From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Ahern Subject: Re: If bridge have no sub-interfaces, it's status may be still with 'RUNNING' Date: Mon, 16 Feb 2015 08:47:11 -0700 Message-ID: <54E210FF.2050502@gmail.com> References: <54DDCA99.4040401@windriver.com> <20150213133056.3944c13e@uryu.home.lan> <54E17853.8070106@windriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: netdev , "Wu, Kuaikuai" , "Tao, Yue" To: yzhu1 , Stephen Hemminger Return-path: Received: from mail-ig0-f180.google.com ([209.85.213.180]:53554 "EHLO mail-ig0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752974AbbBPPrO (ORCPT ); Mon, 16 Feb 2015 10:47:14 -0500 Received: by mail-ig0-f180.google.com with SMTP id b16so24301098igk.1 for ; Mon, 16 Feb 2015 07:47:13 -0800 (PST) In-Reply-To: <54E17853.8070106@windriver.com> Sender: netdev-owner@vger.kernel.org List-ID: On 2/15/15 9:55 PM, yzhu1 wrote: >>> 1. brctl addbr br0 >>> >>> 2. ifconfig br0 up >>> >>> 3. ifconfig br0 (br0's status is with 'RUNNING') >>> >>> 4. brctl addif br0 eth0 >>> >>> 5. brctl delif br0 eth0 >>> >>> 6. ifconfig br0 (br0's status is without 'RUNNING') >>> >>> When there is no sub-interface, the flag "RUNNING" is missing after the >>> last sub-interface is removed. I do not see that behavior with Fedora 21 and 3.18.5-201.fc21.x86_64. ie., after interface is removed br0 is still in up state. Perhaps a regression with 3.19. >>> >>> As such, should we keep "RUNNING" flag after the last sub-interface is >>> removed? >> This is intentional. If there are no active ports in bridge, then >> we want to tell applications that packets will go nowhere. It changes current behavior with respect to tcpdump. Today I can launch tcpdump on a bridge interface before starting a VM. With this change I will not be able to do that. David