/1001/64-bit/index/chan_0.idx, open() returned: No such file or directory (in fd_tracker_open_fs_handle() at fd-tracker.c:550)
PERROR - 14:33:45.030037417 [25108/25115]: Failed to open fs handle to ust/uid/1001/64-bit/index/chan_0.idx, open() returned: No such file or directory (in fd_tracker_open_fs_handle() at fd-tracker.c:550)
PERROR - 14:33:45.130429370 [25108/25115]: Failed to open fs handle to ust/uid/1001/64-bit/index/chan_0.idx, open() returned: No such file or directory (in fd_tracker_open_fs_handle() at fd-tracker.c:550)
PERROR - 14:33:45.230829447 [25108/25115]: Failed to open fs handle to ust/uid/1001/64-bit/index/chan_0.idx, open() returned: No such file or directory (in fd_tracker_open_fs_handle() at fd-tracker.c:550)
PERROR - 14:33:45.331223320 [25108/25115]: Failed to open fs handle to ust/uid/1001/64-bit/index/chan_0.idx, open() returned: No such file or directory (in fd_tracker_open_fs_handle() at fd-tracker.c:550)
This is produced with the following back-trace:
(gdb) bt
#0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1 0x00007ffff69648b1 in __GI_abort () at abort.c:79
#2 0x00005555555b4f1f in fd_tracker_open_fs_handle (tracker=0x55555582c620, directory=0x7fffe8006680,
path=0x7ffff0a25870 "ust/uid/1001/64-bit/index/chan_1.idx", flags=0, mode=0x7ffff0a24508) at fd-tracker.c:550
#3 0x0000555555595c34 in _lttng_trace_chunk_open_fs_handle_locked (chunk=0x7fffe0002130, file_path=0x7ffff0a25870 "ust/uid/1001/64-bit/index/chan_1.idx",
flags=0, mode=432, out_handle=0x7ffff0a24710, expect_no_file=true) at trace-chunk.c:1388
#4 0x0000555555595eef in lttng_trace_chunk_open_fs_handle (chunk=0x7fffe0002130, file_path=0x7ffff0a25870 "ust/uid/1001/64-bit/index/chan_1.idx", flags=0,
mode=432, out_handle=0x7ffff0a24710, expect_no_file=true) at trace-chunk.c:1433
#5 0x00005555555da6c2 in _lttng_index_file_create_from_trace_chunk (chunk=0x7fffe0002130, channel_path=0x7fffe8018c30 "ust/uid/1001/64-bit",
stream_name=0x7fffe8018c10 "chan_1", stream_file_size=0, stream_file_index=0, index_major=1, index_minor=1, unlink_existing_file=false, flags=0,
expect_no_file=true, file=0x7fffe0002270) at index.c:97
#6 0x00005555555dad8a in lttng_index_file_create_from_trace_chunk_read_only (chunk=0x7fffe0002130, channel_path=0x7fffe8018c30 "ust/uid/1001/64-bit",
stream_name=0x7fffe8018c10 "chan_1", stream_file_size=0, stream_file_index=0, index_major=1, index_minor=1, expect_no_file=true, file=0x7fffe0002270)
at index.c:186
#7 0x000055555557640f in try_open_index (vstream=0x7fffe0002250, rstream=0x7fffe8018c50) at live.c:1378
#8 0x0000555555577155 in viewer_get_next_index (conn=0x7fffd4001440) at live.c:1643
lttng#9 0x0000555555579a01 in process_control (recv_hdr=0x7ffff0a27c30, conn=0x7fffd4001440) at live.c:2311
lttng#10 0x000055555557a1db in thread_worker (data=0x0) at live.c:2482
lttng#11 0x00007ffff6d1c6db in start_thread (arg=0x7ffff0a28700) at pthread_create.c:463
lttng#12 0x00007ffff6a45a3f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
That problem is mostly cosmetic in nature (the open can fail
"legitimately") as the PERROR should simply not be printed and is
addressed in a different commit.
This error is also produced after a 'clear' is issued:
PERROR - 14:33:45.532782268 [25108/25115]: Failed to read from file system handle of viewer stream id 1, offset: 4096: No such file or directory (in viewer_get_packet() at live.c:1849)
Which is produced with the following back-trace:
#0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:51
#1 0x00007f53e297c8b1 in __GI_abort () at abort.c:79
#2 0x000055dd77ccef2c in viewer_get_packet (conn=0x7f53c4001100) at live.c:1850
#3 0x000055dd77cd0a15 in process_control (recv_hdr=0x7f53dca3fc30, conn=0x7f53c4001100) at live.c:2315
#4 0x000055dd77cd11db in thread_worker (data=0x0) at live.c:2483
#5 0x00007f53e2d346db in start_thread (arg=0x7f53dca40700) at pthread_create.c:463
#6 0x00007f53e2a5da3f in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
A similar problem occurs, although more rarely, when reading an
index entry in viewer_get_next_index().
Cause
=====
The following situation leads to both failures to get a
packet and failures to get the next index:
- Viewer connects to an existing session,
- Viewer consumes a number of packets, alternating the
GET_NEXT_INDEX and GET_PACKET command,
- The session's streams are rotated to a new trace chunk
(as part of a clear),
- The session is started and stopped, causing new packets
to be produced and received,
- The session is stopped and destroyed, causing the session's
streams to rotate into a "null" trace chunk (no active
trace files),
- Viewer issues GET_NEXT_INDEX or GET_PACKET, but the fact
that a rotation occurred on the receiving end is not detected
as the relay streams' trace chunk are "null".
The crux of the problem is that lttng_trace_chunk_ids_equal() is
bypassed when the current trace chunk of a relay stream is "null".
The rationale for skipping this check is that it is assumed that the
files currently opened by the live server can can still be used even
if the consumer has rotated the corresponding streams into a 'null'
trace chunk, meaning no trace chunk is 'set' for those streams.
This makes sense in one scenario: the session was destroyed and we wish
to allow a connected live client to finish consuming the trace packets
up to the end of the session's lifetime.
Here, the situation is different. The viewer is reading chunk 'A'.
Meanwhile, a rotation occurs into chunk 'B' and packets are received for
chunk 'B'. Then, a rotation to a 'null' chunk (no active chunk) occurs.
In essence, the live server never sees the rotation between chunk 'A'
and 'B', and simply assumes that a rotation from 'A' to 'null' occurred,
as would happen at the end of a session.
In terms of the code, in viewer_get_next_index(), a call to
check_index_status() is performed to determine if an index is available.
The function checks that `index_received_seqcount` is greater than
`index_sent_seqcount`. In that case, it determines that an index must be
available.
Unfortunately, there is no way for the live server to determine that the
remaining indexes are in a chunk that doesn't exist anymore (chunk 'B').
Thus, viewer_get_next_index() attempts to read an index entry from the
current index file and fails.
Solution
========
1) lttng_trace_chunk_ids_equal() is modified to properly handle
'null' trace chunks:
- A null and a non-null trace chunk are not equal,
- Two null trace chunks are equal.
2) Rotation count
A rotation counter is introduced to track the number of rotations
that occurred during a relay stream's lifetime. This counter is
sampled by the matching viewer streams on creation and on rotation
and is used to determine if all rotations were "seen" by the viewer
stream.
Hence, this allows us to handle the special case where a viewer
is consuming the contents of a relay stream that just transitioned
into a 'null' trace chunk (see comments in patch).
The rest of the modifications simply allow the live server to handle
null trace chunks in viewer streams. This fixes another unrelated bug
that I observed while investigating this: sessions that don't have an
active trace chunk are not shown when listing sessions with babeltrace.
To reproduce, simply stop, clear a session, and attempt to list the
sessions of the associated relay daemon.
Known drawbacks
===============
None.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ibb3116990e34b7ec3b477f3482d0c0ff1e848d09
jgalar
pushed a commit
that referenced
this pull request
Jan 15, 2021
…tion
Issue
=====
The code of this function triggers the following heap-buffer-overflow
warning when compiled with `-fsanitize=address` in specific situation:
==247225==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000001310 at pc 0x5559db6c575a bp 0x7f193e6faeb0 sp 0x7f193e6faea0
READ of size 4 at 0x602000001310 thread T4 (Notification)
#0 0x5559db6c5759 in hashlittle /home/frdeso/projets/lttng/tools/src/common/hashtable/utils.c:315
#1 0x5559db6c6df4 in hash_key_str /home/frdeso/projets/lttng/tools/src/common/hashtable/utils.c:490
#2 0x5559db5e3282 in hash_trigger_by_name_uid /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/notification-thread-events.c:378
#3 0x5559db5ecbe3 in trigger_name_taken /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/notification-thread-events.c:2333
#4 0x5559db5ecd7c in generate_trigger_name /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/notification-thread-events.c:2362
#5 0x5559db5ed6e0 in handle_notification_thread_command_register_trigger /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/notification-thread-events.c:2491
#6 0x5559db5ef967 in handle_notification_thread_command /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/notification-thread-events.c:2927
#7 0x5559db5ddbb7 in thread_notification /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/notification-thread.c:693
#8 0x5559db60e56d in launch_thread /home/frdeso/projets/lttng/tools/src/bin/lttng-sessiond/thread.c:66
lttng#9 0x7f19456ec608 in start_thread /build/glibc-ZN95T4/glibc-2.31/nptl/pthread_create.c:477
lttng#10 0x7f1945602292 in __clone (/lib/x86_64-linux-gnu/libc.so.6+0x122292)
Given that the `k` pointer used in this loop is a `uint32_t *` we might
read bytes outside of the allocated key if the key is less than 4 bytes
long. As the comment about Valgrind explains, this is not a real problem
because memory protections are typically word bounded.
I tried to use the `__SANITIZE_ADDRESS__` define to select the
Valgrind implementation of this code when building with AddressSanitizer
but that still triggers the same head-buffer-overflow warning.
Why wasn't that a problem before?
=======================================
The trigger feature will use small default names like "T0".
Workaround
==========
Exclude this function from the sanitizing using the compiler attribute
"no_sanitize_address".
Drawback
========
This removes our sanitizing coverage for this function.
Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I82d0d3539916ed889faa93871f9b700064f2c52a
jgalar
pushed a commit
that referenced
this pull request
Apr 17, 2021
When running the test_utils_expand_path test with ASan enabled, I get:
➜ lttng-tools ./tests/unit/test_utils_expand_path
1..29
INPUT: /a/b/c/d/e
=================================================================
==1485873==ERROR: AddressSanitizer: strncpy-param-overlap: memory ranges [0x621000021d00,0x621000021d0b) and [0x621000021d00, 0x621000021d0b) overlap
#0 0x7ffff761fd97 in __interceptor_strncpy /build/gcc/src/gcc/libsanitizer/asan/asan_interceptors.cpp:481
#1 0x555555573834 in utils_partial_realpath /home/simark/src/lttng-tools/src/common/utils.c:195
#2 0x55555557410b in _utils_expand_path /home/simark/src/lttng-tools/src/common/utils.c:374
#3 0x555555574340 in utils_expand_path /home/simark/src/lttng-tools/src/common/utils.c:420
#4 0x555555570b28 in test_utils_expand_path /home/simark/src/lttng-tools/tests/unit/test_utils_expand_path.c:274
#5 0x55555557119e in main /home/simark/src/lttng-tools/tests/unit/test_utils_expand_path.c:345
#6 0x7ffff725fb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
#7 0x55555556fa3d in _start (/home/simark/build/lttng-tools/tests/unit/test_utils_expand_path+0x1ba3d)
0x621000021d00 is located 0 bytes inside of 4096-byte region [0x621000021d00,0x621000022d00)
allocated by thread T0 here:
#0 0x7ffff7677639 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x55555557269d in zmalloc /home/simark/src/lttng-tools/src/common/macros.h:45
#2 0x555555573d34 in _utils_expand_path /home/simark/src/lttng-tools/src/common/utils.c:335
#3 0x555555574340 in utils_expand_path /home/simark/src/lttng-tools/src/common/utils.c:420
#4 0x555555570b28 in test_utils_expand_path /home/simark/src/lttng-tools/tests/unit/test_utils_expand_path.c:274
#5 0x55555557119e in main /home/simark/src/lttng-tools/tests/unit/test_utils_expand_path.c:345
#6 0x7ffff725fb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
0x621000021d00 is located 0 bytes inside of 4096-byte region [0x621000021d00,0x621000022d00)
allocated by thread T0 here:
#0 0x7ffff7677639 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x55555557269d in zmalloc /home/simark/src/lttng-tools/src/common/macros.h:45
#2 0x555555573d34 in _utils_expand_path /home/simark/src/lttng-tools/src/common/utils.c:335
#3 0x555555574340 in utils_expand_path /home/simark/src/lttng-tools/src/common/utils.c:420
#4 0x555555570b28 in test_utils_expand_path /home/simark/src/lttng-tools/tests/unit/test_utils_expand_path.c:274
#5 0x55555557119e in main /home/simark/src/lttng-tools/tests/unit/test_utils_expand_path.c:345
#6 0x7ffff725fb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
The sole caller of utils_partial_realpath, _utils_expand_path, passes
the same buffer (resolved_path) for the input and output. This causes
utils_partial_realpath to call strncpy with overlapping strings.
Fix it by making utils_partial_realpath allocate new memory for the
returned string itself. This causes one more allocation than the
current code, because we don't re-use the existing buffer, but this
should be fine since this isn't exactly performance-critical code.
I think the code is easier to follow as a result.
Change-Id: I98a9aafc08d3bef45e3a83cbeef049f249b86f59
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
jgalar
pushed a commit
that referenced
this pull request
Apr 17, 2021
When running
$ lttng add-trigger --condition on-event -u ust_tests_demo2:loop --capture intfield --action notify
I get the leaks pasted below. It seems like filter_parser_ctx_free
doesn't free everything in filter_parser_ctx. Add what's missing.
Re-order the frees so that they are in the same order as the members of
the struct, just because it's easier to follow and make sure we didn't
forget anything.
=================================================================
==1073803==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 128 byte(s) in 1 object(s) allocated from:
#0 0x7ffff767783a in __interceptor_realloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:164
#1 0x5555556833be in bytecode_reserve /home/simark/src/lttng-tools/src/common/bytecode/bytecode.c:59
#2 0x55555568360f in bytecode_push /home/simark/src/lttng-tools/src/common/bytecode/bytecode.c:79
#3 0x5555556a3d61 in filter_visitor_bytecode_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-bytecode.c:667
#4 0x55555569c9b1 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:394
#5 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
#6 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
#7 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
#8 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#9 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#10 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#11 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#12 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Direct leak of 112 byte(s) in 1 object(s) allocated from:
#0 0x7ffff767783a in __interceptor_realloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:164
#1 0x5555556833be in bytecode_reserve /home/simark/src/lttng-tools/src/common/bytecode/bytecode.c:59
#2 0x55555568360f in bytecode_push /home/simark/src/lttng-tools/src/common/bytecode/bytecode.c:79
#3 0x5555556a1b94 in visit_node_load_expression_legacy /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-bytecode.c:198
#4 0x5555556a1d18 in visit_node_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-bytecode.c:231
#5 0x5555556a2540 in visit_node_load /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-bytecode.c:399
#6 0x5555556a3a8b in recursive_visit_gen_bytecode /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-bytecode.c:622
#7 0x5555556a12fa in visit_node_root /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-bytecode.c:53
#8 0x5555556a3a76 in recursive_visit_gen_bytecode /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-bytecode.c:620
lttng#9 0x5555556a3c55 in filter_visitor_bytecode_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-bytecode.c:661
lttng#10 0x55555569c9b1 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:394
lttng#11 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
lttng#12 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
lttng#13 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
lttng#14 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#15 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#16 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#17 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#18 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Direct leak of 40 byte(s) in 1 object(s) allocated from:
#0 0x7ffff7677639 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x5555556a3dd2 in make_op_root /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:35
#2 0x5555556a73a5 in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:874
#3 0x5555556a74d6 in filter_visitor_ir_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:903
#4 0x55555569c859 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:353
#5 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
#6 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
#7 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
#8 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#9 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#10 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#11 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#12 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Indirect leak of 40 byte(s) in 1 object(s) allocated from:
#0 0x7ffff7677639 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x5555556a4f1d in make_op_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:280
#2 0x5555556a696f in make_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:637
#3 0x5555556a73df in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:882
#4 0x5555556a7382 in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:870
#5 0x5555556a74d6 in filter_visitor_ir_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:903
#6 0x55555569c859 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:353
#7 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
#8 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
lttng#9 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
lttng#10 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#11 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#12 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#13 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#14 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Indirect leak of 24 byte(s) in 1 object(s) allocated from:
#0 0x7ffff7677639 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x5555556a484d in create_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:201
#2 0x5555556a5040 in make_op_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:287
#3 0x5555556a696f in make_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:637
#4 0x5555556a73df in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:882
#5 0x5555556a7382 in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:870
#6 0x5555556a74d6 in filter_visitor_ir_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:903
#7 0x55555569c859 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:353
#8 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
lttng#9 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
lttng#10 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
lttng#11 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#12 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#13 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#14 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#15 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Indirect leak of 24 byte(s) in 1 object(s) allocated from:
#0 0x7ffff7677639 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x5555556a4e64 in create_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:262
#2 0x5555556a5040 in make_op_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:287
#3 0x5555556a696f in make_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:637
#4 0x5555556a73df in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:882
#5 0x5555556a7382 in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:870
#6 0x5555556a74d6 in filter_visitor_ir_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:903
#7 0x55555569c859 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:353
#8 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
lttng#9 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
lttng#10 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
lttng#11 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#12 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#13 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#14 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#15 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Indirect leak of 24 byte(s) in 1 object(s) allocated from:
#0 0x7ffff7677639 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x5555556a4bbc in create_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:233
#2 0x5555556a5040 in make_op_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:287
#3 0x5555556a696f in make_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:637
#4 0x5555556a73df in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:882
#5 0x5555556a7382 in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:870
#6 0x5555556a74d6 in filter_visitor_ir_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:903
#7 0x55555569c859 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:353
#8 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
lttng#9 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
lttng#10 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
lttng#11 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#12 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#13 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#14 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#15 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Indirect leak of 9 byte(s) in 1 object(s) allocated from:
#0 0x7ffff761fa69 in __interceptor_strdup /build/gcc/src/gcc/libsanitizer/asan/asan_interceptors.cpp:452
#1 0x5555556a4c41 in create_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:238
#2 0x5555556a5040 in make_op_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:287
#3 0x5555556a696f in make_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:637
#4 0x5555556a73df in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:882
#5 0x5555556a7382 in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:870
#6 0x5555556a74d6 in filter_visitor_ir_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:903
#7 0x55555569c859 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:353
#8 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
lttng#9 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
lttng#10 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
lttng#11 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#12 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#13 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#14 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#15 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Indirect leak of 8 byte(s) in 1 object(s) allocated from:
#0 0x7ffff7677639 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x5555556a4829 in create_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:196
#2 0x5555556a5040 in make_op_load_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:287
#3 0x5555556a696f in make_expression /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:637
#4 0x5555556a73df in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:882
#5 0x5555556a7382 in generate_ir_recursive /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:870
#6 0x5555556a74d6 in filter_visitor_ir_generate /home/simark/src/lttng-tools/src/common/filter/filter-visitor-generate-ir.c:903
#7 0x55555569c859 in filter_parser_ctx_create_from_filter_expression /home/simark/src/lttng-tools/src/common/filter/filter-parser.y:353
#8 0x55555560542e in parse_event_rule /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:704
lttng#9 0x555555607429 in handle_condition_event /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1088
lttng#10 0x555555608760 in parse_condition /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1326
lttng#11 0x55555560bca0 in cmd_add_trigger /home/simark/src/lttng-tools/src/bin/lttng/commands/add_trigger.c:1925
lttng#12 0x555555616b55 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#13 0x555555617516 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:421
lttng#14 0x555555617812 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:470
lttng#15 0x7ffff700bb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
SUMMARY: AddressSanitizer: 409 byte(s) leaked in 9 allocation(s).
