Re: linux-next: build warning after merge of the net tree

[Cong Wang]

On Tue, Aug 21, 2018 at 3:04 PM Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
>
> Hi all,
>
> After merging the net tree, today's linux-next build (KCONFIG_NAME)
> produced this warning:
>
> drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c: In function 'tc_fill_actions':
> drivers/net/ethernet/stmicro/stmmac/stmmac_tc.c:64:6: warning: unused variable 'i' [-Wunused-variable]
>   int i;
>       ^
>
> Introduced by commit
>
>   244cd96adb5f ("net_sched: remove list_head from tc_action")

I bet you have CONFIG_NET_CLS_ACT=n?

Here is a quick fix:

diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index c17d51865469..9ec471ffaa5d 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -303,7 +303,7 @@ static inline void tcf_exts_put_net(struct tcf_exts *exts)
        for (i = 0; i < TCA_ACT_MAX_PRIO && ((a) = (exts)->actions[i]); i++)
 #else
 #define tcf_exts_for_each_action(i, a, exts) \
-       for (; 0; )
+       for ((void)i, (void)a; 0; )
 #endif

 static inline void

Interestingly, neither my compiler nor kbuild-bot's compiler doesn't
catch this.

Thanks.