Re: [Qemu-devel] [RFC v1 04/12] atomic: introduce atomic_dec_fetch.

[Sergey Fedorov <serge.fdrv@gmail.com>]

On 15/04/16 17:23, Alex Bennée wrote:
> Useful for counting down.
>
> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>

Reviewed-by: Sergey Fedorov <sergey.fedorov@linaro.org>

> ---
>  include/qemu/atomic.h | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
> index 8f1d8d9..5dba7db 100644
> --- a/include/qemu/atomic.h
> +++ b/include/qemu/atomic.h
> @@ -131,6 +131,8 @@
>  #define atomic_fetch_and(ptr, n) __atomic_fetch_and(ptr, n, __ATOMIC_SEQ_CST)
>  #define atomic_fetch_or(ptr, n)  __atomic_fetch_or(ptr, n, __ATOMIC_SEQ_CST)
>  
> +#define atomic_dec_fetch(ptr)  __atomic_sub_fetch(ptr, 1, __ATOMIC_SEQ_CST)
> +
>  /* And even shorter names that return void.  */
>  #define atomic_inc(ptr)    ((void) __atomic_fetch_add(ptr, 1, __ATOMIC_SEQ_CST))
>  #define atomic_dec(ptr)    ((void) __atomic_fetch_sub(ptr, 1, __ATOMIC_SEQ_CST))
> @@ -326,6 +328,8 @@
>  #define atomic_fetch_or        __sync_fetch_and_or
>  #define atomic_cmpxchg         __sync_val_compare_and_swap
>  
> +#define atomic_dec_fetch(ptr)  __sync_sub_and_fetch(ptr, 1)
> +
>  /* And even shorter names that return void.  */
>  #define atomic_inc(ptr)        ((void) __sync_fetch_and_add(ptr, 1))
>  #define atomic_dec(ptr)        ((void) __sync_fetch_and_add(ptr, -1))