netdev - Re: [PATCH net-next RFC 7/8] udp: gro behind static key

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Date:   Mon, 17 Sep 2018 12:24:19 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Willem de Bruijn <willemdebruijn.kernel@...il.com>,
        netdev@...r.kernel.org
Cc:     steffen.klassert@...unet.com, davem@...emloft.net,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next RFC 7/8] udp: gro behind static key

On Fri, 2018-09-14 at 13:59 -0400, Willem de Bruijn wrote:
> diff --git a/net/ipv4/udp_offload.c b/net/ipv4/udp_offload.c
> index 4f6aa95a9b12..f44fe328aa0f 100644
> --- a/net/ipv4/udp_offload.c
> +++ b/net/ipv4/udp_offload.c
> @@ -405,7 +405,7 @@ static struct sk_buff *udp4_gro_receive(struct list_head *head,
>  {
>  	struct udphdr *uh = udp_gro_udphdr(skb);
>  
> -	if (unlikely(!uh))
> +	if (unlikely(!uh) || !static_branch_unlikely(&udp_encap_needed_key))
>  		goto flush;
>  
>  	/* Don't bother verifying checksum if we're going to flush anyway. */

If I read this correctly, once udp_encap_needed_key is enabled, it will
never be turned off, because the tunnel and encap socket shut down does
not cope with udp_encap_needed_key.

Perhaps we should take care of that, too.

Cheers,

Paolo