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-rw-r--r--linuxthreads/ChangeLog3
-rw-r--r--linuxthreads/spinlock.h14
2 files changed, 16 insertions, 1 deletions
diff --git a/linuxthreads/ChangeLog b/linuxthreads/ChangeLog
index 1351c25495..f14cf0d4a5 100644
--- a/linuxthreads/ChangeLog
+++ b/linuxthreads/ChangeLog
@@ -1,5 +1,8 @@
 2000-07-18  Ulrich Drepper  <drepper@redhat.com>
 
+	* spinlock.h (__pthread_alt_trylock): Fix code used if no
+	compare&swap is available.
+
 	* spinlock.h (__pthread_trylock): Use __compare_and_swap, not
 	compare_and_swap.
 
diff --git a/linuxthreads/spinlock.h b/linuxthreads/spinlock.h
index 17efd183cd..703b72d65e 100644
--- a/linuxthreads/spinlock.h
+++ b/linuxthreads/spinlock.h
@@ -149,7 +149,19 @@ static inline int __pthread_alt_trylock (struct _pthread_fastlock * lock)
 #endif
 #if !defined HAS_COMPARE_AND_SWAP || defined TEST_FOR_COMPARE_AND_SWAP
   {
-    return (testandset(&lock->__spinlock) ? EBUSY : 0);
+    int res = EBUSY;
+
+    if (testandset(&lock->__spinlock) == 0)
+      {
+	if (lock->__status == 0)
+	  {
+	    lock->__status = 1;
+	    WRITE_MEMORY_BARRIER();
+	    res = 0;
+	  }
+	lock->__spinlock = 0;
+      }
+    return res;
   }
 #endif