From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH] net: sched: don't disable bh when accessing action idr Date: Sat, 19 May 2018 23:02:58 -0400 (EDT) Message-ID: <20180519.230258.1374885458106197707.davem@davemloft.net> References: <1526658324-6570-1-git-send-email-vladbu@mellanox.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: xiyou.wangcong@gmail.com, netdev@vger.kernel.org, jhs@mojatatu.com, jiri@resnulli.us, linux-kernel@vger.kernel.org To: vladbu@mellanox.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:37524 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752459AbeETDC7 (ORCPT ); Sat, 19 May 2018 23:02:59 -0400 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: From: Vlad Buslov Date: Sat, 19 May 2018 13:12:49 +0300 > > On Sat 19 May 2018 at 02:59, Cong Wang wrote: >> On Fri, May 18, 2018 at 8:45 AM, Vlad Buslov wrote: >>> Underlying implementation of action map has changed and doesn't require >>> disabling bh anymore. Replace all action idr spinlock usage with regular >>> calls that do not disable bh. >> >> Please explain explicitly why it is not required, don't let people >> dig, this would save everyone's time. > > Underlying implementation of actions lookup has changed from hashtable > to idr. Every current action implementation just calls act_api lookup > function instead of implementing its own lookup. I asked author of idr > change if there is a reason to continue to use _bh versions and he > replied that he just left them as-is. A detailed analysis of the locking requirements both before and after the IDR changes needs to be in you commit message. Nobody who reads this from scratch understands all of this background material, so how can anyone reading your patch review it properly and understand it?