Introduce an atomic_inc_not_zero operation. Make this a special case of atomic_add_unless because lockless pagecache actually wants atomic_inc_not_negativeone due to its offset refcount. Signed-off-by: Nick Piggin Index: linux-2.6/include/asm-ppc64/atomic.h =================================================================== --- linux-2.6.orig/include/asm-ppc64/atomic.h +++ linux-2.6/include/asm-ppc64/atomic.h @@ -164,6 +164,32 @@ static __inline__ int atomic_dec_return( #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +/** + * atomic_add_unless - add unless the number is a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, so long as it was not @u. + * Returns non-zero if @v was not @u, and zero otherwise. + */ +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + for (;;) { \ + if (unlikely(c == (u))) \ + break; \ + old = atomic_cmpxchg((v), c, c + (a)); \ + if (likely(old == c)) \ + break; \ + c = old; \ + } \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + + #define atomic_sub_and_test(a, v) (atomic_sub_return((a), (v)) == 0) #define atomic_dec_and_test(v) (atomic_dec_return((v)) == 0) Index: linux-2.6/include/asm-alpha/atomic.h =================================================================== --- linux-2.6.orig/include/asm-alpha/atomic.h +++ linux-2.6/include/asm-alpha/atomic.h @@ -173,6 +173,16 @@ static __inline__ long atomic64_sub_retu #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_dec_return(v) atomic_sub_return(1,(v)) #define atomic64_dec_return(v) atomic64_sub_return(1,(v)) Index: linux-2.6/include/asm-arm26/atomic.h =================================================================== --- linux-2.6.orig/include/asm-arm26/atomic.h +++ linux-2.6/include/asm-arm26/atomic.h @@ -76,6 +76,21 @@ static inline int atomic_cmpxchg(atomic_ return ret; } +static inline int atomic_add_unless(atomic_t *v, int a, int u) +{ + int ret; + unsigned long flags; + + local_irq_save(flags); + ret = v->counter; + if (ret != u) + v->counter += a; + local_irq_restore(flags); + + return ret != u; +} +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) { unsigned long flags; Index: linux-2.6/include/asm-frv/atomic.h =================================================================== --- linux-2.6.orig/include/asm-frv/atomic.h +++ linux-2.6/include/asm-frv/atomic.h @@ -416,4 +416,14 @@ extern uint32_t __cmpxchg_32(uint32_t *v #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new)) +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #endif /* _ASM_ATOMIC_H */ Index: linux-2.6/include/asm-h8300/atomic.h =================================================================== --- linux-2.6.orig/include/asm-h8300/atomic.h +++ linux-2.6/include/asm-h8300/atomic.h @@ -94,6 +94,19 @@ static __inline__ int atomic_cmpxchg(ato return ret; } +static __inline__ int atomic_add_unless(atomic_t *v, int a, int u) +{ + int ret; + unsigned long flags; + local_irq_save(flags); + ret = v->counter; + if (ret != u) + v->counter += a; + local_irq_restore(flags); + return ret != u; +} +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + static __inline__ void atomic_clear_mask(unsigned long mask, unsigned long *v) { __asm__ __volatile__("stc ccr,r1l\n\t" Index: linux-2.6/include/asm-i386/atomic.h =================================================================== --- linux-2.6.orig/include/asm-i386/atomic.h +++ linux-2.6/include/asm-i386/atomic.h @@ -217,6 +217,25 @@ static __inline__ int atomic_sub_return( #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new)) +/** + * atomic_add_unless - add unless the number is a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, so long as it was not @u. + * Returns non-zero if @v was not @u, and zero otherwise. + */ +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_inc_return(v) (atomic_add_return(1,v)) #define atomic_dec_return(v) (atomic_sub_return(1,v)) Index: linux-2.6/include/asm-ia64/atomic.h =================================================================== --- linux-2.6.orig/include/asm-ia64/atomic.h +++ linux-2.6/include/asm-ia64/atomic.h @@ -90,6 +90,16 @@ ia64_atomic64_sub (__s64 i, atomic64_t * #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new)) +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_add_return(i,v) \ ({ \ int __ia64_aar_i = (i); \ Index: linux-2.6/include/asm-m68k/atomic.h =================================================================== --- linux-2.6.orig/include/asm-m68k/atomic.h +++ linux-2.6/include/asm-m68k/atomic.h @@ -141,6 +141,16 @@ static inline void atomic_set_mask(unsig #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + /* Atomic operations are already serializing */ #define smp_mb__before_atomic_dec() barrier() #define smp_mb__after_atomic_dec() barrier() Index: linux-2.6/include/asm-m68knommu/atomic.h =================================================================== --- linux-2.6.orig/include/asm-m68knommu/atomic.h +++ linux-2.6/include/asm-m68knommu/atomic.h @@ -130,6 +130,16 @@ extern __inline__ int atomic_sub_return( #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_dec_return(v) atomic_sub_return(1,(v)) #define atomic_inc_return(v) atomic_add_return(1,(v)) Index: linux-2.6/include/asm-mips/atomic.h =================================================================== --- linux-2.6.orig/include/asm-mips/atomic.h +++ linux-2.6/include/asm-mips/atomic.h @@ -269,6 +269,25 @@ static __inline__ int atomic_sub_if_posi #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +/** + * atomic_add_unless - add unless the number is a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, so long as it was not @u. + * Returns non-zero if @v was not @u, and zero otherwise. + */ +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_dec_return(v) atomic_sub_return(1,(v)) #define atomic_inc_return(v) atomic_add_return(1,(v)) Index: linux-2.6/include/asm-parisc/atomic.h =================================================================== --- linux-2.6.orig/include/asm-parisc/atomic.h +++ linux-2.6/include/asm-parisc/atomic.h @@ -166,6 +166,25 @@ static __inline__ int atomic_read(const /* exported interface */ #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +/** + * atomic_add_unless - add unless the number is a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, so long as it was not @u. + * Returns non-zero if @v was not @u, and zero otherwise. + */ +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_add(i,v) ((void)(__atomic_add_return( ((int)i),(v)))) #define atomic_sub(i,v) ((void)(__atomic_add_return(-((int)i),(v)))) #define atomic_inc(v) ((void)(__atomic_add_return( 1,(v)))) Index: linux-2.6/include/asm-ppc/atomic.h =================================================================== --- linux-2.6.orig/include/asm-ppc/atomic.h +++ linux-2.6/include/asm-ppc/atomic.h @@ -179,6 +179,25 @@ static __inline__ int atomic_dec_return( #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +/** + * atomic_add_unless - add unless the number is a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, so long as it was not @u. + * Returns non-zero if @v was not @u, and zero otherwise. + */ +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_sub_and_test(a, v) (atomic_sub_return((a), (v)) == 0) #define atomic_dec_and_test(v) (atomic_dec_return((v)) == 0) Index: linux-2.6/include/asm-s390/atomic.h =================================================================== --- linux-2.6.orig/include/asm-s390/atomic.h +++ linux-2.6/include/asm-s390/atomic.h @@ -200,6 +200,16 @@ atomic_compare_and_swap(int expected_old #define atomic_cmpxchg(v, o, n) (atomic_compare_and_swap((o), (n), &((v)->counter))) +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define smp_mb__before_atomic_dec() smp_mb() #define smp_mb__after_atomic_dec() smp_mb() #define smp_mb__before_atomic_inc() smp_mb() Index: linux-2.6/include/asm-sh/atomic.h =================================================================== --- linux-2.6.orig/include/asm-sh/atomic.h +++ linux-2.6/include/asm-sh/atomic.h @@ -101,6 +101,21 @@ static __inline__ int atomic_cmpxchg(ato return ret; } +static __inline__ int atomic_add_unless(atomic_t *v, int a, int u) +{ + int ret; + unsigned long flags; + + local_irq_save(flags); + ret = v->counter; + if (ret != u) + v->counter += a; + local_irq_restore(flags); + + return ret != u; +} +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + static __inline__ void atomic_clear_mask(unsigned int mask, atomic_t *v) { unsigned long flags; Index: linux-2.6/include/asm-sh64/atomic.h =================================================================== --- linux-2.6.orig/include/asm-sh64/atomic.h +++ linux-2.6/include/asm-sh64/atomic.h @@ -113,6 +113,21 @@ static __inline__ int atomic_cmpxchg(ato return ret; } +static __inline__ int atomic_add_unless(atomic_t *v, int a, int u) +{ + int ret; + unsigned long flags; + + local_irq_save(flags); + ret = v->counter; + if (ret != u) + v->counter += a; + local_irq_restore(flags); + + return ret != u; +} +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + static __inline__ void atomic_clear_mask(unsigned int mask, atomic_t *v) { unsigned long flags; Index: linux-2.6/include/asm-sparc/atomic.h =================================================================== --- linux-2.6.orig/include/asm-sparc/atomic.h +++ linux-2.6/include/asm-sparc/atomic.h @@ -20,6 +20,7 @@ typedef struct { volatile int counter; } extern int __atomic_add_return(int, atomic_t *); extern int atomic_cmpxchg(atomic_t *, int, int); +extern int atomic_add_unless(atomic_t *, int, int); extern void atomic_set(atomic_t *, int); #define atomic_read(v) ((v)->counter) @@ -49,6 +50,8 @@ extern void atomic_set(atomic_t *, int); #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0) #define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + /* This is the old 24-bit implementation. It's still used internally * by some sparc-specific code, notably the semaphore implementation. */ Index: linux-2.6/include/asm-sparc64/atomic.h =================================================================== --- linux-2.6.orig/include/asm-sparc64/atomic.h +++ linux-2.6/include/asm-sparc64/atomic.h @@ -72,6 +72,16 @@ extern int atomic64_sub_ret(int, atomic6 #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + /* Atomic operations are already serializing */ #ifdef CONFIG_SMP #define smp_mb__before_atomic_dec() membar_storeload_loadload(); Index: linux-2.6/include/asm-v850/atomic.h =================================================================== --- linux-2.6.orig/include/asm-v850/atomic.h +++ linux-2.6/include/asm-v850/atomic.h @@ -104,6 +104,22 @@ static __inline__ int atomic_cmpxchg(ato return ret; } +static __inline__ int atomic_add_unless(atomic_t *v, int a, int u) +{ + int ret; + unsigned long flags; + + local_irq_save(flags); + ret = v->counter; + if (ret != u) + v->counter += a; + local_irq_restore(flags); + + return ret != u; +} + +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + /* Atomic operations are already serializing on ARM */ #define smp_mb__before_atomic_dec() barrier() #define smp_mb__after_atomic_dec() barrier() Index: linux-2.6/include/asm-x86_64/atomic.h =================================================================== --- linux-2.6.orig/include/asm-x86_64/atomic.h +++ linux-2.6/include/asm-x86_64/atomic.h @@ -362,6 +362,25 @@ static __inline__ int atomic_sub_return( #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new)) +/** + * atomic_add_unless - add unless the number is a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, so long as it was not @u. + * Returns non-zero if @v was not @u, and zero otherwise. + */ +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_inc_return(v) (atomic_add_return(1,v)) #define atomic_dec_return(v) (atomic_sub_return(1,v)) Index: