[PATCH 21/24] make atomic_read() behave consistently on v850
From: Chris Snook <hidden>
Date: 2007-08-09 14:17:26
Also in:
linux-arch, lkml
From: Chris Snook <redacted> Make atomic_read() volatile on v850. 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 <redacted>
--- linux-2.6.23-rc2-orig/include/asm-v850/atomic.h 2007-07-08 19:32:17.000000000 -0400
+++ linux-2.6.23-rc2/include/asm-v850/atomic.h 2007-08-09 07:50:15.000000000 -0400@@ -27,7 +27,11 @@ typedef struct { int counter; } atomic_t #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) #define atomic_set(v,i) (((v)->counter) = (i)) static inline int atomic_add_return (int i, volatile atomic_t *v)