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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6F0ACC388F9 for ; Wed, 11 Nov 2020 22:22:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 04770208CA for ; Wed, 11 Nov 2020 22:22:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="CPdglktB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726723AbgKKWWm (ORCPT ); Wed, 11 Nov 2020 17:22:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:34082 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725933AbgKKWWm (ORCPT ); Wed, 11 Nov 2020 17:22:42 -0500 Received: from localhost (unknown [176.177.123.193]) (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 B23E4208FE; Wed, 11 Nov 2020 22:22:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1605133361; bh=ImNxlyAjJTegTBwA4FTvPm9Lo+Se6ym6Dyb0QhUgXiI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=CPdglktB+ckt5B/6My4oBVWBFUs95i2UJiC8d9MpvtBtsuEFSEOG7OJG0O6Vah/Jo lFOVd6uua1kDHXgVpXqUiKm0J3t1nxMA2mZs4duhMz13seOszsM+V7POKEvYC5PV37 LufyhrDnoT7bgL95k2WOsnIKdWJ3c0m+2sYUG7kM= Date: Wed, 11 Nov 2020 23:22:38 +0100 From: Frederic Weisbecker To: Peter Zijlstra Cc: LKML , "Paul E . McKenney" , Thomas Gleixner , Phil Auld , Marcelo Tosatti Subject: Re: [PATCH 4/5] context_tracking: Only define schedule_user() on !HAVE_CONTEXT_TRACKING_OFFSTACK archs Message-ID: <20201111222238.GB73739@lothringen> References: <20201027150827.148821-1-frederic@kernel.org> <20201027150827.148821-5-frederic@kernel.org> <20201111143458.GV2611@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201111143458.GV2611@hirez.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 11, 2020 at 03:34:58PM +0100, Peter Zijlstra wrote: > On Tue, Oct 27, 2020 at 04:08:26PM +0100, Frederic Weisbecker wrote: > > schedule_user() was traditionally used by the entry code's tail to > > preempt userspace after the call to user_enter(). Indeed the call to > > user_enter() used to be performed upon syscall exit slow path which was > > right before the last opportunity to schedule() while resuming to > > userspace. The context tracking state had to be saved on the task stack > > and set back to CONTEXT_KERNEL temporarily in order to safely switch to > > another task. > > > > Only a few archs use it now and those implementing > > HAVE_CONTEXT_TRACKING_OFFSTACK definetly can't rely on it. > > powerpc64 and sparc64 only, right? Exactly! I can precise that in the changelog. Thanks. > > > Signed-off-by: Frederic Weisbecker > > Cc: Marcelo Tosatti > > Cc: Paul E. McKenney > > Cc: Peter Zijlstra > > Cc: Phil Auld > > Cc: Thomas Gleixner > > --- > > kernel/sched/core.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > > index c23d7cb5aee3..44426e5acde2 100644 > > --- a/kernel/sched/core.c > > +++ b/kernel/sched/core.c > > @@ -4631,7 +4631,7 @@ void __sched schedule_idle(void) > > } while (need_resched()); > > } > > > > -#ifdef CONFIG_CONTEXT_TRACKING > > +#if defined(CONFIG_CONTEXT_TRACKING) && !defined(CONFIG_HAVE_CONTEXT_TRACKING_OFFSTACK) > > asmlinkage __visible void __sched schedule_user(void) > > { > > /* > > -- > > 2.25.1 > >