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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 23116C433DF for ; Tue, 14 Jul 2020 23:58:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E6AF22071B for ; Tue, 14 Jul 2020 23:58:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594771095; bh=0GSa/vVCcx42dxvvYTf+RjT7Q8jkxKwjCrADCf84T9I=; h=Date:From:To:Cc:Subject:In-Reply-To:List-ID:From; b=Lall/AAuRose2pIaYzY66rS0QUo2o6CVPXOhErJH4ay+Pb0kp9qmaWWGEFbdeTe+5 e95dot9CzNWW7jeNn4ne8hKQDo0r5WWSSKne4DuvAh+RQwnbDdyQsJoPrb+Z34du35 3GB94VwahG0Dedrd8wuGYRjKWCctiOAELEgSxBnU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726670AbgGNX6O (ORCPT ); Tue, 14 Jul 2020 19:58:14 -0400 Received: from mail.kernel.org ([198.145.29.99]:42320 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726472AbgGNX6N (ORCPT ); Tue, 14 Jul 2020 19:58:13 -0400 Received: from localhost (mobile-166-175-191-139.mycingular.net [166.175.191.139]) (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 F416420674; Tue, 14 Jul 2020 23:58:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1594771093; bh=0GSa/vVCcx42dxvvYTf+RjT7Q8jkxKwjCrADCf84T9I=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=l/XewjLCrd7mBMmLFyFKhMrkJw6V6+SJWGzw2FiDegtDkHNXyZrIObbeauAIJu7Tv 5DA1MrHRz2/ApdIN6JvRLBeyjYMQP8YsB+cCsfH85ROs1s1w8qpVXCHJQJizdBlS3m LKBPtWwF1Pivdy2kazXUi6s14xHYYsLdbbNwTpcc= Date: Tue, 14 Jul 2020 18:58:11 -0500 From: Bjorn Helgaas To: Lukas Wunner Cc: Ian May , linux-pci@vger.kernel.org Subject: Re: [PATCH 1/2] PCIe hotplug interrupt and AER deadlock with reset_lock and device_lock Message-ID: <20200714235811.GA431846@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200615185650.mzxndbw7ghvh5qiv@wunner.de> Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Mon, Jun 15, 2020 at 08:56:50PM +0200, Lukas Wunner wrote: > On Mon, Jun 15, 2020 at 09:32:49AM -0500, Ian May wrote: > > Currently when a hotplug interrupt and AER recovery triggers simultaneously > > the following deadlock can occur. > > > > Hotplug AER > > ---------------------------- --------------------------- > > device_lock(&dev->dev) down_write(&ctrl->reset_lock) > > down_read(&ctrl->reset_lock) device_lock(&dev->dev) > > > > This patch adds a reset_lock and reset_unlock hotplug_slot_op. > > This would allow the controller reset_lock/reset_unlock to be moved > > from pciehp_reset_slot to pci_slot_reset function allowing the controller > > reset_lock to be acquired before the device lock allowing for both hotplug > > and AER to grab the reset_lock and device lock in proper order. > > I've posted a patch to address such issues on Mar 31, just haven't > gotten around to respin it with a proper commit message: > > https://lore.kernel.org/linux-pci/20200331130139.46oxbade6rcbaicb@wunner.de/ > > I've solved it by moving the reset lock into struct pci_slot. > I think that's simpler than adding two callbacks. > > Do you think the AER deadlock could be fixed based on my approach? How should we proceed on this?