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=-7.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 1A81FC433E0 for ; Fri, 24 Jul 2020 05:59:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E6FCE20768 for ; Fri, 24 Jul 2020 05:59:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Pb4/uDyq" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726716AbgGXF7n (ORCPT ); Fri, 24 Jul 2020 01:59:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52298 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726020AbgGXF7m (ORCPT ); Fri, 24 Jul 2020 01:59:42 -0400 Received: from mail-pl1-x643.google.com (mail-pl1-x643.google.com [IPv6:2607:f8b0:4864:20::643]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6CA86C0619D3; Thu, 23 Jul 2020 22:59:42 -0700 (PDT) Received: by mail-pl1-x643.google.com with SMTP id t6so3899036plo.3; Thu, 23 Jul 2020 22:59:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:subject:to:cc:references:in-reply-to:mime-version :message-id:content-transfer-encoding; bh=2R0lW9dUL1nYb/9lgperk2g748vxQMNCmmnNHRKkl+M=; b=Pb4/uDyqpRTTP9b3ebYsdYcsxNScuYdJIPeDBdZdQ0oiVxIw9UIdugSoUtLX7SJ1/B 3Xdajmy3uy5LYrQAe1LgIUmt9GE2Vm15HXVAfbSCg3F0Qeru3fAvX3RNB/iMTCee5YEf Adelh56xJuUYcwoXbqlzhH99jqeA0YOu72J/OiCuy0fBv5rjilfboH5Vdua2NoTnkgaP NSculWvNNeRGDKrLDX9WSmf3+GTuvKrepedSaFzEn9p46GRTm21RRPTHKGRdD+k0n+GM ofGi26OjkkbLfQt5mu++mN1BJa3/e/9cUcmQdOHUK+ZigZC4XvuAIo2C03brXMwXU575 EKog== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:subject:to:cc:references:in-reply-to :mime-version:message-id:content-transfer-encoding; bh=2R0lW9dUL1nYb/9lgperk2g748vxQMNCmmnNHRKkl+M=; b=duXxVlKM+S1f/30IaC9ZK8TtJeP5va/zq/uO1kGarvC3A7HVu/7uIMSn9XlW+wvlUj Ez/+6+w2/ro7EC2DpaS21tfGKd5diz4uAh/9puM/Smiid/fg2bRQdgoqHm4Di2DLAldL 2Rpcl3l4oF1YUyu5ogpbEsoSsMCPsS+c9qTdQxIhzKBgjVQbHH1nuSrnlSxd/UEK9i/K V1E/IGPUwzQDYfLHp30wOLuaMVcd+hTKeD6NiFDOpvQesLJsYxckIBYMz71J7Bf91ujO IkjfJ/IIk0golrsvlTB8hwH4ozWrN7t9YeX9LaKdqu4P1o2cBS5Mozz9F4djZplM2vFz 4gdg== X-Gm-Message-State: AOAM531oxNj5JbQHpbIHwl2hqN3vF4m3ENfnOjGnrphaqQQn1uTrnADI pvp7Ail1fG5JuTMbAdMIVaK7zFWU X-Google-Smtp-Source: ABdhPJxbeH9FlO3dIACKcXGFcLekN350jP0rI0GOjOvxK+MH/SPj/LKJY2RwdAnGdzEYCg0FKF+/iQ== X-Received: by 2002:a17:902:6181:: with SMTP id u1mr6767335plj.205.1595570381925; Thu, 23 Jul 2020 22:59:41 -0700 (PDT) Received: from localhost (110-174-173-27.tpgi.com.au. [110.174.173.27]) by smtp.gmail.com with ESMTPSA id y24sm4966404pfp.217.2020.07.23.22.59.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Jul 2020 22:59:41 -0700 (PDT) Date: Fri, 24 Jul 2020 15:59:35 +1000 From: Nicholas Piggin Subject: Re: [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state To: Alexey Kardashevskiy , Peter Zijlstra Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ingo Molnar , Will Deacon References: <20200723105615.1268126-1-npiggin@gmail.com> <20200723114010.GO5523@worktop.programming.kicks-ass.net> <1595506730.3mvrxktem5.astroid@bobo.none> <1884dcea-9ecd-a1f3-21bb-213c655e2480@ozlabs.ru> In-Reply-To: <1884dcea-9ecd-a1f3-21bb-213c655e2480@ozlabs.ru> MIME-Version: 1.0 Message-Id: <1595568105.4eodjnxzwp.astroid@bobo.none> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Excerpts from Alexey Kardashevskiy's message of July 24, 2020 2:16 pm: >=20 >=20 > On 23/07/2020 23:11, Nicholas Piggin wrote: >> Excerpts from Peter Zijlstra's message of July 23, 2020 9:40 pm: >>> On Thu, Jul 23, 2020 at 08:56:14PM +1000, Nicholas Piggin wrote: >>> >>>> diff --git a/arch/powerpc/include/asm/hw_irq.h b/arch/powerpc/include/= asm/hw_irq.h >>>> index 3a0db7b0b46e..35060be09073 100644 >>>> --- a/arch/powerpc/include/asm/hw_irq.h >>>> +++ b/arch/powerpc/include/asm/hw_irq.h >>>> @@ -200,17 +200,14 @@ static inline bool arch_irqs_disabled(void) >>>> #define powerpc_local_irq_pmu_save(flags) \ >>>> do { \ >>>> raw_local_irq_pmu_save(flags); \ >>>> - trace_hardirqs_off(); \ >>>> + if (!raw_irqs_disabled_flags(flags)) \ >>>> + trace_hardirqs_off(); \ >>>> } while(0) >>>> #define powerpc_local_irq_pmu_restore(flags) \ >>>> do { \ >>>> - if (raw_irqs_disabled_flags(flags)) { \ >>>> - raw_local_irq_pmu_restore(flags); \ >>>> - trace_hardirqs_off(); \ >>>> - } else { \ >>>> + if (!raw_irqs_disabled_flags(flags)) \ >>>> trace_hardirqs_on(); \ >>>> - raw_local_irq_pmu_restore(flags); \ >>>> - } \ >>>> + raw_local_irq_pmu_restore(flags); \ >>>> } while(0) >>> >>> You shouldn't be calling lockdep from NMI context! >>=20 >> After this patch it doesn't. >>=20 >> trace_hardirqs_on/off implementation appears to expect to be called in N= MI=20 >> context though, for some reason. >>=20 >>> That is, I recently >>> added suport for that on x86: >>> >>> https://lkml.kernel.org/r/20200623083721.155449112@infradead.org >>> https://lkml.kernel.org/r/20200623083721.216740948@infradead.org >>> >>> But you need to be very careful on how you order things, as you can see >>> the above relies on preempt_count() already having been incremented wit= h >>> NMI_MASK. >>=20 >> Hmm. My patch seems simpler. >=20 > And your patches fix my error while Peter's do not: >=20 >=20 > IRQs not enabled as expected > WARNING: CPU: 0 PID: 1377 at /home/aik/p/kernel/kernel/softirq.c:169 > __local_bh_enable_ip+0x118/0x190 I think they would have needed some powerpc bits as well. But I don't see a reason we can't merge my patches, at least they fix this case and don't seem to make things worse in any way. Thanks, Nick