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    Subject[PATCH 10/10] atomic.h : Add atomic64 cmpxchg, xchg and add_unless to x86_64
    Date
    atomic.h : Add atomic64 cmpxchg, xchg and add_unless to x86_64

    Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

    --- a/include/asm-x86_64/atomic.h
    +++ b/include/asm-x86_64/atomic.h
    @@ -375,8 +375,8 @@ static __inline__ long atomic64_add_return(long i, atomic64_t *v)
    long __i = i;
    __asm__ __volatile__(
    LOCK_PREFIX "xaddq %0, %1;"
    - :"=r"(i)
    - :"m"(v->counter), "0"(i));
    + :"+r" (i), "+m" (v->counter)
    + : : "memory");
    return i + __i;
    }

    @@ -388,7 +388,10 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t *v)
    #define atomic64_inc_return(v) (atomic64_add_return(1,v))
    #define atomic64_dec_return(v) (atomic64_sub_return(1,v))

    -#define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
    +#define atomic64_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), old, new))
    +#define atomic64_xchg(v, new) (xchg(&((v)->counter), new))
    +
    +#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), old, new))
    #define atomic_xchg(v, new) (xchg(&((v)->counter), new))

    /**
    @@ -402,7 +405,7 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t *v)
    */
    #define atomic_add_unless(v, a, u) \
    ({ \
    - int c, old; \
    + __typeof__((v)->counter) c, old; \
    c = atomic_read(v); \
    for (;;) { \
    if (unlikely(c == (u))) \
    @@ -416,6 +419,31 @@ static __inline__ long atomic64_sub_return(long i, atomic64_t *v)
    })
    #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)

    +/**
    + * atomic64_add_unless - add unless the number is a given value
    + * @v: pointer of type atomic64_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 atomic64_add_unless(v, a, u) \
    +({ \
    + __typeof__((v)->counter) c, old; \
    + c = atomic64_read(v); \
    + for (;;) { \
    + if (unlikely(c == (u))) \
    + break; \
    + old = atomic64_cmpxchg((v), c, c + (a)); \
    + if (likely(old == c)) \
    + break; \
    + c = old; \
    + } \
    + c != (u); \
    +})
    +#define atomic64_inc_not_zero(v) atomic64_add_unless((v), 1, 0)
    +
    /* These are x86-specific, used by some header files */
    #define atomic_clear_mask(mask, addr) \
    __asm__ __volatile__(LOCK_PREFIX "andl %0,%1" \
    -
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