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=-2.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS,T_DKIMWL_WL_HIGH,USER_AGENT_MUTT 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 0A7E0C4321D for ; Sun, 19 Aug 2018 02:24:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB1A721746 for ; Sun, 19 Aug 2018 02:24:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="Ho9dZTH5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AB1A721746 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725933AbeHSFeb (ORCPT ); Sun, 19 Aug 2018 01:34:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:46828 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725741AbeHSFeb (ORCPT ); Sun, 19 Aug 2018 01:34:31 -0400 Received: from localhost (unknown [69.71.4.100]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C3ED321737; Sun, 19 Aug 2018 02:24:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1534645482; bh=A1B46vlfA7dsimYJDxjShA5tRftYC8uUYKw3uBwQv9o=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Ho9dZTH53APNhdX8sV0gVhyfzZ6S6hHjxVvVJDOsmcLdjaywy+nqVJ/UhnKsDFBS9 IOG+wmACVmqwA8nRBJQSuIYj13KKQ5n5xVHx1bCwZgsxHxJNJVcrukiMzCYacdEKAU Lr28L4aRWwr/FMZ3a/xZAP2cgkqQ0rDn2Rq2Fhoc= Date: Sat, 18 Aug 2018 21:24:40 -0500 From: Bjorn Helgaas To: Benjamin Herrenschmidt Cc: linux-pci@vger.kernel.org, Hari Vyas , Ray Jui , Srinath Mannam , Guenter Roeck , Jens Axboe , Lukas Wunner , Konstantin Khlebnikov , Marta Rybczynska , Pierre-Yves Kerbrat , linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 1/6] Revert "PCI: Fix is_added/is_busmaster race condition" Message-ID: <20180819022440.GG128050@bhelgaas-glaptop.roam.corp.google.com> References: <20180817044902.31420-1-benh@kernel.crashing.org> <20180817044902.31420-2-benh@kernel.crashing.org> <20180817154431.GC128050@bhelgaas-glaptop.roam.corp.google.com> <06c1233b71dea08b1fc32334acefc48c32c46557.camel@kernel.crashing.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <06c1233b71dea08b1fc32334acefc48c32c46557.camel@kernel.crashing.org> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 18, 2018 at 01:24:51PM +1000, Benjamin Herrenschmidt wrote: > On Fri, 2018-08-17 at 10:44 -0500, Bjorn Helgaas wrote: > > On Fri, Aug 17, 2018 at 02:48:57PM +1000, Benjamin Herrenschmidt wrote: > > > This reverts commit 44bda4b7d26e9fffed6d7152d98a2e9edaeb2a76. > > > > Just to be clear, if I understand correctly, this is a pure revert of > > 44bda4b7d26e and as such it reintroduces the problem solved by that > > commit. > > > > If your solution turns out to be better, that's great, but it would be > > nice to avoid the bisection hole of reintroducing the problem, then > > fixing it again later. > > There is no way to do that other than merging the revert and the fix > into one. That said, the race is sufficiently hard to hit that I > wouldn't worry too much about it. OK, then at least mention that in the changelog. > > > The new pci state mutex provides a simpler way of addressing > > > this race and avoids the relative includes added to the powerpc > > > code. >