[PATCH] volatile may be needed in rwsem

[Joe Korty]

'flags' should be declared volatile as rwsem_down_failed_common() spins
waiting for this to change.  Untested.

Against 2.6.1.


diff -Nua 2.6/lib/rwsem-spinlock.c.0 2.6/lib/rwsem-spinlock.c
--- 2.6/lib/rwsem-spinlock.c.0	2004-01-27 14:03:46.000000000 -0500
+++ 2.6/lib/rwsem-spinlock.c	2004-01-27 14:03:38.000000000 -0500
@@ -12,7 +12,7 @@
 struct rwsem_waiter {
 	struct list_head	list;
 	struct task_struct	*task;
-	unsigned int		flags;
+	volatile unsigned int	flags;
 #define RWSEM_WAITING_FOR_READ	0x00000001
 #define RWSEM_WAITING_FOR_WRITE	0x00000002
 };
diff -Nua 2.6/lib/rwsem.c.0 2.6/lib/rwsem.c
--- 2.6/lib/rwsem.c.0	2004-01-27 14:03:46.000000000 -0500
+++ 2.6/lib/rwsem.c	2004-01-27 14:03:19.000000000 -0500
@@ -10,7 +10,7 @@
 struct rwsem_waiter {
 	struct list_head	list;
 	struct task_struct	*task;
-	unsigned int		flags;
+	volatile unsigned int	flags;
 #define RWSEM_WAITING_FOR_READ	0x00000001
 #define RWSEM_WAITING_FOR_WRITE	0x00000002
 };

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