Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755974Ab3EIC0D (ORCPT ); Wed, 8 May 2013 22:26:03 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:15503 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750774Ab3EIC0A (ORCPT ); Wed, 8 May 2013 22:26:00 -0400 X-IronPort-AV: E=Sophos;i="4.87,638,1363104000"; d="scan'208";a="7221291" Message-ID: <518B08BD.4080800@cn.fujitsu.com> Date: Thu, 09 May 2013 10:23:57 +0800 From: Gu Zheng User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:7.0.1) Gecko/20110930 Thunderbird/7.0.1 MIME-Version: 1.0 To: Bjorn Helgaas CC: Yinghai Lu , "linux-pci@vger.kernel.org" , linux-kernel , Yasuaki Ishimatsu , Taku Izumi , tangchen , Lin Feng , Jiang Liu Subject: Re: [PATCH v2 4/4] PCI: Check if the pci device get removed from pci tree already in remove_callback() References: <516FB647.5030203@cn.fujitsu.com> <517FAB9B.6010005@cn.fujitsu.com> In-Reply-To: X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/05/09 10:25:01, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/05/09 10:25:02, Serialize complete at 2013/05/09 10:25:02 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4215 Lines: 111 On 05/09/2013 06:32 AM, Bjorn Helgaas wrote: > On Tue, Apr 30, 2013 at 4:31 AM, Gu Zheng wrote: >> From a870da3615988f53a8949e5f8c907b079162067b Mon Sep 17 00:00:00 2001 >> From: Gu Zheng >> Date: Tue, 30 Apr 2013 18:45:12 +0800 >> Subject: [PATCH v2 4/4] PCI: Check if the pci device get removed from pci tree already in remove_callback >> We found nested removing through: >> echo -n 1 > /sys/bus/pci/devices/0000\:10\:00.0/remove ; echo -n 1 > >> /sys/bus/pci/devices/0000\:1a\:01.0/remove >> >> will cause kernel crash as bus get freed. >> >> [ 418.946462] CPU 4 >> [ 418.968377] Pid: 512, comm: kworker/u:2 Tainted: G W 3.8.0 #2 >> FUJITSU-SV PRIMEQUEST 1800E/SB >> [ 419.081763] RIP: 0010:[] [] >> pci_bus_read_config_word+0x5e/0x90 >> [ 420.494137] Call Trace: >> [ 420.523326] [] ? remove_callback+0x1f/0x40 >> [ 420.591984] [] pci_pme_active+0x4b/0x1c0 >> [ 420.658545] [] pci_stop_bus_device+0x57/0xb0 >> [ 420.729259] [] pci_stop_and_remove_bus_device+0x16/0x30 >> [ 420.811392] [] remove_callback+0x2b/0x40 >> [ 420.877955] [] sysfs_schedule_callback_work+0x26/0x70 >> >> https://bugzilla.kernel.org/show_bug.cgi?id=54411 >> >> We have one patch that will let device hold bus ref to prevent it from >> being freed, but that will still generate warning. >> >> ------------[ cut here ]------------ >> WARNING: at lib/list_debug.c:53 __list_del_entry+0x63/0xd0() >> Hardware name: PRIMEQUEST 1800E >> list_del corruption, ffff8807d1b6c000->next is LIST_POISON1 (dead000000100100) >> Call Trace: >> [] warn_slowpath_common+0x7f/0xc0 >> [] warn_slowpath_fmt+0x46/0x50 >> [] __list_del_entry+0x63/0xd0 >> [] list_del+0x11/0x40 >> [] pci_destroy_dev+0x31/0xc0 >> [] pci_remove_bus_device+0x5b/0x70 >> [] pci_stop_and_remove_bus_device+0x1e/0x30 >> [] remove_callback+0x29/0x40 >> [] sysfs_schedule_callback_work+0x24/0x70 >> >> We can just check if the device get removed from pci tree >> already in the protection under pci_remove_rescan_mutex. >> >> >> Signed-off-by: Gu Zheng >> Signed-off-by: Yinghai Lu >> --- >> drivers/pci/pci-sysfs.c | 13 ++++++++++--- >> 1 files changed, 10 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c >> index 5b4a9d9..18590c1 100644 >> --- a/drivers/pci/pci-sysfs.c >> +++ b/drivers/pci/pci-sysfs.c >> @@ -328,10 +328,17 @@ dev_rescan_store(struct device *dev, struct device_attribute *attr, >> >> static void remove_callback(struct device *dev) >> { >> - struct pci_dev *pdev = to_pci_dev(dev); >> - >> + struct pci_dev *pdev = to_pci_dev(dev), *tmp; >> + bool found = false; >> + struct pci_bus *bus = pdev->bus; >> mutex_lock(&pci_remove_rescan_mutex); >> - pci_stop_and_remove_bus_device(pdev); >> + list_for_each_entry(tmp, &bus->devices, bus_list) >> + if (tmp == pdev) { >> + found = true; >> + break; >> + } >> + if (found) >> + pci_stop_and_remove_bus_device(pdev); > > I assume this series won't be needed when we eventually get the > reference counting sorted out, because we shouldn't have to check > whether the device still exists. Yes, your are right! Thanks for your correction. >Yinghai posted a > "fix_racing_removing_5.patch", which currently doesn't apply cleanly, > but I assume he'll refresh it after v3.10-rc1 is out. OK, let's wait and see! :) Best regards, Gu > > Bjorn > >> mutex_unlock(&pci_remove_rescan_mutex); >> } >> >> -- >> 1.7.7 >> > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/