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| author |   Nick Piggin <nickpiggin@yahoo.com.au> | 2005-11-13 16:07:25 -0800 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@g5.osdl.org> | 2005-11-13 18:14:16 -0800 |
| commit | 8426e1f6af0fd7f44d040af7263750c5a52f3cc3 (patch) | |
| tree | 827bd2588c2b73d11cea6869de8ff42dba134375 /include/asm-arm/atomic.h | |
| parent | [PATCH] atomic: cmpxchg (diff) | |
| download | linux-dev-8426e1f6af0fd7f44d040af7263750c5a52f3cc3.tar.xz linux-dev-8426e1f6af0fd7f44d040af7263750c5a52f3cc3.zip | |
[PATCH] atomic: inc_not_zero
Introduce an atomic_inc_not_zero operation. Make this a special case of
atomic_add_unless because lockless pagecache actually wants
atomic_inc_not_negativeone due to its offset refcount.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-arm/atomic.h')
| -rw-r--r-- | include/asm-arm/atomic.h | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/include/asm-arm/atomic.h b/include/asm-arm/atomic.h index 8ab1689ef56a..75b802719723 100644 --- 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) |