Change-Id: I04f9eb5ab7b18ae4ffdf7a49842768a6fdae5dbc
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
jgalar
pushed a commit
that referenced
this pull request
Apr 17, 2021
After adding a trigger, ASan reports this when exiting the sessiond:
Direct leak of 128 byte(s) in 1 object(s) allocated from:
#0 0x7ffff767783a in __interceptor_realloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:164
#1 0x55555579a415 in lttng_dynamic_buffer_set_capacity /home/simark/src/lttng-tools/src/common/dynamic-buffer.c:166
#2 0x55555579a1df in lttng_dynamic_buffer_set_size /home/simark/src/lttng-tools/src/common/dynamic-buffer.c:118
#3 0x5555556d3cc1 in receive_lttng_trigger /home/simark/src/lttng-tools/src/bin/lttng-sessiond/client.c:712
#4 0x5555556dba46 in process_client_msg /home/simark/src/lttng-tools/src/bin/lttng-sessiond/client.c:2154
#5 0x5555556deef7 in thread_manage_clients /home/simark/src/lttng-tools/src/bin/lttng-sessiond/client.c:2601
#6 0x5555556c8a83 in launch_thread /home/simark/src/lttng-tools/src/bin/lttng-sessiond/thread.c:66
#7 0x7ffff714c298 in start_thread (/usr/lib/libpthread.so.0+0x9298)
It seems like we don't free the payload in receive_lttng_trigger, fix
that.
Change-Id: Ie9bc3bad24fb55b98c8232c0cd63483a3e94bfb0
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
eepp
pushed a commit
to eepp/lttng-tools
that referenced
this pull request
Apr 29, 2021
Issue observed ============== lt-trigger_name: trigger.c:302: int lttng_trigger_serialize(const struct lttng_trigger *, struct lttng_payload *): Assertion `(creds->uid).is_set' failed. Program terminated with signal SIGABRT, Aborted. #0 0x00007fb74129eef5 in raise () from /usr/lib/libc.so.6 jgalar#1 0x00007fb741288862 in abort () from /usr/lib/libc.so.6 jgalar#2 0x00007fb741288747 in __assert_fail_base.cold () from /usr/lib/libc.so.6 jgalar#3 0x00007fb741297646 in __assert_fail () from /usr/lib/libc.so.6 jgalar#4 0x00007fb74169bab7 in lttng_trigger_serialize (trigger=0x5616f6f70060, payload=0x7ffe5819d140) at trigger.c:302 jgalar#5 0x00007fb74169cef0 in lttng_trigger_copy (trigger=0x5616f6f70060) at trigger.c:859 jgalar#6 0x00007fb74164302e in lttng_unregister_trigger (trigger=0x5616f6f70060) at lttng-ctl.c:3350 jgalar#7 0x00005616f50c675f in register_named_trigger () at trigger_name.c:295 jgalar#8 0x00005616f50c6879 in main (argc=1, argv=0x7ffe581a07d8) at trigger_name.c:343 Cause ===== When creating a trigger instance and using it to unregister an existing trigger, its credentials are unset (meaning 'default'). Expecting this, lttng_unregister_trigger() copies the source trigger to change its credentials to those of the caller. Unfortunately, the trigger copy operation expects credentials to be set. We don't run into this situation typically since the trigger instance used to perform the unregistration is sourced from a listing or is the same instance that was used to perform the registration (which sets the credentials before serializing). Solution ======== A proper implementation of "copy" is provided for the trigger object itself. For its condition and action, we still use the same "trick" of leveraging the serdes code to perform a deep-copy, keeping the change small Drawbacks ========= None really, except that we lose some of the code sharing between copy and serdes. Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I71b7b075c959bc4935621543c4d379f62b7dabdf
eepp
pushed a commit
to eepp/lttng-tools
that referenced
this pull request
Apr 29, 2021
Observed issue ============== A dead lock is observed during the start-stop test suite for triggers. Cause ===== A start session action is executed by the action executor, the `cmd_start_trace` function is called and effectively holds the `session_list_lock.`. During `cmd_start_trace` a call to `notification_thread_command_add_channel` is performed to inform the notification thread of the new channel presence. At the same time, a tracer event notification is received by the notification thread. The actions are queued up and the sample of the session id take place and a call to `session_lock_list` is performed and blocks on the lock operation. The notification thread wait on the `session_list_lock` and the `session_list_lock` holder, the action executor, waits on the completion of a command the be run by the notification thread: deadlock. The backtrace: Thread 6 (Thread 0x7f831c8a6700 (LWP 3046458)): #0 syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38 jgalar#1 0x000000000053b852 in futex (uaddr=0x7f831c8a45e0, op=0, val=0, timeout=0x0, uaddr2=0x0, val3=0) at /home/joraj/lttng/master/install/include/urcu/futex.h:72 jgalar#2 0x000000000053b4f9 in futex_noasync (uaddr=0x7f831c8a45e0, op=0, val=0, timeout=0x0, uaddr2=0x0, val3=0) at /home/joraj/lttng/master/install/include/urcu/futex.h:81 jgalar#3 0x000000000053af10 in lttng_waiter_wait (waiter=0x7f831c8a45d8) at waiter.c:55 jgalar#4 0x000000000046b0f2 in run_command_wait (handle=0xe60520, cmd=0x7f831c8a4588) at notification-thread-commands.c:49 jgalar#5 0x000000000046b270 in notification_thread_command_add_channel (handle=0xe60520, session_name=0x7f8300006c30 "my_triggered_session", uid=1000, gid=1000, channel_name=0x7f82dc00be04 "channel0", key=1, domain=LTTNG_DOMAIN_UST, capacity=2097152) at notification-thread-commands.c:184 jgalar#6 0x00000000004c7f65 in create_channel_per_uid (app=0x7f82d8000bf0, usess=0x7f8300000bb0, ua_sess=0x7f82dc002600, ua_chan=0x7f82dc00bde0) at ust-app.c:3360 jgalar#7 0x00000000004c6f98 in ust_app_channel_send (app=0x7f82d8000bf0, usess=0x7f8300000bb0, ua_sess=0x7f82dc002600, ua_chan=0x7f82dc00bde0) at ust-app.c:3514 jgalar#8 0x00000000004c6bde in ust_app_channel_create (usess=0x7f8300000bb0, ua_sess=0x7f82dc002600, uchan=0x7f8300005a90, app=0x7f82d8000bf0, _ua_chan=0x7f831c8a48b0) at ust-app.c:4771 lttng#9 0x00000000004c6968 in find_or_create_ust_app_channel (usess=0x7f8300000bb0, ua_sess=0x7f82dc002600, app=0x7f82d8000bf0, uchan=0x7f8300005a90, ua_chan=0x7f831c8a48b0) at ust-app.c:5610 lttng#10 0x00000000004c4f09 in ust_app_synchronize_all_channels (usess=0x7f8300000bb0, ua_sess=0x7f82dc002600, app=0x7f82d8000bf0) at ust-app.c:5820 lttng#11 0x00000000004b958c in ust_app_synchronize (usess=0x7f8300000bb0, app=0x7f82d8000bf0) at ust-app.c:5886 lttng#12 0x00000000004b8500 in ust_app_global_update (usess=0x7f8300000bb0, app=0x7f82d8000bf0) at ust-app.c:5960 lttng#13 0x00000000004b7ec2 in ust_app_start_trace_all (usess=0x7f8300000bb0) at ust-app.c:5520 lttng#14 0x0000000000444e86 in cmd_start_trace (session=0x7f8300006c30) at cmd.c:2707 lttng#15 0x00000000004a5af9 in action_executor_start_session_handler (executor=0x7f8314004410, work_item=0x7f8314005100, item=0x7f83140050b0) at action-executor.c:342 lttng#16 0x00000000004a537f in action_executor_generic_handler (executor=0x7f8314004410, work_item=0x7f8314005100, item=0x7f83140050b0) at action-executor.c:696 lttng#17 0x00000000004a4dbc in action_work_item_execute (executor=0x7f8314004410, work_item=0x7f8314005100) at action-executor.c:715 lttng#18 0x00000000004a37e6 in action_executor_thread (_data=0x7f8314004410) at action-executor.c:797 lttng#19 0x0000000000486193 in launch_thread (data=0x7f83140044b0) at thread.c:66 lttng#20 0x00007f8320b60609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#21 0x00007f8320a87293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 5 (Thread 0x7f831d0a7700 (LWP 3046457)): #0 __lll_lock_wait (futex=futex@entry=0x5e1c10 <ltt_session_list>, private=0) at lowlevellock.c:52 jgalar#1 0x00007f8320b630a3 in __GI___pthread_mutex_lock (mutex=0x5e1c10 <ltt_session_list>) at ../nptl/pthread_mutex_lock.c:80 jgalar#2 0x00000000004378c3 in session_lock_list () at session.c:156 jgalar#3 0x00000000004a871c in add_action_to_subitem_array (action=0x7f830001a730, subitems=0x7f83140051d0) at action-executor.c:1081 jgalar#4 0x00000000004a8578 in add_action_to_subitem_array (action=0x7f830001a620, subitems=0x7f83140051d0) at action-executor.c:1025 jgalar#5 0x00000000004a4922 in populate_subitem_array_from_trigger (trigger=0x7f830001a950, subitems=0x7f83140051d0) at action-executor.c:1116 jgalar#6 0x00000000004a416e in action_executor_enqueue_trigger (executor=0x7f8314004410, trigger=0x7f830001a950, evaluation=0x7f8314005190, object_creds=0x0, client_list=0x7f8314004980) at action-executor.c:924 jgalar#7 0x0000000000479481 in dispatch_one_event_notifier_notification (state=0x7f831d0a63e8, notification=0x7f8314005160) at notification-thread-events.c:4613 jgalar#8 0x0000000000472324 in handle_one_event_notifier_notification (state=0x7f831d0a63e8, pipe=65, domain=LTTNG_DOMAIN_UST) at notification-thread-events.c:4702 lttng#9 0x0000000000472271 in handle_notification_thread_event_notification (state=0x7f831d0a63e8, pipe=65, domain=LTTNG_DOMAIN_UST) at notification-thread-events.c:4717 lttng#10 0x00000000004695a3 in handle_event_notification_pipe (event_source_fd=65, domain=LTTNG_DOMAIN_UST, revents=1, state=0x7f831d0a63e8) at notification-thread.c:591 lttng#11 0x000000000046849b in thread_notification (data=0xe60520) at notification-thread.c:727 lttng#12 0x0000000000486193 in launch_thread (data=0xe60610) at thread.c:66 lttng#13 0x00007f8320b60609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#14 0x00007f8320a87293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Solution ======== Instead of using session_find_by_name() which requires the `session_list_lock`, we introduce `sample_session_id_by_name` that uses a urcu backed data structure. This allows the sampling of the session id without holding the session list lock. We accept the small window where a session object is still accessible but concretely not valid since the actual execution context will be validated at the moment of execution. The execution side already handles the possibility that the session is removed at that point or is not the same session. The execution side acquires the session_list_lock for validation. Known drawbacks ========= None Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I5ad2c57acc0d03d2814dda59f8ecf2d831fd961e
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Issue observed ============== When running the test_notification_ust_buffer_usage test on x86 (32 bit), the session daemon and test client both crash. The session daemon dies while attempting to lock a NULL client list during the execution of an enqueued action in the action executor. See the following backtrace: #0 0xf7c6c756 in __GI___pthread_mutex_lock (mutex=0x0) at ../nptl/pthread_mutex_lock.c:67 jgalar#1 0x565afe96 in notification_client_list_send_evaluation (client_list=0x0, trigger=0xf0f225e0, evaluation=0xf330c830, source_object_creds=0xf330e5cc, client_report=0x565cf81b <client_handle_transmission_status>, user_data=0xf330c320) at notification-thread-events.c:4372 jgalar#2 0x565cfb41 in action_executor_notify_handler (executor=0xf330c320, work_item=0xf330e5b0, item=0xf330c7b0) at action-executor.c:269 jgalar#3 0x565d1a58 in action_executor_generic_handler (executor=0xf330c320, work_item=0xf330e5b0, item=0xf330c7b0) at action-executor.c:696 jgalar#4 0x565d1b7f in action_work_item_execute (executor=0xf330c320, work_item=0xf330e5b0) at action-executor.c:715 jgalar#5 0x565d212f in action_executor_thread (_data=0xf330c320) at action-executor.c:797 jgalar#6 0x565b9d0e in launch_thread (data=0xf330c390) at thread.c:66 jgalar#7 0xf7c69fd2 in start_thread (arg=<optimized out>) at pthread_create.c:486 jgalar#8 0xf7b7f6d6 in clone () at ../sysdeps/unix/sysv/linux/i386/clone.S:108 This crash causes an assertion to fail in the test client; checking for data pending was not expected to return a negative value. In this case, the negative return value is justified as it is -LTTNG_ERR_NO_SESSIOND. Cause ===== Equipped with coffee, a debugger, and a healthy dose of print statements, it appeared that the following was taking place: - Register a trigger (T1): high buffer usage (0.99) -> notify (succeeds) - Subscribe to high buffer usage (0.99) notifications (succeeds) - Subscribe to high buffer usage (0.99) notifications (fails duplicate, expected) - Unregister trigger (fails unexpectedly) - Notification client destroys its channel, causing the condition to be unsubscribed-from - Another test registers a trigger (T2): high buffer usage (0.90) -> notify (succeeds) - Session daemon evaluates a channel sample against T1's condition, which evaluates to true and produces an "evaluation" to send to clients - The client list associated to T1's condition is not found (but this isn't checked) - An action executor work item is queued to run T1's actions (notify), but without a client list, resulting in the crash when it is executed. We could confirm that the client list associated to T1's condition was created and never destroyed making the failure to find it rather puzzling. It turns out that the hash of T1's condition did not match the hash of the client list's condition. This is unexpected as both conditions are copies of one another. It turns out that, on x86, the scheme being used to transmit the condition's buffer usage threshold floating point value is not compiled to numerically stable code. Serializing such a buffer condition and creating it from the resulting payload in a loop showed that the threshold value gradually drifted. This isn't the case on the other architectures we support. On x86-64, gcc makes use of SSE instructions to perform the conversion to an integral value (with double precision). However, on x86, it makes use of the x87 fpu stack instructions which carry 80-bit of precision internally, resulting in a loss of precision as the value is transformed, back and forth, between 80-bit to double precision representations. Solution ======== Since conditions are not carried between hosts (only between clients and the session daemon), a fixed-point conversion scheme is unnecessary. The 'double' value provided by the client is carried directly which bypasses the problem completely. Drawbacks ========= None. Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ie524e7362626406327f4f56e1dba5c8cf469df31
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… rule matches Issue ===== Adding the following trigger makes the sessiond abort: lttng add-trigger --condition=event-rule-matches --domain=python --action=notify With the following stacktrace: (gdb) bt #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 jgalar#1 0x00007ffff7a71859 in __GI_abort () at abort.c:79 jgalar#2 0x00000000004a1eeb in event_notifier_error_accounting_register_event_notifier (trigger=0x7fffe0000f50, error_counter_index=0x7fffefffde38) at event-notifier-error-accounting.c:1075 jgalar#3 0x00000000004743e6 in setup_tracer_notifier (state=0x7fffefffe3e8, trigger=0x7fffe0000f50) at notification-thread-events.c:2606 jgalar#4 0x000000000046dacb in handle_notification_thread_command_register_trigger (state=0x7fffefffe3e8, trigger=0x7fffe0000f50, is_trigger_anonymous=false, cmd_result=0x7fffedfdd6e8) at notification-thread-events.c:2751 jgalar#5 0x000000000046d083 in handle_notification_thread_command (handle=0x601460, state=0x7fffefffe3e8) at notification-thread-events.c:3112 jgalar#6 0x00000000004687bd in thread_notification (data=0x601460) at notification-thread.c:710 jgalar#7 0x0000000000486703 in launch_thread (data=0x601550) at thread.c:66 jgalar#8 0x00007ffff7c47609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#9 0x00007ffff7b6e293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 This happens because the LTTNG_DOMAIN_PYTHON domain is not handled by the switch-case. Fix === Add LTTNG_DOMAIN_PYTHON (all other agent domains) as a fallthrough LTTNG_DOMAIN_UST. Note ==== Add a basic test case for python agent. Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I9971cdad8bbc6adca8f6ba49964483c42a25be7d
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When doing `lttng stop`, I get:
Direct leak of 656 byte(s) in 1 object(s) allocated from:
#0 0x7f970719e459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
jgalar#1 0x7f9706eba29a in zmalloc /home/simark/src/lttng-tools/src/common/macros.h:45
jgalar#2 0x7f9706ebbb9d in recv_sessiond_optional_data /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:494
jgalar#3 0x7f9706ebbf9a in lttng_ctl_ask_sessiond_fds_varlen /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:596
jgalar#4 0x7f9706eba714 in lttng_ctl_ask_sessiond_varlen_no_cmd_header /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl-helper.h:58
jgalar#5 0x7f9706eba747 in lttng_ctl_ask_sessiond /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl-helper.h:78
jgalar#6 0x7f9706ec4604 in lttng_list_channels /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:2262
jgalar#7 0x55837235c4e7 in get_session_stats_str /home/simark/src/lttng-tools/src/bin/lttng/utils.c:499
jgalar#8 0x55837235bf73 in print_session_stats /home/simark/src/lttng-tools/src/bin/lttng/utils.c:445
lttng#9 0x55837231cc12 in stop_tracing /home/simark/src/lttng-tools/src/bin/lttng/commands/stop.c:138
lttng#10 0x55837231d062 in cmd_stop /home/simark/src/lttng-tools/src/bin/lttng/commands/stop.c:229
lttng#11 0x55837235e63e in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#12 0x55837235f0f2 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:426
lttng#13 0x55837235f3f4 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:475
lttng#14 0x7f9706adcb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
Direct leak of 308 byte(s) in 1 object(s) allocated from:
#0 0x7f970719e459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
jgalar#1 0x7f9706eba29a in zmalloc /home/simark/src/lttng-tools/src/common/macros.h:45
jgalar#2 0x7f9706ebbb9d in recv_sessiond_optional_data /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:494
jgalar#3 0x7f9706ebbf9a in lttng_ctl_ask_sessiond_fds_varlen /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:596
jgalar#4 0x7f9706eba714 in lttng_ctl_ask_sessiond_varlen_no_cmd_header /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl-helper.h:58
jgalar#5 0x7f9706eba747 in lttng_ctl_ask_sessiond /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl-helper.h:78
jgalar#6 0x7f9706ec421c in lttng_list_domains /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:2220
jgalar#7 0x55837235c3d3 in get_session_stats_str /home/simark/src/lttng-tools/src/bin/lttng/utils.c:484
jgalar#8 0x55837235bf73 in print_session_stats /home/simark/src/lttng-tools/src/bin/lttng/utils.c:445
lttng#9 0x55837231cc12 in stop_tracing /home/simark/src/lttng-tools/src/bin/lttng/commands/stop.c:138
lttng#10 0x55837231d062 in cmd_stop /home/simark/src/lttng-tools/src/bin/lttng/commands/stop.c:229
lttng#11 0x55837235e63e in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#12 0x55837235f0f2 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:426
lttng#13 0x55837235f3f4 in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:475
lttng#14 0x7f9706adcb24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
This is due to the get_session_stats_str function not free'ing the
results of lttng_list_channels and lttng_list_domains. Fix that.
