[Valgrind-users] alarm signals and deadlock detection in valgrind

[Godmar B. <go...@gm...>]

Hi,

I have a program for which valgrind 2.1.0 flags a deadlock condition
because it doesn't take into account that a sigitimer-delivered signal
will resume waiting threads in the future via sem_post(). It seems to
me that valgrind should be more conservative in bailing when signals
are involved, or provide an option to turn deadlock detection off.

My question is whether there is such an option in valgrind?

 - Godmar

PS 1:
On a related note, I noticed this stack trace:
==14308==    at 0x4022AFAD: pthread_cond_wait (vg_libpthread.c:1087)
==14308==    by 0x4022CDC9: sem_wait (vg_libpthread.c:2328)

which would seem to imply that sem_post might be implemented via
pthread_cond_signal.
This seems surprising to me in the sense that you'd then implement an
async-signal-safe function (sem_post) on top of one that is commonly
async-signal-unsafe (pthread_cond_signal) - I hope you considered this
when implementing your pthread_cond_signal.

PS 2: A work-around for my problem is to fire off an additional thread that does
for(;;) sleep(1) - valgrind's scheduler will not flag a deadlock in that case.