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    Subject[RFC][PATCH 09/31] locking,h8300: Implement atomic_fetch_{add,sub,and,or,xor}()
    Implement FETCH-OP atomic primitives, these are very similar to the
    existing OP-RETURN primitives we already have, except they return the
    value of the atomic variable _before_ modification.

    This is especially useful for irreversible operations -- such as
    bitops (because it becomes impossible to reconstruct the state prior
    to modification).

    Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    ---
    arch/h8300/include/asm/atomic.h | 31 +++++++++++++++++++++++++------
    1 file changed, 25 insertions(+), 6 deletions(-)

    --- a/arch/h8300/include/asm/atomic.h
    +++ b/arch/h8300/include/asm/atomic.h
    @@ -28,6 +28,19 @@ static inline int atomic_##op##_return(i
    return ret; \
    }

    +#define ATOMIC_FETCH_OP(op, c_op) \
    +static inline int atomic_fetch_##op(int i, atomic_t *v) \
    +{ \
    + h8300flags flags; \
    + int ret; \
    + \
    + flags = arch_local_irq_save(); \
    + ret = v->counter; \
    + v->counter c_op i; \
    + arch_local_irq_restore(flags); \
    + return ret; \
    +}
    +
    #define ATOMIC_OP(op, c_op) \
    static inline void atomic_##op(int i, atomic_t *v) \
    { \
    @@ -41,17 +54,23 @@ static inline void atomic_##op(int i, at
    ATOMIC_OP_RETURN(add, +=)
    ATOMIC_OP_RETURN(sub, -=)

    -ATOMIC_OP(and, &=)
    -ATOMIC_OP(or, |=)
    -ATOMIC_OP(xor, ^=)
    +#define atomic_fetch_or atomic_fetch_or

    +#define ATOMIC_OPS(op, c_op) \
    + ATOMIC_OP(op, c_op) \
    + ATOMIC_FETCH_OP(op, c_op)
    +
    +ATOMIC_OPS(and, &=)
    +ATOMIC_OPS(or, |=)
    +ATOMIC_OPS(xor, ^=)
    +ATOMIC_OPS(add, +=)
    +ATOMIC_OPS(sub, -=)
    +
    +#undef ATOMIC_OPS
    #undef ATOMIC_OP_RETURN
    #undef ATOMIC_OP

    -#define atomic_add(i, v) (void)atomic_add_return(i, v)
    #define atomic_add_negative(a, v) (atomic_add_return((a), (v)) < 0)
    -
    -#define atomic_sub(i, v) (void)atomic_sub_return(i, v)
    #define atomic_sub_and_test(i, v) (atomic_sub_return(i, v) == 0)

    #define atomic_inc_return(v) atomic_add_return(1, v)

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      Last update: 2016-04-22 12:21    [W:4.093 / U:0.108 seconds]
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