Change-Id: I4c200d3df41bf09bdce8eadb000abbff7fe5a751
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
eepp
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When doing `lttng destroy`, I get:
Direct leak of 4385 byte(s) in 1 object(s) allocated from:
#0 0x7f74ae025459 in __interceptor_calloc /build/gcc/src/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
jgalar#1 0x7f74add4129a in zmalloc /home/simark/src/lttng-tools/src/common/macros.h:45
jgalar#2 0x7f74add42b9d in recv_sessiond_optional_data /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:494
jgalar#3 0x7f74add42f9a in lttng_ctl_ask_sessiond_fds_varlen /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:596
jgalar#4 0x7f74add41714 in lttng_ctl_ask_sessiond_varlen_no_cmd_header /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl-helper.h:58
jgalar#5 0x7f74add41747 in lttng_ctl_ask_sessiond /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl-helper.h:78
jgalar#6 0x7f74add4a922 in lttng_list_sessions /home/simark/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.c:2105
jgalar#7 0x56472bcbdf80 in cmd_destroy /home/simark/src/lttng-tools/src/bin/lttng/commands/destroy.c:330
jgalar#8 0x56472bd00764 in handle_command /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:237
lttng#9 0x56472bd01218 in parse_args /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:426
lttng#10 0x56472bd0151a in main /home/simark/src/lttng-tools/src/bin/lttng/lttng.c:475
lttng#11 0x7f74ad963b24 in __libc_start_main (/usr/lib/libc.so.6+0x27b24)
This is due to cmd_destroy not free'ing the result of
lttng_list_sessions. Fix that.
Change-Id: Iff2e75e6ec1cdcd0bdfdbbc3d5099422e592905b
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
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Jan 13, 2022
Observed issue ============== The following scenario leads to an abort of lttng-sessiond. lttng-sessiond (with kernel tracing available) lttng create system-trace --snapshot -U /tmp/snapshot lttng enable-channel -k system-trace --subbuf-size=4k --num-subbuf=256 lttng enable-event -c system-trace -k 'sched_wak*' -s system-trace lttng start system-trace lttng enable-event -u -a Fails as expected with: Error: Events: The command tried to enable an event in a new domain for a session that has already been started once. (channel channel0, session system-trace) Launch any ust app such as easy_ust from the lttng-ust repository. The following backtrace is generated: (gdb) bt #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x00007ffff7af0859 in __GI_abort () at abort.c:79 #2 0x00007ffff7af0729 in __assert_fail_base (fmt=0x7ffff7c86588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x55555564b765 "usess->active", file=0x555555649a60 "ust-app.c", line #3 0x00007ffff7b01f36 in __GI___assert_fail (assertion=0x55555564b765 "usess->active", file=0x555555649a60 "ust-app.c", line=5123, function=0x55555564ecf0 <__PRETTY_FUNCTION__.14199> "ust_ #4 0x00005555555d1f5e in ust_app_global_update (usess=0x7fffe001fb90, app=0x7fffac000b80) at ust-app.c:5123 #5 0x00005555555b60d4 in update_ust_app (app_sock=82) at dispatch.c:71 #6 0x00005555555b7025 in thread_dispatch_ust_registration (data=0x5555556a07f0) at dispatch.c:409 #7 0x00005555555ad5ab in launch_thread (data=0x5555556a0810) at thread.c:65 #8 0x00007ffff7ce6609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#9 0x00007ffff7bed293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 This also happens for the track command. You can replace the `lttng enable-event -u -a` with `lttng track --userspace --vuid=0` then launch an app and the same backtrace gets generated. Cause ===== During `process_client_msg` the `create_ust_session` function is called and a ust session is assigned to the "system_trace" session with a state of `active` set to 0 (false). This is not a problem. The problem seems to lie with a single call site for `ust_app_global_update` in `update_ust_app`. The status of the ust session is not checked before calling the `ust_app_global_update`. It is important to note that all `ust_app_global_update_all` callsites guard the call with a check against the status of the session. Solution ======== Guard the call to `ust_app_global_update` with a check of the ust session active state. Known drawbacks ========= None. Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I14d25d99d0609689247cdfa86130bd0219613581
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Observed issue ============== The following backtrace have been reported [1]. #0 __GI_raise (sig=sig@entry=6) at /usr/src/debug/glibc/2.31+gitAUTOINC+f84949f1c4-r0/git/sysdeps/unix/sysv/linux/raise.c:50 #1 0x0000003123025528 in __GI_abort () at /usr/src/debug/glibc/2.31+gitAUTOINC+f84949f1c4-r0/git/stdlib/abort.c:79 #2 0x0000000000419884 in lttng_trace_archive_location_serialize (location=0x7f1c9c001160, buffer=0x7f1cb961c320) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/common/location.c:230 #3 0x00000000004c8f06 in lttng_evaluation_session_rotation_serialize (evaluation=0x7f1cb000a7f0, payload=0x7f1cb961c320) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/common/conditions/session-rotation.c:539 #4 0x00000000004a80fa in lttng_evaluation_serialize (evaluation=0x7f1cb000a7f0, payload=0x7f1cb961c320) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/common/evaluation.c:42 #5 0x00000000004bc24f in lttng_notification_serialize (notification=0x7f1cb961c310, payload=0x7f1cb961c320) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/common/notification.c:63 #6 0x0000000000458b7d in notification_client_list_send_evaluation (client_list=0x7f1cb0008f90, trigger=0x7f1ca40113d0, evaluation=<optimized out>, source_object_creds=0x7f1cb000a874, client_report=0x475840 <client_handle_transmission_status>, user_data=0x7f1cb0006010) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/bin/lttng-sessiond/notification-thread-events.c:4379 #7 0x0000000000476586 in action_executor_generic_handler (item=0x7f1cb0009600, work_item=0x7f1cb000a820, executor=0x7f1cb0006010) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/bin/lttng-sessiond/action-executor.c:696 #8 action_work_item_execute (work_item=0x7f1cb000a820, executor=0x7f1cb0006010) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/bin/lttng-sessiond/action-executor.c:715 lttng#9 action_executor_thread (_data=0x7f1cb0006010) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/bin/lttng-sessiond/action-executor.c:797 lttng#10 0x0000000000462327 in launch_thread (data=0x7f1cb00060b0) at /usr/src/debug/lttng-tools/2.13.0-r0/lttng-tools-2.13.0/src/bin/lttng-sessiond/thread.c:66 lttng#11 0x0000003123408ea4 in start_thread (arg=<optimized out>) at /usr/src/debug/glibc/2.31+gitAUTOINC+f84949f1c4-r0/git/nptl/pthread_create.c:477 lttng#12 0x00000031230f8dcf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 This can be easily reproduced with the following session and trigger configuration: lttng create test lttng enable-event -u -a lttng start # Register two similar triggers via a dummy C program since rotation # completed condition is not exposed on the CLI for now. Yielding the # following triggers: lttng list-triggers - name: trigger0 owner uid: 1000 condition: session rotation completed session name: test errors: none action:notify errors: none - name: trigger1 owner uid: 1000 condition: session rotation completed session name: test errors: none action:notify errors: none lttng rotate <- abort happens here. Cause ===== The problem lies in how the location (`lttng_trace_archive_location`) object is assigned to the `lttng_evaluation` objects. A single location object can end up being shared between multiple `lttng_evaluation` objects since we iterate over all triggers and create an `lttng_evaluation` object with the location each time as needed. See `src/bin/lttng-sessiond/notification-thread-events.c:1956`. The location object is then freed when the first notification is completely serialized. The second serialization end up having a reference to a freed `lttng_trace_archive_location` object. Solution ======== Implement ref counting for the lttng_trace_archive_location object. Note ======= This also fixes a leak that was present in `cmd_destroy_session_reply`. The location is created by `session_get_trace_archive_location` and is never `destroyed`/`put`. Known drawbacks ========= None. References ========== [1] https://bugs.lttng.org/issues/1325 Fixes: #1325 Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Change-Id: I99dc595ee5b0288c727b193ed061f5273752bd24 Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
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Jan 13, 2022
Observed issue ============== A segmentation fault is observed for multiple UST timeout scenarios. Backtrace: #0 __memmove_avx_unaligned_erms () at ../sysdeps/x86_64/multiarch/memmove-vec-unaligned-erms.S:384 #1 0x0000557fe0395df9 in copy_filter_bytecode (orig_f=0x7f9c5802b790) at ust-app.c:1196 #2 0x0000557fe0397702 in shadow_copy_event (ua_event=0x7f9c58025ff0, uevent=0x7f9c58033560) at ust-app.c:1824 #3 0x0000557fe039ac46 in create_ust_app_event (ua_sess=0x7f9c5802ec20, ua_chan=0x7f9c58025cc0, uevent=0x7f9c58033560, app=0x7f9c5c001da0) at ust-app.c:3192 #4 0x0000557fe03a054d in ust_app_channel_synchronize_event (ua_chan=0x7f9c58025cc0, uevent=0x7f9c58033560, ua_sess=0x7f9c5802ec20, app=0x7f9c5c001da0) at ust-app.c:5096 #5 0x0000557fe03a0772 in ust_app_synchronize (usess=0x7f9c580074a0, app=0x7f9c5c001da0) at ust-app.c:5173 #6 0x0000557fe03a0a70 in ust_app_global_update (usess=0x7f9c580074a0, app=0x7f9c5c001da0) at ust-app.c:5255 #7 0x0000557fe03a00e0 in ust_app_start_trace_all (usess=0x7f9c580074a0) at ust-app.c:4987 #8 0x0000557fe0355c6a in cmd_start_trace (session=0x7f9c5800a190) at cmd.c:2668 lttng#9 0x0000557fe0382e70 in process_client_msg (cmd_ctx=0x7f9c58003d70, sock=0x7f9c74bf44e0, sock_error=0x7f9c74bf44e4) at client.c:1527 lttng#10 0x0000557fe03848a2 in thread_manage_clients (data=0x557fe06d9440) at client.c:2200 lttng#11 0x0000557fe037d1cb in launch_thread (data=0x557fe06d94b0) at thread.c:75 lttng#12 0x00007f9c796af609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#13 0x00007f9c795b6293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 The scenario: # Start an instrumented app ./app gdb lttng-sessiond # put a breakpoint on ustctl_set_filter lttng create my_session lttng enable-event -u tp:tp_test lttng start lttng enable-event -u __dummy --filter 'my_field == "user34"' # The tracepoint should hit. Do not continue. kill -s SIGSTOP $(pgrep app) # Continue lttng-sessiond. # enable-event will return an error. This a bug in itself, still let's # continue with the current bug. lttng stop # Start a new app that will register. ./app & sleep 1 lttng start # lttng-sessiond should segfault. Cause ===== During the "lttng enable-event" command, the timeout error bubbles up all the way to event_ust_enable_tracepoint and is different from LTTNG_UST_ERR_EXIST. `trace_ust_destroy_event` is called and frees the `uevent` object. Note that contrary to the comment `uevent` is added to the channel event hash table at this point. On the next `lttng start` command, the event node is still present in the hash table and is iterated on. lttng-sessiond segfault on the first data access of the previously freed memory. The problem was introduced by commit 88e3c2f [1]. Which essentially move the callsite of `add_unique_ust_event` before `ust_app_*_event_glb` calls. Solution ======== Go to `end` label to prevent freeing of the uevent object. Note that app synchronization should not force an error at the channel level, since a single app can fail but the whole channel should not. The `error` label is now obsolete. Known drawbacks ========= None. References ========== [1] lttng@88e3c2f Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Change-Id: Ifaf3f4c71bb2da869c7b441aaa4b367f8f7cbdd6 Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
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Observed issue ============== The following scenario lead to the UST thread to be "stuck" on recvmsg on the notify socket. The problem manifest itself when an application is unresponsive during the ustctl_start_session call. Note that the default timeout for ust communication is 5 seconds. # Start an instrumented app ./app gdb lttng-sessiond # put a breakpoint on ustctl_start_session lttng create my_session lttng enable-event -u -a lttng start # The tracepoint should hit. Do not continue. kill -s SIGSTOP $(pgrep app) # Continue lttng-sessiond. sleep 5 # This make sure lttng-sessiond unregister the app from its point of view kill -s SIGCONT $(pgrep app) gdb -p $(pgrep app) thread apply all bt App stack trace: Thread 3 (Thread 0x7fe2c6f58700 (LWP 48172)): #0 __libc_recvmsg (flags=0, msg=0x7fe2c6f56ac0, fd=4) at ../sysdeps/unix/sysv/linux/recvmsg.c:28 #1 __libc_recvmsg (fd=fd@entry=4, msg=msg@entry=0x7fe2c6f56ac0, flags=flags@entry=0) at ../sysdeps/unix/sysv/linux/recvmsg.c:25 #2 0x00007fe2c7a010ba in ustcomm_recv_unix_sock (sock=sock@entry=4, buf=buf@entry=0x7fe2c6f56ea0, len=len@entry=48) at lttng-ust-comm.c:308 #3 0x00007fe2c7a037c3 in ustcomm_register_channel (sock=4, session=session@entry=0x7fe2c0000ba0, session_objd=<optimized out>, channel_objd=<optimized out>, nr_ctx_fields=nr_ctx_fields@entry=0, ctx_fields=<optimized out>, chan_id=0x7fe2 c6f5716c, header_type=0x7fe2c0012b18) at lttng-ust-comm.c:1544 #4 0x00007fe2c7a10787 in lttng_session_enable (session=0x7fe2c0000ba0) at lttng-events.c:444 #5 0x00007fe2c7a0b785 in lttng_session_cmd (objd=1, cmd=128, arg=140611977311672, uargs=0x7fe2c6f57800, owner=0x7fe2c7a5da00 <local_apps>) at lttng-ust-abi.c:576 #6 0x00007fe2c7a07d6d in handle_message (lum=0x7fe2c6f57590, sock=3, sock_info=0x7fe2c7a5da00 <local_apps>) at lttng-ust-comm.c:1003 #7 ust_listener_thread (arg=0x7fe2c7a5da00 <local_apps>) at lttng-ust-comm.c:1712 #8 0x00007fe2c7993609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#9 0x00007fe2c78ba293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 ... Cause ===== When the app continues after the timeout from lttng-sessiond side, the actual start_session message is received on the application side then UST, app side, send commands on the notify socket. On lttng-sessiond side, the command is received but no reply is sent. This is due to the fact that the lookup against the ust_app_ht_by_notify_sock hash table (find_app_by_notify_sock) return nothing since the app is unregistered at this point and the hash table node was removed on unregistration. Solution ======== When the app lookup fails, return an error that will trigger the cleanup of the notify socket. Known drawbacks ========= None Note ========= Subsequent error path in reply_ust_register_channel, add_event_ust_registry, and add_enum_ust_registry might lead to the same type of problem since no reply is sent to the app. Still, for those cases the complete application/notify socket should not be destroyed since the error path relate to either a session or a sub object of a session. Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Change-Id: Iea0dc027ca1ee772e84c7e545114f1be69fd1f63 Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
