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dynamic_lib misuses task::atomically in the check_for_errors_in implementations #8156

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mstewartgallus opened this issue Jul 31, 2013 · 0 comments · Fixed by #9713
Closed

dynamic_lib misuses task::atomically in the check_for_errors_in implementations #8156

mstewartgallus opened this issue Jul 31, 2013 · 0 comments · Fixed by #9713

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@mstewartgallus
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Issue #8140 brought to my attention that some code in the dynamic library implementation was incorrect. After chatting to @bblum on IRC, I figured out my mistake in creating the implementation. Apparently the function task::atomically only asserts that no context switching occurs, and does not in fact prevent it. A corrected pair of check_for_errors_in functions should replace the use of task::atomically with some locking mechanism to prevent threads from stepping on each others use of errno (or the equivalent Win32 error variable.) Maybe this locking mechanism for safely accessing the error variable should also be exposed separately in Rust's OS interaction facilities.
@mstewartgallus mstewartgallus mentioned this issue Sep 19, 2013
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@sfackler sfackler mentioned this issue Oct 4, 2013
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bors added a commit that referenced this issue Oct 5, 2013
@bors
auto merge of #9713 : sfackler/rust/dynamic_lib, r=alexcrichton
bf416e7 
The root issue is that dlerror isn't reentrant or even thread safe.

The solution implemented here is to make a yielding spin lock over an
AtomicFlag. This is pretty hacky, but the best we can do at this point.
As far as I can tell, it isn't possible to create a global mutex without
having to initialize it in a single threaded context.

The Windows code isn't affected since errno is thread-local on Windows
and it's running in an atomically block to ensure there isn't a green
thread context switch.

Closes #8156
@bors bors closed this as completed in 1d19ad9 Oct 5, 2013
flip1995 pushed a commit to flip1995/rust that referenced this issue Oct 6, 2022
@bors
Auto merge of rust-lang#9497 - kraktus:needless_return2, r=llogiq
47c9145 
[`needless_return`] Recursively remove unneeded semicolons

fix rust-lang#8336,
fix rust-lang#8156,
fix rust-lang/rust-clippy#7358,
fix rust-lang#9192,
fix rust-lang/rust-clippy#9503

changelog: [`needless_return`] Recursively remove unneeded semicolons

For now the suggestion about removing the semicolons are hidden because they would be very noisy and should be obvious if the user wants to apply the lint manually instead of using `--fix`. This could be an issue for beginner, but haven't found better way to display it.
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Hackily fix thread safety issues in dynamic_lib sfackler/rust
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@mstewartgallus