htl: Make pthread_cond_destroy wait for threads to be woken

This allows to reuse the storage after calling pthread_cond_destroy.

* sysdeps/htl/bits/types/struct___pthread_cond.h (__pthread_cond):
Replace unused struct __pthread_condimpl *__impl field with unsigned int
__wrefs.
(__PTHREAD_COND_INITIALIZER): Update accordingly.
* sysdeps/htl/pt-cond-timedwait.c (__pthread_cond_timedwait_internal):
Register as waiter in __wrefs field. On unregistering, wake any pending
pthread_cond_destroy.
* sysdeps/htl/pt-cond-destroy.c (__pthread_cond_destroy): Register wake
request in __wrefs.
* nptl/Makefile (tests): Move tst-cond20 tst-cond21 to...
* sysdeps/pthread/Makefile (tests): ... here.
* nptl/tst-cond20.c nptl/tst-cond21.c: Move to...
* sysdeps/pthread/tst-cond20.c sysdeps/pthread/tst-cond21.c: ... here.

1 files changed, 15 insertions, 3 deletions

diff --git a/sysdeps/htl/pt-cond-destroy.c b/sysdeps/htl/pt-cond-destroy.c
index 0664f3f6cc..722516a8e2 100644
--- a/sysdeps/htl/pt-cond-destroy.c
+++ b/sysdeps/htl/pt-cond-destroy.c
@@ -22,14 +22,26 @@
 int
 __pthread_cond_destroy (pthread_cond_t *cond)
 {
-  int ret = 0;
+  /* Set the wake request flag. */
+  unsigned int wrefs = atomic_fetch_or_acquire (&cond->__wrefs, 1);
 
   __pthread_spin_wait (&cond->__lock);
   if (cond->__queue)
-    ret = EBUSY;
+    {
+      __pthread_spin_unlock (&cond->__lock);
+      return EBUSY;
+    }
   __pthread_spin_unlock (&cond->__lock);
 
-  return ret;
+  while (wrefs >> 1 != 0)
+    {
+      gsync_wait (__mach_task_self (), (vm_offset_t) &cond->__wrefs, wrefs,
+		  0, 0, 0);
+      wrefs = atomic_load_acquire (&cond->__wrefs);
+    }
+  /* The memory the condvar occupies can now be reused.  */
+
+  return 0;
 }
 
 weak_alias (__pthread_cond_destroy, pthread_cond_destroy);