[Bridge] [PATCH net] net: bridge: mcast: don't delete permanent entries when fast leave is enabled

Nikolay Aleksandrov nikolay at cumulusnetworks.com
Tue Jul 30 17:21:06 UTC 2019

On 30/07/2019 20:18, David Miller wrote:
> From: Nikolay Aleksandrov <nikolay at cumulusnetworks.com>
> Date: Tue, 30 Jul 2019 14:21:00 +0300
>> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
>> index 3d8deac2353d..f8cac3702712 100644
>> --- a/net/bridge/br_multicast.c
>> +++ b/net/bridge/br_multicast.c
>> @@ -1388,6 +1388,9 @@ br_multicast_leave_group(struct net_bridge *br,
>>  			if (!br_port_group_equal(p, port, src))
>>  				continue;
>> +			if (p->flags & MDB_PG_FLAGS_PERMANENT)
>> +				break;
>> +
> Like David, I also don't understand why this can be a break.  Is it because
> permanent entries are always the last on the list?  Why will there be no
> other entries that might need to be processed on the list?

The reason is that only one port can match. See the first clause of br_port_group_equal,
that port can participate only once. We could easily add a break statement in the end
when a match is found and it will be correct. Even in the presence of MULTICAST_TO_UNICAST
flag, the port must match and can be added only once.

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