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    Subject[patch 3/5] atomic: inc_not_zero
    3/5

    --
    SUSE Labs, Novell Inc.

    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 <npiggin@suse.de>

    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
    @@ -179,6 +179,16 @@ 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 @@ static inline int atomic_sub_return(int

    #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
    @@ -289,6 +289,25 @@ 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-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)
    Index: linux-2.6/include/asm-powerpc/atomic.h
    ===================================================================
    --- linux-2.6.orig/include/asm-powerpc/atomic.h
    +++ linux-2.6/include/asm-powerpc/atomic.h
    @@ -174,6 +174,31 @@ 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)
    \
     
     \ /
      Last update: 2005-11-05 08:58    [W:0.049 / U:120.508 seconds]
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