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Tue, 08 Sep 2020 09:09:03 -0700 (PDT) Date: Tue, 08 Sep 2020 19:09:00 +0300 In-Reply-To: <20200908090049.7e528e7f@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> References: <20200908130000.7d33d787@canb.auug.org.au> <20200908071713.916165-1-nikolay@cumulusnetworks.com> <20200908090049.7e528e7f@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Subject: Re: [PATCH net-next] net: bridge: mcast: fix unused br var when lockdep isn't defined To: Jakub Kicinski CC: netdev@vger.kernel.org, davem@davemloft.net, roopa@nvidia.com, Stephen Rothwell From: nikolay@cumulusnetworks.com Message-ID: <3DB9AD39-8B58-42C3-8C13-929C8B9F1719@cumulusnetworks.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 8 September 2020 19:00:49 EEST, Jakub Kicinski wrote= : >On Tue, 8 Sep 2020 10:17:13 +0300 Nikolay Aleksandrov wrote: >> Stephen reported the following warning: >> net/bridge/br_multicast=2Ec: In function 'br_multicast_find_port': >> net/bridge/br_multicast=2Ec:1818:21: warning: unused variable 'br' >[-Wunused-variable] >> 1818 | struct net_bridge *br =3D mp->br; >> | ^~ >>=20 >> It happens due to bridge's mlock_dereference() when lockdep isn't >defined=2E >> Silence the warning by annotating the variable as __maybe_unused=2E >>=20 >> Fixes: 0436862e417e ("net: bridge: mcast: support for IGMPv3/MLDv2 >ALLOW_NEW_SOURCES report") >> Reported-by: Stephen Rothwell >> Signed-off-by: Nikolay Aleksandrov >> --- >> net/bridge/br_multicast=2Ec | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >>=20 >> diff --git a/net/bridge/br_multicast=2Ec b/net/bridge/br_multicast=2Ec >> index b83f11228948=2E=2E33adf44ef7ec 100644 >> --- a/net/bridge/br_multicast=2Ec >> +++ b/net/bridge/br_multicast=2Ec >> @@ -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 =3D mp->br; >> struct net_bridge_port_group *pg; >> - struct net_bridge *br =3D mp->br; >> =20 >> for (pg =3D 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=2E When the local variable's only used for lockdep, I guess=2E :)=20 Here we don't actually need it at all, alternatively we can just drop it a= nd use mp->br=2E=20