Re: sem_post() does not signal waiting threads

Hello!

On Fri, Aug 30, 2002 at 03:20:08PM +0200, [email protected] wrote:
> Am Freitag den, 30. August 2002, um 11:33, schrieb Dr. Uwe Girlich:
> >
> > On Fri, Aug 30, 2002 at 09:56:20AM +0200, Dr. Uwe Girlich wrote:
> >> There is an error in the POSIX semaphore implementation in NGPT:
> > ...
> >> The attached patch file corrects this strange behaviour.
> > This correction corrects the behaviour of process shared semaphores.
> > Process local semaphores are still wrong. I'll look into it.
It is a problem of pthread_cond_signal(). See extra posting.

> Does your code uses sem_trywait()?
No.

> In that function the mutex is not released in every code path.
Looks really bad. Thanks for the patch.

> Another question: Is that double locking required? When all functions
> accessing the semaphore use __sem_waiting->__lock, why is
> __sem_waiting->__sem_lock needed? Just for destroying it safely?
I'm not really sure but I think one (shared or not shared) mutex alone should
be enough.

Bye, Uwe