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Observed issue ============== As reported in #1323 (https://bugs.lttng.org/issues/1323), crashes of the relay daemon are observed when running the user space clear tests. The crash occurs with the following stack trace: #0 0x000055fbb861d6ae in urcu_ref_get_unless_zero (ref=0x28) at /usr/local/include/urcu/ref.h:85 #1 lttng_trace_chunk_get (chunk=0x0) at trace-chunk.c:1836 #2 0x000055fbb86051e2 in make_viewer_streams (relay_session=relay_session@entry=0x7f6ea002d540, viewer_session=<optimized out>, seek_t=seek_t@entry=LTTNG_VIEWER_SEEK_BEGINNING, nb_total=nb_total@entry=0x7f6ea9607b00, nb_unsent=nb_unsent@entry=0x7f6ea9607aec, nb_created=nb_created@entry=0x7f6ea9607ae8, closed=<optimized out>) at live.c:405 #3 0x000055fbb86061d9 in viewer_get_new_streams (conn=0x7f6e94000fc0) at live.c:1155 #4 process_control (conn=0x7f6e94000fc0, recv_hdr=0x7f6ea9607af0) at live.c:2353 #5 thread_worker (data=<optimized out>) at live.c:2515 #6 0x00007f6eae86a609 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #7 0x00007f6eae78f293 in clone () from /lib/x86_64-linux-gnu/libc.so.6 The race window during which this occurs seems very small as it can take hours to reproduce this crash. However, a minimal reproducer could be identified, as stated in the bug report. Essentially, the same crash can be reproduced by attaching a live viewer to a session that has seen events being produced, been stopped and been cleared. Cause ===== The crash occurs as an attempt is made to take a reference to a viewer session’s trace chunk as viewer streams are created. The crux of the problem is that the code doesn’t expect a viewer session’s trace chunk to be NULL. The viewer session’s current trace chunk is initially set, when a viewer attaches to the viewer session, to a copy the corresponding relay_session’s current trace chunk. A live session always attempts to "catch-up" to the newest available trace chunk. This means that when a viewer reaches the end of a trace chunk, the viewer session may not transition to the "next" one: it jumps to the most recent trace chunk available (the one being produced by the relay_session). Hence, if the producer performs multiple rotations before a viewer completes the consumption of a trace chunk, it will skip over those "intermediary" trace chunks. A viewer session updates its current trace chunk when: 1) new viewer streams are created, 2) a new index is requested, 3) metadata is requested. Hence, as a general principle, the viewer session will reference the most recent trace chunk available _even if its streams do not point to it_. It indicates which trace chunk viewer streams should transition to when the end of their current trace chunk is reached. The live code properly handles transitions to a null chunk. This can be verified by attaching a viewer to a live session, stopping the session, clearing it (thus entering a null trace chunk), and resuming tracing. The only issue is that the case where the first trace chunk of a viewer session is "null" (no active trace chunk) is mishandled in two places: 1) in make_viewer_streams(), where the crash is observed, 2) in viewer_get_metadata(). Solution ======== In make_viewer_streams(), it is assumed that a viewer session will have a non-null trace chunk whenever a rotation is not ongoing. This is reflected by the fact that a reference is always acquired on the viewer session’s trace chunk. That code is one of the three places that can cause a viewer session’s trace chunk to be updated. We still want to update the viewer session to the most recently seen trace chunk (null, in this case). However, there is no reference to acquire and the trace chunk to use for the creation of the viewer stream is NULL. This is properly handled by viewer_stream_create(). The second site to change is viewer_get_metadata() which doesn’t handle a viewer metadata stream not having an active trace chunk at all. Thankfully, the protocol allows us to express this condition by returning the LTTNG_VIEWER_NO_NEW_METADATA status code when a viewer metadata stream doesn’t have an open file and doesn’t have a current trace chunk. Surprisingly, this bug didn’t trigger in the case where a transition to a null chunk occurred _after_ attaching to a viewer session. This is because viewers will typically ask for metadata as a result of an LTTNG_VIEWER_FLAG_NEW_METADATA reply to the GET_NEXT_INDEX command. When a session is stopped and all data was consumed, this command returns that no new data is available, causing the viewers to wait and ask again later. However, when attaching, babeltrace2 (at least, and probably babeltrace 1.x) always asks for an initial segment of metadata before asking for an index. Known drawbacks =============== None. Fixes: #1323 Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I516fca60755e6897f6b7170c12d706ef57ad61a5
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Observed issue ============== When performing: #!/bin/bash lttng create py_syscalls --live lttng enable-event -u -a lttng enable-event -k -a lttng start babeltrace2 -i lttng-live net://localhost/host/raton/py_syscalls The relay daemon hits this assertion: Thread 8 (Thread 0x7fffeeffd700 (LWP 167040) "lttng-relayd"): #0 0x00007ffff7b1618b in raise () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007ffff7af5859 in abort () from /lib/x86_64-linux-gnu/libc.so.6 #2 0x00007ffff7af5729 in ?? () from /lib/x86_64-linux-gnu/libc.so.6 #3 0x00007ffff7b06f36 in __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6 #4 0x00005555555889bb in viewer_session_attach (vsession=0x7fffdc001400, session=session@entry=0x7fffe8001180) at viewer-session.c:80 #5 0x000055555557bcff in viewer_attach_session (conn=0x7fffd0001140) at live.c:1275 #6 process_control (conn=0x7fffd0001140, recv_hdr=0x7fffeeffcaf0) at live.c:2341 #7 thread_worker (data=<optimized out>) at live.c:2515 #8 0x00007ffff7ccd609 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 lttng#9 0x00007ffff7bf2293 in clone () from /lib/x86_64-linux-gnu/libc.so.6 Cause ===== This assert appears to be entirely wrong. It checks that the "viewer session" has a NULL current trace chunk when attaching a session to a viewer session, but in the case where a viewer session has multiple sessions (e.g. with kernel and ust tracing combined), we are attaching each session individually to the viewer session, and we set the current trace chunk of the viewer session when we attach the first session to it. So it is expected to be non-NULL when attaching the second session. Solution ======== Remove the assertion. Known limitations ================= None. Fixes: #1335 Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I4d8f5d5347b4588144ddf449976cae5a94b81b3a
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…y_name Observed issue ============== The lttng-sessiond asserts with the following backtrace on lttng create: #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x00007ffff7ab5859 in __GI_abort () at abort.c:79 #2 0x00007ffff7ab5729 in __assert_fail_base (fmt=0x7ffff7c4b588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x5555556ab0a6 "node_ptr == &node->node", file=0x5555556ab085 "hashtable.c", line=298, function=<optimized out>) at a #3 0x00007ffff7ac6f36 in __GI___assert_fail (assertion=assertion@entry=0x5555556ab0a6 "node_ptr == &node->node", file=file@entry=0x5555556ab085 "hashtable.c", line=line@entry=298, function=function@entry=0x5555556ab380 <__PRETTY_FUNCTIO #4 0x000055555560be44 in lttng_ht_add_unique_str (ht=<optimized out>, node=0x7fffe0026c58) at hashtable.c:298 #5 0x000055555558fb6a in add_session_ht (ls=0x7fffe0024970) at session.c:372 #6 session_create (name=<optimized out>, uid=1000, gid=1000, out_session=out_session@entry=0x7fffedfddbd8) at session.c:1308 #7 0x000055555559b219 in cmd_create_session_from_descriptor (creds=<optimized out>, creds=<optimized out>, home_path=<optimized out>, descriptor=<optimized out>) at cmd.c:3040 #8 cmd_create_session (cmd_ctx=cmd_ctx@entry=0x7fffedfe5fa0, sock=<optimized out>, return_descriptor=return_descriptor@entry=0x7fffedfddd68) at cmd.c:3176 lttng#9 0x00005555555cc341 in process_client_msg (sock_error=0x7fffedfddd10, sock=0x7fffedfddd0c, cmd_ctx=0x7fffedfe5fa0) at client.c:2177 lttng#10 thread_manage_clients (data=<optimized out>) at client.c:2742 lttng#11 0x00005555555c5fff in launch_thread (data=0x55555571b780) at thread.c:66 lttng#12 0x00007ffff7c8b609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#13 0x00007ffff7bb2293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 The issue can be reproduced with modifications to the rotation thread code and the following scenario: $ lttng create test $ lttng enable-event -u -a $ lttng start run any app just so that we have a complete valid session. (might not be necessary) $ lttng destroy --no-wait $ lttng create test ^ Should assert here. The diff to be applied: diff --git a/src/bin/lttng-sessiond/rotation-thread.cpp b/src/bin/lttng-sessiond/rotation-thread.cpp index ac149c845..c11f068ed 100644 --- a/src/bin/lttng-sessiond/rotation-thread.cpp +++ b/src/bin/lttng-sessiond/rotation-thread.cpp @@ -565,6 +565,8 @@ int handle_job_queue(struct rotation_thread_handle *handle, { int ret = 0; + sleep(5); + for (;;) { struct ltt_session *session; struct rotation_thread_job *job; Note that the initial report for this issue was on a system under load for which the `lttng destroy` completion check failed and a `lttng create` was performed. As of today the exact reason why the completion check failed is not known. Still we can "fix" the race leading to the lttng-sessiond assertion considering a user might use the `--no-wait` variant of `lttng destroy` and could easily end up in this situation. Cause ===== Note: all `lttng create` commands have the same session name passed as argument. On `lttng destroy` the ltt_session object is flagged as destroyed (ltt_session::destroyed). The removal of the object from the hash table (ltt_sessions_ht_by_name) will be performed during the `session_release` which is driven by the session refcount. A reference on the `ltt_session` object is held for the rotation initiated by the `lttng destroy` command. The rotation is enqueued by the rotation thread. At this point the system is busy and the rotation thread does not run. We simulate this with a `sleep(5)` during the `handle_job_queue`. The `lttng destroy --no-wait` returns. If the `--no-wait` option is not passed the `lttng destroy` command will work as expected and wait for completion. We can SIGINT the `lttng destroy` command and perform a `lttng create` yielding the same backtrace. On `lttng create`, `session_create` validates that the name does not conflict with an existing session using `session_find_by_name`. It is important to note that `session_find_by_name` discriminates also on the `session->destroyed` flag (introduced by [1]). The `ltt_sessions_ht_by_name` hash table was introduced by [2] to remove the need to lock the session list to sample a session id during the queueing of actions to be executed related to a trigger. The assumption was made that, during the creation phase, the session would always be unique in that hash table based on its name. This is simply not true since multiple sessions with the same name can coexist as long as only a single one is marked as "not destroyed". This is an important concept due to the refcounting of the object and the feature relying on the lifetime of the object (i.e rotation). This is mostly valid when talking about the global session list. Solution ======== Move the hash table removal earlier during the release of the session object. Move the removal from `del_session_ht`, which is done during the `session_release` function, to the `lttng_session_destroy` function. It is safe to do so since currently the only user of that hash table (the action executor) does not care much about destroyed session at that point. This ensures that we maintain the uniqueness property of the key (name) for that hash table on insertion. The alternative was to expose an hash table that could contain duplicates and force the handling of a set on all lookups. Known drawbacks ========= None. References ========== [1] https://git.lttng.org/?p=lttng-tools.git;a=commit;h=e32d7f274604b77bcd83c24994e88df3761ed658 [2] https://git.lttng.org/?p=lttng-tools.git;a=commit;h=e1bbf98908a6399f39a9a8bc95bd8b59cecaa816 Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I2f1d0d6c04ee7210166e9847a850afbe6eaa7609
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Observed issue ============== lttng-consumerd segfaults for the following scenario: $ lttng create test --snapshot $ lttng enable-event -u -an $ lttng start # Run an app just to have some events $ lttng regenerate metadata $ lttng snapshot record The following backtrace is obtained: (gdb) bt #0 __GI___pthread_mutex_lock (mutex=0x130) at ../nptl/pthread_mutex_lock.c:67 #1 0x000055b383cfaed3 in lttng_ustconsumer_recv_metadata (sock=29, key=4, offset=0, len=12391, version=1, channel=0x7fe90000a760, timer=0, wait=1) at ust-consumer.c:1347 #2 0x000055b383d00197 in lttng_ustconsumer_request_metadata (ctx=0x55b3855a1e50, channel=0x7fe90000a760, timer=0, wait=1) at ust-consumer.c:3336 #3 0x000055b383cf9e76 in snapshot_metadata (metadata_channel=0x7fe90000a760, key=4, path=0x7fe911a09944 "uid/1000/64-bit", relayd_id=18446744073709551615, ctx=0x55b3855a1e50) at ust-consum #4 0x000055b383cfbe73 in lttng_ustconsumer_recv_cmd (ctx=0x55b3855a1e50, sock=28, consumer_sockpoll=0x7fe911a0dbb0) at ust-consumer.c:1853 #5 0x000055b383ccf9b7 in lttng_consumer_recv_cmd (ctx=0x55b3855a1e50, sock=28, consumer_sockpoll=0x7fe911a0dbb0) at consumer.c:2097 #6 0x000055b383cd3bfd in consumer_thread_sessiond_poll (data=0x55b3855a1e50) at consumer.c:3284 #7 0x00007fe914c22609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #8 0x00007fe914b47293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 (gdb) up #1 0x000055b383cfaed3 in lttng_ustconsumer_recv_metadata (sock=29, key=4, offset=0, len=12391, version=1, channel=0x7fe90000a760, timer=0, wait=1) at ust-consumer.c:1347 1347 pthread_mutex_lock(&channel->metadata_stream->lock); (gdb) print channel->metadata_stream $1 = (struct lttng_consumer_stream *) 0x0 Note that the following scenario also leads to a similar backtrace: $ lttng create test --snapshot $ lttng enable-event -u -an $ lttng start # Run an app just to have some events with a short duration $ lttng regenerate metadata # Run a second app just to have some events and a metadata flush while # the metadata cache status is set as `invalidated`. ^ lttng-consumerd segfault on app termination. The backtrace: (gdb) bt #0 __GI___pthread_mutex_lock (mutex=0x130) at ../nptl/pthread_mutex_lock.c:67 #1 0x00005612a5a13ed3 in lttng_ustconsumer_recv_metadata (sock=28, key=2, offset=0, len=12391, version=1, channel=0x7f3978005400, timer=0, wait=1) at ust-consumer.c:1347 #2 0x00005612a5a14d0a in lttng_ustconsumer_recv_cmd (ctx=0x5612a6feee50, sock=28, consumer_sockpoll=0x7f3989494bb0) at ust-consumer.c:1818 #3 0x00005612a59e89b7 in lttng_consumer_recv_cmd (ctx=0x5612a6feee50, sock=28, consumer_sockpoll=0x7f3989494bb0) at consumer.c:2097 #4 0x00005612a59ecbfd in consumer_thread_sessiond_poll (data=0x5612a6feee50) at consumer.c:3284 #5 0x00007f398c6a9609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #6 0x00007f398c5ce293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 (gdb) up #1 0x00005612a5a13ed3 in lttng_ustconsumer_recv_metadata (sock=28, key=2, offset=0, len=12391, version=1, channel=0x7f3978005400, timer=0, wait=1) at ust-consumer.c:1347 1347 pthread_mutex_lock(&channel->metadata_stream->lock); (gdb) print channel->metadata_stream $1 = (struct lttng_consumer_stream *) 0x0 (gdb) Cause ===== For session configured in snapshot mode the metadata channel metadata_stream field is NULL except for a "short" window during the actual snapshot record action (snapshot_metadata). The `regenerate metadata` effectively flag the metadata cache as invalid leading to handling the cache invalidation state (`CONSUMER_METADATA_CACHE_WRITE_STATUS_INVALIDATED`) in `lttng_ustconsumer_recv_metadata`. This was introduced by b1316da [1]. At that point the function expects the `channel->metadata_stream` to be non null. This is simply not true for snapshot session metadata channels. Note that we cannot simply swap `lttng_ustconsumer_request_metadata` and `create_ust_streams` in `snapshot_metadata` to ensure that the `channel->metadata_stream` is non null since `lttng_ustconsumer_recv_metadata` ends up being called on metadata flush when an app quit. This sequence of events corresponds to the second scenario put forward in the `Observed Issue` section. Solution ======== Null check `channel->metadata_stream` and perform only the operation when it is non null. This partly mirror what is done in `consumer_metadata_wakeup_pipe`. I am not sure if the check on `channel->monitor` is required but it seems irrelevant to the notion of resetting the stream consumed position when the stream exists. With this taken care off, we find ourself with another backtrace: #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 [93/122] #1 0x00007f75cf9b3859 in __GI_abort () at abort.c:79 #2 0x00007f75cf9b3729 in __assert_fail_base (fmt=0x7f75cfb49588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x55ab004e9c68 "pthread_mutex_trylock(&stream->lock)", file=0x55ab004 #3 0x00007f75cf9c4f36 in __GI___assert_fail (assertion=0x55ab004e9c68 "pthread_mutex_trylock(&stream->lock)", file=0x55ab004e8d7a "ust-consumer.c", line=1285, function=0x55ab004eb8a0 <__PR #4 0x000055ab004b1b9c in metadata_stream_reset_cache_consumed_position (stream=0x7f75b400a850) at ust-consumer.c:1285 #5 0x000055ab004b4fef in commit_one_metadata_packet (stream=0x7f75b400a850) at ust-consumer.c:2551 #6 0x000055ab004b5f46 in get_next_subbuffer_metadata (stream=0x7f75b400a850, subbuffer=0x7f75cc972630) at ust-consumer.c:2927 #7 0x000055ab0048b6a9 in lttng_consumer_read_subbuffer (stream=0x7f75b400a850, ctx=0x55ab01d4ee50, locked_by_caller=true) at consumer.c:3522 #8 0x000055ab004b0f66 in snapshot_metadata (metadata_channel=0x7f75b4005400, key=2, path=0x7f75cc972944 "uid/1000/64-bit", relayd_id=18446744073709551615, ctx=0x55ab01d4ee50) at ust-consum lttng#9 0x000055ab004b2e86 in lttng_ustconsumer_recv_cmd (ctx=0x55ab01d4ee50, sock=28, consumer_sockpoll=0x7f75cc976bb0) at ust-consumer.c:1861 lttng#10 0x000055ab004869b7 in lttng_consumer_recv_cmd (ctx=0x55ab01d4ee50, sock=28, consumer_sockpoll=0x7f75cc976bb0) at consumer.c:2097 lttng#11 0x000055ab0048abfd in consumer_thread_sessiond_poll (data=0x55ab01d4ee50) at consumer.c:3284 lttng#12 0x00007f75cfb8b609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#13 0x00007f75cfab0293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Which is also caused in part to the invalidation of the cache. `metadata_stream_reset_cache_consumed_position` expect that the stream at that point be locked. Which is not the case despite what the last argument to `lttng_consumer_read_subbuffer` indicates. To alleviate that we hold the lock during the call to `lttng_consumer_read_subbuffer`. Known drawbacks ========= None. References ========= [1] https://git.lttng.org/?p=lttng-tools.git;a=commit;h=b1316da1ffbd276fc8271e7a9438e683ad352781 Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ib09fdc989b1baae26d0f496afeabc3e7cb27228c
