From patchwork Wed Sep 16 06:34:15 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Wengang Wang X-Patchwork-Id: 518267 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 9CE611401DA for ; Wed, 16 Sep 2015 16:33:01 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752379AbbIPGc5 (ORCPT ); Wed, 16 Sep 2015 02:32:57 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:43256 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752226AbbIPGc4 (ORCPT ); Wed, 16 Sep 2015 02:32:56 -0400 Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by aserp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id t8G6Wtjm028266 (version=TLSv1 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 16 Sep 2015 06:32:56 GMT Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userv0022.oracle.com (8.13.8/8.13.8) with ESMTP id t8G6WtZ0019225 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=FAIL) for ; Wed, 16 Sep 2015 06:32:55 GMT Received: from abhmp0006.oracle.com (abhmp0006.oracle.com [141.146.116.12]) by aserv0122.oracle.com (8.13.8/8.13.8) with ESMTP id t8G6Wsjb011706 for ; Wed, 16 Sep 2015 06:32:55 GMT Received: from oracle.com (/10.182.64.160) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 15 Sep 2015 23:32:54 -0700 From: Wengang Wang To: netdev@vger.kernel.org Cc: wen.gang.wang@oracle.com Subject: [PATCH] ip: find correct route for socket which is not bound to a device Date: Wed, 16 Sep 2015 14:34:15 +0800 Message-Id: <1442385255-27014-1-git-send-email-wen.gang.wang@oracle.com> X-Mailer: git-send-email 2.1.0 MIME-Version: 1.0 X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org For multi-cast, we should find valid route(thus get the meaniful pmtu) for the package on the socket which is not bound to a device(sk_bound_dev_if being 0) too. From man page of socket(7) SO_BINDTODEVICE Bind this socket to a particular device like “eth0”, as specified in the passed interface name. If the name is an empty string or the option length is zero, the socket device binding is removed. The passed option is a variable-length null-terminated interface name string with the maximum size of IFNAMSIZ. If a socket is bound to an interface, only packets received from that particular interface are processed by the socket. Note that this works only for some socket types, particularly AF_INET sockets. It is not supported for packet sockets (use normal bind(2) there). The man page doesn't say when socket not bound packages won't be routed. A problem is hit that all multi-cast packages dropped by kernel(from sender host). The lower layer is IPoIB with MTU being 7000. And I was sending 4096 length multi-cast package. In side IPoIB the first send is dropped because is exeeding the internal package size limitation mcast_mtu which is 2044. So IPoIB calls ip_rt_update_pmtu (indirectly) trying to set path mtu. A correct route is configured for the multi-cast, so the setting of pmtu cucceeded and the next multi-cast package(to the same target) is expected to succeed(it would be well fragmented accroding to the pmtu I just set). But actually the second and later multi-cast packages got dropped too. And the reason is that the neighor looking up(fib_lookup) is skipped because of the socket is not bound to device(sk_bound_dev_if being 0). After applied the patch I proposed here, it works fine. Signed-off-by: Wengang Wang --- net/ipv4/route.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/ipv4/route.c b/net/ipv4/route.c index 5f4a556..032481a 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -2097,7 +2097,7 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4) */ fl4->flowi4_oif = dev_out->ifindex; - goto make_route; + goto lookup; } if (!(fl4->flowi4_flags & FLOWI_FLAG_ANYSRC)) { @@ -2153,6 +2153,7 @@ struct rtable *__ip_route_output_key(struct net *net, struct flowi4 *fl4) goto make_route; } +lookup: if (fib_lookup(net, fl4, &res, 0)) { res.fi = NULL; res.table = NULL;