linux-2.6/include/asm-xtensa/atomic.h =================================================================== --- linux-2.6.orig/include/asm-xtensa/atomic.h +++ linux-2.6/include/asm-xtensa/atomic.h @@ -225,6 +225,25 @@ static inline int atomic_sub_return(int #define atomic_cmpxchg(v, o, n) ((int)cmpxchg(&((v)->counter), (o), (n))) +/** + * atomic_add_unless - add unless the number is a given value + * @v: pointer of type atomic_t + * @a: the amount to add to v... + * @u: ...unless v is equal to u. + * + * Atomically adds @a to @v, so long as it was not @u. + * Returns non-zero if @v was not @u, and zero otherwise. + */ +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + static inline void atomic_clear_mask(unsigned int mask, atomic_t *v) { unsigned int all_f = -1; Index: linux-2.6/include/asm-cris/atomic.h =================================================================== --- linux-2.6.orig/include/asm-cris/atomic.h +++ linux-2.6/include/asm-cris/atomic.h @@ -135,6 +135,19 @@ static __inline__ int atomic_cmpxchg(ato return ret; } +static __inline__ int atomic_add_unless(atomic_t *v, int a, int u) +{ + int ret; + unsigned long flags; + cris_atomic_save(v, flags); + ret = v->counter; + if (ret != u) + v->counter += a; + cris_atomic_restore(v, flags); + return ret != u; +} +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) /* Atomic operations are already serializing */ #define smp_mb__before_atomic_dec() barrier() Index: linux-2.6/arch/sparc/lib/atomic32.c =================================================================== --- linux-2.6.orig/arch/sparc/lib/atomic32.c +++ linux-2.6/arch/sparc/lib/atomic32.c @@ -52,6 +52,20 @@ int atomic_cmpxchg(atomic_t *v, int old, return ret; } +int atomic_add_unless(atomic_t *v, int a, int u) +{ + int ret; + unsigned long flags; + spin_lock_irqsave(ATOMIC_HASH(v), flags); + ret = v->counter; + if (ret != u) + v->counter += a; + spin_unlock_irqrestore(ATOMIC_HASH(v), flags); + return ret != u; +} + +static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) +/* Atomic operations are already serializing */ void atomic_set(atomic_t *v, int i) { unsigned long flags; Index: linux-2.6/Documentation/atomic_ops.txt =================================================================== --- linux-2.6.orig/Documentation/atomic_ops.txt +++ linux-2.6/Documentation/atomic_ops.txt @@ -115,7 +115,7 @@ boolean is return which indicates whethe is negative. It requires explicit memory barrier semantics around the operation. -Finally: +Then: int atomic_cmpxchg(atomic_t *v, int old, int new); @@ -129,6 +129,18 @@ atomic_cmpxchg requires explicit memory The semantics for atomic_cmpxchg are the same as those defined for 'cas' below. +Finally: + + int atomic_add_unless(atomic_t *v, int a, int u); + +If the atomic value v is not equal to u, this function adds a to v, and +returns non zero. If v is equal to u then it returns zero. This is done as +an atomic operation. + +atomic_add_unless requires explicit memory barriers around the operation. + +atomic_inc_not_zero, equivalent to atomic_add_unless(v, 1, 0) + If a caller requires memory barrier semantics around an atomic_t operation which does not return a value, a set of interfaces are Index: linux-2.6/include/asm-arm/atomic.h =================================================================== --- linux-2.6.orig/include/asm-arm/atomic.h +++ linux-2.6/include/asm-arm/atomic.h @@ -174,6 +174,16 @@ static inline void atomic_clear_mask(uns #endif /* __LINUX_ARM_ARCH__ */ +static inline int atomic_add_unless(atomic_t *v, int a, int u) +{ + int c, old; + c = atomic_read(v); + while (c != u && (old = atomic_cmpxchg((v), c, c + a)) != c) + c = old; + return c != u; +} +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + #define atomic_add(i, v) (void) atomic_add_return(i, v) #define atomic_inc(v) (void) atomic_add_return(1, v) #define atomic_sub(i, v) (void) atomic_sub_return(i, v)