diff options
| author | Shaohua Li <shli@kernel.org> | 2012-10-08 19:32:18 -0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-09 03:22:46 -0400 |
| commit | e79bee24fd6134f90af4228cfebd010136d67631 (patch) | |
| tree | ecc678106bbf4672becca8f798aaf94276eaa2c4 | |
| parent | 435b405c06119d93333738172b8060b0ed12af41 (diff) | |
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>
| -rw-r--r-- | arch/microblaze/include/asm/atomic.h | 1 | ||||
| -rw-r--r-- | arch/powerpc/include/asm/atomic.h | 1 | ||||
| -rw-r--r-- | arch/x86/include/asm/atomic.h | 24 | ||||
| -rw-r--r-- | include/linux/atomic.h | 25 |
4 files changed, 27 insertions, 24 deletions
diff --git a/arch/microblaze/include/asm/atomic.h b/arch/microblaze/include/asm/atomic.h index 472d8bf726df..42ac382a09da 100644 --- a/arch/microblaze/include/asm/atomic.h +++ b/arch/microblaze/include/asm/atomic.h | |||
| @@ -22,5 +22,6 @@ static inline int atomic_dec_if_positive(atomic_t *v) | |||
| 22 | 22 | ||
| 23 | return res; | 23 | return res; |
| 24 | } | 24 | } |
| 25 | #define atomic_dec_if_positive atomic_dec_if_positive | ||
| 25 | 26 | ||
| 26 | #endif /* _ASM_MICROBLAZE_ATOMIC_H */ | 27 | #endif /* _ASM_MICROBLAZE_ATOMIC_H */ |
diff --git a/arch/powerpc/include/asm/atomic.h b/arch/powerpc/include/asm/atomic.h index da29032ae38f..e3b1d41c89be 100644 --- a/arch/powerpc/include/asm/atomic.h +++ b/arch/powerpc/include/asm/atomic.h | |||
| @@ -268,6 +268,7 @@ static __inline__ int atomic_dec_if_positive(atomic_t *v) | |||
| 268 | 268 | ||
| 269 | return t; | 269 | return t; |
| 270 | } | 270 | } |
| 271 | #define atomic_dec_if_positive atomic_dec_if_positive | ||
| 271 | 272 | ||
| 272 | #define smp_mb__before_atomic_dec() smp_mb() | 273 | #define smp_mb__before_atomic_dec() smp_mb() |
| 273 | #define smp_mb__after_atomic_dec() smp_mb() | 274 | #define smp_mb__after_atomic_dec() smp_mb() |
diff --git a/arch/x86/include/asm/atomic.h b/arch/x86/include/asm/atomic.h index 250b8774c158..b6c3b821acf6 100644 --- a/arch/x86/include/asm/atomic.h +++ b/arch/x86/include/asm/atomic.h | |||
| @@ -240,30 +240,6 @@ static inline int __atomic_add_unless(atomic_t *v, int a, int u) | |||
| 240 | return c; | 240 | return c; |
| 241 | } | 241 | } |
| 242 | 242 | ||
| 243 | |||
| 244 | /* | ||
| 245 | * atomic_dec_if_positive - decrement by 1 if old value positive | ||
| 246 | * @v: pointer of type atomic_t | ||
| 247 | * | ||
| 248 | * The function returns the old value of *v minus 1, even if | ||
| 249 | * the atomic variable, v, was not decremented. | ||
| 250 | */ | ||
| 251 | static inline int atomic_dec_if_positive(atomic_t *v) | ||
| 252 | { | ||
| 253 | int c, old, dec; | ||
| 254 | c = atomic_read(v); | ||
| 255 | for (;;) { | ||
| 256 | dec = c - 1; | ||
| 257 | if (unlikely(dec < 0)) | ||
| 258 | break; | ||
| 259 | old = atomic_cmpxchg((v), c, dec); | ||
| 260 | if (likely(old == c)) | ||
| 261 | break; | ||
| 262 | c = old; | ||
| 263 | } | ||
| 264 | return dec; | ||
| 265 | } | ||
| 266 | |||
| 267 | /** | 243 | /** |
| 268 | * atomic_inc_short - increment of a short integer | 244 | * atomic_inc_short - increment of a short integer |
| 269 | * @v: pointer to type int | 245 | * @v: pointer to type int |
diff --git a/include/linux/atomic.h b/include/linux/atomic.h index 70cfcb2d63c4..5b08a8540ecf 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h | |||
| @@ -86,6 +86,31 @@ static inline int atomic_dec_unless_positive(atomic_t *p) | |||
| 86 | } | 86 | } |
| 87 | #endif | 87 | #endif |
| 88 | 88 | ||
| 89 | /* | ||
| 90 | * atomic_dec_if_positive - decrement by 1 if old value positive | ||
| 91 | * @v: pointer of type atomic_t | ||
| 92 | * | ||
| 93 | * The function returns the old value of *v minus 1, even if | ||
| 94 | * the atomic variable, v, was not decremented. | ||
| 95 | */ | ||
| 96 | #ifndef atomic_dec_if_positive | ||
| 97 | static inline int atomic_dec_if_positive(atomic_t *v) | ||
| 98 | { | ||
| 99 | int c, old, dec; | ||
| 100 | c = atomic_read(v); | ||
| 101 | for (;;) { | ||
| 102 | dec = c - 1; | ||
| 103 | if (unlikely(dec < 0)) | ||
| 104 | break; | ||
| 105 | old = atomic_cmpxchg((v), c, dec); | ||
| 106 | if (likely(old == c)) | ||
| 107 | break; | ||
| 108 | c = old; | ||
| 109 | } | ||
| 110 | return dec; | ||
| 111 | } | ||
| 112 | #endif | ||
| 113 | |||
| 89 | #ifndef CONFIG_ARCH_HAS_ATOMIC_OR | 114 | #ifndef CONFIG_ARCH_HAS_ATOMIC_OR |
| 90 | static inline void atomic_or(int i, atomic_t *v) | 115 | static inline void atomic_or(int i, atomic_t *v) |
| 91 | { | 116 | { |