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-rw-r--r--nptl/pthread_mutex_trylock.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/nptl/pthread_mutex_trylock.c b/nptl/pthread_mutex_trylock.c
index aae506739f..394a9cba9b 100644
--- a/nptl/pthread_mutex_trylock.c
+++ b/nptl/pthread_mutex_trylock.c
@@ -1,4 +1,4 @@
-/* Copyright (C) 2002 Free Software Foundation, Inc.
+/* Copyright (C) 2002, 2003 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
 
@@ -36,6 +36,10 @@ __pthread_mutex_trylock (mutex)
       if (mutex->__data.__owner == pd)
 	{
 	  /* Just bump the counter.  */
+	  if (__builtin_expect (mutex->__data.__count + 1 == 0, 0))
+	    /* Overflow of the counter.  */
+	    return EAGAIN;
+
 	  ++mutex->__data.__count;
 	  return 0;
 	}