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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 AFC55C47082 for ; Mon, 7 Jun 2021 11:10:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99C2961107 for ; Mon, 7 Jun 2021 11:10:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231265AbhFGLMs (ORCPT ); Mon, 7 Jun 2021 07:12:48 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37178 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230230AbhFGLMq (ORCPT ); Mon, 7 Jun 2021 07:12:46 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60354C061766; Mon, 7 Jun 2021 04:10:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=NLj4NYDQW6SbenCIcbS9QrwkO4aohp/HPEuCGPuaREs=; b=cPnEKquwt970ZOfmptV8ZPqMgA nDKIN3sS9ih9nuu8IzgPQnkE+3vwyvAnDc2ZrMU9wmERzTb3IGMYGi4WE6+4lUgqF2JtL/lM/I5kJ eiHF9IMB2d+Y9lTFFFVOwPJJI9S76oa/nkFLOGjGCPqHZTpDXHEuTaeqYbLfHC8bQodhRsFoh+Qy8 dTHV3vTaUZfqdQXrfYxuM6d63mJeyrNKoQ2Zm8n4XPuwlvYtbjKQlZwLanaf8FCczQxwMbK2aY9KZ 5ZBbcHBMtWS/MR3PhHmCJk3dhHVW0UT+bEq4donFnJVNzTVZUBUUF9jUBREUKuzW6aCVhr/V5xCxL LVjMXPEw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1lqD9Y-004Mvp-0K; Mon, 07 Jun 2021 11:10:51 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id C9BD33002A6; Mon, 7 Jun 2021 13:10:49 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id A8BB82CF3852B; Mon, 7 Jun 2021 13:10:49 +0200 (CEST) Date: Mon, 7 Jun 2021 13:10:49 +0200 From: Peter Zijlstra To: Daniel Thompson Cc: Thomas Gleixner , Ingo Molnar , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Jens Axboe , Alasdair Kergon , Mike Snitzer , dm-devel@redhat.com, "David S. Miller" , Jakub Kicinski , Felipe Balbi , Greg Kroah-Hartman , Alexander Viro , Tejun Heo , Zefan Li , Johannes Weiner , Jason Wessel , Douglas Anderson , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , "Rafael J. Wysocki" , Pavel Machek , Will Deacon , Waiman Long , Boqun Feng , Oleg Nesterov , Davidlohr Bueso , "Paul E. McKenney" , Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , John Stultz , Stephen Boyd , Andrew Morton , Paolo Bonzini , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, netdev@vger.kernel.org, linux-usb@vger.kernel.org, linux-fsdevel@vger.kernel.org, cgroups@vger.kernel.org, kgdb-bugreport@lists.sourceforge.net, linux-perf-users@vger.kernel.org, linux-pm@vger.kernel.org, rcu@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org Subject: Re: [PATCH 6/6] sched: Change task_struct::state Message-ID: References: <20210602131225.336600299@infradead.org> <20210602133040.587042016@infradead.org> <20210607104500.sopvslejuoxwzhrs@maple.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210607104500.sopvslejuoxwzhrs@maple.lan> Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Jun 07, 2021 at 11:45:00AM +0100, Daniel Thompson wrote: > On Wed, Jun 02, 2021 at 03:12:31PM +0200, Peter Zijlstra wrote: > > Change the type and name of task_struct::state. Drop the volatile and > > shrink it to an 'unsigned int'. Rename it in order to find all uses > > such that we can use READ_ONCE/WRITE_ONCE as appropriate. > > > > Signed-off-by: Peter Zijlstra (Intel) > > --- > > ... > > kernel/debug/kdb/kdb_support.c | 18 +++++++------ > > ... > > --- a/kernel/debug/kdb/kdb_support.c > > +++ b/kernel/debug/kdb/kdb_support.c > > @@ -609,23 +609,25 @@ unsigned long kdb_task_state_string(cons > > */ > > char kdb_task_state_char (const struct task_struct *p) > > { > > - int cpu; > > - char state; > > + unsigned int p_state; > > unsigned long tmp; > > + char state; > > + int cpu; > > > > if (!p || > > copy_from_kernel_nofault(&tmp, (char *)p, sizeof(unsigned long))) > > return 'E'; > > > > cpu = kdb_process_cpu(p); > > - state = (p->state == 0) ? 'R' : > > - (p->state < 0) ? 'U' : > > - (p->state & TASK_UNINTERRUPTIBLE) ? 'D' : > > - (p->state & TASK_STOPPED) ? 'T' : > > - (p->state & TASK_TRACED) ? 'C' : > > + p_state = READ_ONCE(p->__state); > > + state = (p_state == 0) ? 'R' : > > + (p_state < 0) ? 'U' : > > Looks like the U here stands for Unreachable since this patch makes it > more obvious that this clause is (and previously was) exactly that! > > Dropping the U state would be good since I guess this will show up as a > "new" warning in some tools. However it was a preexisting problem so with > or without this cleaned up: > Acked-by: Daniel Thompson Thanks! Note that there's a second instance of this exact code in arch/powerpc/xmon/xmon.c, with the same 'U' issue. I'll repost this soon, as it seems I've fixed all robot failout (fingers crossed).