From: Chris Snook <[email protected]>
Purify volatile use for atomic_t on sparc.
Leave atomic24_t alone, since it's only used by sparc-specific code.
Signed-off-by: Chris Snook <[email protected]>
--- linux-2.6.23-rc2-orig/include/asm-sparc/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-sparc/atomic.h 2007-08-09 07:29:31.000000000 -0400
@@ -13,7 +13,7 @@
#include <linux/types.h>
-typedef struct { volatile int counter; } atomic_t;
+typedef struct { int counter; } atomic_t;
#ifdef __KERNEL__
@@ -61,7 +61,11 @@ extern int atomic_cmpxchg(atomic_t *, in
extern int atomic_add_unless(atomic_t *, int, int);
extern void atomic_set(atomic_t *, int);
-#define atomic_read(v) ((v)->counter)
+/*
+ * Casting to volatile here minimizes the need for barriers,
+ * without having to declare the type itself as volatile.
+ */
+#define atomic_read(v) (*(volatile int *)&(v)->counter)
#define atomic_add(i, v) ((void)__atomic_add_return( (int)(i), (v)))
#define atomic_sub(i, v) ((void)__atomic_add_return(-(int)(i), (v)))
-
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