From: Chris Snook <[EMAIL PROTECTED]>
Make atomic_read() volatile on m68knommu. 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]>
--- linux-2.6.23-rc2-orig/include/asm-m68knommu/atomic.h 2007-07-08
19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-m68knommu/atomic.h 2007-08-09
07:00:24.000000000 -0400
@@ -15,7 +15,11 @@
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)
static __inline__ void atomic_add(int i, atomic_t *v)
-
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