From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935094Ab3E2HWM (ORCPT ); Wed, 29 May 2013 03:22:12 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:44084 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935045Ab3E2HWL (ORCPT ); Wed, 29 May 2013 03:22:11 -0400 Date: Wed, 29 May 2013 00:22:08 -0700 (PDT) Message-Id: <20130529.002208.1948977466672387293.davem@davemloft.net> To: jasowang@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, mst@redhat.com Subject: Re: [PATCH] tuntap: forbid changing mq flag for persistent device From: David Miller In-Reply-To: <1369801931-6856-1-git-send-email-jasowang@redhat.com> References: <1369801931-6856-1-git-send-email-jasowang@redhat.com> X-Mailer: Mew version 6.5 on Emacs 24.1 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Jason Wang Date: Wed, 29 May 2013 12:32:11 +0800 > We currently allow changing the mq flag (IFF_MULTI_QUEUE) for a persistent > device. This will result a mismatch between the number the queues in netdev and > tuntap. This is because we only allocate a 1q netdevice when IFF_MULTI_QUEUE was > not specified, so when we set the IFF_MULTI_QUEUE and try to attach more queues > later, netif_set_real_num_tx_queues() may fail which result a single queue > netdevice with multiple sockets attached. > > Solve this by disallowing changing the mq flag for persistent device. > > Bug was introduced by commit edfb6a148ce62e5e19354a1dcd9a34e00815c2a1 > (tuntap: reduce memory using of queues). > > Reported-by: Sriram Narasimhan > Cc: Michael S. Tsirkin > Signed-off-by: Jason Wang Applied, thanks Jason.