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| author | Helge Deller <deller@gmx.de> | 2013-05-06 21:13:33 +0200 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2013-05-06 23:10:04 +0200 |
| commit | f21dda025ab00da197ac30b6c6690c380d838683 (patch) | |
| tree | 3059c205f6fe3cbbf5e098524aab36a64aabeecc /arch/parisc/include | |
| parent | parisc: use long branch in fork_like macro (diff) | |
| download | linux-f21dda025ab00da197ac30b6c6690c380d838683.tar.xz linux-f21dda025ab00da197ac30b6c6690c380d838683.zip | |
parisc: implement atomic64_dec_if_positive()
Signed-off-by: Helge Deller <deller@gmx.de>
Diffstat (limited to 'arch/parisc/include')
| -rw-r--r-- | arch/parisc/include/asm/atomic.h | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/arch/parisc/include/asm/atomic.h b/arch/parisc/include/asm/atomic.h index f38e1984b242..472886ceab1d 100644 --- a/arch/parisc/include/asm/atomic.h +++ b/arch/parisc/include/asm/atomic.h @@ -229,6 +229,29 @@ static __inline__ int atomic64_add_unless(atomic64_t *v, long a, long u) #define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0) +/* + * atomic64_dec_if_positive - decrement by 1 if old value positive + * @v: pointer of type atomic_t + * + * The function returns the old value of *v minus 1, even if + * the atomic variable, v, was not decremented. + */ +static inline long atomic64_dec_if_positive(atomic64_t *v) +{ + long c, old, dec; + c = atomic64_read(v); + for (;;) { + dec = c - 1; + if (unlikely(dec < 0)) + break; + old = atomic64_cmpxchg((v), c, dec); + if (likely(old == c)) + break; + c = old; + } + return dec; +} + #endif /* !CONFIG_64BIT */ |