From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753017AbcFBKoq (ORCPT ); Thu, 2 Jun 2016 06:44:46 -0400 Received: from mout.kundenserver.de ([217.72.192.74]:61764 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751326AbcFBKoo (ORCPT ); Thu, 2 Jun 2016 06:44:44 -0400 From: Arnd Bergmann To: Pan Xinhui Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, waiman.long@hp.com, peterz@infradead.org Subject: Re: [PATCH] locking/qrwlock: fix write unlock issue in big endian Date: Thu, 02 Jun 2016 12:44:51 +0200 Message-ID: <4399273.0kije2Qdx5@wuerfel> User-Agent: KMail/5.1.3 (Linux/4.4.0-22-generic; KDE/5.18.0; x86_64; ; ) In-Reply-To: <1464862148-5672-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> References: <1464862148-5672-1-git-send-email-xinhui.pan@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="nextPart5489986.skLWY62fJ9" Content-Transfer-Encoding: 7Bit X-Provags-ID: V03:K0:tU3RECfDY3TfHnLwPtCyvDkjhD3c0WD7EcSma+90V6rzeQul2u8 hWtv6oRaar4M+NWjlfodgUeAZNL/RG2sbcsQlqFE2gKQxZcsMeYFz9SI1cNx//jYS7qLNgA 1jFVJ5CRzr1wtCCK8YRO/sIWyq19tIWy1NDMoBxtiUFrRkTkV3gcAKFimE11Zh7K3+Z6Azm xh6yzFQEOd5Kt/rgUjOLA== X-UI-Out-Filterresults: notjunk:1;V01:K0:rr8YdQUa74s=:j8hVjt67WhvagvfvzSlshQ bS2v3qvolpnabWqNLN/9rNnjHUSGh61a74/oPINXY6Z1sKBMwudUbR5Hw3949gouW1CeYRlHi GC9jkvafjyCOVENCU7npoTZq45uN6D7YUjKKMpAB+PtaFjRgn4SupWE002b0+3OBtrnm5xsi4 iXH//lfFV7ufrAmhYgHOt+UEEMA9a0WPF0/AkQynJmbowmukDi8MUz+/dGhu2ORmlzYLhuqJW /3m50zTvR7TH0iMaqm/o2RgeAgMf++89CjO2Om3Ic2zOiZpixCsrfmt8Y4PUwRcPHULzVrFtI MSqRwcW+q0GhBeONBHzGfjtyoPpeZ8HoSum3U2oRV/jngypo8Aw4gMOcnL+jc2QKxJ5luY/zU fXGraPPo2c5rDjfeSatA4BVkNHf0GAw3gZsb9Iu6jAhNK5UKaQNHpFV4hgOKwHPLHHrA87T8A gQ9PuVcEgP2SS87zuGV5brpkT9GCn5n52jZy1y9dbsyCfwXvgOdLoyTT2tIx+PXRghBekZ7ju 5679YjqGMXkE+EY8PaxhbszTtOys7fDm3Imfj71f7OAf1LsGSyTz7FBJ51tDgHpGuOD5KxAVo 9hPrWRxx/iUWEt02zBO23H9yALot4rF6NYyse3IHql7ChRjqCydQ2ZnY2tftNyMUVOslhTQW5 IFHCL2S1Yb9AmNeoykvgWZngwLojfWmVNoeTsk+J3/1R+t9wjjxJ9BTPPhgqqLD9czrs= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --nextPart5489986.skLWY62fJ9 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" 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? 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