Optimize strspn. #603

V0idk · 2018-10-02T17:51:52Z

Variable count is redundant.

KernelPRBot · 2018-10-02T17:54:37Z

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lieuwex · 2018-10-04T16:27:01Z

lib/string.c


 	for (p = s; *p != '\0'; ++p) {
 		for (a = accept; *a != '\0'; ++a) {
 			if (*p == *a)
 				break;
 		}
 		if (*a == '\0')
-			return count;
-		++count;
+			p - s;


shouldn't this be return p-s;

...my falut

While running the linux-nex with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Cc: stable <stable@vger.kernel.org> # 5.1+

While running the linux-nex with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

While running the linux-next with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> [Fixed a typograhic error in the changelog] Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

While running the linux-next with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Cc: stable <stable@vger.kernel.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> [Fixed a typograhic error in the changelog] Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Link: https://lore.kernel.org/r/20190801172323.18359-2-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

commit 5511c0c upstream. While running the linux-next with CONFIG_DEBUG_LOCKS_ALLOC enabled, I get the following splat. BUG: key ffffcb5636929298 has not been registered! ------------[ cut here ]------------ DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 1 PID: 53 at kernel/locking/lockdep.c:3669 lockdep_init_map+0x164/0x1f0 CPU: 1 PID: 53 Comm: kworker/1:1 Tainted: G W 5.2.0-next-20190712-00015-g00ad4634222e-dirty torvalds#603 Workqueue: events amba_deferred_retry_func pstate: 60c00005 (nZCv daif +PAN +UAO) pc : lockdep_init_map+0x164/0x1f0 lr : lockdep_init_map+0x164/0x1f0 [ trimmed ] Call trace: lockdep_init_map+0x164/0x1f0 __kernfs_create_file+0x9c/0x158 sysfs_add_file_mode_ns+0xa8/0x1d0 sysfs_add_file_to_group+0x88/0xd8 etm_perf_add_symlink_sink+0xcc/0x138 coresight_register+0x110/0x280 tmc_probe+0x160/0x420 [ trimmed ] ---[ end trace ab4cc669615ba1b0 ]--- Fix this by initialising the dynamically allocated attribute properly. Cc: Mathieu Poirier <mathieu.poirier@linaro.org> Fixes: bb8e370 ("coresight: perf: Add "sinks" group to PMU directory") Cc: stable <stable@vger.kernel.org> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com> [Fixed a typograhic error in the changelog] Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Link: https://lore.kernel.org/r/20190801172323.18359-2-mathieu.poirier@linaro.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Fixes checkpatch issues: CHECK: Alignment should match open parenthesis torvalds#87: FILE: drivers/reset/core.c:87: +static int of_reset_simple_xlate(struct reset_controller_dev *rcdev, + const struct of_phandle_args *reset_spec) CHECK: Lines should not end with a '(' torvalds#540: FILE: drivers/reset/core.c:540: +static struct reset_control *__reset_control_get_internal( CHECK: Alignment should match open parenthesis torvalds#603: FILE: drivers/reset/core.c:603: +struct reset_control *__of_reset_control_get(struct device_node *node, + const char *id, int index, bool shared, CHECK: Alignment should match open parenthesis torvalds#781: FILE: drivers/reset/core.c:781: +struct reset_control *__devm_reset_control_get(struct device *dev, + const char *id, int index, bool shared, Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

rust: file: Add flags() method to `File`

PD#150465: driver defect clean up: torvalds#71 torvalds#77 torvalds#109 torvalds#127 torvalds#411 torvalds#600 torvalds#602 torvalds#603 torvalds#604 torvalds#611 torvalds#612 Change-Id: I38ac5ed6583bd6e57df9f42eaab04d05ee4ed663 Signed-off-by: Evoke Zhang <evoke.zhang@amlogic.com>

According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>

According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net>

[ Upstream commit 6ca3c00 ] According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org>

[ Upstream commit 6ca3c00 ] According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Ulrich Hecht <uli@kernel.org>

