Fix a race in pthread_rwlock caused by simultanoues unlock and cancelation.

* thread.h (pthread_rwlock::release): New method.
* thread.cc (pthread_rwlock::unlock): Use release to signal
waiting threads.
(pthread_rwlock::rdlock_cleanup): Signal waiting threads after a
cancelation.
(pthread_rwlock::wrlock_cleanup): Ditto.

3 files changed, 24 insertions, 7 deletions

diff --git a/winsup/cygwin/ChangeLog b/winsup/cygwin/ChangeLog
index dbb152639..454b756cd 100644
--- a/winsup/cygwin/ChangeLog
+++ b/winsup/cygwin/ChangeLog
@@ -1,3 +1,12 @@
+2003-04-15  Thomas Pfaff  <tpfaff@gmx.net>
+
+	* thread.h (pthread_rwlock::release): New method.
+	* thread.cc (pthread_rwlock::unlock): Use release to signal
+	waiting threads.
+	(pthread_rwlock::rdlock_cleanup): Signal waiting threads after a
+	cancelation.
+	(pthread_rwlock::wrlock_cleanup): Ditto.
+
 2003-04-13  Pierre Humblet  <pierre.humblet@ieee.org>
 
 	* mkvers.sh: Prefix day with 0 in date only when day < 10.
diff --git a/winsup/cygwin/thread.cc b/winsup/cygwin/thread.cc
index 0eadd03c5..5f0917ad6 100644
--- a/winsup/cygwin/thread.cc
+++ b/winsup/cygwin/thread.cc
@@ -1210,13 +1210,7 @@ pthread_rwlock::unlock ()
       delete reader;
     }
 
-  if (waiting_writers)
-    {
-      if (!readers)
-        cond_writers.unblock (false);
-    }
-  else if (waiting_readers)
-    cond_readers.unblock (true);
+  release ();
 
  DONE:
   mtx.unlock ();
@@ -1263,6 +1257,7 @@ pthread_rwlock::rdlock_cleanup (void *arg)
   pthread_rwlock *rwlock = (pthread_rwlock *) arg;
 
   --(rwlock->waiting_readers);
+  rwlock->release ();
   rwlock->mtx.unlock ();
 }
 
@@ -1272,6 +1267,7 @@ pthread_rwlock::wrlock_cleanup (void *arg)
   pthread_rwlock *rwlock = (pthread_rwlock *) arg;
 
   --(rwlock->waiting_writers);
+  rwlock->release ();
   rwlock->mtx.unlock ();
 }
 
diff --git a/winsup/cygwin/thread.h b/winsup/cygwin/thread.h
index 05638d9c6..121d35af9 100644
--- a/winsup/cygwin/thread.h
+++ b/winsup/cygwin/thread.h
@@ -587,6 +587,18 @@ private:
   void remove_reader (struct RWLOCK_READER *rd);
   struct RWLOCK_READER *lookup_reader (pthread_t thread);
 
+  void release ()
+  {
+    if (waiting_writers)
+      {
+        if (!readers)
+          cond_writers.unblock (false);
+      }
+    else if (waiting_readers)
+      cond_readers.unblock (true);
+  }
+
+
   static void rdlock_cleanup (void *arg);
   static void wrlock_cleanup (void *arg);