On Wed, Dec 27, 2017 at 2:31 PM, Samuel Thibault <samuel.thiba...@gnu.org>
wrote:
> Hello,
>
> Brent W. Baccala, on mar. 26 déc. 2017 23:06:13 -0500, wrote:
> > Also, the Linux source code in nptl/ includes the following comment:
> >
> > /* If there are waiters which have been already signalled or
> > broadcasted, but still are using the pthread_cond_t structure,
> > pthread_cond_destroy needs to wait for them. */
>
> Ok, so even if Posix explicitly says that it has undefined behavior,
> since nptl behaves fine we should probably behave fine too.
>
Let me clarify - that comment precedes a block of code in
pthread_cond_destroy() that waits for the other threads.
See glibc-2.23/nptl/pthread_cond_destroy.c, around line 50.
That code's been rewritten in glibc-2.25, but the requirement is still
there.
glibc-2.25/nptl/pthread_cond_destroy.c, lines 38-40:
Thus, we can assume that all waiters that are still accessing the condvar
> have been woken. We wait until they have confirmed to have woken up by
> decrementing __wrefs.
... and then it waits for "wrefs >> 3" to become zero.
My point was that since Linux waits for the other threads in
pthread_cond_destroy(), we should too.
agape
brent
