On 8 September 2020 19:00:49 EEST, Jakub Kicinski <k...@kernel.org> wrote:
>On Tue, 8 Sep 2020 10:17:13 +0300 Nikolay Aleksandrov wrote:
>> Stephen reported the following warning:
>> net/bridge/br_multicast.c: In function 'br_multicast_find_port':
>> net/bridge/br_multicast.c:1818:21: warning: unused variable 'br'
>[-Wunused-variable]
>> 1818 | struct net_bridge *br = mp->br;
>> | ^~
>>
>> It happens due to bridge's mlock_dereference() when lockdep isn't
>defined.
>> Silence the warning by annotating the variable as __maybe_unused.
>>
>> Fixes: 0436862e417e ("net: bridge: mcast: support for IGMPv3/MLDv2
>ALLOW_NEW_SOURCES report")
>> Reported-by: Stephen Rothwell <s...@canb.auug.org.au>
>> Signed-off-by: Nikolay Aleksandrov <niko...@cumulusnetworks.com>
>> ---
>> net/bridge/br_multicast.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
>> index b83f11228948..33adf44ef7ec 100644
>> --- a/net/bridge/br_multicast.c
>> +++ b/net/bridge/br_multicast.c
>> @@ -1814,8 +1814,8 @@ br_multicast_find_port(struct
>net_bridge_mdb_entry *mp,
>> struct net_bridge_port *p,
>> const unsigned char *src)
>> {
>> + struct net_bridge *br __maybe_unused = mp->br;
>> struct net_bridge_port_group *pg;
>> - struct net_bridge *br = mp->br;
>>
>> for (pg = mlock_dereference(mp->ports, br);
>> pg;
>
>That's a lazy fix :( Is everyone using lockdep annotations going to
>sprinkle __maybe_unused throughout the code? Macros should also always
>evaluate their arguments.
When the local variable's only used for lockdep, I guess. :)
Here we don't actually need it at all, alternatively we can just drop it and
use mp->br.
