From patchwork Sun May 20 02:59:21 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jianjun Kong X-Patchwork-Id: 160225 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 8A692B6FAB for ; Sun, 20 May 2012 12:59:39 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758264Ab2ETC7h (ORCPT ); Sat, 19 May 2012 22:59:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:51259 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758241Ab2ETC7h (ORCPT ); Sat, 19 May 2012 22:59:37 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q4K2xUP7031978 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sat, 19 May 2012 22:59:30 -0400 Received: from t400.nay.redhat.com (vpn1-112-165.nay.redhat.com [10.66.112.165]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id q4K2xQik001469; Sat, 19 May 2012 22:59:27 -0400 From: kongjianjun@gmail.com To: liuj97@gmail.com, linux-pci@vger.kernel.org, qemu-devel@nongnu.org, jbarnes@virtuousgeek.org, kaneshige.kenji@jp.fujitsu.com, bhelgaas@google.com Cc: Amos Kong Subject: [PATCH v5] pci: clean all funcs when hot-removing multifunc device Date: Sun, 20 May 2012 10:59:21 +0800 Message-Id: <1337482761-6265-1-git-send-email-kongjianjun@gmail.com> In-Reply-To: References: X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org From: Amos Kong Hotplug CallTrace: int acpiphp_enable_slot(struct acpiphp_slot *slot) \_enable_device(slot); \_pci_bus_add_devices(bus); # un-added new devs(all funcs in slot) will be added list_for_each_entry(dev, &bus->devices, bus_list) { if (dev->is_added) continue; pci_bus_add_device(dev); device_add(&dev->dev); dev->is_added = 1; 'dev->is_added' is used to trace if pci dev is added to bus, all funcs in same slot would be added to bus in enable_device(slot). So we need to clean all funcs of same slot in disable_device(slot). But hot-remove exists bug: https://bugzilla.kernel.org/show_bug.cgi?id=43219 (dmesg and DSDT were attached in bz), detail: . Boot up a Linux VM with 8 pci block devices which are the 8 functions in one pci slot. | # qemu-kvm ... | -drive file=images/u0,if=none,id=drv0,format=qcow2,cache=none \ | -device virtio-blk-pci,drive=drv0,id=v0,multifunction=on,addr=0x03.0 \ | .... | -drive file=images/u7,if=none,id=drv7,format=qcow2,cache=none \ | -device virtio-blk-pci,drive=drv7,id=v7,multifunction=on,addr=0x03.7 \ . Check devices in guest. | vm)# ls /dev/vd* | vda vdb vdc vde vdf vdg vdh | vm)# lspci |grep block | 00:03.0 SCSI storage controller: Red Hat, Inc Virtio block device | ... | 00:03.7 SCSI storage controller: Red Hat, Inc Virtio block device | . Func1~7 still exist in guest after hot-removing the whole slot by qemu monitor cmd. | vm)# lspci |grep block (00:03.0 disappeared) | 00:03.1 SCSI storage controller: Red Hat, Inc Virtio block device (rev ff) | ... | 00:03.7 SCSI storage controller: Red Hat, Inc Virtio block device (rev ff) | vm)# ls /dev/vd* (vda disappeared) | vdb vdc vde vdf vdg vdh | vm)# mkfs /dev/vdb | INFO: task mkfs.ext2:1784 blocked for more than 120 seconds. We process pci slot as a whole device in pciphp spec, seabios only defines one device for a slot in ACPI DSDT table. In acpiphp_glue.c:register_slot(), only one entry is added (for func#0) into 'slot->funcs' list. When we release the whole slot, only the entry in 'slot->funcs' will be cleaned, so func#1~7 could not be cleaned from system. | drivers/pci/hotplug/acpiphp_glue.c: | static int disable_device(struct acpiphp_slot *slot) { | list_for_each_entry(func, &slot->funcs, sibling) { | pdev = pci_get_slot(slot->bridge->pci_bus, | PCI_DEVFN(slot->device, func->function)); | ..clean code.. // those code is only executed 1 time(for func#0) | __pci_remove_bus_device(pdev); | pci_dev_put(pdev); Hotpluging multifunc of guests(WinXp/Win7) is fine. Changes from v1: - rebase patch to latest linux.git - remove unnecessary multiplefunction check - rename 'i' to meaningful 'fn' - fix coding style Changes from v2: - update detail reason(calltrace) to commitlog - remove hardcode 8, find funcs in pci devlist Changes from v3: - use pci_bus_sem lock when walking bus->devices list Changes from V4: - check null point of pdev Signed-off-by: Amos Kong --- drivers/pci/hotplug/acpiphp_glue.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c index 806c44f..ba46724 100644 --- a/drivers/pci/hotplug/acpiphp_glue.c +++ b/drivers/pci/hotplug/acpiphp_glue.c @@ -893,6 +893,7 @@ static int disable_device(struct acpiphp_slot *slot) pdev = pci_get_slot(bus, PCI_DEVFN(slot->device, 0)); if (!pdev) goto err_exit; + pci_dev_put(pdev); list_for_each_entry(func, &slot->funcs, sibling) { if (func->bridge) { @@ -902,9 +903,20 @@ static int disable_device(struct acpiphp_slot *slot) func->bridge = NULL; } - pdev = pci_get_slot(slot->bridge->pci_bus, - PCI_DEVFN(slot->device, func->function)); - if (pdev) { + while (1) { + /* pci_bus_sem is used to protect bus->devices list, + it may cause invalid memory access if threads + modify bus->devices list concurrently. */ + down_read(&pci_bus_sem); + list_for_each_entry(pdev, &bus->devices, bus_list) + if (PCI_SLOT(pdev->devfn) == slot->device) { + pci_dev_get(pdev); + break; + } + up_read(&pci_bus_sem); + + if (!pdev || PCI_SLOT(pdev->devfn) != slot->device) + break; pci_stop_bus_device(pdev); if (pdev->subordinate) { disable_bridges(pdev->subordinate);