Patch: HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS

[H . J . Lu]

Hi,

This patch implements HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS. It
is used by ia64.


-- 
H.J. Lu (hjl@gnu.org)
--
2000-06-19  H.J. Lu  <hjl@gnu.org>

	* spinlock.h (HAS_COMPARE_AND_SWAP): Defined if
	HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS is defined.
	(compare_and_swap_with_release_semantics): New. Default to
	compare_and_swap if HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS
	is not defined.

	* spinlock.c (__pthread_unlock): Call
	compare_and_swap_with_release_semantics () instead of
	compare_and_swap ().
Index: spinlock.c
===================================================================
RCS file: /work/cvs/gnu/glibc/linuxthreads/spinlock.c,v
retrieving revision 1.1.1.2
diff -u -p -r1.1.1.2 spinlock.c
--- spinlock.c	2000/06/09 18:40:09	1.1.1.2
+++ spinlock.c	2000/06/19 16:49:27
@@ -95,7 +95,9 @@ again:
     /* No threads are waiting for this lock.  Please note that we also
        enter this case if the lock is not taken at all.  If this wouldn't
        be done here we would crash further down.  */
-    if (! compare_and_swap(&lock->__status, oldstatus, 0, &lock->__spinlock))
+    if (! compare_and_swap_with_release_semantics (&lock->__status,
+						   oldstatus, 0,
+						   &lock->__spinlock))
       goto again;
     return 0;
   }
@@ -126,9 +128,9 @@ again:
     /* If max prio thread is at head, remove it with compare-and-swap
        to guard against concurrent lock operation */
     thr = (pthread_descr) oldstatus;
-    if (! compare_and_swap(&lock->__status,
-                           oldstatus, (long)(thr->p_nextlock),
-                           &lock->__spinlock))
+    if (! compare_and_swap_with_release_semantics
+	    (&lock->__status, oldstatus, (long)(thr->p_nextlock),
+	     &lock->__spinlock))
       goto again;
   } else {
     /* No risk of concurrent access, remove max prio thread normally */
Index: spinlock.h
===================================================================
RCS file: /work/cvs/gnu/glibc/linuxthreads/spinlock.h,v
retrieving revision 1.1.1.2
diff -u -p -r1.1.1.2 spinlock.h
--- spinlock.h	2000/06/09 18:40:09	1.1.1.2
+++ spinlock.h	2000/06/19 16:49:27
@@ -12,6 +12,12 @@
 /* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the        */
 /* GNU Library General Public License for more details.                 */
 
+#ifndef HAS_COMPARE_AND_SWAP
+#ifdef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS
+#define HAS_COMPARE_AND_SWAP
+#endif
+#endif
+
 #if defined(TEST_FOR_COMPARE_AND_SWAP)
 
 extern int __pthread_has_cas;
@@ -29,6 +35,18 @@ static inline int compare_and_swap(long 
 
 #elif defined(HAS_COMPARE_AND_SWAP)
 
+#ifdef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS
+
+static inline int
+compare_and_swap_with_release_semantics (long * ptr, long oldval,
+					 long newval, int * spinlock)
+{
+  return __compare_and_swap_with_release_semantics (ptr, oldval,
+						    newval);
+}
+
+#endif
+
 static inline int compare_and_swap(long * ptr, long oldval, long newval,
                                    int * spinlock)
 {
@@ -46,6 +64,10 @@ static inline int compare_and_swap(long 
   return __pthread_compare_and_swap(ptr, oldval, newval, spinlock);
 }
 
+#endif
+
+#ifndef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS
+#define compare_and_swap_with_release_semantics compare_and_swap
 #endif
 
 /* Internal locks */