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Observed issue ============== While running tests/regression/tools/clear/test_ust test in a loop we eventually witness the following error: The symptom on the Babeltrace side is a Connection reset by peer. This is caused by a relayd abort after an assertion failure due to a reference count being lower than 0. Test case: # Test ust streaming live clear with viewer # Parameters: tracing_active=0, clear_twice=0, buffer_type=pid Tools commit: https://review.lttng.org/c/lttng-tools/+/6754/1 Relay daemon assertion failure stack trace: (gdb) bt #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x00007ffa2e850859 in __GI_abort () at abort.c:79 #2 0x00007ffa2e850729 in __assert_fail_base (fmt=0x7ffa2e9e6588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x56221bdb96f4 "res >= 0", file=0x56221bdb97a0 "/root/virtenv/usr/include/urcu/ref.h", line=66, function=<optimized out>) at assert.c:92 #3 0x00007ffa2e861f36 in __GI___assert_fail (assertion=assertion@entry=0x56221bdb96f4 "res >= 0", file=file@entry=0x56221bdb97a0 "/root/virtenv/usr/include/urcu/ref.h", line=line@entry=66, function=function@entry=0x56221bdbd638 <__PRETTY_FUNCTION__.7554> "urcu_ref_put") at assert.c:101 #4 0x000056221bd6a1cc in urcu_ref_put (release=<optimized out>, ref=0x7ffa24008cb0) at /root/virtenv/usr/include/urcu/ref.h:66 #5 viewer_stream_put (vstream=vstream@entry=0x7ffa24008cb0) at viewer-stream.c:279 #6 0x000056221bd5e4c5 in viewer_get_metadata (conn=conn@entry=0x7ffa0c000fc0) at live.c:2211 #7 0x000056221bd63778 in process_control (conn=0x7ffa0c000fc0, recv_hdr=0x7ffa297c5af0) at live.c:2376 #8 thread_worker (data=<optimized out>) at live.c:2541 lttng#9 0x00007ffa2ea28609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#10 0x00007ffa2e94d293 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Babeltrace crash: 11-17 05:13:05.197 47007 47007 D PLUGIN/SRC.CTF.LTTNG-LIVE/VIEWER lttng_live_get_next_index@viewer-connection.c:1494 [live] Requesting next index for stream: cmd=GET_NEXT_INDEX, viewer-stream-id=3352 11-17 05:13:05.215 47007 47007 E PLUGIN/SRC.CTF.LTTNG-LIVE/VIEWER lttng_live_recv@viewer-connection.c:245 [live] Error receiving from Relay: Connection reset by peer. 11-17 05:13:05.215 47007 47007 E PLUGIN/SRC.CTF.LTTNG-LIVE/VIEWER lttng_live_get_next_index@viewer-connection.c:1522 [live] Error receiving get next index reply 11-17 05:13:05.215 47007 47007 D PLUGIN/SRC.CTF.LTTNG-LIVE lttng_live_iterator_next_msg_on_stream@lttng-live.c:1069 [live] Returning from advancing live stream iterator: status=LTTNG_LIVE_ITERATOR_STATUS_ERROR, stream-name="stream-3352", viewer-stream-id=3352 11-17 05:13:05.215 47007 47007 E PLUGIN/SRC.CTF.LTTNG-LIVE lttng_live_msg_iter_next@lttng-live.c:1802 [live] Error preparing the next batch of messages: live-iter-status=LTTNG_LIVE_ITERATOR_STATUS_ERROR 11-17 05:13:05.216 47007 47007 W LIB/MSG-ITER bt_message_iterator_next@iterator.c:866 Component input port message iterator's "next" method failed: iter-addr=0x563b7dd07700, iter-upstream-comp-name="live", iter-upstream-comp-log-level=TRACE, iter-upstream-comp-class-type=SOURCE, iter-upstream-comp-class-name="lttng-live", iter-upstream-comp-class-partial-descr="Connect to an LTTng relay daemon", iter-upstream-port-type=OUT PUT, iter-upstream-port-name="out", status=ERROR 11-17 05:13:05.216 47007 47007 E PLUGIN/FLT.UTILS.MUXER muxer_upstream_msg_iter_next@muxer.c:446 [mux] Upstream iterator's next method returned an error: status=ERROR 11-17 05:13:05.216 47007 47007 E PLUGIN/FLT.UTILS.MUXER validate_muxer_upstream_msg_iters@muxer.c:989 [mux] Cannot validate muxer's upstream message iterator wrapper: muxer-msg-iter-addr=0x563b7dd04740, muxer-upstream-msg-iter-wrap-addr=0x563b7dd0db30 11-17 05:13:05.216 47007 47007 E PLUGIN/FLT.UTILS.MUXER muxer_msg_iter_next@muxer.c:1417 [mux] Cannot get next message: comp-addr=0x563b7dd1a760, muxer-comp-addr=0x563b7dd1b930, muxer-msg-iter-addr=0x563b7dd04740, msg-iter-addr=0x563b7dd07590, status=ERROR 11-17 05:13:05.216 47007 47007 W LIB/MSG-ITER bt_message_iterator_next@iterator.c:866 Component input port message iterator's "next" method failed: iter-addr=0x563b7dd07590, iter-upstream-comp-name="mux", iter-upstream-comp-log-level=WARNING, iter-upstream-comp-class-type=FILTER, iter-upstream-comp-class-name="muxer", iter-upstream-comp-class-partial-descr="Sort messages from multiple inpu", iter-upstream-port-type=OUTPUT, iter-upstream-port-name="out", status=ERROR 11-17 05:13:05.216 47007 47007 W LIB/GRAPH consume_graph_sink@graph.c:462 Component's "consume" method failed: status=ERROR, comp-addr=0x563b7dd06d20, comp-name="pretty", comp-log-level=WARNING, comp-class-type=SINK, comp-class-name="pretty", comp-class-partial-descr="Pretty-print messages (`text` fo", comp-class-is-frozen=1, comp-class-so-handle-addr=0x563b7dd051b0, comp-class-so-handle-path="/root/virtenv/usr/lib/babeltr ace2/plugins/babeltrace-plugin-text.so", comp-input-port-count=1, comp-output-port-count=0 11-17 05:13:05.217 47007 47007 E CLI cmd_run@babeltrace2.c:2537 Graph failed to complete successfully Cause ===== Both relay and live threads can put the ownership reference on the metadata viewer stream concurrently without synchronization, thus leading to a reference count going lower than 0. The viewer stream ownership design initially planned for being owned by the live thread, thus allowing the live thread to put the ownership reference as soon as the associated relay stream is observed as closed, and the viewer stream is considered as hung up. However, in the specific case of the metadata viewer stream, the responsibility of closing the metadata viewer stream is shared between the relay and live threads, because the viewers expect to observe a LTTNG_VIEWER_NO_NEW_METADATA message before the metadata stream hangs up (see comment in viewer_get_metadata()). Therefore, if viewer_get_metadata() is done before the metadata stream is closed, the viewer will receive the LTTNG_VIEWER_NO_NEW_METADATA message, and set the no_new_metadata_notified state to true. It's then the relay thread's relay_close_stream() which will invoke the ownership put. However, the live thread may concurrently try to put the viewer stream ownership as well from a subsequent viewer_get_metadata(), thus leading to a reference count < 0. Solution ======== Fix this by putting the ownership reference from the live viewer thread rather than the relay thread. This can be done by tracking the state of no_new_metadata_notified within the live viewer thread. Known drawbacks =============== This will postpone reclaim of the metadata viewer stream from the relay stream close to the following viewer_get_metadata (after a LTTNG_VIEWER_NO_NEW_METADATA message has been replied), which I don't think is an issue. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I9783d3a8402dddaa364a7a69c0764eaf30c16fde
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Observed issue
==============
When consumer_stream_destroy() is called from, for example, the error
path in setup_metadata(), consumer_stream_free() can end up being called
twice on the same stream. Since the stream->metadata_bucket is not set
to NULL after being destroyed, it leads to a use-after-free:
ERROR: AddressSanitizer: heap-use-after-free on address 0x604000000318
READ of size 8 at 0x604000000318 thread T7
#0 in metadata_bucket_destroy
#1 in consumer_stream_free
#2 in consumer_stream_destroy
#3 in setup_metadata
#4 in lttng_ustconsumer_recv_cmd
#5 in lttng_consumer_recv_cmd
#6 in consumer_thread_sessiond_poll
#7 in start_thread nptl/pthread_create.c:481
#8 in clone (/lib/x86_64-linux-gnu/libc.so.6+0xfcbde)
0x604000000318 is located 8 bytes inside of 48-byte region [0x604000000310,0x604000000340)
freed by thread T7 here:
#0 in __interceptor_free
#1 in metadata_bucket_destroy
#2 in consumer_stream_free
#3 in consumer_stream_destroy
#4 in clean_channel_stream_list
#5 in consumer_del_channel
#6 in consumer_stream_destroy
#7 in setup_metadata
#8 in lttng_ustconsumer_recv_cmd
lttng#9 in lttng_consumer_recv_cmd
lttng#10 in consumer_thread_sessiond_poll
lttng#11 in start_thread nptl/pthread_create.c:481
previously allocated by thread T7 here:
#0 in __interceptor_calloc
#1 in zmalloc
#2 in metadata_bucket_create
#3 in consumer_stream_enable_metadata_bucketization
#4 in lttng_ustconsumer_set_stream_ops
#5 in lttng_ustconsumer_on_recv_stream
#6 in lttng_consumer_on_recv_stream
#7 in create_ust_streams
#8 in ask_channel
lttng#9 in lttng_ustconsumer_recv_cmd
lttng#10 in lttng_consumer_recv_cmd
lttng#11 in consumer_thread_sessiond_poll
lttng#12 in start_thread nptl/pthread_create.c:481
Thread T7 created by T0 here:
#0 in __interceptor_pthread_create
#1 in main
#2 in __libc_start_main ../csu/libc-start.c:332
SUMMARY: AddressSanitizer: heap-use-after-free in metadata_bucket_destroy
This can be easily reproduced by forcing a failure during the setup
of the metadata reproducible using the following change:
diff --git a/src/common/ust-consumer/ust-consumer.c b/src/common/ust-consumer/ust-consumer.c
index fa1c71299..97ed59632 100644
--- a/src/common/ust-consumer/ust-consumer.c
+++ b/src/common/ust-consumer/ust-consumer.c
@@ -908,8 +908,7 @@ static int setup_metadata(struct lttng_consumer_local_data *ctx, uint64_t key)
/* Send metadata stream to relayd if needed. */
if (metadata->metadata_stream->net_seq_idx != (uint64_t) -1ULL) {
- ret = consumer_send_relayd_stream(metadata->metadata_stream,
- metadata->pathname);
+ ret = -1;
if (ret < 0) {
ret = LTTCOMM_CONSUMERD_ERROR_METADATA;
goto error;
Cause
=====
Channels have a list of streams that are being "setup" and are not
yet monitored for consumption. During this setup phase, the streams are
owned by the channel. On destruction of the channel, any stream in that
list will thus be cleaned-up.
When destroying a consumer stream, a reference to its channel is 'put'.
This can result in the destruction of the channel.
In the situation described above, the release of the channel's reference
is done before the stream is removed from the channel's stream list.
This causes the channel's clean-up to invoke (again) the current
stream's clean-up, resulting in the double-free of the metadata bucket.
This problem is present in a number of error paths.
Solution
========
Some error paths already manually removed the consumer stream from it's
channel's stream list before invoking consumer_stream_destroy(). The
various error paths that have to deal with this possible situation are
changed to simply invoke consumer_stream_destroy().
consumer_stream_destroy() is modified to always remove the stream from
its channel's list before performing the rest of the clean-up. This
ensures that those double clean-ups can't occur.
Drawbacks
=========
None.
Reported-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Tested-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ibeca9b675b86fc46be3f57826f7158de4da43df8
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Observed issue ============== Scenario: gdb lttng-sessiond set non-stop break rotation-thread.cpp:584 ^ simulates a slow rotation thread or not scheduled thread. lttng create test1 lttng enable-event -u -a lttng start test1 lttng create test2 lttng enable-event -u -a lttng start test2 lttng destroy test1 This will hang on rotation pending checks on the CLI side. In another shell: lttng destroy test2 This will hang on rotation pending checks on the CLI side. Back to gdb thread 7 continue Results in: #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x00007ffff786c859 in __GI_abort () at abort.c:79 #2 0x00007ffff786c729 in __assert_fail_base (fmt=0x7ffff7a02588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x5555556bb148 "count == lttng_ht_get_count(ltt_sessions_ht_by_name)", file=0x5555556bae9f "session.cpp", line=395, function=<optimized out>) at assert.c:92 #3 0x00007ffff787e006 in __GI___assert_fail (assertion=0x5555556bb148 "count == lttng_ht_get_count(ltt_sessions_ht_by_name)", file=0x5555556bae9f "session.cpp", line=395, function=0x5555556bb129 "int ltt_sessions_ht_empty()") at assert.c:101 #4 0x0000555555586d59 in ltt_sessions_ht_empty () at session.cpp:395 #5 0x0000555555586e53 in del_session_ht (ls=0x7fffdc000c30) at session.cpp:418 #6 0x0000555555588a95 in session_release (ref=0x7fffdc001e50) at session.cpp:999 #7 0x000055555558620f in urcu_ref_put (ref=0x7fffdc001e50, release=0x5555555886eb <session_release(urcu_ref*)>) at /home/joraj/lttng/master/install/include/urcu/ref.h:68 #8 0x0000555555588c8f in session_put (session=0x7fffdc000c30) at session.cpp:1048 lttng#9 0x00005555555bf995 in handle_job_queue (handle=0x55555575d260, state=0x7fffeeffc240, queue=0x555555758960) at rotation-thread.cpp:612 lttng#10 0x00005555555c05da in thread_rotation (data=0x55555575d260) at rotation-thread.cpp:847 lttng#11 0x00005555555c3b1c in launch_thread (data=0x55555575d2f0) at thread.cpp:66 lttng#12 0x00007ffff7a46609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#13 0x00007ffff7969163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Other scenarios can lead to a similar backtrace when using the `--no-wait` lttng destroy option. Cause ===== Since ed41e57 [1], hash table removal for the session object for the `ltt_sessions_ht_by_name` and `ltt_sessions_ht_by_name` are "decoupled". Removal from `ltt_sessions_ht_by_name` is done early in `session_destroy()` while removal from `ltt_sessions_ht_by_id` is done during `session_release` when the last reference of a session object is released. This can leads to `imbalances` between the size of the two hash tables when multiple sessions are at play. Solution ======== Rework `ltt_sessions_ht_empty()` to exit early when `ltt_sessions_ht_by_id` is not empty. Perform a sanity check on `ltt_sessions_ht_by_name` only when `ltt_sessions_ht_by_id` is empty. Note ======== Ideally both hash tables' lifetime would be managed separately but it seems easier in term of initialization to bundle them together for now considering the limited scope of the `ltt_sessions_ht_by_name` hash table. Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I66c459f80298f929add703ac977cccd1da6dd556
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May 25, 2022
Observed issue ============== Using the notification client from doc/examples/trigger-condition-event-matches/notification-client.cpp, an assert is hit when the notification subsystem is under load. #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x00007f69eab58859 in __GI_abort () at abort.c:79 #2 0x00007f69eab58729 in __assert_fail_base (fmt=0x7f69eacee588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x7f69eae1d5dd "len > 0", file=0x7f69eae1d5cb "unix.cpp", line=179, function=<optimized out>) at assert.c:92 #3 0x00007f69eab6a006 in __GI___assert_fail (assertion=0x7f69eae1d5dd "len > 0", file=0x7f69eae1d5cb "unix.cpp", line=179, function=0x7f69eae1d598 "ssize_t lttcomm_recv_unix_sock(int, void*, size_t)") at assert.c:101 #4 0x00007f69eadd5fe6 in lttcomm_recv_unix_sock (sock=3, buf=0x55da9ecd5f89, len=0) at unix.cpp:179 #5 0x00007f69ead7df3f in receive_message (channel=0x55da9ecd6ee0) at channel.cpp:64 #6 0x00007f69ead7e478 in lttng_notification_channel_get_next_notification (channel=0x55da9ecd6ee0, _notification=0x7ffdefed2570) at channel.cpp:279 #7 0x000055da9e0e742f in main (argc=2, argv=0x7ffdefed2698) at notification-client.cpp:506 (gdb) frame #5 0x00007f69ead7df3f in receive_message (channel=0x55da9ecd6ee0) at channel.cpp:64 64 ret = lttcomm_recv_unix_sock(channel->socket, (gdb) print msg $2 = {type = 5 '\005', size = 0, fds = 0, payload = 0x7ffdefed24a8 ""} The msg type 5 is `LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED` Cause ===== The msg portion of a `LTTNG_NOTIFICATION_CHANNEL_MESSAGE_TYPE_NOTIFICATION_DROPPED` is indeed zero. There is no extra payload. Solution ======== When the msg size is zero, skip the 'payload' reception phase. Known drawbacks ========= None. Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ibabb922d0e410c9902414a5eabbe04738861d772
