On Thursday, June 2, 2016 6:09:08 PM CEST Pan Xinhui wrote:
> diff --git a/include/asm-generic/qrwlock.h b/include/asm-generic/qrwlock.h
> index 54a8e65..eadd7a3 100644
> --- a/include/asm-generic/qrwlock.h
> +++ b/include/asm-generic/qrwlock.h
> @@ -139,7 +139,7 @@ static inline void queued_read_unlock(struct qrwlock *lock)
>   */
>  static inline void queued_write_unlock(struct qrwlock *lock)
>  {
> -       smp_store_release((u8 *)&lock->cnts, 0);
> +       (void)atomic_sub_return_release(_QW_LOCKED, &lock->cnts);
>  }

Isn't this more expensive than the existing version?

	Arnd