From: Chris Snook <[email protected]>
Purify volatile use for atomic[64]_t on powerpc.
Signed-off-by: Chris Snook <[email protected]>
--- linux-2.6.23-rc2-orig/include/asm-powerpc/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-powerpc/atomic.h 2007-08-09 07:15:21.000000000 -0400
@@ -5,7 +5,7 @@
* PowerPC atomic operations
*/
-typedef struct { volatile int counter; } atomic_t;
+typedef struct { int counter; } atomic_t;
#ifdef __KERNEL__
#include <linux/compiler.h>
@@ -15,7 +15,11 @@ typedef struct { volatile int counter; }
#define ATOMIC_INIT(i) { (i) }
-#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_set(v,i) (((v)->counter) = (i))
static __inline__ void atomic_add(int a, atomic_t *v)
@@ -240,11 +244,11 @@ static __inline__ int atomic_dec_if_posi
#ifdef __powerpc64__
-typedef struct { volatile long counter; } atomic64_t;
+typedef struct { long counter; } atomic64_t;
#define ATOMIC64_INIT(i) { (i) }
-#define atomic64_read(v) ((v)->counter)
+#define atomic64_read(v) (*(volatile long *)&(v)->counter)
#define atomic64_set(v,i) (((v)->counter) = (i))
static __inline__ void atomic64_add(long a, atomic64_t *v)
-
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