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

From Arnd Bergmann <arnd@arndb.de>
Newsgroups linux.kernel
Subject Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian
Date 2016-06-02 12:50 +0200
Message-ID <rFyml-4Qa-9@gated-at.bofh.it> (permalink)
References <rFxJE-4D3-35@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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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Thread

[PATCH] locking/qrwlock: fix write unlock issue in big endian Pan Xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-06-02 12:10 +0200
  Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian Arnd Bergmann <arnd@arndb.de> - 2016-06-02 12:50 +0200
    Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-06-02 13:10 +0200
      Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian Peter Zijlstra <peterz@infradead.org> - 2016-06-02 13:20 +0200
        Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-06-03 09:30 +0200
    Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian Peter Zijlstra <peterz@infradead.org> - 2016-06-02 13:10 +0200
      Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-06-03 09:20 +0200
      Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian xinhui <xinhui.pan@linux.vnet.ibm.com> - 2016-06-06 05:20 +0200
  Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian Will Deacon <will.deacon@arm.com> - 2016-06-08 11:30 +0200

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