BugLink: https://bugs.launchpad.net/bugs/2034469 [ Upstream commit 6ca3c00 ] According to the synchronization rules for .ndo_get_stats() as seen in Documentation/networking/netdevices.rst, acquiring a plain spin_lock() should not be illegal, but the bridge driver implementation makes it so. After running these commands, I am being faced with the following lockdep splat: $ ip link add link swp0 name macsec0 type macsec encrypt on && ip link set swp0 up $ ip link add dev br0 type bridge vlan_filtering 1 && ip link set br0 up $ ip link set macsec0 master br0 && ip link set macsec0 up ======================================================== WARNING: possible irq lock inversion dependency detected 6.4.0-04295-g31b577b4bd4a torvalds#603 Not tainted -------------------------------------------------------- swapper/1/0 just changed the state of lock: ffff6bd348724cd8 (&br->lock){+.-.}-{3:3}, at: br_forward_delay_timer_expired+0x34/0x198 but this lock took another, SOFTIRQ-unsafe lock in the past: (&ocelot->stats_lock){+.+.}-{3:3} and interrupts could create inverse lock ordering between them. other info that might help us debug this: Chain exists of: &br->lock --> &br->hash_lock --> &ocelot->stats_lock Possible interrupt unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ocelot->stats_lock); local_irq_disable(); lock(&br->lock); lock(&br->hash_lock); <Interrupt> lock(&br->lock); *** DEADLOCK *** (details about the 3 locks skipped) swp0 is instantiated by drivers/net/dsa/ocelot/felix.c, and this only matters to the extent that its .ndo_get_stats64() method calls spin_lock(&ocelot->stats_lock). Documentation/locking/lockdep-design.rst says: | A lock is irq-safe means it was ever used in an irq context, while a lock | is irq-unsafe means it was ever acquired with irq enabled. (...) | Furthermore, the following usage based lock dependencies are not allowed | between any two lock-classes:: | | <hardirq-safe> -> <hardirq-unsafe> | <softirq-safe> -> <softirq-unsafe> Lockdep marks br->hash_lock as softirq-safe, because it is sometimes taken in softirq context (for example br_fdb_update() which runs in NET_RX softirq), and when it's not in softirq context it blocks softirqs by using spin_lock_bh(). Lockdep marks ocelot->stats_lock as softirq-unsafe, because it never blocks softirqs from running, and it is never taken from softirq context. So it can always be interrupted by softirqs. There is a call path through which a function that holds br->hash_lock: fdb_add_hw_addr() will call a function that acquires ocelot->stats_lock: ocelot_port_get_stats64(). This can be seen below: ocelot_port_get_stats64+0x3c/0x1e0 felix_get_stats64+0x20/0x38 dsa_slave_get_stats64+0x3c/0x60 dev_get_stats+0x74/0x2c8 rtnl_fill_stats+0x4c/0x150 rtnl_fill_ifinfo+0x5cc/0x7b8 rtmsg_ifinfo_build_skb+0xe4/0x150 rtmsg_ifinfo+0x5c/0xb0 __dev_notify_flags+0x58/0x200 __dev_set_promiscuity+0xa0/0x1f8 dev_set_promiscuity+0x30/0x70 macsec_dev_change_rx_flags+0x68/0x88 __dev_set_promiscuity+0x1a8/0x1f8 __dev_set_rx_mode+0x74/0xa8 dev_uc_add+0x74/0xa0 fdb_add_hw_addr+0x68/0xd8 fdb_add_local+0xc4/0x110 br_fdb_add_local+0x54/0x88 br_add_if+0x338/0x4a0 br_add_slave+0x20/0x38 do_setlink+0x3a4/0xcb8 rtnl_newlink+0x758/0x9d0 rtnetlink_rcv_msg+0x2f0/0x550 netlink_rcv_skb+0x128/0x148 rtnetlink_rcv+0x24/0x38 the plain English explanation for it is: The macsec0 bridge port is created without p->flags & BR_PROMISC, because it is what br_manage_promisc() decides for a VLAN filtering bridge with a single auto port. As part of the br_add_if() procedure, br_fdb_add_local() is called for the MAC address of the device, and this results in a call to dev_uc_add() for macsec0 while the softirq-safe br->hash_lock is taken. Because macsec0 does not have IFF_UNICAST_FLT, dev_uc_add() ends up calling __dev_set_promiscuity() for macsec0, which is propagated by its implementation, macsec_dev_change_rx_flags(), to the lower device: swp0. This triggers the call path: dev_set_promiscuity(swp0) -> rtmsg_ifinfo() -> dev_get_stats() -> ocelot_port_get_stats64() with a calling context that lockdep doesn't like (br->hash_lock held). Normally we don't see this, because even though many drivers that can be bridge ports don't support IFF_UNICAST_FLT, we need a driver that (a) doesn't support IFF_UNICAST_FLT, *and* (b) it forwards the IFF_PROMISC flag to another driver, and (c) *that* driver implements ndo_get_stats64() using a softirq-unsafe spinlock. Condition (b) is necessary because the first __dev_set_rx_mode() calls __dev_set_promiscuity() with "bool notify=false", and thus, the rtmsg_ifinfo() code path won't be entered. The same criteria also hold true for DSA switches which don't report IFF_UNICAST_FLT. When the DSA master uses a spin_lock() in its ndo_get_stats64() method, the same lockdep splat can be seen. I think the deadlock possibility is real, even though I didn't reproduce it, and I'm thinking of the following situation to support that claim: fdb_add_hw_addr() runs on a CPU A, in a context with softirqs locally disabled and br->hash_lock held, and may end up attempting to acquire ocelot->stats_lock. In parallel, ocelot->stats_lock is currently held by a thread B (say, ocelot_check_stats_work()), which is interrupted while holding it by a softirq which attempts to lock br->hash_lock. Thread B cannot make progress because br->hash_lock is held by A. Whereas thread A cannot make progress because ocelot->stats_lock is held by B. When taking the issue at face value, the bridge can avoid that problem by simply making the ports promiscuous from a code path with a saner calling context (br->hash_lock not held). A bridge port without IFF_UNICAST_FLT is going to become promiscuous as soon as we call dev_uc_add() on it (which we do unconditionally), so why not be preemptive and make it promiscuous right from the beginning, so as to not be taken by surprise. With this, we've broken the links between code that holds br->hash_lock or br->lock and code that calls into the ndo_change_rx_flags() or ndo_get_stats64() ops of the bridge port. Fixes: 2796d0c ("bridge: Automatically manage port promiscuous mode.") Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com> Reviewed-by: Ido Schimmel <idosch@nvidia.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

