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_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 3F7C1C34044 for ; Tue, 18 Feb 2020 16:43:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1956D22B48 for ; Tue, 18 Feb 2020 16:43:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582044197; bh=wuFZ+80meI/wCrT4fcDqibe9FS/MNqI4Yqa+RTE6mSU=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=dXV2J6YEkK5VJvKsW/omubspQbOYpYU1CaiPVDEC5sijwzW3mcVDv+MPdcVH+usQ5 xlKZVPh3SHqkL97Z0fDlpNIOAz8QUYNyRSaAl0wOtODBhY+S6sWvZ8MER12sXhQAoa +atbjALO1S0A5a2V8aLFnMvaCf8fa+xq2swORwl4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726672AbgBRQnQ (ORCPT ); Tue, 18 Feb 2020 11:43:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:59986 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726528AbgBRQnP (ORCPT ); Tue, 18 Feb 2020 11:43:15 -0500 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id D8F9B21D56; Tue, 18 Feb 2020 16:43:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582044194; bh=wuFZ+80meI/wCrT4fcDqibe9FS/MNqI4Yqa+RTE6mSU=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=jDQweW1cjYLyQePTP6bA+ueGikUn5TNmIqZFse63qinGEqoLROoiVVIEvOrIcn60e 4tbCHoIX8ydAylg/+PhgrtO/JV9wFVmxYr3k2AR7kjo7d+RbvrWCDK7uv0BfYo36Kj YAXjOQ4FB3KUD9ZVgbAgrem4wN+qBWpO539bk+qw= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id AD4263520365; Tue, 18 Feb 2020 08:43:14 -0800 (PST) Date: Tue, 18 Feb 2020 08:43:14 -0800 From: "Paul E. McKenney" To: Steven Rostedt Cc: Lai Jiangshan , Boqun Feng , linux-kernel@vger.kernel.org, Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , rcu@vger.kernel.org, Peter Zijlstra , Borislav Petkov , Sebastian Andrzej Siewior Subject: Re: [PATCH V2 2/7] rcu: cleanup rcu_preempt_deferred_qs() Message-ID: <20200218164314.GG2935@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20191102124559.1135-3-laijs@linux.alibaba.com> <20191103020150.GA23770@tardis> <7489f817-adaf-275b-b19d-18ad248b071f@linux.alibaba.com> <20191104145539.GY20975@paulmck-ThinkPad-P72> <20191105071911.GL20975@paulmck-ThinkPad-P72> <20191111143238.GA13306@paulmck-ThinkPad-P72> <20200217232307.GA17570@paulmck-ThinkPad-P72> <20200218094124.339c0315@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200218094124.339c0315@gandalf.local.home> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 18, 2020 at 09:41:24AM -0500, Steven Rostedt wrote: > On Mon, 17 Feb 2020 15:23:07 -0800 > "Paul E. McKenney" wrote: > > > > I'm still asking for more comments. > > > > > > By now, I have received some precious comments, mainly due to my > > > stupid naming mistakes and a misleading changelog. I should have > > How about typos? We appear to have enough typos, thank you! > > > updated all these with a new series patches. But I hope I > > > can polish more in the new patchset with more suggestions from > > > valuable comments, especially in x86,scheduler,percpu and rcu > > > areas. > > > > > > I'm very obliged to hear anything. > > > > commit 23a58acde0eea57ac77377e5d50d9562b2dbdfaa > > Author: Lai Jiangshan > > Date: Sat Feb 15 14:37:26 2020 -0800 > > > > rcu: Don't set nesting depth negative in rcu_preempt_deferred_qs() > > > > Now that RCU flavors have been consolidated, an RCU-preempt > > rcu_rea_unlock() in an interrupt or softirq handler cannot possibly > > What's a "rea"? ;-) A typo. Probably mine. Thank you for catching it, will fix! ;-) But maybe an rcu_rhea_lock()? Just in case the rheas are getting loose? Thanx, Paul > -- Steve > > > end the RCU read-side critical section. Consider the old vulnerability > > involving rcu_preempt_deferred_qs() being invoked within such a handler > > that interrupted an extended RCU read-side critical section, in which > > a wakeup might be invoked with a scheduler lock held. Because > > rcu_read_unlock_special() no longer does wakeups in such situations, > > it is no longer necessary for rcu_preempt_deferred_qs() to set the > > nesting level negative. > > > > This commit therfore removes this recursion-protection code from > > rcu_preempt_deferred_qs(). > > > > Signed-off-by: Lai Jiangshan > > Signed-off-by: Paul E. McKenney > > > >