From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: Re: IGMP snooping: set mrouters_only flag for IPv4 traffic properly Date: Tue, 14 Jun 2011 13:22:12 -0400 Message-ID: <20110614132212.2ac83c6c@s6510.ftrdhcpuser.net> References: <1307933995.2704.11.camel@nausicaa> <1307934163.3550.2.camel@nausicaa> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Herbert Xu , netdev@vger.kernel.org, Hayato Kakuta To: Fernando Luis Vazquez Cao Return-path: Received: from mail.vyatta.com ([76.74.103.46]:46464 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751214Ab1FNRWK (ORCPT ); Tue, 14 Jun 2011 13:22:10 -0400 In-Reply-To: <1307934163.3550.2.camel@nausicaa> Sender: netdev-owner@vger.kernel.org List-ID: On Mon, 13 Jun 2011 12:02:43 +0900 Fernando Luis Vazquez Cao wrote: > Upon reception of a IGMP/IGMPv2 membership report the kernel sets the > mrouters_only flag in a skb that may be a clone of the original skb, which > means that sometimes the bridge loses track of membership report packets (cb > buffers are tied to a specifici skb and not shared) and it ends up forwading > join requests to the bridge interface. > > This can cause unexpected membership timeouts and intermitent/permanent loss of connectivity as described in RFC 4541 [2.1.1. IGMP Forwarding Rules]: > > A snooping switch should forward IGMP Membership Reports only to > those ports where multicast routers are attached. > [...] > Sending membership reports to other hosts can result, for IGMPv1 > and IGMPv2, in unintentionally preventing a host from joining a > specific multicast group. > > > Signed-off-by: Fernando Luis Vazquez Cao > Tested-by: Hayato Kakuta > --- > > diff -urNp linux-3.0-rc2-orig/net/bridge/br_multicast.c linux-3.0-rc2/net/bridge/br_multicast.c > --- linux-3.0-rc2-orig/net/bridge/br_multicast.c 2011-06-09 13:34:04.164261031 +0900 > +++ linux-3.0-rc2/net/bridge/br_multicast.c 2011-06-09 20:04:23.473930447 +0900 > @@ -1424,7 +1424,7 @@ static int br_multicast_ipv4_rcv(struct > switch (ih->type) { > case IGMP_HOST_MEMBERSHIP_REPORT: > case IGMPV2_HOST_MEMBERSHIP_REPORT: > - BR_INPUT_SKB_CB(skb2)->mrouters_only = 1; > + BR_INPUT_SKB_CB(skb)->mrouters_only = 1; > err = br_ip4_multicast_add_group(br, port, ih->group); > break; > case IGMPV3_HOST_MEMBERSHIP_REPORT: Acked-by: Stephen Hemminger