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Observed issue ============== During high throughput event notification generation scenarios the following deadlock happens: Thread 14 (Thread 0x7f74b4ff9700 (LWP 76062)): #0 __lll_lock_wait (futex=futex@entry=0x56408765dde8, private=0) at lowlevellock.c:52 #1 0x00007f74c941a0a3 in __GI___pthread_mutex_lock (mutex=0x56408765dde8) at ../nptl/pthread_mutex_lock.c:80 #2 0x000056408704b207 in run_command_wait (handle=0x56408765ddd0, cmd=0x7f74b4ff7f70) at notification-thread-commands.cpp:31 #3 0x000056408704bcef in notification_thread_command_remove_tracer_event_source (handle=0x56408765ddd0, tracer_event_source_fd=54) at notification-thread-commands.cpp:319 #4 0x000056408708a0c1 in delete_ust_app (app=0x7f749c000bf0) at ust-app.cpp:1059 #5 0x000056408708a511 in delete_ust_app_rcu (head=0x7f749c000ca0) at ust-app.cpp:1122 #6 0x00007f74c988b4a7 in call_rcu_thread (arg=0x7f74b8004a80) at ../src/urcu-call-rcu-impl.h:369 #7 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #8 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 13 (Thread 0x7f74b57fa700 (LWP 76047)): #0 0x00007f74c933a49e in epoll_wait (epfd=48, events=0x7f74a4000b60, maxevents=2, timeout=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00005640870eafa6 in compat_epoll_wait (events=0x7f74b57f9240, timeout=-1, interruptible=false) at compat/poll.cpp:280 #2 0x00005640870abb65 in thread_agent_management (data=0x56408765f0b0) at agent-thread.cpp:424 #3 0x0000564087062b1a in launch_thread (data=0x56408765f150) at thread.cpp:66 #4 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #5 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 12 (Thread 0x7f74b5ffb700 (LWP 76046)): [630/709] #0 0x00007f74c933a49e in epoll_wait (epfd=47, events=0x7f74a0000b60, maxevents=2, timeout=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00005640870eafa6 in compat_epoll_wait (events=0x7f74b5ffa170, timeout=-1, interruptible=false) at compat/poll.cpp:280 #2 0x00005640870a4095 in thread_application_notification (data=0x56408765ee40) at notify-apps.cpp:78 #3 0x0000564087062b1a in launch_thread (data=0x56408765eed0) at thread.cpp:66 #4 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #5 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 11 (Thread 0x7f74b67fc700 (LWP 76045)): #0 0x00007f74c933a49e in epoll_wait (epfd=44, events=0x7f74ac000b60, maxevents=2, timeout=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00005640870eafa6 in compat_epoll_wait (events=0x7f74b67fb170, timeout=-1, interruptible=false) at compat/poll.cpp:280 #2 0x00005640870723db in thread_application_management (data=0x56408765ebd0) at manage-apps.cpp:93 #3 0x0000564087062b1a in launch_thread (data=0x56408765ec60) at thread.cpp:66 #4 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #5 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 10 (Thread 0x7f74b6ffd700 (LWP 76044)): #0 0x00007f74c933a49e in epoll_wait (epfd=39, events=0x7f74a8000b60, maxevents=2, timeout=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00005640870eafa6 in compat_epoll_wait (events=0x7f74b6ffc130, timeout=-1, interruptible=false) at compat/poll.cpp:280 #2 0x0000564087070a27 in thread_application_registration (data=0x56408765e940) at register.cpp:214 #3 0x0000564087062b1a in launch_thread (data=0x56408765e9f0) at thread.cpp:66 #4 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #5 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 9 (Thread 0x7f74b77fe700 (LWP 76043)): [654/709] #0 syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38 #1 0x00005640870c8e25 in futex (uaddr=0x5640871e2800 <ust_cmd_queue>, op=0, val=-1, timeout=0x0, uaddr2=0x0, val3=0) at /home/joraj/lttng/master/install/include/urcu/futex.h:72 #2 0x00005640870c8e6d in futex_async (uaddr=0x5640871e2800 <ust_cmd_queue>, op=0, val=-1, timeout=0x0, uaddr2=0x0, val3=0) at /home/joraj/lttng/master/install/include/urcu/futex.h:104 #3 0x00005640870c939a in futex_nto1_wait (futex=0x5640871e2800 <ust_cmd_queue>) at futex.cpp:77 #4 0x000056408706f2af in thread_dispatch_ust_registration (data=0x56408765e740) at dispatch.cpp:453 #5 0x0000564087062b1a in launch_thread (data=0x56408765e760) at thread.cpp:66 #6 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #7 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 8 (Thread 0x7f74b7fff700 (LWP 76042)): #0 0x00007f74c933a49e in epoll_wait (epfd=33, events=0x7f74b0000b60, maxevents=2, timeout=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00005640870eafa6 in compat_epoll_wait (events=0x7f74b7ffad40, timeout=-1, interruptible=false) at compat/poll.cpp:280 #2 0x000056408706c424 in thread_manage_clients (data=0x56408765e4f0) at client.cpp:2528 #3 0x0000564087062b1a in launch_thread (data=0x56408765e560) at thread.cpp:66 #4 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #5 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 7 (Thread 0x7f74c4b8f700 (LWP 76041)): [672/709] #0 0x00007f74c933a49e in epoll_wait (epfd=31, events=0x7f74bc000b60, maxevents=3, timeout=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00005640870eafa6 in compat_epoll_wait (events=0x7f74c4b8e240, timeout=-1, interruptible=false) at compat/poll.cpp:280 #2 0x000056408705f2b6 in thread_rotation (data=0x56408765e280) at rotation-thread.cpp:804 #3 0x0000564087062b1a in launch_thread (data=0x56408765e310) at thread.cpp:66 #4 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #5 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 6 (Thread 0x7f74c5390700 (LWP 76040)): #0 0x00007f74c925f1d2 in __GI___sigtimedwait (set=0x7f74c538f090, info=0x7f74c538f110, timeout=0x0) at ../sysdeps/unix/sysv/linux/sigtimedwait.c:29 #1 0x000056408706138a in thread_timer (data=0x7ffc1fcbe3f0) at timer.cpp:359 #2 0x0000564087062b1a in launch_thread (data=0x56408765e0a0) at thread.cpp:66 #3 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #4 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 5 (Thread 0x7f74c5b91700 (LWP 76039)): #0 __libc_write (nbytes=8, buf=0x7f74c5b8fc88, fd=24) at ../sysdeps/unix/sysv/linux/write.c:26 #1 __libc_write (fd=24, buf=0x7f74c5b8fc88, nbytes=8) at ../sysdeps/unix/sysv/linux/write.c:24 #2 0x00005640870eeb4f in lttng_write (fd=24, buf=0x7f74c5b8fc88, count=8) at readwrite.cpp:77 #3 0x000056408704b535 in run_command_no_wait (handle=0x56408765ddd0, in_cmd=0x7f74c5b8fdf0) at notification-thread-commands.cpp:92 #4 0x000056408704bf49 in notification_thread_client_communication_update (handle=0x56408765ddd0, id=2, transmission_status=CLIENT_TRANSMISSION_STATUS_QUEUED) at notification-thread-command #5 0x000056408707bc62 in client_handle_transmission_status (client=0x7f74b80050d0, status=CLIENT_TRANSMISSION_STATUS_QUEUED, user_data=0x7f74b8004410) at action-executor.cpp:258 #6 0x0000564087057525 in notification_client_list_send_evaluation (client_list=0x7f74b8004df0, trigger=0x7f74b0001030, evaluation=0x7f74b815d1d0, source_object_creds=0x0, client_report=0x5 #7 0x000056408707bce9 in action_executor_notify_handler (executor=0x7f74b8004410, work_item=0x7f74b815d430, item=0x7f74b80e48e0) at action-executor.cpp:269 #8 0x000056408707dd6d in action_executor_generic_handler (executor=0x7f74b8004410, work_item=0x7f74b815d430, item=0x7f74b80e48e0) at action-executor.cpp:670 lttng#9 0x000056408707df01 in action_work_item_execute (executor=0x7f74b8004410, work_item=0x7f74b815d430) at action-executor.cpp:689 lttng#10 0x000056408707e525 in action_executor_thread (_data=0x7f74b8004410) at action-executor.cpp:771 [698/709] lttng#11 0x0000564087062b1a in launch_thread (data=0x7f74b80044b0) at thread.cpp:66 lttng#12 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#13 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 4 (Thread 0x7f74c6392700 (LWP 76038)): #0 __lll_lock_wait (futex=futex@entry=0x56408765dde8, private=0) at lowlevellock.c:52 #1 0x00007f74c941a0a3 in __GI___pthread_mutex_lock (mutex=0x56408765dde8) at ../nptl/pthread_mutex_lock.c:80 #2 0x0000564087053c89 in handle_notification_thread_command (handle=0x56408765ddd0, state=0x7f74c63911b0) at notification-thread-events.cpp:3142 #3 0x000056408704ac81 in thread_notification (data=0x56408765ddd0) at notification-thread.cpp:715 #4 0x0000564087062b1a in launch_thread (data=0x56408765dec0) at thread.cpp:66 #5 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #run_command_no_wait6 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 3 (Thread 0x7f74c6b93700 (LWP 76037)): #0 0x00007f74c933a49e in epoll_wait (epfd=21, events=0x7f74c0000b60, maxevents=2, timeout=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00005640870eafa6 in compat_epoll_wait (events=0x7f74c6b92170, timeout=-1, interruptible=false) at compat/poll.cpp:280 #2 0x000056408706400a in thread_manage_health (data=0x56408765db50) at health.cpp:140 #3 0x0000564087062b1a in launch_thread (data=0x56408765dbf0) at thread.cpp:66 #4 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #5 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 2 (Thread 0x7f74c7394700 (LWP 76036)): #0 syscall () at ../sysdeps/unix/sysv/linux/x86_64/syscall.S:38 #1 0x00007f74c987d238 in futex (uaddr=0x564087659b10, op=0, val=-1, timeout=0x0, uaddr2=0x0, val3=0) at ../include/urcu/futex.h:72 #2 futex_async (uaddr=0x564087659b10, op=0, val=-1, timeout=0x0, uaddr2=0x0, val3=0) at ../include/urcu/futex.h:104 #3 futex_wait (futex=0x564087659b10) at workqueue.c:136 #4 0x00007f74c987ced2 in workqueue_thread (arg=0x564087659ad0) at workqueue.c:237 #5 0x00007f74c9417609 in start_thread (arg=<optimized out>) at pthread_create.c:477 #6 0x00007f74c933a163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 Thread 1 (Thread 0x7f74c73cd300 (LWP 76034)): #0 0x00007f74c933a49e in epoll_wait (epfd=50, events=0x564087666880, maxevents=1, timeout=-1) at ../sysdeps/unix/sysv/linux/epoll_wait.c:30 #1 0x00005640870eafa6 in compat_epoll_wait (events=0x7ffc1fcbe280, timeout=-1, interruptible=false) at compat/poll.cpp:280 #2 0x0000564087062244 in sessiond_wait_for_quit_pipe (timeout_ms=-1) at thread-utils.cpp:83 #3 0x00005640870127dc in main (argc=1, argv=0x7ffc1fcbe668) at main.cpp:1921 Cause ===== The event_pipe used to notify the notification poll loop is full and the lttng_write call blocks with the locks for both the client and the cmd_queue held. Solution ======== Go back to using eventfd but without the use of EFD_SEMAPHORE (linux 2.6.30) to continue supporting kernel between 2.6.27 and 2.6.29. The EFD_SEMAPHORE is emulated with a read, decrement, write as explained by the initial committer of EFD_SEMAPHORE [1]. Known drawbacks ========= This does not solve the actual block+lock problem but simply push it back further. The lttng_write on the eventfd can block when reaching UINT64_MAX. This would represent, at 1 command queued per ns (which is ridiculous), ~584 years of queueing without a dequeue operation. Reference ======= [1] https://lwn.net/Articles/318151/ Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: Ie749c4169708f57463fe3cfab2366f1015bae4e0
jgalar
added a commit
that referenced
this pull request
May 25, 2022
Observed issue ============== When servicing a large number of tracer notifications and sending notifications to clients, the session daemon occasionally hits an assertion: #4 0x00007fb224d7d116 in __assert_fail () from /usr/lib/libc.so.6 #5 0x000056038b2fe4d7 in client_flush_outgoing_queue (client=0x7fb21400c3b0) at notification-thread-events.cpp:3586 #6 0x000056038b2ff819 in handle_notification_thread_client_out (state=0x7fb221974090, socket=77) at notification-thread-events.cpp:4104 #7 0x000056038b2f3d77 in thread_notification (data=0x56038cc7fe90) at notification-thread.cpp:763 #8 0x000056038b30ca7d in launch_thread (data=0x56038cc7e220) at thread.cpp:66 lttng#9 0x00007fb224dcf5c2 in start_thread () from /usr/lib/libc.so.6 lttng#10 0x00007fb224e54584 in clone () from /usr/lib/libc.so.6 Cause ===== A client "out" event can be received when no payload is left to send under some circumstances. Many threads can flush a client's outgoing queue and, if they had to queue their message (socket was full), will use the "communication update" command to signal the (e)poll thread to monitor for space being made available in the socket. Commands are sent over an internal pipe serviced by the same thread as the client sockets. When space is made available in the socket, there is a race between the (e)poll thread and the other threads that may wish to use the client's socket to flush its outgoing queue. A non-(e)poll thread may attempt (and succeed) in flushing the queue before the (e)poll thread gets a chance to service the client's "out" event. In this situation, the (e)poll thread processing the client out event will see an empty payload: there is nothing to do. Solution ======== The (e)poll thread can simply ignore the "client out" event when an empty payload is seen. There is also no need to update the transmission status as the other thread has already enqueued a "communication update" command to do so. Known drawbacks =============== None. Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I8a181bea1e37e8e14cc67b624b76d139b488eded
jgalar
added a commit
that referenced
this pull request
May 25, 2022
Issue observed
==============
Address sanitizer reports the following invalid accesses while running
the test_mi test.
❯ ASAN_OPTIONS=detect_odr_violation=0 lttng-sessiond
=================================================================
==289173==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60400000e280 at pc 0x55cbbe35e2e0 bp 0x7f01672f1550 sp 0x7f01672f1540
WRITE of size 4 at 0x60400000e280 thread T13
#0 0x55cbbe35e2df in mark_thread_as_ready /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/manage-consumer.cpp:32
#1 0x55cbbe360160 in thread_consumer_management /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/manage-consumer.cpp:267
#2 0x55cbbe336ac4 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:66
#3 0x7f01729c15c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
#4 0x7f0172a46583 in __clone (/usr/lib/libc.so.6+0x112583)
0x60400000e280 is located 8 bytes to the right of 40-byte region [0x60400000e250,0x60400000e278)
allocated by thread T7 here:
#0 0x7f01733b1fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x55cbbe33adf3 in zmalloc_internal ../../../src/common/macros.hpp:60
#2 0x55cbbe33ae03 in thread_notifiers* zmalloc<thread_notifiers>() ../../../src/common/macros.hpp:89
#3 0x55cbbe3617f9 in launch_consumer_management_thread(consumer_data*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/manage-consumer.cpp:440
#4 0x55cbbe33cf49 in spawn_consumer_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:188
#5 0x55cbbe33f7cf in start_consumerd /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:394
#6 0x55cbbe345713 in process_client_msg /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:1277
#7 0x55cbbe34d74b in thread_manage_clients /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2622
#8 0x55cbbe336ac4 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:66
lttng#9 0x7f01729c15c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
Thread T13 created by T7 here:
#0 0x7f0173353eb7 in __interceptor_pthread_create /usr/src/debug/gcc/libsanitizer/asan/asan_interceptors.cpp:216
#1 0x55cbbe336f9e in lttng_thread_create(char const*, void* (*)(void*), bool (*)(void*), void (*)(void*), void*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:106
#2 0x55cbbe3618cc in launch_consumer_management_thread(consumer_data*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/manage-consumer.cpp:453
#3 0x55cbbe33cf49 in spawn_consumer_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:188
#4 0x55cbbe33f7cf in start_consumerd /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:394
#5 0x55cbbe345713 in process_client_msg /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:1277
#6 0x55cbbe34d74b in thread_manage_clients /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2622
#7 0x55cbbe336ac4 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:66
#8 0x7f01729c15c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
Thread T7 created by T0 here:
#0 0x7f0173353eb7 in __interceptor_pthread_create /usr/src/debug/gcc/libsanitizer/asan/asan_interceptors.cpp:216
#1 0x55cbbe336f9e in lttng_thread_create(char const*, void* (*)(void*), bool (*)(void*), void (*)(void*), void*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:106
#2 0x55cbbe34eebf in launch_client_thread() /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2756
#3 0x55cbbe27f31a in main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/main.cpp:1838
#4 0x7f017296130f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
SUMMARY: AddressSanitizer: heap-buffer-overflow /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/manage-consumer.cpp:32 in mark_thread_as_ready
Shadow bytes around the buggy address:
0x0c087fff9c00: fa fa fd fd fd fd fd fa fa fa fd fd fd fd fd fa
0x0c087fff9c10: fa fa fd fd fd fd fd fa fa fa fd fd fd fd fd fa
0x0c087fff9c20: fa fa fd fd fd fd fd fa fa fa fd fd fd fd fd fa
0x0c087fff9c30: fa fa fd fd fd fd fd fa fa fa fd fd fd fd fd fa
0x0c087fff9c40: fa fa fd fd fd fd fd fa fa fa 00 00 00 00 00 fa
=>0x0c087fff9c50:[fa]fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff9c60: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff9c70: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff9c80: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff9c90: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c087fff9ca0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
Shadow gap: cc
==289173==ABORTING
Cause
=====
The start functions of the various worker threads of the session daemon
are implemented in separate translation units (TU). To make use of the
lttng_thread API, they all define different control structures to
control their shutdown.
Those structures are all named 'thread_notifiers' and are all allocated
using zmalloc<>. The various instances of zmalloc<thread_notifiers> all
end up having the same mangled name (e.g.
_Z7zmallocI16thread_notifiersEPT_v).
At link time, only one instance of zmalloc<thread_notifiers> is kept.
Since those structures all have different layout/sizes, this is
problematic. However, it is an acceptable behaviour according to the ODR
[1].
