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new helpers: atomic_inc_unless_negative()/atomic_dec_unless_positive()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2011-06-20 10:52:57 -04:00
parent f4d6ff89d8
commit 07b8ce1ee8
3 changed files with 52 additions and 49 deletions
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26
include/linux/atomic.h
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@ -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)
{