From mboxrd@z Thu Jan 1 00:00:00 1970 From: Giuseppe CAVALLARO Subject: Re: [net-next.git 1/7] stmmac: review napi gro support Date: Thu, 04 Apr 2013 08:16:56 +0200 Message-ID: <515D1AD8.409@st.com> References: <1364967689-11155-1-git-send-email-peppe.cavallaro@st.com> <1364972715.5113.197.camel@edumazet-glaptop> <515BDD1C.5010306@st.com> <1364996374.13853.15.camel@edumazet-glaptop> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Eric Dumazet Return-path: Received: from eu1sys200aog111.obsmtp.com ([207.126.144.131]:40573 "EHLO eu1sys200aog111.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756023Ab3DDGRA (ORCPT ); Thu, 4 Apr 2013 02:17:00 -0400 In-Reply-To: <1364996374.13853.15.camel@edumazet-glaptop> Sender: netdev-owner@vger.kernel.org List-ID: On 4/3/2013 3:39 PM, Eric Dumazet wrote: > On Wed, 2013-04-03 at 09:41 +0200, Giuseppe CAVALLARO wrote: > >> Hmm, I'm in trouble on this :-). Indeed I can understand the (fatal) >> race and why napi_complete should be used. Sorry! So my fault and this >> patch has to be discarded. I don't understand why I have not seen any >> problems while running/stressing on SMP system. Have you got any idea? >> > > So because you don't hit the race on your machine and your tests, we can > remove all the needed spinlock() and various hard irq masking, and > introduce all sort of races ? No, no this was not my intention. If fact, I asked to discard the patch ;-) ... it is clear to me the race that can happen in that case. I'll rework the patch to only add the GRO in the feature. peppe > > Try to use a combination of two NICS, and you'll hit the bug even on UP. > > There is a single poll_list per cpu, and we insert new elements in this > list under hard irq. > > So deleting elements _must_ be done under the protection of hard irq > masking. > > > > >