linux-kernel - [PATCH 3.16 18/83] net: bridge: mcast: don't delete permanent entries when fast leave is enabled

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Message-ID: <lsq.1574264230.440959526@decadent.org.uk>
Date:   Wed, 20 Nov 2019 15:37:28 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Nikolay Aleksandrov" <nikolay@...ulusnetworks.com>
Subject: [PATCH 3.16 18/83] net: bridge: mcast: don't delete permanent
 entries when fast leave is enabled

3.16.78-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>

commit 5c725b6b65067909548ac9ca9bc777098ec9883d upstream.

When permanent entries were introduced by the commit below, they were
exempt from timing out and thus igmp leave wouldn't affect them unless
fast leave was enabled on the port which was added before permanent
entries existed. It shouldn't matter if fast leave is enabled or not
if the user added a permanent entry it shouldn't be deleted on igmp
leave.

Before:
$ echo 1 > /sys/class/net/eth4/brport/multicast_fast_leave
$ bridge mdb add dev br0 port eth4 grp 229.1.1.1 permanent
$ bridge mdb show
dev br0 port eth4 grp 229.1.1.1 permanent

< join and leave 229.1.1.1 on eth4 >

$ bridge mdb show
$

After:
$ echo 1 > /sys/class/net/eth4/brport/multicast_fast_leave
$ bridge mdb add dev br0 port eth4 grp 229.1.1.1 permanent
$ bridge mdb show
dev br0 port eth4 grp 229.1.1.1 permanent

< join and leave 229.1.1.1 on eth4 >

$ bridge mdb show
dev br0 port eth4 grp 229.1.1.1 permanent

Fixes: ccb1c31a7a87 ("bridge: add flags to distinguish permanent mdb entires")
Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
[bwh: Backported to 3.16: Check PERMANENT flag in net_bridge_port_group::state,
 not net_bridge_port_group::flags.]
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/bridge/br_multicast.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -1471,6 +1471,9 @@ br_multicast_leave_group(struct net_brid
 			if (p->port != port)
 				continue;
 
+			if (p->state & MDB_PERMANENT)
+				break;
+
 			rcu_assign_pointer(*pp, p->next);
 			hlist_del_init(&p->mglist);
 			del_timer(&p->timer);