From mboxrd@z Thu Jan 1 00:00:00 1970 From: Cong Wang Subject: [Patch net-next] vxlan: fix a soft lockup in vxlan module removal Date: Wed, 7 Aug 2013 16:43:22 +0800 Message-ID: <1375865002-8732-1-git-send-email-amwang@redhat.com> Cc: "David S. Miller" , Stephen Hemminger , Cong Wang To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([209.132.183.28]:26401 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756023Ab3HGInc (ORCPT ); Wed, 7 Aug 2013 04:43:32 -0400 Sender: netdev-owner@vger.kernel.org List-ID: From: Cong Wang This is a regression introduced by: commit fe5c3561e6f0ac7c9546209f01351113c1b77ec8 Author: stephen hemminger Date: Sat Jul 13 10:18:18 2013 -0700 vxlan: add necessary locking on device removal The problem is that vxlan_dellink(), which is called with RTNL lock held, tries to flush the workqueue synchronously, but apparently igmp_join and igmp_leave work need to hold RTNL lock too, therefore we have a soft lockup! As suggested by Stephen, probably the flush_workqueue can just be removed and let the normal refcounting work. The workqueue has a reference to device and socket, therefore the cleanups should work correctly. Suggested-by: Stephen Hemminger Cc: Stephen Hemminger Cc: David S. Miller Tested-by: Cong Wang Signed-off-by: Cong Wang --- diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c index 8bf31d9..c51ef9b 100644 --- a/drivers/net/vxlan.c +++ b/drivers/net/vxlan.c @@ -1837,8 +1837,6 @@ static void vxlan_dellink(struct net_device *dev, struct list_head *head) struct vxlan_net *vn = net_generic(dev_net(dev), vxlan_net_id); struct vxlan_dev *vxlan = netdev_priv(dev); - flush_workqueue(vxlan_wq); - spin_lock(&vn->sock_lock); hlist_del_rcu(&vxlan->hlist); spin_unlock(&vn->sock_lock);