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=-16.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 ED19FC07E96 for ; Thu, 8 Jul 2021 11:38:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CEEE561420 for ; Thu, 8 Jul 2021 11:38:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231765AbhGHLko (ORCPT ); Thu, 8 Jul 2021 07:40:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:38600 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231758AbhGHLkn (ORCPT ); Thu, 8 Jul 2021 07:40:43 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3A70861436; Thu, 8 Jul 2021 11:38:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625744281; bh=XCxvllQ/KD+p9FxitaUkqrANLpqAIhFcRBSM/MmUgQg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=qNgQlrQSej9qvj5IpDGyJO8hLbhjXbUbgpHpwZuGskaUzjJxXBFKweAz+o0jJhYRz xySP/0gEhtrFch2B1hHjYhZvmTlWDZcACJK5tMxIF2GcrAREyLucYMimIHoH2vqsXS dYbP06HMpzwnp7rwRnqmAwy2NiqRo0U9HDMfj5hhEAhjO7KWZiRQS1zKgNgRcDv1Up s27x4h2QvUsq8y7grfyBcvXt6ywwN10xr3XnOD+2ycliNlidcy8cjolGnH+uuj5hG1 CB6uNb81PDi842af4bcWcIzQvp4X4t7VpqiDrbBqq08kOGbi2mfWTs+FwpXfQ/ZctO 2mFlTubY6K7WA== Date: Thu, 8 Jul 2021 13:37:59 +0200 From: Frederic Weisbecker To: Valentin Schneider Cc: linux-kernel@vger.kernel.org, Peter Zijlstra , Ingo Molnar , Thomas Gleixner Subject: Re: [PATCH] preempt: Allow CONFIG_DEBUG_PREEMPT for CONFIG_PREEMPT_VOLUNTARY Message-ID: <20210708113759.GB130061@lothringen> References: <20210707192306.2297497-1-valentin.schneider@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210707192306.2297497-1-valentin.schneider@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 07, 2021 at 08:23:06PM +0100, Valentin Schneider wrote: > While recently staring at some preempt_count dumpster fire for a > CONFIG_PREEMPT_VOLUNTARY kernel, I wished I could turn on > CONFIG_DEBUG_PREEMPT on top of CONFIG_DEBUG_ATOMIC_SLEEP to see *where* > preemption had been disabled. It didn't take much to get that, and although > it didn't help my particular case, I think it can still be useful. > > Signed-off-by: Valentin Schneider > --- > kernel/sched/core.c | 3 +-- > lib/Kconfig.debug | 2 +- > 2 files changed, 2 insertions(+), 3 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 0c22cd026440..5673b85fa22d 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -5109,8 +5109,7 @@ static inline void sched_tick_start(int cpu) { } > static inline void sched_tick_stop(int cpu) { } > #endif > > -#if defined(CONFIG_PREEMPTION) && (defined(CONFIG_DEBUG_PREEMPT) || \ > - defined(CONFIG_TRACE_PREEMPT_TOGGLE)) > +#if defined(CONFIG_DEBUG_PREEMPT) || defined(CONFIG_TRACE_PREEMPT_TOGGLE) > /* > * If the value passed in is equal to the current preempt count > * then we just disabled preemption. Start timing the latency. > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 678c13967580..7fdd45eee343 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1204,7 +1204,7 @@ config DEBUG_TIMEKEEPING > > config DEBUG_PREEMPT > bool "Debug preemptible kernel" > - depends on DEBUG_KERNEL && PREEMPTION && TRACE_IRQFLAGS_SUPPORT > + depends on DEBUG_KERNEL && PREEMPT_COUNT && TRACE_IRQFLAGS_SUPPORT IIRC it used to be that way before. That was the reason for the split of CONFIG_PREEMPT_COUNT from CONFIG_PREEMPT in the first place. Not sure what happened. But anyway, your patch looks welcome. Thanks. > default y > help > If you say Y here then the kernel will use a debug variant of the > -- > 2.25.1 >