From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C653C43381 for ; Fri, 22 Mar 2019 17:43:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1FFB22190A for ; Fri, 22 Mar 2019 17:43:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553276621; bh=P04ycmRQabKa/iPZr0GWLzGOmbAlXTRlfFFLOj7omBE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=GGc9UQPJUGROLHIOeuWNi67lHA9xg1dNOPTmbB/9siV+zhBf2UjnM1+Wm58z8sz8+ DIkEXVHKWjaBwWedyCmUe+PzJezDvuo2MxlKXnHz38V8L9e9H27FwEwPpH4jbcSDmE butXINVDGZiNYAFaVF43VUGta4fwlZUoXoCJFXvU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728705AbfCVRnj (ORCPT ); Fri, 22 Mar 2019 13:43:39 -0400 Received: from mail-yw1-f66.google.com ([209.85.161.66]:32908 "EHLO mail-yw1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727752AbfCVRnj (ORCPT ); Fri, 22 Mar 2019 13:43:39 -0400 Received: by mail-yw1-f66.google.com with SMTP id l5so2248715ywa.0 for ; Fri, 22 Mar 2019 10:43:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=PxGrj3YpzJKFMovhkJSQsQJvxgAYX8oxnUko0NLoCPs=; b=cd37aVQqUsw7LSQEVoWJemXqGaTVjozyQg0gr0yBmgwWBXN+ofpblQ9GvifVPHu9/n IiA8gVX+k/6pEXOK/gcbNzRc8tSI83Eh8UnJIjGDqEUByjYf1I3lfZgMD3EmrxVfO16h lf9v27qhfitXG8IQqd27v8V8dl/5erztpFnukO9/p3ZDMfqivxj3f1m0GwlKhgEeokCp C0o70v9nHtCtlBYXyb/+KsN69Q8WBe122nqUgXEUUcj4SKCeR+PL2T+vnetXYpejPgWE TvLlqu+xRFjSPB4CeaZGhOT+EG7GxIcvGe0t5CXNl7w0RXpfZWGaL+gfvLTWySOWjsnV 1LqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=PxGrj3YpzJKFMovhkJSQsQJvxgAYX8oxnUko0NLoCPs=; b=V5i5/cpfD/ALe1GTts34zkmpXpSSVjOm55AFRN+UTftLcmL8B9b5KTsV3XsajR3D/w eIw1Ap/0nOJdQpctG84WTWkKc2KL0uqIa/uY6vo/qFNOUvSR4HZaaUTxBnNJfGZaQqhe UV65a/joezyFH0asWhjB5FmoTCEHHrCV6DldRYiLcBD5UdDJaeCW0sYURCM02vh3i7L6 F3SdOVemmHQ1HvyR2rWtXaRbkeVUTCs2uNBC2mcGHrs2dU7jIGrd6jT+ehtwBZTixfVW OCNvY5oSAvFmzBaZkS4JpIzaApWTrD6UMTYSwI5owZvJJYQdF6MCaT99U85JjqNOpIU0 x9qg== X-Gm-Message-State: APjAAAVjJo3FhVwqdSXTANIiV6UvVHPfxGBah8/fiJYGi07Ha4oAE9l4 xgvrVUyY0+CWbaGn6siBuEg= X-Google-Smtp-Source: APXvYqzD1z8khaelCCdFCHMyik+Z5Xn/bVFEVH2LYJSkA7D6GQyP17QP/CY3h/UFzufeg4p7B2o31g== X-Received: by 2002:a25:5785:: with SMTP id l127mr9152244ybb.395.1553276618250; Fri, 22 Mar 2019 10:43:38 -0700 (PDT) Received: from localhost ([2620:10d:c091:180::bab1]) by smtp.gmail.com with ESMTPSA id t126sm4583929ywa.83.2019.03.22.10.43.36 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 22 Mar 2019 10:43:37 -0700 (PDT) Date: Fri, 22 Mar 2019 10:43:34 -0700 From: Tejun Heo To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, Lai Jiangshan , Ingo Molnar , Peter Zijlstra , Thomas Gleixner Subject: Re: [PATCH 1/2] workqueue: Use normal rcu Message-ID: <20190322174334.GC69236@devbig004.ftw2.facebook.com> References: <20190313165548.19713-1-bigeasy@linutronix.de> <20190313165548.19713-2-bigeasy@linutronix.de> <20190321205935.7ndo5k5zumc77h37@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190321205935.7ndo5k5zumc77h37@linutronix.de> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, Mar 21, 2019 at 09:59:35PM +0100, Sebastian Andrzej Siewior wrote: > On 2019-03-13 17:55:47 [+0100], To linux-kernel@vger.kernel.org wrote: > > From: Thomas Gleixner > > > > There is no need for sched_rcu. The undocumented reason why sched_rcu > > is used is to avoid a few explicit rcu_read_lock()/unlock() pairs by > > the fact that sched_rcu reader side critical sections are also protected > > by preempt or irq disabled regions. > > > > Replace rcu_read_lock_sched with rcu_read_lock and acquire the RCU lock > > where it is not yet explicit acquired. Replace local_irq_disable() with > > rcu_read_lock(). Update asserts. > > > > Signed-off-by: Thomas Gleixner > > [bigeasy: mangle changelog a little] > > Signed-off-by: Sebastian Andrzej Siewior > > A gentle ping. We can switch but it doesn't really say why we'd want to. Can you please explain why this is better? Thanks. -- tejun