[PATCH 16/24] make atomic_read() behave consistently on s390
From: Chris Snook <hidden>
Date: 2007-08-09 14:07:41
Also in:
linux-arch, lkml
From: Chris Snook <redacted> Make atomic[64]_read() volatile on s390, to ensure memory is actually read each time. Signed-off-by: Chris Snook <redacted>
--- linux-2.6.23-rc2-orig/include/asm-s390/atomic.h 2007-08-08 17:48:53.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-s390/atomic.h 2007-08-09 07:18:56.000000000 -0400@@ -67,7 +67,11 @@ typedef struct { #endif /* __GNUC__ */ -#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__ int atomic_add_return(int i, atomic_t * v)
@@ -182,7 +186,7 @@ typedef struct { #endif /* __GNUC__ */ -#define atomic64_read(v) ((v)->counter) +#define atomic64_read(v) (*(volatile long long *)&(v)->counter) #define atomic64_set(v,i) (((v)->counter) = (i)) static __inline__ long long atomic64_add_return(long long i, atomic64_t * v)