From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758538Ab0EUQ7z (ORCPT ); Fri, 21 May 2010 12:59:55 -0400 Received: from kroah.org ([198.145.64.141]:39118 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934245Ab0EUQyX (ORCPT ); Fri, 21 May 2010 12:54:23 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Hugh Daschbach , Greg Kroah-Hartman Subject: [PATCH 16/38] Driver core: Protect device shutdown from hot unplug events. Date: Fri, 21 May 2010 09:53:46 -0700 Message-Id: <1274460848-11377-16-git-send-email-gregkh@suse.de> X-Mailer: git-send-email 1.7.0.3 In-Reply-To: <20100521165106.GA11216@kroah.com> References: <20100521165106.GA11216@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Hugh Daschbach While device_shutdown() walks through devices_kset to shutdown all devices, device unplug events may race to shutdown individual devices. Specifically, sd_shutdown(), on behalf of fc_starget_delete(), has been observed deleting devices during device_shutdown()'s list traversal. So we factor out list_for_each_entry_safe_reverse(...) in favor of while (!list_empty(...)). Signed-off-by: Hugh Daschbach Signed-off-by: Greg Kroah-Hartman --- drivers/base/core.c | 25 ++++++++++++++++++++++--- 1 files changed, 22 insertions(+), 3 deletions(-) diff --git a/drivers/base/core.c b/drivers/base/core.c index 4c5be85..356dd01 100644 --- a/drivers/base/core.c +++ b/drivers/base/core.c @@ -1734,10 +1734,25 @@ EXPORT_SYMBOL_GPL(device_move); */ void device_shutdown(void) { - struct device *dev, *devn; + struct device *dev; + + spin_lock(&devices_kset->list_lock); + /* + * Walk the devices list backward, shutting down each in turn. + * Beware that device unplug events may also start pulling + * devices offline, even as the system is shutting down. + */ + while (!list_empty(&devices_kset->list)) { + dev = list_entry(devices_kset->list.prev, struct device, + kobj.entry); + get_device(dev); + /* + * Make sure the device is off the kset list, in the + * event that dev->*->shutdown() doesn't remove it. + */ + list_del_init(&dev->kobj.entry); + spin_unlock(&devices_kset->list_lock); - list_for_each_entry_safe_reverse(dev, devn, &devices_kset->list, - kobj.entry) { if (dev->bus && dev->bus->shutdown) { dev_dbg(dev, "shutdown\n"); dev->bus->shutdown(dev); @@ -1745,6 +1760,10 @@ void device_shutdown(void) dev_dbg(dev, "shutdown\n"); dev->driver->shutdown(dev); } + put_device(dev); + + spin_lock(&devices_kset->list_lock); } + spin_unlock(&devices_kset->list_lock); async_synchronize_full(); } -- 1.7.0.3