[SSI] openssi/kernel/include/asm-i386 semaphore.h,1.5,1.6

Update of /cvsroot/ssic-linux/openssi/kernel/include/asm-i386
In directory fdv4jf1.ch3.sourceforge.com:/tmp/cvs-serv8553/include/asm-i386

Modified Files:
      Tag: OPENSSI-FC
	semaphore.h 
Log Message:
Bug fixes and enhancements. (see ChangeLog)


Index: semaphore.h
===================================================================
RCS file: /cvsroot/ssic-linux/openssi/kernel/include/asm-i386/semaphore.h,v
retrieving revision 1.5
retrieving revision 1.6
diff -u -d -r1.5 -r1.6
--- semaphore.h	10 Oct 2008 08:10:32 -0000	1.5
+++ semaphore.h	3 Feb 2009 06:18:13 -0000	1.6
@@ -49,8 +49,12 @@
 	int sleepers;
 #ifdef CONFIG_SSI
 	void *owner;
-#ifdef SSI_RECURSIVE_SEMAPHORE
-	atomic_t depth;
+#ifdef CFS_FILE_WRITE_LIVELOCK_FIX
+/* Support recursive non-interruptible acquired sempahore. This is needed
+ * for OpenSSI CFS client@server because in those code paths
+ * the VM revisits -eg. generic_file_writev() on memory pressure.	-Roger
+ */
+	void *flusher;
 #endif
 #endif
 	wait_queue_head_t wait;
@@ -58,13 +62,13 @@
 
 
 #ifdef CONFIG_SSI
-#ifdef SSI_RECURSIVE_SEMAPHORE
+#ifdef CFS_FILE_WRITE_LIVELOCK_FIX
 #define __SEMAPHORE_INITIALIZER(name, n)				\
 {									\
 	.count		= ATOMIC_INIT(n),				\
 	.sleepers	= 0,						\
 	.owner		= NULL,						\
-	.depth		= ATOMIC_INIT(0),				\
+	.flusher	= NULL,						\
 	.wait		= __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)	\
 }
 #else
@@ -75,7 +79,7 @@
 	.owner		= NULL,						\
 	.wait		= __WAIT_QUEUE_HEAD_INITIALIZER((name).wait)	\
 }
-#endif /* !SSI_RECURSIVE_SEMAPHORE */
+#endif /* !CFS_FILE_WRITE_LIVELOCK_FIX */
 #else
 #define __SEMAPHORE_INITIALIZER(name, n)				\
 {									\
@@ -106,12 +110,8 @@
 	sem->sleepers = 0;
 #ifdef CONFIG_SSI
 	sem->owner = NULL;
-#ifdef SSI_RECURSIVE_SEMAPHORE
-	/* Shared semaphores are not supported */
-	if (val <= 1)
-		atomic_set(&sem->depth, 0);
-	else
-		atomic_set(&sem->depth, -1);
+#ifdef CFS_FILE_WRITE_LIVELOCK_FIX
+	sem->flusher = NULL;
 #endif
 #endif
 	init_waitqueue_head(&sem->wait);
@@ -137,17 +137,32 @@
 fastcall int  __down_trylock(struct semaphore * sem);
 fastcall void __up(struct semaphore * sem);
 
+#ifdef CONFIG_SSI
+static inline int sem_owned(struct semaphore *sem)
+{
+	return (sem->owner == current);
+}
+#ifdef CFS_FILE_WRITE_LIVELOCK_FIX
+static inline int sem_flushing(struct semaphore *sem)
+{
+	return (sem->flusher == current);
+}
+#endif
+#endif
+
 /*
  * This is ugly, but we want the default case to fall through.
  * "__down_failed" is a special asm handler that calls the C
  * routine that actually waits. See arch/i386/kernel/semaphore.c
  */
-#ifdef SSI_RECURSIVE_SEMAPHORE
-static inline void down_nofail(struct semaphore * sem)
-#else
 static inline void down(struct semaphore * sem)
-#endif
 {
+#ifdef CONFIG_SSI
+#ifdef CFS_FILE_WRITE_LIVELOCK_FIX
+	if (sem_flushing(sem))
+		return;
+#endif
+#endif
 	might_sleep();
 	__asm__ __volatile__(
 		"# atomic down operation\n\t"
@@ -236,8 +251,8 @@
 static inline void up(struct semaphore * sem)
 {
 #ifdef CONFIG_SSI
-#ifdef SSI_RECURSIVE_SEMAPHORE
-	if (atomic_test_and_add(-1, &sem->depth))
+#ifdef CFS_FILE_WRITE_LIVELOCK_FIX
+	if (sem_flushing(sem))
 		return;
 #endif
 	set_mb(sem->owner, NULL);
@@ -258,31 +273,5 @@
 		:"memory","ax");
 }
 
-#ifdef CONFIG_SSI
-#ifdef SSI_RECURSIVE_SEMAPHORE
-/* Support recursive non-interruptible acquired sempahore. This is needed
- * for OpenSSI CFS client@server because in those code paths
- * the VM revisits generic_file_writev() on memory pressure.	-Roger
- * Note: Shared semaphores are not supported.
- */
-static inline void down(struct semaphore * sem)
-{
-	if (down_trylock(sem)) {
-		if (sem->owner == current && atomic_read(&sem->depth) >= 0) {
-			atomic_inc(&sem->depth);
-			WARN_ON(sem->owner != current);
-			return;
-		}
-		down_nofail(sem);
-	}
-}
-#endif
-
-static inline int sem_owned(struct semaphore *sem)
-{
-	return (sem->owner == current);
-}
-#endif
-
 #endif
 #endif


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