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make atomic_read() behave consistently on sh64

PATCH In review Chris Snook 2 participants 3 messages Aug 9, 2007

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Networking Network drivers Generic include/asm header files Atomic infrastructure
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Chris Snook

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

From: Chris Snook <[email protected]>

Purify volatile use for atomic_t on sh64.

Signed-off-by Chris Snook <[email protected]>
include/asm-sh64/atomic.h +6 -2
@@ -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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#1 lore raw

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]>
include/asm-sh/atomic.h +6 -2
@@ -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>