From mboxrd@z Thu Jan 1 00:00:00 1970 From: Duan Jiong Subject: Re: [PATCH net-next] ipv6: remove useless spin_lock/spin_unlock Date: Wed, 3 Dec 2014 10:05:19 +0800 Message-ID: <547E6FDF.2040809@cn.fujitsu.com> References: <547E6832.4070403@cn.fujitsu.com> <1417571879.5303.83.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , netdev To: Eric Dumazet Return-path: Received: from cn.fujitsu.com ([59.151.112.132]:34785 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1750862AbaLCCIA (ORCPT ); Tue, 2 Dec 2014 21:08:00 -0500 In-Reply-To: <1417571879.5303.83.camel@edumazet-glaptop2.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: On 12/03/2014 09:57 AM, Eric Dumazet wrote: > On Wed, 2014-12-03 at 09:32 +0800, Duan Jiong wrote: >> xchg is atomic, so there is no necessary to use spin_lock/spin_unlock >> to protect it. >> >> Signed-off-by: Duan Jiong >> --- >> net/ipv6/ipv6_sockglue.c | 2 -- >> 1 file changed, 2 deletions(-) >> >> diff --git a/net/ipv6/ipv6_sockglue.c b/net/ipv6/ipv6_sockglue.c >> index e1a9583..92ca907 100644 >> --- a/net/ipv6/ipv6_sockglue.c >> +++ b/net/ipv6/ipv6_sockglue.c >> @@ -112,9 +112,7 @@ struct ipv6_txoptions *ipv6_update_options(struct sock *sk, >> } >> opt = xchg(&inet6_sk(sk)->opt, opt); >> } else { >> - spin_lock(&sk->sk_dst_lock); >> opt = xchg(&inet6_sk(sk)->opt, opt); >> - spin_unlock(&sk->sk_dst_lock); >> } >> sk_dst_reset(sk); >> > > Why keeping 2 copies of opt = xchg(&inet6_sk(sk)->opt, opt); then ? > Thanks for you remind, i didn't notice that. The else statement could be removed, opt = xchg(&inet6_sk(sk)->opt, opt); should be moved out, and i will send v2. Thanks, Duan > > >