From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753899Ab2KVSeT (ORCPT ); Thu, 22 Nov 2012 13:34:19 -0500 Received: from mail.kernel.org ([198.145.19.201]:49016 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753751Ab2KVSd7 (ORCPT ); Thu, 22 Nov 2012 13:33:59 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , alan@lxorguk.ukuu.org.uk, Huang Ying , Bjorn Helgaas , "Rafael J. Wysocki" , Zhang Yanmin Subject: [ 006/171] PCI/PM: Fix deadlock when unbinding device if parent in D3cold Date: Wed, 21 Nov 2012 16:39:12 -0800 Message-Id: <20121122004033.949092835@linuxfoundation.org> X-Mailer: git-send-email 1.8.0.197.g5a90748 In-Reply-To: <20121122004033.298367941@linuxfoundation.org> References: <20121122004033.298367941@linuxfoundation.org> User-Agent: quilt/0.60-2.1.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Huang Ying commit 90b5c1d7c45eeb622302680ff96ed30c1a2b6f0e upstream. If a PCI device and its parents are put into D3cold, unbinding the device will trigger deadlock as follow: - driver_unbind - device_release_driver - device_lock(dev) <--- previous lock here - __device_release_driver - pm_runtime_get_sync ... - rpm_resume(dev) - rpm_resume(dev->parent) ... - pci_pm_runtime_resume ... - pci_set_power_state - __pci_start_power_transition - pci_wakeup_bus(dev->parent->subordinate) - pci_walk_bus - device_lock(dev) <--- deadlock here If we do not do device_lock in pci_walk_bus, we can avoid deadlock. Device_lock in pci_walk_bus is introduced in commit: d71374dafbba7ec3f67371d3b7e9f6310a588808, corresponding email thread is: https://lkml.org/lkml/2006/5/26/38. The patch author Zhang Yanmin said device_lock is added to pci_walk_bus because: Some error handling functions call pci_walk_bus. For example, PCIe aer. Here we lock the device, so the driver wouldn't detach from the device, as the cb might call driver's callback function. So I fixed the deadlock as follows: - remove device_lock from pci_walk_bus - add device_lock into callback if callback will call driver's callback I checked pci_walk_bus users one by one, and found only PCIe aer needs device lock. Signed-off-by: Huang Ying Signed-off-by: Bjorn Helgaas Acked-by: Rafael J. Wysocki CC: Zhang Yanmin Signed-off-by: Greg Kroah-Hartman --- drivers/pci/bus.c | 3 --- drivers/pci/pcie/aer/aerdrv_core.c | 20 ++++++++++++++++---- 2 files changed, 16 insertions(+), 7 deletions(-) --- a/drivers/pci/bus.c +++ b/drivers/pci/bus.c @@ -314,10 +314,7 @@ void pci_walk_bus(struct pci_bus *top, i } else next = dev->bus_list.next; - /* Run device routines with the device locked */ - device_lock(&dev->dev); retval = cb(dev, userdata); - device_unlock(&dev->dev); if (retval) break; } --- a/drivers/pci/pcie/aer/aerdrv_core.c +++ b/drivers/pci/pcie/aer/aerdrv_core.c @@ -244,6 +244,7 @@ static int report_error_detected(struct struct aer_broadcast_data *result_data; result_data = (struct aer_broadcast_data *) data; + device_lock(&dev->dev); dev->error_state = result_data->state; if (!dev->driver || @@ -262,12 +263,14 @@ static int report_error_detected(struct dev->driver ? "no AER-aware driver" : "no driver"); } - return 0; + goto out; } err_handler = dev->driver->err_handler; vote = err_handler->error_detected(dev, result_data->state); result_data->result = merge_result(result_data->result, vote); +out: + device_unlock(&dev->dev); return 0; } @@ -278,14 +281,17 @@ static int report_mmio_enabled(struct pc struct aer_broadcast_data *result_data; result_data = (struct aer_broadcast_data *) data; + device_lock(&dev->dev); if (!dev->driver || !dev->driver->err_handler || !dev->driver->err_handler->mmio_enabled) - return 0; + goto out; err_handler = dev->driver->err_handler; vote = err_handler->mmio_enabled(dev); result_data->result = merge_result(result_data->result, vote); +out: + device_unlock(&dev->dev); return 0; } @@ -296,14 +302,17 @@ static int report_slot_reset(struct pci_ struct aer_broadcast_data *result_data; result_data = (struct aer_broadcast_data *) data; + device_lock(&dev->dev); if (!dev->driver || !dev->driver->err_handler || !dev->driver->err_handler->slot_reset) - return 0; + goto out; err_handler = dev->driver->err_handler; vote = err_handler->slot_reset(dev); result_data->result = merge_result(result_data->result, vote); +out: + device_unlock(&dev->dev); return 0; } @@ -311,15 +320,18 @@ static int report_resume(struct pci_dev { struct pci_error_handlers *err_handler; + device_lock(&dev->dev); dev->error_state = pci_channel_io_normal; if (!dev->driver || !dev->driver->err_handler || !dev->driver->err_handler->resume) - return 0; + goto out; err_handler = dev->driver->err_handler; err_handler->resume(dev); +out: + device_unlock(&dev->dev); return 0; }