From: Chris Snook <[email protected]>
Purify volatile use for atomic[64]_t on sparc64.
Signed-off-by: Chris Snook <[email protected]>
--- linux-2.6.23-rc2-orig/include/asm-sparc64/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-sparc64/atomic.h 2007-08-09 07:48:01.000000000 -0400
@@ -11,14 +11,18 @@
#include <linux/types.h>
#include <asm/system.h>
-typedef struct { volatile int counter; } atomic_t;
-typedef struct { volatile __s64 counter; } atomic64_t;
+typedef struct { int counter; } atomic_t;
+typedef struct { __s64 counter; } atomic64_t;
#define ATOMIC_INIT(i) { (i) }
#define ATOMIC64_INIT(i) { (i) }
-#define atomic_read(v) ((v)->counter)
-#define atomic64_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 atomic64_read(v) (*(volatile __s64 *)&(v)->counter)
#define atomic_set(v, i) (((v)->counter) = i)
#define atomic64_set(v, i) (((v)->counter) = i)
-
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