Date: Wed, 12 Mar 2014 15:33:40 -0500 From: Eric van Gyzen <eric@vangyzen.net> To: FreeBSD current <freebsd-current@freebsd.org> Subject: sem_wait(3) is not always a cancellation point Message-ID: <5320C4A4.7020109@vangyzen.net>
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>From my understand of POSIX, sem_wait(3) should always be a cancellation
point. However, when the semaphore's count is positive and the caller
successfully decrements the count, sem_wait(3) does not call
_pthread_testcancel(), so it's not a cancellation point.
See this totally contrived test case:
http://www.vangyzen.net/FreeBSD/patches/sem_wait_cancel.c
This patch seems like an appropriate fix:
http://www.vangyzen.net/FreeBSD/patches/sem_wait_cancel.diff
It adds a call to _pthread_testcancel() in the same location as
_libc_sem_timedwait_compat() in libc/gen/sem.c.
Is this a real bug, or am I missing something?
Eric
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