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| author | Al Viro <viro@zeniv.linux.org.uk> | 2011-06-20 10:52:57 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2011-07-20 01:43:14 -0400 |
| commit | 07b8ce1ee87d291ff564c02cf878fae973317a52 (patch) | |
| tree | 94f07ed2b5d18aef71f1b28193375f88c0c947bc /include/linux/atomic.h | |
| parent | f4d6ff89d8e54b68a4322388d26d518d6133fa4e (diff) | |
| download | lwn-07b8ce1ee87d291ff564c02cf878fae973317a52.tar.gz lwn-07b8ce1ee87d291ff564c02cf878fae973317a52.zip | |
lockless get_write_access/deny_write_access
new helpers: atomic_inc_unless_negative()/atomic_dec_unless_positive()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'include/linux/atomic.h')
| -rw-r--r-- | include/linux/atomic.h | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/include/linux/atomic.h b/include/linux/atomic.h index ee456c79b0e6..bc6615d4132b 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -34,6 +34,32 @@ static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint) } #endif +#ifndef atomic_inc_unless_negative +static inline int atomic_inc_unless_negative(atomic_t *p) +{ + int v, v1; + for (v = 0; v >= 0; v = v1) { + v1 = atomic_cmpxchg(p, v, v + 1); + if (likely(v1 == v)) + return 1; + } + return 0; +} +#endif + +#ifndef atomic_dec_unless_positive +static inline int atomic_dec_unless_positive(atomic_t *p) +{ + int v, v1; + for (v = 0; v <= 0; v = v1) { + v1 = atomic_cmpxchg(p, v, v - 1); + if (likely(v1 == v)) + return 1; + } + return 0; +} +#endif + #ifndef CONFIG_ARCH_HAS_ATOMIC_OR static inline void atomic_or(int i, atomic_t *v) { |