From mboxrd@z Thu Jan 1 00:00:00 1970 From: John Fastabend Subject: Re: [PATCH net RESEND] vlan: don't allow to add VLAN on VLAN device Date: Thu, 27 Feb 2014 19:45:59 -0800 Message-ID: <53100677.2060705@intel.com> References: <530FF7BF.4030706@huawei.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: Patrick McHardy , "David S. Miller" , Netdev , "linux-kernel@vger.kernel.org" To: Ding Tianhong Return-path: In-Reply-To: <530FF7BF.4030706@huawei.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 2/27/2014 6:43 PM, Ding Tianhong wrote: > I run these steps: > > modprobe 8021q > vconfig add eth2 20 > vconfig add eth2.20 20 > ifconfig eth2 xx.xx.xx.xx > > then the Call Trace happened: > [...] > ======================================================================== > > The reason is that if add vlan on vlan dev, the vlan dev will create vlan_info, > then the notification will let the real dev to run dev_set_rx_mode() and hold > netif_addr_lock, and then the real dev will call ndo_set_rx_mode(), if the real > dev is vlan dev, the ndo_set_rx_mode() will hold netif_addr_lock again, so deadlock > happened. > > Don't allow to add vlan on vlan dev to fix this problem. > > Signed-off-by: Ding Tianhong > --- I'm not sure we can just disable stacked vlans. There might be something using them today and they have worked in the past. Lets try to find a better fix. .John