I first considered making the various memory allocation functions in
macros.hpp 'static' which results in each TU holding the appropriate
specialization of the various functions. While this works, it doesn't
make us ODR-compliant. To make a long story short, a program defining
multiple types sharing the same name, in the same namespace, is
ill-formed.
Another concern is that marking all templated free-functions as static
will eventually result in code bloat.
Solution
========
All structures defined in TUs (but not in a header) are placed in
unnamed namespaces (also called anonymous namespaces) [2].
This results in separate copies of the templated functions being
generated when specialized using a structure in an anonymous
namespace (e.g. _Z7zmallocIN12_GLOBAL__N_116thread_notifiersEEPT_v).
We could have renamed the various `thread_notifiers` structures to give
them different names. However, I found those are not the only structures
sharing a name in different TUs. For instance, the same problem applies
to `struct lttng_index` (index in a stream, index in a map).
I propose we systematically namespace structures defined in TUs in the
future.
This will also save us trouble if those POD structures eventually become
non-POD: we would experience the same "clashes" if those structures had
constructors, for example.
References
==========
[1] https://en.cppreference.com/w/cpp/language/definition
[2] https://en.cppreference.com/w/cpp/language/namespace
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I867e5a287ad8cf3ada617335bc1a80b800bf0833
jgalar
added a commit
that referenced
this pull request
May 25, 2022
LeakSanitizer reports the following leak:
==974957==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 32 byte(s) in 1 object(s) allocated from:
#0 0x7fdb86fcd1b2 in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:164
#1 0x7fdb86d7c296 in lttng_dynamic_buffer_set_capacity(lttng_dynamic_buffer*, unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-buffer.cpp:159
#2 0x7fdb86d7c060 in lttng_dynamic_buffer_set_size(lttng_dynamic_buffer*, unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-buffer.cpp:112
#3 0x7fdb86d2589a in recv_payload_sessiond /home/jgalar/EfficiOS/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.cpp:230
#4 0x7fdb86d26fa5 in lttng_ctl_ask_sessiond_payload(lttng_payload_view*, lttng_payload*) /home/jgalar/EfficiOS/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.cpp:662
#5 0x7fdb86d2cd8d in lttng_list_tracepoint_fields /home/jgalar/EfficiOS/src/lttng-tools/src/lib/lttng-ctl/lttng-ctl.cpp:1767
#6 0x56481623cb4c in list_ust_event_fields commands/list.cpp:850
#7 0x5648162448d9 in cmd_list(int, char const**) commands/list.cpp:2394
#8 0x56481628fb3e in handle_command /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:238
lttng#9 0x564816290601 in parse_args /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:427
lttng#10 0x564816290908 in main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:476
lttng#11 0x7fdb8661730f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
SUMMARY: AddressSanitizer: 32 byte(s) leaked in 1 allocation(s).
The session daemon's reply is indeed never released in
lttng_list_tracepoint_fields.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Idd244b52a69f3b74e5c131c1c36c6ee6d76f4285
jgalar
added a commit
that referenced
this pull request
May 25, 2022
==1175545==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 8696 byte(s) in 1 object(s) allocated from:
#0 0x7efed0f39fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x55707ddc6004 in zmalloc_internal ../../../src/common/macros.hpp:60
#2 0x55707ddceb17 in ltt_ust_session* zmalloc<ltt_ust_session>() ../../../src/common/macros.hpp:89
#3 0x55707ddc81e7 in trace_ust_create_session(unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/trace-ust.cpp:274
#4 0x55707ddc2bea in test_create_one_ust_session /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_ust_data.cpp:63
#5 0x55707ddc4941 in main /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_ust_data.cpp:283
#6 0x7efed04f930f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Indirect leak of 24672 byte(s) in 1 object(s) allocated from:
#0 0x7efed0f39fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x55707dee4ec1 in zmalloc_internal ../../../src/common/macros.hpp:60
#2 0x55707def774e in consumer_output* zmalloc<consumer_output>() ../../../src/common/macros.hpp:89
#3 0x55707dee90df in consumer_create_output(consumer_dst_type) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/consumer.cpp:523
#4 0x55707ddc8821 in trace_ust_create_session(unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/trace-ust.cpp:321
#5 0x55707ddc2bea in test_create_one_ust_session /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_ust_data.cpp:63
#6 0x55707ddc4941 in main /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_ust_data.cpp:283
#7 0x7efed04f930f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Indirect leak of 1024 byte(s) in 1 object(s) allocated from:
#0 0x7efed0f39fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x7efed0bf985f in alloc_split_items_count /home/jgalar/EfficiOS/src/userspace-rcu/src/rculfhash.c:688
#2 0x7efed0bf985f in _cds_lfht_new /home/jgalar/EfficiOS/src/userspace-rcu/src/rculfhash.c:1642
Indirect leak of 656 byte(s) in 1 object(s) allocated from:
#0 0x7efed0f39fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x7efed0bfac68 in __default_alloc_cds_lfht ../src/rculfhash-internal.h:172
#2 0x7efed0bfac68 in alloc_cds_lfht /home/jgalar/EfficiOS/src/userspace-rcu/src/rculfhash-mm-order.c:81
Indirect leak of 48 byte(s) in 2 object(s) allocated from:
#0 0x7efed0f39fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x7efed0bfabd4 in cds_lfht_alloc_bucket_table /home/jgalar/EfficiOS/src/userspace-rcu/src/rculfhash-mm-order.c:35
#2 0x7efed0bfabd4 in cds_lfht_alloc_bucket_table /home/jgalar/EfficiOS/src/userspace-rcu/src/rculfhash-mm-order.c:28
Indirect leak of 24 byte(s) in 1 object(s) allocated from:
#0 0x7efed0f39fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x55707de3a9af in zmalloc_internal ../../src/common/macros.hpp:60
#2 0x55707de3a9bf in lttng_ht* zmalloc<lttng_ht>() ../../src/common/macros.hpp:89
#3 0x55707de38461 in lttng_ht_new(unsigned long, lttng_ht_type) hashtable/hashtable.cpp:113
#4 0x55707dee9340 in consumer_create_output(consumer_dst_type) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/consumer.cpp:535
#5 0x55707ddc8821 in trace_ust_create_session(unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/trace-ust.cpp:321
#6 0x55707ddc2bea in test_create_one_ust_session /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_ust_data.cpp:63
#7 0x55707ddc4941 in main /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_ust_data.cpp:283
#8 0x7efed04f930f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Indirect leak of 16 byte(s) in 1 object(s) allocated from:
#0 0x7efed0f39fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x7efed0bfac15 in cds_lfht_alloc_bucket_table /home/jgalar/EfficiOS/src/userspace-rcu/src/rculfhash-mm-order.c:31
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ib2ad82a197f2a4ccb86ae5799c1d93ff059888e3
jgalar
added a commit
that referenced
this pull request
May 25, 2022
==1190137==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 8 byte(s) in 1 object(s) allocated from:
#0 0x7f40a9d4c1b2 in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:164
#1 0x55ab716e1def in lttng_dynamic_buffer_set_capacity(lttng_dynamic_buffer*, unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-buffer.cpp:159
#2 0x55ab716e1956 in lttng_dynamic_buffer_append(lttng_dynamic_buffer*, void const*, unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-buffer.cpp:52
#3 0x55ab716ca64e in lttng_log_level_rule_serialize(lttng_log_level_rule const*, lttng_payload*) /home/jgalar/EfficiOS/src/lttng-tools/src/common/log-level-rule.cpp:177
#4 0x55ab716c760f in test_log_level_rule_serialize_deserialize /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_log_level_rule.cpp:60
#5 0x55ab716c8457 in test_log_level_rule_at_least_as_severe_as /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_log_level_rule.cpp:177
#6 0x55ab716c84d3 in main /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_log_level_rule.cpp:185
#7 0x7f40a938830f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Direct leak of 8 byte(s) in 1 object(s) allocated from:
#0 0x7f40a9d4c1b2 in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:164
#1 0x55ab716e1def in lttng_dynamic_buffer_set_capacity(lttng_dynamic_buffer*, unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-buffer.cpp:159
#2 0x55ab716e1956 in lttng_dynamic_buffer_append(lttng_dynamic_buffer*, void const*, unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-buffer.cpp:52
#3 0x55ab716ca64e in lttng_log_level_rule_serialize(lttng_log_level_rule const*, lttng_payload*) /home/jgalar/EfficiOS/src/lttng-tools/src/common/log-level-rule.cpp:177
#4 0x55ab716c760f in test_log_level_rule_serialize_deserialize /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_log_level_rule.cpp:60
#5 0x55ab716c8135 in test_log_level_rule_exactly /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_log_level_rule.cpp:154
#6 0x55ab716c84ce in main /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_log_level_rule.cpp:184
#7 0x7f40a938830f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I2d1eafabbd5c101c188bad8a2137615b29c0ef68
jgalar
added a commit
that referenced
this pull request
May 25, 2022
==1198508==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 56 byte(s) in 1 object(s) allocated from:
#0 0x7f8b62634fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x557871869adb in zmalloc_internal ../../src/common/macros.hpp:60
#2 0x55787186c8a0 in zmalloc<(anonymous namespace)::lttng_rate_policy_once_after_n> ../../src/common/macros.hpp:89
#3 0x55787186c173 in lttng_rate_policy_once_after_n_create actions/rate-policy.cpp:707
#4 0x55787186a368 in lttng_rate_policy_once_after_n_create_from_payload actions/rate-policy.cpp:183
#5 0x55787186ad02 in lttng_rate_policy_create_from_payload(lttng_payload_view*, lttng_rate_policy**) actions/rate-policy.cpp:287
#6 0x557871865b5b in test_rate_policy_once_after_n /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_rate_policy.cpp:231
#7 0x557871865dc9 in main /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_rate_policy.cpp:250
#8 0x7f8b61c7130f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Direct leak of 56 byte(s) in 1 object(s) allocated from:
#0 0x7f8b62634fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x557871869adb in zmalloc_internal ../../src/common/macros.hpp:60
#2 0x55787186c890 in zmalloc<(anonymous namespace)::lttng_rate_policy_every_n> ../../src/common/macros.hpp:89
#3 0x55787186b6cd in lttng_rate_policy_every_n_create actions/rate-policy.cpp:492
#4 0x55787186a699 in lttng_rate_policy_every_n_create_from_payload actions/rate-policy.cpp:220
#5 0x55787186ad02 in lttng_rate_policy_create_from_payload(lttng_payload_view*, lttng_rate_policy**) actions/rate-policy.cpp:287
#6 0x557871864cae in test_rate_policy_every_n /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_rate_policy.cpp:122
#7 0x557871865dc4 in main /home/jgalar/EfficiOS/src/lttng-tools/tests/unit/test_rate_policy.cpp:249
#8 0x7f8b61c7130f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
SUMMARY: AddressSanitizer: 112 byte(s) leaked in 2 allocation(s).
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I3a9b4d99e93f355ddb8623a289f8397907486ab0
jgalar
added a commit
that referenced
this pull request
May 25, 2022
==1429021==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 8 byte(s) in 1 object(s) allocated from:
#0 0x7fe305f031b2 in __interceptor_realloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:164
#1 0x559f1b022238 in lttng_dynamic_buffer_set_capacity(lttng_dynamic_buffer*, unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-buffer.cpp:159
#2 0x559f1b021d9f in lttng_dynamic_buffer_append(lttng_dynamic_buffer*, void const*, unsigned long) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-buffer.cpp:52
#3 0x559f1b02144a in lttng_dynamic_array_add_element(lttng_dynamic_array*, void const*) /home/jgalar/EfficiOS/src/lttng-tools/src/common/dynamic-array.cpp:58
#4 0x559f1b07d07b in lttng_action_path_copy(lttng_action_path const*, lttng_action_path*) actions/path.cpp:116
#5 0x559f1b02383f in lttng_error_query_action_create /home/jgalar/EfficiOS/src/lttng-tools/src/common/error-query.cpp:232
#6 0x559f1b02760e in lttng_error_query_create_from_payload(lttng_payload_view*, lttng_error_query**) /home/jgalar/EfficiOS/src/lttng-tools/src/common/error-query.cpp:911
#7 0x559f1af5c361 in receive_lttng_error_query /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:740
#8 0x559f1af64eba in process_client_msg /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2336
lttng#9 0x559f1af67378 in thread_manage_clients /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2624
lttng#10 0x559f1af50642 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:68
lttng#11 0x7fe3055225c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I7a6f7d2a9746124581eebf30877466f16db67a6b
jgalar
added a commit
that referenced
this pull request
May 25, 2022
==1480456==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 112 byte(s) in 1 object(s) allocated from:
#0 0x7fdb9260cfb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x7fdb9242348d in zmalloc_internal ../../src/common/macros.hpp:60
#2 0x7fdb924295a9 in lttng_trigger* zmalloc<lttng_trigger>() ../../src/common/macros.hpp:89
#3 0x7fdb92423dbe in lttng_trigger_create /home/jgalar/EfficiOS/src/lttng-tools/src/common/trigger.cpp:58
#4 0x56304832331f in register_trigger /home/jgalar/EfficiOS/src/lttng-tools/tests/regression/tools/trigger/utils/register-some-triggers.cpp:24
#5 0x5630483233f1 in register_trigger_action_list_notify /home/jgalar/EfficiOS/src/lttng-tools/tests/regression/tools/trigger/utils/register-some-triggers.cpp:46
#6 0x5630483239a0 in test_session_rotation_conditions /home/jgalar/EfficiOS/src/lttng-tools/tests/regression/tools/trigger/utils/register-some-triggers.cpp:246
#7 0x563048323d4d in main /home/jgalar/EfficiOS/src/lttng-tools/tests/regression/tools/trigger/utils/register-some-triggers.cpp:309
#8 0x7fdb91c6630f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ie163989a70f65f9c2c4e93c36cc9fc6ba6bdeeb5
jgalar
added a commit
that referenced
this pull request
May 25, 2022
==1501334==ERROR: LeakSanitizer: detected memory leaks
Indirect leak of 16386 byte(s) in 1 object(s) allocated from:
#0 0x7f95efc3cdd9 in __interceptor_malloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:145
#1 0x55acb0681ed3 in lttng_filter_yyalloc(unsigned long, void*) filter/filter-lexer.cpp:2511
#2 0x55acb067f2f2 in lttng_filter_yy_create_buffer(_IO_FILE*, int, void*) filter/filter-lexer.cpp:1895
#3 0x55acb067ea44 in yyrestart(_IO_FILE*, void*) filter/filter-lexer.cpp:1824
#4 0x55acb0649a43 in filter_parser_ctx_alloc(_IO_FILE*) filter/filter-parser.ypp:271
#5 0x55acb0649e7f in filter_parser_ctx_create_from_filter_expression(char const*, filter_parser_ctx**) filter/filter-parser.ypp:332
#6 0x55acb058ee89 in parse_event_rule commands/add_trigger.cpp:783
#7 0x55acb05920c0 in handle_condition_event commands/add_trigger.cpp:1361
#8 0x55acb0592739 in parse_condition commands/add_trigger.cpp:1457
lttng#9 0x55acb0596b56 in cmd_add_trigger(int, char const**) commands/add_trigger.cpp:2304
lttng#10 0x55acb05a5b80 in handle_command /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:238
lttng#11 0x55acb05a6643 in parse_args /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:427
lttng#12 0x55acb05a694a in main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:476
lttng#13 0x7f95ef28730f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I6fa21e7d066e0cf48afc3f91ceefbfd19c6b86fd
jgalar
added a commit
that referenced
this pull request
May 25, 2022
==1769573==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 24 byte(s) in 1 object(s) allocated from:
#0 0x7fef37a29fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x7fef37792f2f in zmalloc_internal ../../../src/common/macros.hpp:60
#2 0x7fef3779573a in lttng_rotation_schedules* zmalloc<lttng_rotation_schedules>() ../../../src/common/macros.hpp:89
#3 0x7fef377947cc in lttng_rotation_schedules_create /home/jgalar/EfficiOS/src/lttng-tools/src/lib/lttng-ctl/rotate.cpp:353
#4 0x7fef37794aa0 in get_schedules /home/jgalar/EfficiOS/src/lttng-tools/src/lib/lttng-ctl/rotate.cpp:392
#5 0x7fef377956dc in lttng_session_list_rotation_schedules /home/jgalar/EfficiOS/src/lttng-tools/src/lib/lttng-ctl/rotate.cpp:665
#6 0x5646131713f2 in test_add_list_remove_schedule /home/jgalar/EfficiOS/src/lttng-tools/tests/regression/tools/rotation/schedule_api.c:252
#7 0x56461317157b in test_add_list_remove_size_schedule /home/jgalar/EfficiOS/src/lttng-tools/tests/regression/tools/rotation/schedule_api.c:270
#8 0x564613171680 in main /home/jgalar/EfficiOS/src/lttng-tools/tests/regression/tools/rotation/schedule_api.c:307
lttng#9 0x7fef373ae30f in __libc_start_call_main (/usr/lib/libc.so.6+0x2d30f)
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I9b7eb537d158791db76f9a7676ffeb5d4a1f2203
jgalar
added a commit
that referenced
this pull request
May 25, 2022
==1801304==ERROR: LeakSanitizer: detected memory leaks
Direct leak of 224 byte(s) in 2 object(s) allocated from:
#0 0x7fe0f4e73fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x559fbeb64175 in zmalloc_internal ../../src/common/macros.hpp:60
#2 0x559fbeb6a291 in lttng_trigger* zmalloc<lttng_trigger>() ../../src/common/macros.hpp:89
#3 0x559fbeb64aa6 in lttng_trigger_create /home/jgalar/EfficiOS/src/lttng-tools/src/common/trigger.cpp:58
#4 0x559fbe9dc417 in subscribe_session_consumed_size_rotation(ltt_session*, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/rotate.cpp:87
#5 0x559fbe995d6f in cmd_rotation_set_schedule(ltt_session*, bool, lttng_rotation_schedule_type, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/cmd.cpp:5993
#6 0x559fbe9fe559 in process_client_msg /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2246