With driver_async_probe=* on kernel command line, the following trace is produced because on i.MX8M Plus hardware because the soc-imx8m.c driver calls of_clk_get_by_name() which returns -EPROBE_DEFER because the clock driver is not yet probed. This was not detected during regular testing without driver_async_probe. Attempt to fix it by probing the SoC driver late, but I don't think that is the correct approach here. " ------------[ cut here ]------------ WARNING: CPU: 1 PID: 1 at drivers/soc/imx/soc-imx8m.c:115 imx8mm_soc_revision+0xdc/0x180 CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.11.0-next-20240924-00002-g2062bb554dea torvalds#603 Hardware name: DH electronics i.MX8M Plus DHCOM Premium Developer Kit (3) (DT) pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : imx8mm_soc_revision+0xdc/0x180 lr : imx8mm_soc_revision+0xd0/0x180 sp : ffff8000821fbcc0 x29: ffff8000821fbce0 x28: 0000000000000000 x27: ffff800081810120 x26: ffff8000818a9970 x25: 0000000000000006 x24: 0000000000824311 x23: ffff8000817f42c8 x22: ffff0000df8be210 x21: fffffffffffffdfb x20: ffff800082780000 x19: 0000000000000001 x18: ffffffffffffffff x17: ffff800081fff418 x16: ffff8000823e1000 x15: ffff0000c03b65e8 x14: ffff0000c00051b0 x13: ffff800082790000 x12: 0000000000000801 x11: ffff80008278ffff x10: ffff80008209d3a6 x9 : ffff80008062e95c x8 : ffff8000821fb9a0 x7 : 0000000000000000 x6 : 00000000000080e3 x5 : ffff0000df8c03d8 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : fffffffffffffdfb x0 : fffffffffffffdfb Call trace: imx8mm_soc_revision+0xdc/0x180 imx8_soc_init+0xb0/0x1e0 do_one_initcall+0x94/0x1a8 kernel_init_freeable+0x240/0x2a8 kernel_init+0x28/0x140 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- SoC: i.MX8MP revision 1.1 " Signed-off-by: Marek Vasut <marex@denx.de>

