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.

1 files changed, 6 insertions, 4 deletions

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);