From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matti Linnanvuori Subject: [Bug 9750] [patch 2.6.24] dev: avoid a race that triggers assertion failure Date: Tue, 22 Jan 2008 22:34:05 -0800 (PST) Message-ID: <912509.75954.qm@web52011.mail.re2.yahoo.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: bugme-daemon@kernel-bugs.osdl.org To: netdev@vger.kernel.org, jgarzik@pobox.com Return-path: Received: from web52011.mail.re2.yahoo.com ([206.190.48.27]:31402 "HELO web52011.mail.re2.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753338AbYAWGeH (ORCPT ); Wed, 23 Jan 2008 01:34:07 -0500 Sender: netdev-owner@vger.kernel.org List-ID: From: Matti Linnanvuori There is a race in Linux kernel file net/core/dev.c, function dev_close. The function calls function dev_deactivate, which calls function dev_watchdog_down that deletes the watchdog timer. However, after that, a driver can call netif_carrier_ok, which calls function __netdev_watchdog_up that can add the watchdog timer again. Function unregister_netdevice calls function dev_shutdown that traps the bug !timer_pending(&dev->watchdog_timer). Moving dev_deactivate after netif_running() has been cleared prevents function netif_carrier_on from calling __netdev_watchdog_up and adding the watchdog timer again. Signed-off-by: Matti Linnanvuori --- --- linux-2.6.24/net/core/dev.c 2008-01-23 08:20:55.733012300 +0200 +++ b/net/core/dev.c 2008-01-23 08:24:32.818766600 +0200 @@ -1068,8 +1068,6 @@ int dev_close(struct net_device *dev) */ call_netdevice_notifiers(NETDEV_GOING_DOWN, dev); - dev_deactivate(dev); - clear_bit(__LINK_STATE_START, &dev->state); /* Synchronize to scheduled poll. We cannot touch poll list, @@ -1080,6 +1078,8 @@ int dev_close(struct net_device *dev) */ smp_mb__after_clear_bit(); /* Commit netif_running(). */ + dev_deactivate(dev); + /* * Call the device specific close. This cannot fail. * Only if device is UP ____________________________________________________________________________________ Never miss a thing. Make Yahoo your home page. http://www.yahoo.com/r/hs