[PATCH 2/24] make atomic_read() behave consistently on arm
From: Chris Snook <hidden>
Date: 2007-08-09 13:31:22
Also in:
linux-arch, lkml
From: Chris Snook <redacted> Purify volatile use for atomic_t on arm. Signed-off-by: Chris Snook <redacted>
--- linux-2.6.23-rc2-orig/include/asm-arm/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-arm/atomic.h 2007-08-09 06:30:40.000000000 -0400@@ -14,13 +14,17 @@ #include <linux/compiler.h> #include <asm/system.h> -typedef struct { volatile int counter; } atomic_t; +typedef struct { int counter; } atomic_t; #define ATOMIC_INIT(i) { (i) } #ifdef __KERNEL__ -#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) #if __LINUX_ARM_ARCH__ >= 6