* [PATCH 19/24] make atomic_read() behave consistently on sparc64
@ 2007-08-09 14:12 Chris Snook
0 siblings, 0 replies; only message in thread
From: Chris Snook @ 2007-08-09 14:12 UTC (permalink / raw)
To: linux-kernel, linux-arch, torvalds
Cc: netdev, akpm, ak, heiko.carstens, davem, schwidefsky, wensong,
horms, wjiang, cfriesen, zlynx, rpjday, jesper.juhl
From: Chris Snook <csnook@redhat.com>
Purify volatile use for atomic[64]_t on sparc64.
Signed-off-by: Chris Snook <csnook@redhat.com>
--- 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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2007-08-09 14:12 [PATCH 19/24] make atomic_read() behave consistently on sparc64 Chris Snook
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