Differential D60030

sysvshm: Fix locking in shm_prison_set()
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Authored by markj on Fri, Sep 25, 6:09 PM.

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jamie

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rG546d15061962: sysvshm: Fix locking in shm_prison_set()

Summary

We were not acquiring the global sysvshm lock when handling cleanup of
sysvshm segments. Acquire the lock in shm_prison_cleanup() instead, to
be consistent with the sysv semaphore code.

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rG FreeBSD src repository

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Buildable 77337
Build 74220: arc lint + arc unit

Event Timeline

markj created this revision.Fri, Sep 25, 6:09 PM

Herald added subscribers: olce, imp. · View Herald TranscriptFri, Sep 25, 6:09 PM

markj requested review of this revision.Fri, Sep 25, 6:09 PM

Harbormaster completed remote builds in B77337: Diff 187698.Fri, Sep 25, 6:09 PM

Look good. I was hesitant because it's an sx lock, but I don't see any mutexes held when it's locked. I suspect that hesitance was why I didn't do it tthe same as sysv_sem and sysv_msg in the first place, but that was a while ago and has totally escaped my memory.

This revision is now accepted and ready to land.Fri, Sep 25, 7:51 PM

In D60030#1377266, @jamie wrote:

Look good. I was hesitant because it's an sx lock, but I don't see any mutexes held when it's locked. I suspect that hesitance was why I didn't do it tthe same as sysv_sem and sysv_msg in the first place, but that was a while ago and has totally escaped my memory.

For what it's worth I tested this a bit (and confirmed as well that the bug is there, since shm_deallocate_segment() asserts that the global lock is held) and didn't see any warnings from witness either.

Closed by commit rG546d15061962: sysvshm: Fix locking in shm_prison_set() (authored by markj). · Explain WhyFri, Sep 25, 9:40 PM

This revision was automatically updated to reflect the committed changes.

markj added a commit: rG546d15061962: sysvshm: Fix locking in shm_prison_set().