2007-08-09 14:11:25

by Chris Snook

Subject: [PATCH 18/24] make atomic_read() behave consistently on sh

From: Chris Snook <[email protected]>

Purify volatile use for atomic_t on sh.

Signed-off-by: Chris Snook <[email protected]>

--- linux-2.6.23-rc2-orig/include/asm-sh/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-sh/atomic.h 2007-08-09 07:21:33.000000000 -0400
@@ -7,11 +7,15 @@
*
*/

-typedef struct { volatile int counter; } atomic_t;
+typedef struct { int counter; } atomic_t;

#define ATOMIC_INIT(i) ( (atomic_t) { (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))

#include <linux/compiler.h>

2007-08-09 16:41:41

by Paul Mundt

Subject: Re: [PATCH 17/24] make atomic_read() behave consistently on sh64

On Thu, Aug 09, 2007 at 10:09:08AM -0400, Chris Snook wrote:
> Purify volatile use for atomic_t on sh64.
>
> Signed-off-by: Chris Snook <[email protected]>

On Thu, Aug 09, 2007 at 10:10:34AM -0400, Chris Snook wrote:
> Purify volatile use for atomic_t on sh.
>
> Signed-off-by: Chris Snook <[email protected]>

Acked-by: Paul Mundt <[email protected]>