With driver_async_probe=* on kernel command line, the following trace is produced because on i.MX8M Plus hardware because the soc-imx8m.c driver calls of_clk_get_by_name() which returns -EPROBE_DEFER because the clock driver is not yet probed. This was not detected during regular testing without driver_async_probe. Convert the SoC code to platform driver and instantiate a platform device in its current device_initcall() to probe the platform driver. Rework .soc_revision callback to always return valid error code and return SoC revision via parameter. This way, if anything in the .soc_revision callback return -EPROBE_DEFER, it gets propagated to .probe and the .probe will get retried later. " ------------[ cut here ]------------ WARNING: CPU: 1 PID: 1 at drivers/soc/imx/soc-imx8m.c:115 imx8mm_soc_revision+0xdc/0x180 CPU: 1 UID: 0 PID: 1 Comm: swapper/0 Not tainted 6.11.0-next-20240924-00002-g2062bb554dea torvalds#603 Hardware name: DH electronics i.MX8M Plus DHCOM Premium Developer Kit (3) (DT) pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : imx8mm_soc_revision+0xdc/0x180 lr : imx8mm_soc_revision+0xd0/0x180 sp : ffff8000821fbcc0 x29: ffff8000821fbce0 x28: 0000000000000000 x27: ffff800081810120 x26: ffff8000818a9970 x25: 0000000000000006 x24: 0000000000824311 x23: ffff8000817f42c8 x22: ffff0000df8be210 x21: fffffffffffffdfb x20: ffff800082780000 x19: 0000000000000001 x18: ffffffffffffffff x17: ffff800081fff418 x16: ffff8000823e1000 x15: ffff0000c03b65e8 x14: ffff0000c00051b0 x13: ffff800082790000 x12: 0000000000000801 x11: ffff80008278ffff x10: ffff80008209d3a6 x9 : ffff80008062e95c x8 : ffff8000821fb9a0 x7 : 0000000000000000 x6 : 00000000000080e3 x5 : ffff0000df8c03d8 x4 : 0000000000000000 x3 : 0000000000000000 x2 : 0000000000000000 x1 : fffffffffffffdfb x0 : fffffffffffffdfb Call trace: imx8mm_soc_revision+0xdc/0x180 imx8_soc_init+0xb0/0x1e0 do_one_initcall+0x94/0x1a8 kernel_init_freeable+0x240/0x2a8 kernel_init+0x28/0x140 ret_from_fork+0x10/0x20 ---[ end trace 0000000000000000 ]--- SoC: i.MX8MP revision 1.1 " Signed-off-by: Marek Vasut <marex@denx.de>

Optimize strspn.

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Variable count is redundant.

lieuwex reviewed Oct 4, 2018

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Update string.c

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danobi pushed a commit to danobi/linux that referenced this pull request Jan 9, 2022

Merge pull request torvalds#603 from danobi/file_flags

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rust: file: Add flags() method to `File`

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Optimize strspn. #603

Optimize strspn. #603

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Optimize strspn. #603

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Optimize strspn. #603

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