Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian

From: Arnd Bergmann
Date: Thu Jun 02 2016 - 06:44:49 EST


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

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