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 7260EC47094 for ; Mon, 7 Jun 2021 10:46:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5992D611C0 for ; Mon, 7 Jun 2021 10:46:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230443AbhFGKr5 (ORCPT ); Mon, 7 Jun 2021 06:47:57 -0400 Received: from mail-wr1-f54.google.com ([209.85.221.54]:34693 "EHLO mail-wr1-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230127AbhFGKrz (ORCPT ); Mon, 7 Jun 2021 06:47:55 -0400 Received: by mail-wr1-f54.google.com with SMTP id q5so17058265wrm.1 for ; Mon, 07 Jun 2021 03:46:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=aqlB3nweefXMBd+1n3TfVg5Imk7mqG7GGko5Cn1Ypjk=; b=fokBrG+2G1fkq/XmZlW8Qn8gNsGVee/kxIBq16SYHHcihUEHhxAiLiYioDzjZCKPWV 9QEZOxcXx7fkFSqzCPab9ejYwiSWHFrBFKIvS4T83XVPbmSdXZpWw/7QLttpVgGupn7M FoWs2xbakjWUMbWyKY9toPvBiRJY2NSMoomhdLwJgft1TVJGXI1KGV/tNqHpK+0t4K/c ssThtjIQ5Gd6U2Vgt07NOm/v5UajEDZu6QDpCKD4dz0UaryRPm6OwVwk+zBYdDwhZepP 9jCgvqxA0rUhD0TtVGl/Sk+NMb0qRwm6JS3LOkQ+swNNoK5wt0XeTzNUgGulkw29L99w ZQaw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=aqlB3nweefXMBd+1n3TfVg5Imk7mqG7GGko5Cn1Ypjk=; b=icObjEVh3qtUu9lvCYc2dRTEVigkrJnPhsYmrcdf7MLiWDZO9GIOcM3u7Hf1LQ2Hhi iZPuDpZif039nTR/X4nG+Xk+6Uy2z6wtMdLiVV6RS/pdzvioybAHMnvfW6Af5Taaieab 7FeQsqf+CjyiE2B0ACSAB15VXcfB35lhDVofAgVRPC1JUTAfh4xzgvDk5QfwGhZBIIsi zHLoFjGPoirxt0oqnfgs2+vJShVexqr4Lw6e9xGsCV5t8r06rPt1vo9WYJfo4z1QwRvB bshCfQMOhKlY6AXGv9LWvsdL9ihC3bbx8Rtyvg+QSgjP3YmaT/IHNV6jrAawU5qB33LJ LShQ== X-Gm-Message-State: AOAM531LLRvjY11bxcZ7BkKIAtx7+dgpr9dIO2bw1eX42Wlc12q/MnUK ZilBMOUGOh//ESIiKZoqEGdDRA== X-Google-Smtp-Source: ABdhPJwqNBSGH0k0cJir/i3kAe7gRK7bFBO/b5hmcAfd7Z+SvyV8tZwYe+ey/npaVItqY9949tYt3w== X-Received: by 2002:a05:6000:1563:: with SMTP id 3mr16068224wrz.59.1623062703694; Mon, 07 Jun 2021 03:45:03 -0700 (PDT) Received: from maple.lan (cpc141216-aztw34-2-0-cust174.18-1.cable.virginm.net. [80.7.220.175]) by smtp.gmail.com with ESMTPSA id p16sm16000678wrs.52.2021.06.07.03.45.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Jun 2021 03:45:03 -0700 (PDT) Date: Mon, 7 Jun 2021 11:45:00 +0100 From: Daniel Thompson To: Peter Zijlstra 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: <20210607104500.sopvslejuoxwzhrs@maple.lan> References: <20210602131225.336600299@infradead.org> <20210602133040.587042016@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210602133040.587042016@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Daniel. > + (p_state & TASK_UNINTERRUPTIBLE) ? 'D' : > + (p_state & TASK_STOPPED) ? 'T' : > + (p_state & TASK_TRACED) ? 'C' : > (p->exit_state & EXIT_ZOMBIE) ? 'Z' : > (p->exit_state & EXIT_DEAD) ? 'E' : > - (p->state & TASK_INTERRUPTIBLE) ? 'S' : '?'; > + (p_state & TASK_INTERRUPTIBLE) ? 'S' : '?'; > if (is_idle_task(p)) { > /* Idle task. Is it really idle, apart from the kdb > * interrupt? */