[PATCH] atomic: inc_not_zero

[deliverable/linux.git] / include / asm-arm / atomic.h

diff --git a/include/asm-arm/atomic.h b/include/asm-arm/atomic.h
index 8ab1689ef56a1c3388fd0d25801230fd3b6516e7..75b802719723ad459d719b6f598254fe0dfe02e4 100644 (file)
--- a/include/asm-arm/atomic.h
+++ b/include/asm-arm/atomic.h
@@ -173,6 +173,17 @@ static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
 
 #endif /* __LINUX_ARM_ARCH__ */
 
+static inline int atomic_add_unless(atomic_t *v, int a, int u)
+{
+       int c, old;
+
+       c = atomic_read(v);
+       while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c)
+               c = old;
+       return c != u;
+}
+#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
+
 #define atomic_add(i, v)       (void) atomic_add_return(i, v)
 #define atomic_inc(v)          (void) atomic_add_return(1, v)
 #define atomic_sub(i, v)       (void) atomic_sub_return(i, v)