Re: [PATCH net] net: sched: fix initialiser warning in sch_frag.c

[Davide Caratti <dcaratti@redhat.com>]

On Sun, Sep 19, 2021 at 11:40:33PM +0100, Russell King (Oracle) wrote:
> Debian gcc 10.2.1 complains thusly:
> 
> net/sched/sch_frag.c:93:10: warning: missing braces around initializer [-Wmissing-braces]
>    struct rtable sch_frag_rt = { 0 };
>           ^
> net/sched/sch_frag.c:93:10: warning: (near initialization for 'sch_frag_rt.dst') [-Wmissing-braces]
> 
> Fix it by removing the unnecessary '0' initialiser, leaving the
> braces.

hello Russell, thanks a lot for reporting!
 
> diff --git a/net/sched/sch_frag.c b/net/sched/sch_frag.c
> index 8c06381391d6..ab359d63287c 100644
> --- a/net/sched/sch_frag.c
> +++ b/net/sched/sch_frag.c
> @@ -90,7 +90,7 @@ static int sch_fragment(struct net *net, struct sk_buff *skb,
>  	}
>  
>  	if (skb_protocol(skb, true) == htons(ETH_P_IP)) {
> -		struct rtable sch_frag_rt = { 0 };
> +		struct rtable sch_frag_rt = { };

this surely fixes the -Wmissing-braces, but then -Wpedantic
would complain about usage of GNU extension (I just tried on godbolt
with x86_64 gcc 11.2):

warning: ISO C forbids empty initializer braces [-Wpedantic]

While we are fixing this, probably the best thing is to initialize the
'dst' struct member  to 0: in my understanding this should be sufficient
to let the compiler fill all the struct members with 0.

Oh, and I might have inserted a similar thing in openvswitch kernel
module (see [1]), if you agree I will send a patch that fixes this as
well. WDYT?

-- 
davide

[1] https://lore.kernel.org/netdev/80dbe764b5ae660bba3cf6edcb045a74b0f85853.1618844973.git.dcaratti@redhat.com/