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=-12.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 10316C43332 for ; Wed, 27 Jan 2021 03:35:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DE526206DB for ; Wed, 27 Jan 2021 03:35:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236453AbhA0Ded (ORCPT ); Tue, 26 Jan 2021 22:34:33 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730156AbhAZVhP (ORCPT ); Tue, 26 Jan 2021 16:37:15 -0500 Received: from mail-io1-xd2a.google.com (mail-io1-xd2a.google.com [IPv6:2607:f8b0:4864:20::d2a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0A535C061574 for ; Tue, 26 Jan 2021 13:36:35 -0800 (PST) Received: by mail-io1-xd2a.google.com with SMTP id u17so36849348iow.1 for ; Tue, 26 Jan 2021 13:36:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=/ustJ0/aPlx4iAkk4IQ7oOTUDCbseUwYBGj9G/doyi0=; b=aRQPVtVQWvj+0JgMoeSv1tbxkyyKJKp5rhr+iKTA+dqaYS5cAcTj0yb69/ROdSPTVs awqkofJxKIYC+3lALvwuxeUYNWxIhxsVdfaZsfGU/9TVu88A53J2zFxhsA71d3WLUDIX 555139CXWDue9MMhcnwtw1r926W3gNac1W8rIe4qgxqO3UyvIcagtRfQlML1WO+lKruO EBVBK1yuo615WTIXa9WGH5nbwMl4c6EP3xr+FedOSbKmp2xsFyTJQfLV0RnwujhbNls8 8YdckUwosOCRojjTNk9D23BaUu3ytsnn0gwOaMjyA2J4M8nVZFsPU/9TIDg76sLXMPJ1 BLUA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=/ustJ0/aPlx4iAkk4IQ7oOTUDCbseUwYBGj9G/doyi0=; b=cKBdKYOAVfOVuslvr7olBWuF380uLLLfkE47Gy3Tp5GK+KgQb07vfH9KOE5YkA4BjE RGZnqUI12kaiesxn58chABR57j4zESMr94vjzZEDDxd9j60xXb6772H6N15Dhj6fRWW3 ixSDSXYtuXl0mcUIFOsCjjhropR5idncqcmGYen0RwjYoec/SEVNVp/viBvAZHK3wzZ0 IOrX/oMaOZQVnSZXFvahBkYgHlD6pP12RbE+7E76q183+ms3GnvWwazaDsIElLUjNSt6 mlJygkM4r4UJ3qwxlsQpGRVCsEbKMTED2qohyQejE1/iDxkjmwJR3sX1tcdWUvvXXELS S6QA== X-Gm-Message-State: AOAM531ewGLYSWA9YduQWQTOf715xKcL6HVq1lRGfDNEBJx6qG8DHf+R UsdzvhvjLzmFiwXi/Nz95k82JQjizVQXb1n1Gzw= X-Google-Smtp-Source: ABdhPJxZsKjbMvUBw7jG6/aVnfplIA3VZdiKLNfG8H8yOQPCusbf9QUiQztyi1mZ2Iae/ZStL2V4RsH7GwIlsy91f3M= X-Received: by 2002:a92:aac5:: with SMTP id p66mr6386791ill.238.1611696994232; Tue, 26 Jan 2021 13:36:34 -0800 (PST) MIME-Version: 1.0 References: <20210126171141.122639-1-paul.gortmaker@windriver.com> <20210126171141.122639-9-paul.gortmaker@windriver.com> In-Reply-To: <20210126171141.122639-9-paul.gortmaker@windriver.com> From: Yury Norov Date: Tue, 26 Jan 2021 13:36:23 -0800 Message-ID: Subject: Re: [PATCH 8/8] rcu: deprecate "all" option to rcu_nocbs= To: Paul Gortmaker Cc: Linux Kernel Mailing List , lizefan@huawei.com, Ingo Molnar , Thomas Gleixner , josh@joshtriplett.org, Peter Zijlstra , "Paul E. McKenney" , fweisbec@gmail.com, Rasmus Villemoes , Andy Shevchenko Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 26, 2021 at 9:12 AM Paul Gortmaker wrote: > > With the core bitmap support now accepting "N" as a placeholder for > the end of the bitmap, "all" can be represented as "0-N" and has the > advantage of not being specific to RCU (or any other subsystem). > > So deprecate the use of "all" by removing documentation references > to it. The support itself needs to remain for now, since we don't > know how many people out there are using it currently, but since it > is in an __init area anyway, it isn't worth losing sleep over. > > Cc: Yury Norov > Cc: Peter Zijlstra > Cc: "Paul E. McKenney" > Cc: Josh Triplett > Signed-off-by: Paul Gortmaker > --- > Documentation/admin-guide/kernel-parameters.txt | 4 +--- > kernel/rcu/tree_plugin.h | 6 ++---- > 2 files changed, 3 insertions(+), 7 deletions(-) > > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt > index a10b545c2070..a116c0ff0a91 100644 > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -4037,9 +4037,7 @@ > see CONFIG_RAS_CEC help text. > > rcu_nocbs= [KNL] > - The argument is a cpu list, as described above, > - except that the string "all" can be used to > - specify every CPU on the system. > + The argument is a cpu list, as described above. > > In kernels built with CONFIG_RCU_NOCB_CPU=y, set > the specified list of CPUs to be no-callback CPUs. > diff --git a/kernel/rcu/tree_plugin.h b/kernel/rcu/tree_plugin.h > index 7e291ce0a1d6..56788dfde922 100644 > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -1463,14 +1463,12 @@ static void rcu_cleanup_after_idle(void) > > /* > * Parse the boot-time rcu_nocb_mask CPU list from the kernel parameters. > - * The string after the "rcu_nocbs=" is either "all" for all CPUs, or a > - * comma-separated list of CPUs and/or CPU ranges. If an invalid list is > - * given, a warning is emitted and all CPUs are offloaded. > + * If the list is invalid, a warning is emitted and all CPUs are offloaded. > */ > static int __init rcu_nocb_setup(char *str) > { > alloc_bootmem_cpumask_var(&rcu_nocb_mask); > - if (!strcasecmp(str, "all")) > + if (!strcasecmp(str, "all")) /* legacy: use "0-N" instead */ I think 'all' and 'none' is a good idea. It's simple and convenient. But if you don't like it, can you please at least put this comment in system log using WARN_ON_ONCE(). It's quite possible that Linux users don't read source code comments. > cpumask_setall(rcu_nocb_mask); > else > if (cpulist_parse(str, rcu_nocb_mask)) { > -- > 2.17.1 >