From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pavel Emelyanov Subject: [PATCH 8/8][BONDING]: Deadlock between bonding_store_bonds and bond_destroy_sysfs. Date: Tue, 29 Apr 2008 19:11:48 +0400 Message-ID: <48173AB4.4080009@openvz.org> References: <481735F4.30909@openvz.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: bonding-devel@lists.sourceforge.net, Linux Netdev List To: Jay Vosburgh , David Miller Return-path: Received: from sacred.ru ([62.205.161.221]:42017 "EHLO sacred.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751497AbYD2Pto (ORCPT ); Tue, 29 Apr 2008 11:49:44 -0400 In-Reply-To: <481735F4.30909@openvz.org> Sender: netdev-owner@vger.kernel.org List-ID: The sysfs layer has an internal protection, that ensures, that all the process sitting inside ->sore/->show callback exits before the appropriate entry is unregistered (the calltraces are rather big, but I can provide them if required). On the other hand, bonding takes rtnl_lock in a) the bonding_store_bonds, i.e. in ->store callback, b) module exit before calling the sysfs unregister routines. Thus, the classical AB-BA deadlock may occur. To reproduce run # while :; do modprobe bonding; rmmod bonding; done and # while :; do echo '+bond%d' > /sys/class/net/bonding_masters ; done in parallel. The fix is to move the bond_destroy_sysfs out of the rtnl_lock, but _before_ bond_free_all to make sure no bonding devices exist after module unload. Signed-off-by: Pavel Emelyanov --- drivers/net/bonding/bond_main.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 4d852ab..7e7b0b8 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -4984,9 +4984,10 @@ err: destroy_workqueue(bond->wq); } + bond_destroy_sysfs(); + rtnl_lock(); bond_free_all(); - bond_destroy_sysfs(); rtnl_unlock(); out: return res; @@ -4998,9 +4999,10 @@ static void __exit bonding_exit(void) unregister_netdevice_notifier(&bond_netdev_notifier); unregister_inetaddr_notifier(&bond_inetaddr_notifier); + bond_destroy_sysfs(); + rtnl_lock(); bond_free_all(); - bond_destroy_sysfs(); rtnl_unlock(); } -- 1.5.3.4