Received: by 2002:ac0:a594:0:0:0:0:0 with SMTP id m20-v6csp6180152imm; Sat, 19 May 2018 20:03:42 -0700 (PDT) X-Google-Smtp-Source: AB8JxZqsv1+w5u6mmO9rBfwUBAQCdiu27RJXVe7PP1E/2RGDl1JnQarbJNpTmmt0PoJArVZF7XB3 X-Received: by 2002:a65:5a0d:: with SMTP id y13-v6mr12115642pgs.15.1526785422186; Sat, 19 May 2018 20:03:42 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1526785422; cv=none; d=google.com; s=arc-20160816; b=lg++qHQgThmc2Q8iRE29Ar1bLWudb5zqgpj0d6fEQO7eJdjWgsqx5RphVb3lBxrfTV LjQQPJK5/CMeldy7QWGXy0YUga3AVQMrWEhUTT+Y+W6aU60QSTr6ySKKEmSLhnPNl+SK Vs1mKtcVRD5fj0gRLKXJegc2bqVxM9C+Yp7GEjT31BzdQUwn31ylFvnCj+ttlp53gw/f 6kVLRv5Wb8c50kDuIC9YQu9EKtunYihdlhgm1BztZu6Bpivgj4wbC1n34SReA3MWpZwR FPBemMls3oNDyPZd6h0TN+Afa4x+OjlCXq2BrkI0f7Lp2MMe4dHvv9YIA41YWRCHb2xy yffA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :references:in-reply-to:from:subject:cc:to:message-id:date :arc-authentication-results; bh=6/FB0yE/iAfFh8dNAM4FdFxcucjJchy34Jq2qyWwWeo=; b=yHeqQq7xGr6U/c8mMBKVZjLKG0TuV4QSupQMbQgkLwywBED36dgJybTs7XpmDh4lWU MxZuxiWdfrXmV1POR1QLhFXs3VB3ke7Nea4tNKfLFOSfZV+LhBXl93SnHYEF5ChZ1RgM oqyNQVwLmeonYp188deZ6kzUDPtgoV7LjTmCm3jgvP4jfHrRIgCQuDhcbJaM1Sslx6lb EFzJi6OgJUIVuCZXONxxKyHUAnTNUiJ1qY11tOu68SIZipSoTfmUY+HTiA/W1AfA35GI Zgd26jSAMFS27SsPjxnlC5JtvxcezELtc0360KWEgA/u9OgB/gelbif4tvxHwmDJHNLZ /58Q== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 3-v6si11297349plu.564.2018.05.19.20.03.27; Sat, 19 May 2018 20:03:42 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752576AbeETDDA (ORCPT + 99 others); Sat, 19 May 2018 23:03:00 -0400 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 Received: from localhost (pool-173-77-163-54.nycmny.fios.verizon.net [173.77.163.54]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id F2833127152BC; Sat, 19 May 2018 20:02:58 -0700 (PDT) Date: Sat, 19 May 2018 23:02:58 -0400 (EDT) Message-Id: <20180519.230258.1374885458106197707.davem@davemloft.net> To: vladbu@mellanox.com Cc: xiyou.wangcong@gmail.com, netdev@vger.kernel.org, jhs@mojatatu.com, jiri@resnulli.us, linux-kernel@vger.kernel.org Subject: Re: [PATCH] net: sched: don't disable bh when accessing action idr From: David Miller In-Reply-To: References: <1526658324-6570-1-git-send-email-vladbu@mellanox.com> X-Mailer: Mew version 6.7 on Emacs 25.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Sat, 19 May 2018 20:02:59 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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?