#7 0x559fbea01378 in thread_manage_clients /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2624
#8 0x559fbe9ea642 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:68
lttng#9 0x7fe0f44935c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
Indirect leak of 208 byte(s) in 2 object(s) allocated from:
#0 0x7fe0f4e73fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x559fbeb16e21 in zmalloc_internal ../../src/common/macros.hpp:60
#2 0x559fbeb16e31 in lttng_action_notify* zmalloc<lttng_action_notify>() ../../src/common/macros.hpp:89
#3 0x559fbeb168a0 in lttng_action_notify_create actions/notify.cpp:135
#4 0x559fbe9dc34b in subscribe_session_consumed_size_rotation(ltt_session*, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/rotate.cpp:80
#5 0x559fbe995d6f in cmd_rotation_set_schedule(ltt_session*, bool, lttng_rotation_schedule_type, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/cmd.cpp:5993
#6 0x559fbe9fe559 in process_client_msg /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2246
#7 0x559fbea01378 in thread_manage_clients /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2624
#8 0x559fbe9ea642 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:68
lttng#9 0x7fe0f44935c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
Indirect leak of 160 byte(s) in 2 object(s) allocated from:
#0 0x7fe0f4e73fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x559fbeb3d7a1 in zmalloc_internal ../../src/common/macros.hpp:60
#2 0x559fbeb3fa35 in lttng_condition_session_consumed_size* zmalloc<lttng_condition_session_consumed_size>() ../../src/common/macros.hpp:89
#3 0x559fbeb3e6fd in lttng_condition_session_consumed_size_create conditions/session-consumed-size.cpp:206
#4 0x559fbe9dc0f1 in subscribe_session_consumed_size_rotation(ltt_session*, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/rotate.cpp:54
#5 0x559fbe995d6f in cmd_rotation_set_schedule(ltt_session*, bool, lttng_rotation_schedule_type, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/cmd.cpp:5993
#6 0x559fbe9fe559 in process_client_msg /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2246
#7 0x559fbea01378 in thread_manage_clients /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2624
#8 0x559fbe9ea642 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:68
lttng#9 0x7fe0f44935c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
Indirect leak of 112 byte(s) in 2 object(s) allocated from:
#0 0x7fe0f4e73fb9 in __interceptor_calloc /usr/src/debug/gcc/libsanitizer/asan/asan_malloc_linux.cpp:154
#1 0x559fbeb242ad in zmalloc_internal ../../src/common/macros.hpp:60
#2 0x559fbeb27062 in zmalloc<(anonymous namespace)::lttng_rate_policy_every_n> ../../src/common/macros.hpp:89
#3 0x559fbeb25e9f in lttng_rate_policy_every_n_create actions/rate-policy.cpp:492
#4 0x559fbeb168b9 in lttng_action_notify_create actions/notify.cpp:141
#5 0x559fbe9dc34b in subscribe_session_consumed_size_rotation(ltt_session*, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/rotate.cpp:80
#6 0x559fbe995d6f in cmd_rotation_set_schedule(ltt_session*, bool, lttng_rotation_schedule_type, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/cmd.cpp:5993
#7 0x559fbe9fe559 in process_client_msg /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2246
#8 0x559fbea01378 in thread_manage_clients /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2624
lttng#9 0x559fbe9ea642 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:68
lttng#10 0x7fe0f44935c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
Indirect leak of 34 byte(s) in 2 object(s) allocated from:
#0 0x7fe0f4e19319 in __interceptor_strdup /usr/src/debug/gcc/libsanitizer/asan/asan_interceptors.cpp:454
#1 0x559fbeb3f603 in lttng_condition_session_consumed_size_set_session_name conditions/session-consumed-size.cpp:442
#2 0x559fbe9dc2c4 in subscribe_session_consumed_size_rotation(ltt_session*, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/rotate.cpp:71
#3 0x559fbe995d6f in cmd_rotation_set_schedule(ltt_session*, bool, lttng_rotation_schedule_type, unsigned long, notification_thread_handle*) /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/cmd.cpp:5993
#4 0x559fbe9fe559 in process_client_msg /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2246
#5 0x559fbea01378 in thread_manage_clients /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/client.cpp:2624
#6 0x559fbe9ea642 in launch_thread /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng-sessiond/thread.cpp:68
#7 0x7fe0f44935c1 in start_thread (/usr/lib/libc.so.6+0x8d5c1)
The rotation trigger of a session (used for size-based rotations) is
never cleaned-up. It is now cleaned up every time its condition is
hit and whenever the session is destroyed.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I5a89341535f87b7851b548ded9838c18bd1ccb95
jgalar
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that referenced
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Apr 19, 2023
Observed issue ============== While a snapshot is being taken, the containing folder can disappear unexpectedly. This can lead to the following errors, which are expected and mostly handled fine: PERROR - 14:47:32.002564464 [2922498/2922507]: Failed to open file relative to trace chunk file_path = "channel0_0", flags = 577, mode = 432: No such file or directory (in _lttng_trace_chunk_open_fs_handle_locked() at trace-chunk.cpp:1411) Error: Failed to open stream file "channel0_0" Error: Snapshot channel failed The problem happens on the subsequent snapshot for the session: #0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50 #1 0x00007fbbdadb3859 in __GI_abort () at abort.c:79 #2 0x00007fbbdadb3729 in __assert_fail_base (fmt=0x7fbbdaf49588 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", assertion=0x55c4212cfbb5 "!stream->trace_chunk", file=0x55c4212cf820 "kernel-co #3 0x00007fbbdadc5006 in __GI___assert_fail (assertion=0x55c4212cfbb5 "!stream->trace_chunk", file=0x55c4212cf820 "kernel-consumer/kernel-consumer.cpp", line=188, function=0x55c4212cfb00 " #4 0x000055c421268cc6 in lttng_kconsumer_snapshot_channel (channel=0x7fbbc4000b60, key=1, path=0x7fbbd37f8fd4 "", relayd_id=18446744073709551615, nb_packets_per_stream=0) at kernel-consume #5 0x000055c42126b39d in lttng_kconsumer_recv_cmd (ctx=0x55c421b80a90, sock=31, consumer_sockpoll=0x7fbbd37fd280) at kernel-consumer/kernel-consumer.cpp:986 #6 0x000055c4212546d1 in lttng_consumer_recv_cmd (ctx=0x55c421b80a90, sock=31, consumer_sockpoll=0x7fbbd37fd280) at consumer/consumer.cpp:2090 #7 0x000055c421259963 in consumer_thread_sessiond_poll (data=0x55c421b80a90) at consumer/consumer.cpp:3281 #8 0x00007fbbdaf8b609 in start_thread (arg=<optimized out>) at pthread_create.c:477 lttng#9 0x00007fbbdaeb0163 in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95 How to reproduce: 1. Setting a breakpoint on snapshot_channel() inside src/common/ust-consumer/ust-consumer.cpp 2. When the breakpoint hits, remove the the complete lttng directory containing the session data. 3. Continue the lttng_consumerd process from gdb. 4. In that case you see a negative return value -1 from consumer_stream_create_output_files() inside snapshot_channel(). 5. Take another snapshot and lttng_consumerd crashes because of the `assert(!stream->trace_chunk)` in snapshot_channel(). This last action does not require any breakpoint intervention. Cause ===== During the snapshot, the stream is assigned the channel current chunk. It is expected that the stream does not have a chunk at this point. The error handling is faulty here, the stream chunk must be invalidated/reset on error to allow its reuse later on. The problem exists for both consumer domains (user/kernel). Solution ======== For the ust consumer, we can directly use the `error_close_stream` label. For the kernel consumer, the code path is slightly different since it does not uses `consumer_stream_close`. Note that `consumer_stream_close` cannot be used as is for the kernel consumer. The current implementation partially resembles `consumer_stream_close` at the end of the iteration. It is extracted to its own function for easier reuse from the new `error_finalize_stream` label. Known drawbacks ========= None. Fixes: #1352 Signed-off-by: Marcel Hamer <marcel.hamer@windriver.com> Signed-off-by: Jonathan Rajotte <jonathan.rajotte-julien@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I9fc81917b19aa436ed8e8679672648f2d5baf41a
jgalar
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that referenced
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Apr 19, 2023
When converting msgpack objects to their event_field_value equivalent, the following assertion fails: LTTNG_ASSERT(val); #4 0x00007f1f65349486 in __assert_fail () from /usr/lib/libc.so.6 #5 0x00007f1f65584da7 in lttng_event_field_value_string_create_with_size (val=0x0, size=0) at event-field-value.cpp:186 #6 0x00007f1f65576a1a in event_field_value_from_obj (obj=0x557f597ccdb8, field_val=0x7ffcc9675dd0) at conditions/event-rule-matches.cpp:1120 #7 0x00007f1f65577176 in event_field_value_from_capture_payload (condition=0x557f597c8520, capture_payload=0x557f597c825b "\221\240", capture_payload_size=2) at conditions/event-rule-matches.cpp:1340 #8 0x00007f1f655772ea in lttng_evaluation_event_rule_matches_create (condition=0x557f597c8520, capture_payload=0x557f597c825b "\221\240", capture_payload_size=2, decode_capture_payload=true) at conditions/event-rule-matches.cpp:1398 lttng#9 0x00007f1f655765fc in lttng_evaluation_event_rule_matches_create_from_payload (condition=0x557f597c8520, view=0x7ffcc9675ff0, _evaluation=0x7ffcc9676080) at conditions/event-rule-matches.cpp:990 lttng#10 0x00007f1f6557f273 in lttng_evaluation_create_from_payload (condition=0x557f597c8520, src_view=0x7ffcc9676100, evaluation=0x7ffcc9676080) at evaluation.cpp:120 lttng#11 0x00007f1f6559ba36 in lttng_notification_create_from_payload (src_view=0x7ffcc9676190, notification=0x7ffcc9676180) at notification.cpp:123 lttng#12 0x00007f1f65552577 in create_notification_from_current_message (channel=0x557f597c8ee0) at channel.cpp:124 lttng#13 0x00007f1f6555298c in lttng_notification_channel_get_next_notification (channel=0x557f597c8ee0, _notification=0x7ffcc9676280) at channel.cpp:292 The msgpack API represents string as p-style while the implementation of event_field_value relies on null-terminated strings. When an empty string is captured by a tracer, it is decoded as a msgpack_object with `str = {size = 0, ptr = 0x0}`. lttng_event_field_value_string_create_with_size does not require a null-terminated string since it also receives the length. Hence, this fix causes lttng_event_field_value_string_create_with_size to accept null strings when their length is zero. A copy of an empty string is made to accomodate the null-termination convention used by the rest of that API. Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com> Change-Id: I7c3a839dbbeeb95a1b3bf6ddc3205a2f6b4538e3
jgalar
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Dec 18, 2023
Issue observed -------------- When using the CLI to list the configuration of a session that has an event rule which makes use of multiple exclusions, the session daemon crashes with the following stack trace: (gdb) bt #0 0x00007fa9ed401445 in ?? () from /usr/lib/libc.so.6 #1 0x0000560cd5fc5199 in lttng_strnlen (str=0x615f6f6c6c6568 <error: Cannot access memory at address 0x615f6f6c6c6568>, max=256) at ../../src/common/compat/string.h:19 #2 0x0000560cd5fc6b39 in lttng_event_serialize (event=0x7fa9cc01d8b0, exclusion_count=2, exclusion_list=0x7fa9cc011794, filter_expression=0x0, bytecode_len=0, bytecode=0x0, payload=0x7fa9d3ffda88) at event.c:767 #3 0x0000560cd5f380b5 in list_lttng_ust_global_events (nb_events=<synthetic pointer>, reply_payload=0x7fa9d3ffda88, ust_global=<optimized out>, channel_name=<optimized out>) at cmd.c:472 #4 cmd_list_events (domain=<optimized out>, session=<optimized out>, channel_name=<optimized out>, reply_payload=0x7fa9d3ffda88) at cmd.c:3860 #5 0x0000560cd5f6d76a in process_client_msg (cmd_ctx=0x7fa9d3ffa710, sock=0x7fa9d3ffa5b0, sock_error=0x7fa9d3ffa5b4) at client.c:1890 #6 0x0000560cd5f6f876 in thread_manage_clients (data=0x560cd7879490) at client.c:2629 #7 0x0000560cd5f65a54 in launch_thread (data=0x560cd7879500) at thread.c:66 #8 0x00007fa9ed32d44b in ?? () from /usr/lib/libc.so.6 lttng#9 0x00007fa9ed3b0e40 in ?? () from /usr/lib/libc.so.6 Cause ----- lttng_event_serialize expects a `char **` list of exclusion names, as provided by the other callsite in liblttng-ctl. However, the callsite in list_lttng_ust_global_events passes pointer to the exclusions as stored in lttng_event_exclusion. lttng_event_exclusion contains an array of fixed-length strings (with a stride of 256 bytes) which isn't an expected layout for lttng_event_serialize. Solution -------- A temporary array of pointers is constructed before invoking lttng_event_serialize to construct a list of exclusions with the layout that lttng_event_serialize expects. The array itself is reused for all events, limiting the number of allocations. Note ---- None. Change-Id: I266a1cc9e9f18e0476177a0047b1d8f468110575 Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
jgalar
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Dec 18, 2023
Issue observed
--------------
When running the session daemon under ASAN, the following report is
produced:
Direct leak of 104 byte(s) in 1 object(s) allocated from:
#0 0x7f93866e0cd1 in __interceptor_calloc /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:77
#1 0x55c55a7c4963 in zmalloc_internal /home/simark/src/lttng-tools/src/common/macros.hpp:60
#2 0x55c55a7c4973 in lttng_pipe* zmalloc<lttng_pipe>() /home/simark/src/lttng-tools/src/common/macros.hpp:88
#3 0x55c55a7c26eb in _pipe_create /home/simark/src/lttng-tools/src/common/pipe.cpp:111
#4 0x55c55a7c351d in lttng_pipe_open(int) /home/simark/src/lttng-tools/src/common/pipe.cpp:185
#5 0x55c55a586dd6 in operator() /home/simark/src/lttng-tools/src/bin/lttng-sessiond/rotation-thread.cpp:403
#6 0x55c55a58744a in lttng::sessiond::rotation_thread::rotation_thread(lttng::sessiond::rotation_thread_timer_queue&, notification_thread_handle&) /home/simark/src/lttng-tools/src/bin/lttng-sessiond/rotation-thread.cpp:402
#7 0x55c55a46377f in std::unique_ptr<lttng::sessiond::rotation_thread, std::default_delete<lttng::sessiond::rotation_thread> > lttng::make_unique<lttng::sessiond::rotation_thread, lttng::sessiond::rotation_thread_timer_queue&, notification_thread_handle&>(lttng::sessiond::rotation_thread_timer_queue&, notification_thread_handle&) /home/simark/src/lttng-tools/src/common/make-unique.hpp:18
#8 0x55c55a455024 in _main /home/simark/src/lttng-tools/src/bin/lttng-sessiond/main.cpp:1773
lttng#9 0x55c55a455c2e in main /home/simark/src/lttng-tools/src/bin/lttng-sessiond/main.cpp:1982
lttng#10 0x7f9385c1484f (/usr/lib/libc.so.6+0x2384f) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e)
Cause
-----
On destruction, the std::unique_ptr wrapper of
lttng_pipe (lttng_pipe::uptr) invokes `lttng_pipe_close` (which only
closes the file descriptors of the underlying pipe) rather than
`lttng_pipe_destroy` which closes the file descriptors _and_ frees the
memory allocated by lttng_open.
Currently, the rotation thread is the only user of this wrapper (through
its quit_pipe).
Solution
--------
The deleter of lttng_pipe::uptr is replaced to invoke lttng_pipe_destroy.
Fixes #1380
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I5715ac6131c5aa134cfd18d8b677f31aabed36f0
jgalar
added a commit
that referenced
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Dec 18, 2023
Issue observed
--------------
ASAN reports the following leak when running the
tests/regression/tools/context/test_ust.py test suite:
Direct leak of 8 byte(s) in 1 object(s) allocated from:
#0 0x7f32e5ae0cd1 in __interceptor_calloc /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:77
#1 0x5653e1092088 in zmalloc_internal ../../../src/common/macros.hpp:60
#2 0x5653e10922b3 in char* calloc<char>(unsigned long) string-utils/../macros.hpp:113
#3 0x5653e119d68f in get_context_type commands/add_context.cpp:1012
#4 0x5653e119ddf5 in cmd_add_context(int, char const**) commands/add_context.cpp:1059
#5 0x5653e11e12e7 in handle_command /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:237
#6 0x5653e11e2027 in parse_args /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:427
#7 0x5653e11e24e1 in _main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:474
#8 0x5653e11e25bd in main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:485
lttng#9 0x7f32e3e3984f (/usr/lib/libc.so.6+0x2384f) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e)
Direct leak of 5 byte(s) in 1 object(s) allocated from:
#0 0x7f32e5ae0cd1 in __interceptor_calloc /usr/src/debug/gcc/gcc/libsanitizer/asan/asan_malloc_linux.cpp:77
#1 0x5653e1092088 in zmalloc_internal ../../../src/common/macros.hpp:60
#2 0x5653e10922b3 in char* calloc<char>(unsigned long) string-utils/../macros.hpp:113
#3 0x5653e119d2ae in get_context_type commands/add_context.cpp:1003
#4 0x5653e119ddf5 in cmd_add_context(int, char const**) commands/add_context.cpp:1059
#5 0x5653e11e12e7 in handle_command /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:237
#6 0x5653e11e2027 in parse_args /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:427
#7 0x5653e11e24e1 in _main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:474
#8 0x5653e11e25bd in main /home/jgalar/EfficiOS/src/lttng-tools/src/bin/lttng/lttng.cpp:485
lttng#9 0x7f32e3e3984f (/usr/lib/libc.so.6+0x2384f) (BuildId: 2f005a79cd1a8e385972f5a102f16adba414d75e)
Cause
-----
The context and provider names are dynamically allocated by
get_context_type() and stored in ctx_type. However, destroy_ctx_type()
never frees those members when the structure is of type
CONTEXT_APP_CONTEXT.
Solution
--------
Free both names when an application context type is destroyed.
Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: I86dde1eed9f0cc63499c936cf373b094168035e2
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Mostly fix error path.
These are "least intrusive change", we might want to review some method signature for error propagation.