Mutex logic fix

2 files changed, 12 insertions, 2 deletions

diff --git a/ChangeLog b/ChangeLog
index 88756a2..ceec5f0 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2004-10-21  Ross Johnson  <rpj at callisto.canberra.edu.au>

+
+	* pthread_mutex_unlock.c (pthread_mutex_unlock): Must use PulseEvent()
+	rather than SetEvent() to reset the event if there are no waiters.
+
 2004-10-19  Ross Johnson  <rpj at callisto.canberra.edu.au>

 
 	* sem_init.c (sem_init): New semaphore model based on the same idea
diff --git a/pthread_mutex_unlock.c b/pthread_mutex_unlock.c
index e28b38a..9b8e504 100644
--- a/pthread_mutex_unlock.c
+++ b/pthread_mutex_unlock.c
@@ -67,8 +67,13 @@ pthread_mutex_unlock (pthread_mutex_t * mutex)
 	    {
 	      if (idx < 0)
 		{
-		  /* Someone may be waiting on that mutex */
-		  if (SetEvent (mx->event) == 0)
+		  /*
+		   * Someone may be waiting on that mutex.
+		   * Pulse event on an auto-reset event will
+		   * release one waiter if possible, otherwise
+		   * it will just reset the event.
+		   */
+		  if (PulseEvent (mx->event) == 0)
 		    {
 		      result = EINVAL;
 		    }