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=-8.3 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 C2227C433E0 for ; Thu, 23 Jul 2020 14:59:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9A1BA207BB for ; Thu, 23 Jul 2020 14:59:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="YevgOcOa" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729406AbgGWO7O (ORCPT ); Thu, 23 Jul 2020 10:59:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53912 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727885AbgGWO7N (ORCPT ); Thu, 23 Jul 2020 10:59:13 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 640FDC0619DC; Thu, 23 Jul 2020 07:59:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=8Gt1hFpE3q2wE3LOCsagXAgF4SokTskzV+hSBzd+h94=; b=YevgOcOaHex/SgwKEBjKklY9ML EOz76F9PRoMjWXYbh8Q+m/GbZsxZzpaftQUDGL6i0rkl4d3XOsti2q6zidbbAOdlaQCoDEkMbBo/3 uibNzMdLQFmkllHyPKj3GT64ohKnBbGPeTcObiayUHZKr6mpih1MPL/xTlmXNwMkbz0YYUTrokLxc e+ansIggeKN0bMmp5DAW7L3MyHSOAaMAbgr26KCQ+j5BOGanY609zpdhmuxph9F1tP80dQDAtzqoT O61aCCCF81d39djAdwbpYFPQ/yDWx2bIuB8dtmgMTTFEzaQfBByrk9i+tOsYEg/FELh+tePD+S6hu wE5r4t3w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jycgc-0000Ed-C9; Thu, 23 Jul 2020 14:59:06 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id 01DF5983422; Thu, 23 Jul 2020 16:59:04 +0200 (CEST) Date: Thu, 23 Jul 2020 16:59:04 +0200 From: Peter Zijlstra To: Nicholas Piggin Cc: Alexey Kardashevskiy , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Ingo Molnar , Will Deacon Subject: Re: [PATCH 1/2] lockdep: improve current->(hard|soft)irqs_enabled synchronisation with actual irq state Message-ID: <20200723145904.GU5523@worktop.programming.kicks-ass.net> References: <20200723105615.1268126-1-npiggin@gmail.com> <20200723114010.GO5523@worktop.programming.kicks-ass.net> <1595506730.3mvrxktem5.astroid@bobo.none> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1595506730.3mvrxktem5.astroid@bobo.none> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 23, 2020 at 11:11:03PM +1000, 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! > > After this patch it doesn't. You sure, trace_hardirqs_{on,off}() calls into lockdep. (FWIW they're also broken vs entry ordering, but that's another story). > trace_hardirqs_on/off implementation appears to expect to be called in NMI > context though, for some reason. Hurpm, not sure.. I'll have to go grep arch code now :/ The generic NMI code didn't touch that stuff. Argh, yes, there might be broken there... damn! I'll go frob around.