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=-11.6 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=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 DDDC5C43463 for ; Mon, 21 Sep 2020 12:16:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8CDD20708 for ; Mon, 21 Sep 2020 12:16:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600690580; bh=eBBhAlX3XFV5kv5wITd4mE3fjJvue5h4/NKL4o0iD3k=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=F2khNfzVaxKk8d9mAOOgpef34NgdbxTzfUWeQrCGH02VhMUfwNT93YZsI+xVatWHQ JhMTPgjBztQ2MiONKvV5l27G4uDGbGWwMJJBg5/jBOnoYIV/ykT7yUB1G3fhsBDvwB 0zKJSQ6JpSufVPrwsFIogexUCo4t5+fCTzMOfkdY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726413AbgIUMQO (ORCPT ); Mon, 21 Sep 2020 08:16:14 -0400 Received: from mail-oi1-f194.google.com ([209.85.167.194]:42688 "EHLO mail-oi1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726341AbgIUMQO (ORCPT ); Mon, 21 Sep 2020 08:16:14 -0400 Received: by mail-oi1-f194.google.com with SMTP id x14so16667491oic.9; Mon, 21 Sep 2020 05:16:13 -0700 (PDT) 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=XcFPSidHF3BVoPv8XvLOttLzybHltg4dD5z0pmUwA4k=; b=BHACPtf71A42ThNl5cbAaffQiYBjgIjSIr19OH/UIiM4BsXK+oyV+h17hZ+t8fXJNR qTG5jV0p9CY/o7h52gUvqcMdTTjXJuVSLT1FNRBoDwVdLqMwcwSgk/hqpDzV4kJiimCs PtCSHYL9WyTj1Rds5NbZjKIwygFpWLzhd7AHsaja0oVqcX9Vf/JUlUoWbRw0EbepxnJj uF5NuhFoN2Ya+MLus371WE8UxpoUno03C3Osk7PgvDh7ytU5Dnbyz7fhztHVJMZNCtRA wyxiIVkyTYqLpNEFNEqG+Azb7plCefW8EE/6MEJp4Tx09YGAMyI+kOtVWeTu/biRyxaz Ta3w== X-Gm-Message-State: AOAM532W8dw/Gx0kozDvoKD9wfQbN0AdZJ5IEIL7iQYz5WELtCIs/ikB k2AcUIkREXoxa4yl7vEMReKkBYenQQO9TtRnr/BifPYQ X-Google-Smtp-Source: ABdhPJxrhYmJXx4HqgrQAwiD/iI/AFKi/FS63u8LkFKXt79EwBh06A4HspKgmhCScDgCaweYOBOoq4S9EXW29sbf18I= X-Received: by 2002:a05:6808:491:: with SMTP id z17mr18128162oid.110.1600690573429; Mon, 21 Sep 2020 05:16:13 -0700 (PDT) MIME-Version: 1.0 References: <20200915103157.345404192@infradead.org> <20200915103806.479637218@infradead.org> <87wo0npk72.fsf@turtle.gmx.de> <20200921103741.GC5901@zn.tnic> In-Reply-To: <20200921103741.GC5901@zn.tnic> From: "Rafael J. Wysocki" Date: Mon, 21 Sep 2020 14:15:58 +0200 Message-ID: Subject: Re: [PATCH] rcu/tree: Export rcu_idle_{enter,exit} to module To: Borislav Petkov , "Paul E. McKenney" Cc: Sven Joachim , Peter Zijlstra , "Rafael J. Wysocki" , "the arch/x86 maintainers" , Tony Luck , Len Brown , Daniel Lezcano , Linux Kernel Mailing List , ACPI Devel Maling List , Linux PM , Ulf Hansson , Thomas Gleixner , Naresh Kamboju , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , rcu@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Mon, Sep 21, 2020 at 12:37 PM Borislav Petkov wrote: > > Lemme add whatever get_maintainer spits, to Cc. > > On Mon, Sep 21, 2020 at 11:12:33AM +0200, Sven Joachim wrote: > > On 2020-09-15 12:32 +0200, Peter Zijlstra wrote: > > > > > The C3 BusMaster idle code takes lock in a number of places, some deep > > > inside the ACPI code. Instead of wrapping it all in RCU_NONIDLE, have > > > the driver take over RCU-idle duty and avoid flipping RCU state back > > > and forth a lot. > > > > > > ( by marking 'C3 && bm_check' as RCU_IDLE, we _must_ call enter_bm() for > > > that combination, otherwise we'll loose RCU-idle, this requires > > > shuffling some code around ) > > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > I got modpost errors in 5.9-rc6 after this patch: > > > > ERROR: modpost: "rcu_idle_enter" [drivers/acpi/processor.ko] undefined! > > ERROR: modpost: "rcu_idle_exit" [drivers/acpi/processor.ko] undefined! > > > > Reverting commit 1fecfdbb7acc made them go away. Notably my > > configuration had CONFIG_ACPI_PROCESSOR=m, changing that > > to CONFIG_ACPI_PROCESSOR=y let the build succeed as well. > > I guess this. Running randconfigs on it for a while, to see what else > breaks. > > --- > From: Borislav Petkov > Date: Mon, 21 Sep 2020 12:31:36 +0200 > > Fix this link error: > > ERROR: modpost: "rcu_idle_enter" [drivers/acpi/processor.ko] undefined! > ERROR: modpost: "rcu_idle_exit" [drivers/acpi/processor.ko] undefined! > > when CONFIG_ACPI_PROCESSOR is built as module. PeterZ says that in light > of ARM needing those soon too, they should simply be exported. > > Fixes: 1fecfdbb7acc ("ACPI: processor: Take over RCU-idle for C3-BM idle") > Reported-by: Sven Joachim > Suggested-by: Peter Zijlstra > Signed-off-by: Borislav Petkov Well, I guess I should take this through cpuidle? Any concerns about doing that? Paul? > --- > kernel/rcu/tree.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 8ce77d9ac716..f78ee759af9c 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -673,6 +673,7 @@ void rcu_idle_enter(void) > lockdep_assert_irqs_disabled(); > rcu_eqs_enter(false); > } > +EXPORT_SYMBOL_GPL(rcu_idle_enter); > > #ifdef CONFIG_NO_HZ_FULL > /** > @@ -886,6 +887,7 @@ void rcu_idle_exit(void) > rcu_eqs_exit(false); > local_irq_restore(flags); > } > +EXPORT_SYMBOL_GPL(rcu_idle_exit); > > #ifdef CONFIG_NO_HZ_FULL > /** > -- > 2.21.0 > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette