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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,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 74AA7C3402F for ; Mon, 17 Feb 2020 23:23:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4C6E920801 for ; Mon, 17 Feb 2020 23:23:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581981836; bh=sDfs6Rya63GdiVLCpdtRhuNERReZPePVMOMqKNqMLQk=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=ukLbKR3RStsamY1mzF7rKaGQnKib5yvYpR0m46ZCZG5xkLB2mykYfHtrSM+A41LL2 PSU88mkt5bv+iVSsT49F5Xyov2cnIwrlIVaOJV21xbgQ7ZqOOAf4I9iyh//GZ6n5Cm ybv0ppjSATfidRoXZ3MnYNUjFyyQ2IMzSwsjGJhI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726276AbgBQXXz (ORCPT ); Mon, 17 Feb 2020 18:23:55 -0500 Received: from mail.kernel.org ([198.145.29.99]:54268 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725959AbgBQXXy (ORCPT ); Mon, 17 Feb 2020 18:23:54 -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 1E700206E2; Mon, 17 Feb 2020 23:23:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581981834; bh=sDfs6Rya63GdiVLCpdtRhuNERReZPePVMOMqKNqMLQk=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=gMn9FqcahSPeHf8pBojukyalgPQiSj6YPALVPUvP+FkwBTV/S1qvTc9/MMZQSgU+5 MTJ1bOgIKe8F4Q2DXeQ6VFhWKmD1qGzOLWXXE1Ptu87xSn6xmoULKXCDZjVOBsx8gH dhevFiCTBPPXHwcAi7z+G9ARMotG9D9LLkOJdWgo= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id F40C035227A8; Mon, 17 Feb 2020 15:23:53 -0800 (PST) Date: Mon, 17 Feb 2020 15:23:53 -0800 From: "Paul E. McKenney" To: Lai Jiangshan Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , rcu@vger.kernel.org Subject: Re: [PATCH V2 3/7] rcu: remove useless special.b.deferred_qs Message-ID: <20200217232353.GB17570@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20191102124559.1135-1-laijs@linux.alibaba.com> <20191102124559.1135-4-laijs@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191102124559.1135-4-laijs@linux.alibaba.com> 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 Sat, Nov 02, 2019 at 12:45:55PM +0000, Lai Jiangshan wrote: > ->read_read_unlock_special.b.deferred_qs is set when > ->read_read_unlock_special is non-zero, and it is cleared when > ->read_read_unlock_special is cleared. > > So it is useless. > > Signed-off-by: Lai Jiangshan I have queued this on -rcu for further review and testing, thank you! Thanx, Paul > --- > include/linux/sched.h | 2 +- > kernel/rcu/tree_plugin.h | 1 - > 2 files changed, 1 insertion(+), 2 deletions(-) > > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 2c2e56bd8913..3ba392d71de9 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -604,7 +604,7 @@ union rcu_special { > u8 blocked; > u8 need_qs; > u8 exp_hint; /* Hint for performance. */ > - u8 deferred_qs; > + u8 pad; /* No garbage from compiler! */ > } b; /* Bits. */ > u32 s; /* Set of bits. */ > }; > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 2fab8be2061f..f2fd7d687bdb 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -622,7 +622,6 @@ static void rcu_read_unlock_special(struct task_struct *t) > irq_work_queue_on(&rdp->defer_qs_iw, rdp->cpu); > } > } > - t->rcu_read_unlock_special.b.deferred_qs = true; > local_irq_restore(flags); > return; > } > -- > 2.20.1 >