Return-path: Received: from mail2.candelatech.com ([208.74.158.173]:60984 "EHLO mail2.candelatech.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751955AbcILQhr (ORCPT ); Mon, 12 Sep 2016 12:37:47 -0400 Subject: Re: [PATCH 2/3] ath10k: Grab rcu_read_lock before the txqs spinlock. To: Johannes Berg , "Valo, Kalle" References: <1471569995-10028-1-git-send-email-greearb@candelatech.com> <1471569995-10028-2-git-send-email-greearb@candelatech.com> <87k2elp53z.fsf@kamboji.qca.qualcomm.com> <57D2CB92.3020407@candelatech.com> <1473662509.4201.0.camel@sipsolutions.net> Cc: "ath10k@lists.infradead.org" , "linux-wireless@vger.kernel.org" From: Ben Greear Message-ID: (sfid-20160912_183751_021530_3358042B) Date: Mon, 12 Sep 2016 09:37:46 -0700 MIME-Version: 1.0 In-Reply-To: <1473662509.4201.0.camel@sipsolutions.net> Content-Type: text/plain; charset=utf-8; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: On 09/11/2016 11:41 PM, Johannes Berg wrote: > >>>> - rcu_read_unlock(); >>>> spin_unlock_bh(&ar->txqs_lock); >>>> + rcu_read_unlock(); >>> >>> I'm no RCU expert but this isn't making any sense. Maybe it changes >>> timings on your kernel so that it hides the real problem? >> >> I'm not sure this fixed anything or not, it just seemed weird so I >> changed it. >> >> I was hoping someone that understood rcu locking would comment... >> > > RCU is no "locking". The sooner you get over that notion, the better. > > This therefore make no sense whatsoever. > > In fact, you want to keep the RCU protected section *small*, so having > the spinlock inside hurts overall system performance. Ok, thanks for the review. I'll drop this patch from my tree. Thanks, Ben -- Ben Greear Candela Technologies Inc http://www.candelatech.com