Unlocking a robust mutex in a cleanup handler
kostikbel at gmail.com
Tue Dec 6 11:26:04 UTC 2016
On Tue, Dec 06, 2016 at 11:49:24AM +0100, Dimitri Staessens wrote:
> Dear devs,
> first of all, thank you for supporting robust mutexes in FreeBSD 11.
> I'm having some issues with a thread that holds a robust mutex (residing
> in a POSIX shared memory (shm) segment) in conjunctions with a condition
> variable (also in that POSIX shm) on which that thread is blocked via a
> pthread_cond_wait() call. pthread_cond_wait tries to retake the mutex
> after the thread cancellation signal is received, and there is a
> pthread_mutex_unlock pushed to the cleanup stack to unlock that robust
> mutex in case of a cancellation.
> Cancelling that thread works fine on Linux, however, on FreeBSD
> 11.0-RELEASE, if I pthread_cancel that thread I can't get past the
> following check and resulting PANIC call:
> After removing the check and recompiling libthr everything seems to work
> Could this be a bug in libthr or am I missing a nuance in the use of a
> shared robust mutexes in conjunction with condition variables?
Most likely, this is a bug in libthr. But please extract the minimal
reproduction case and send it to me.
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