atomic: implement generic atomic_dec_if_positive()
The x86 implementation of atomic_dec_if_positive is quite generic, so make it available to all architectures. This is needed for "swap: add a simple detector for inappropriate swapin readahead". [akpm@linux-foundation.org: do the "#define foo foo" trick in the conventional manner] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Stephen Rothwell <sfr@canb.auug.org.au> Cc: "David S. Miller" <davem@davemloft.net> Cc: Rik van Riel <riel@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Michal Simek <monstr@monstr.eu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -22,5 +22,6 @@ static inline int atomic_dec_if_positive(atomic_t *v)
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return res;
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return res;
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}
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}
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#define atomic_dec_if_positive atomic_dec_if_positive
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#endif /* _ASM_MICROBLAZE_ATOMIC_H */
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#endif /* _ASM_MICROBLAZE_ATOMIC_H */
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@ -268,6 +268,7 @@ static __inline__ int atomic_dec_if_positive(atomic_t *v)
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return t;
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return t;
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}
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}
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#define atomic_dec_if_positive atomic_dec_if_positive
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#define smp_mb__before_atomic_dec() smp_mb()
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#define smp_mb__before_atomic_dec() smp_mb()
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#define smp_mb__after_atomic_dec() smp_mb()
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#define smp_mb__after_atomic_dec() smp_mb()
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@ -240,30 +240,6 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u)
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return c;
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return c;
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}
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}
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/*
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* atomic_dec_if_positive - decrement by 1 if old value positive
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* @v: pointer of type atomic_t
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*
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* The function returns the old value of *v minus 1, even if
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* the atomic variable, v, was not decremented.
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*/
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static inline int atomic_dec_if_positive(atomic_t *v)
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{
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int c, old, dec;
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c = atomic_read(v);
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for (;;) {
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dec = c - 1;
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if (unlikely(dec < 0))
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break;
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old = atomic_cmpxchg((v), c, dec);
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if (likely(old == c))
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break;
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c = old;
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}
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return dec;
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}
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/**
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/**
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* atomic_inc_short - increment of a short integer
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* atomic_inc_short - increment of a short integer
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* @v: pointer to type int
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* @v: pointer to type int
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@ -86,6 +86,31 @@ static inline int atomic_dec_unless_positive(atomic_t *p)
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}
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}
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#endif
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#endif
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/*
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* atomic_dec_if_positive - decrement by 1 if old value positive
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* @v: pointer of type atomic_t
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*
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* The function returns the old value of *v minus 1, even if
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* the atomic variable, v, was not decremented.
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*/
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#ifndef atomic_dec_if_positive
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static inline int atomic_dec_if_positive(atomic_t *v)
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{
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int c, old, dec;
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c = atomic_read(v);
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for (;;) {
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dec = c - 1;
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if (unlikely(dec < 0))
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break;
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old = atomic_cmpxchg((v), c, dec);
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if (likely(old == c))
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break;
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c = old;
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}
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return dec;
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}
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#endif
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#ifndef CONFIG_ARCH_HAS_ATOMIC_OR
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#ifndef CONFIG_ARCH_HAS_ATOMIC_OR
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static inline void atomic_or(int i, atomic_t *v)
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static inline void atomic_or(int i, atomic_t *v)
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{
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{
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