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

[Chris Snook <csnook@redhat.com>]

From: Chris Snook <csnook@redhat.com>

Purify volatile use for atomic_t on sh64.

Signed-off-by: Chris Snook <csnook@redhat.com>

--- linux-2.6.23-rc2-orig/include/asm-sh64/atomic.h	2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-sh64/atomic.h	2007-08-09 07:22:50.000000000 -0400
@@ -19,11 +19,15 @@
  *
  */
 
-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 <asm/system.h>
-
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