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commit 4565083abc972bffe810e4151f8f3cb48531e526
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date: Mon Aug 22 22:27:24 2022 +0200
htl: Make pthread*_cond_timedwait register wref before releasing mutex
Otherwise another thread could be rightly trying to destroy the condition,
see e.g. tst-cond20.
diff --git a/sysdeps/htl/pt-cond-timedwait.c b/sysdeps/htl/pt-cond-timedwait.c
index 6f4cb41bf1..4352e54fff 100644
--- a/sysdeps/htl/pt-cond-timedwait.c
+++ b/sysdeps/htl/pt-cond-timedwait.c
@@ -142,13 +142,15 @@ __pthread_cond_timedwait_internal (pthread_cond_t *cond,
__pthread_mutex_unlock (&self->cancel_lock);
- /* Release MUTEX before blocking. */
- __pthread_mutex_unlock (mutex);
-
/* Increase the waiter reference count. Relaxed MO is sufficient because
- we only need to synchronize when decrementing the reference count. */
+ we only need to synchronize when decrementing the reference count.
+ We however need to have the mutex held to prevent concurrency with
+ a pthread_cond_destroy. */
atomic_fetch_add_relaxed (&cond->__wrefs, 2);
+ /* Release MUTEX before blocking. */
+ __pthread_mutex_unlock (mutex);
+
/* Block the thread. */
if (abstime != NULL)
err = __pthread_timedblock (self, abstime, clock_id);
diff --git a/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c b/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c
index 16f0d3b309..1677925755 100644
--- a/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c
+++ b/sysdeps/mach/hurd/htl/pt-hurd-cond-timedwait.c
@@ -103,6 +103,12 @@ __pthread_hurd_cond_timedwait_internal (pthread_cond_t *cond,
__pthread_spin_unlock (&cond->__lock);
__spin_unlock (&ss->lock);
+ /* Increase the waiter reference count. Relaxed MO is sufficient because
+ we only need to synchronize when decrementing the reference count.
+ We however need to have the mutex held to prevent concurrency with
+ a pthread_cond_destroy. */
+ atomic_fetch_add_relaxed (&cond->__wrefs, 2);
+
if (cancel)
{
/* Cancelled on entry. Just leave the mutex locked. */
@@ -115,10 +121,6 @@ __pthread_hurd_cond_timedwait_internal (pthread_cond_t *cond,
/* Release MUTEX before blocking. */
__pthread_mutex_unlock (mutex);
- /* Increase the waiter reference count. Relaxed MO is sufficient because
- we only need to synchronize when decrementing the reference count. */
- atomic_fetch_add_relaxed (&cond->__wrefs, 2);
-
/* Block the thread. */
if (abstime != NULL)
err = __pthread_timedblock (self, abstime, clock_id);
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