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make atomic_read() behave consistently on h8300

PATCH In review Chris Snook 1 participant 1 message Aug 9, 2007

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Chris Snook

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PATCH 7/24 make atomic_read() behave consistently on h8300

From: Chris Snook <[email protected]>

Make atomic_read() volatile on h8300. This ensures that busy-waiting for an interrupt handler to change an atomic_t won't get compiled to an infinite loop, consistent with SMP architectures.

Signed-off-by Chris Snook <[email protected]>
include/asm-h8300/atomic.h +5 -1
@@ -9,7 +9,11 @@
 typedef struct { int counter; } atomic_t;
 #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)
 
 #include <asm/system.h>