From: Chris Snook <[email protected]>
Purify volatile use for atomic[64]_t on parisc.
Signed-off-by: Chris Snook <[email protected]>
--- linux-2.6.23-rc2-orig/include/asm-parisc/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-parisc/atomic.h 2007-08-09 07:11:38.000000000 -0400
@@ -128,7 +128,7 @@ __cmpxchg(volatile void *ptr, unsigned l
* Cache-line alignment would conflict with, for example, linux/module.h
*/
-typedef struct { volatile int counter; } atomic_t;
+typedef struct { int counter; } atomic_t;
/* It's possible to reduce all atomic operations to either
* __atomic_add_return, atomic_set and atomic_read (the latter
@@ -157,9 +157,13 @@ static __inline__ void atomic_set(atomic
_atomic_spin_unlock_irqrestore(v, flags);
}
+/*
+ * Casting to volatile here minimizes the need for barriers,
+ * without having to declare the type itself as volatile.
+ */
static __inline__ int atomic_read(const atomic_t *v)
{
- return v->counter;
+ return (*(volatile int *)&(v)->counter);
}
/* exported interface */
@@ -227,7 +231,7 @@ static __inline__ int atomic_add_unless(
#ifdef CONFIG_64BIT
-typedef struct { volatile s64 counter; } atomic64_t;
+typedef struct { s64 counter; } atomic64_t;
#define ATOMIC64_INIT(i) ((atomic64_t) { (i) })
@@ -258,7 +262,7 @@ atomic64_set(atomic64_t *v, s64 i)
static __inline__ s64
atomic64_read(const atomic64_t *v)
{
- return v->counter;
+ return (*(volatile s64 *)&(v)->counter);
}
#define atomic64_add(i,v) ((void)(__atomic64_add_return( ((s64)i),(v))))
-
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