Re: [PATCH next] net/core/dev: Warn on an impossibly short offload frame

[Joe Perches <joe@perches.com>]

On Sat, 2016-01-02 at 19:25 -0500, Aaron Conole wrote:
> When signaling that a GRO frame is ready to be processed, the network stack
> correctly checks length and aborts processing when a frame is less than 14
> bytes. However, such a condition is really indicative of a broken driver,
> and should be loudly signaled, rather than silently dropped as the case is
> today.
> 
> Convert the condition to use WARN_ON() to ensure that the stack loudly
> complains about such broken drivers.
[]
> diff --git a/net/core/dev.c b/net/core/dev.c
[]
> @@ -4579,7 +4579,7 @@ static struct sk_buff *napi_frags_skb(struct napi_struct *napi)
>  	eth = skb_gro_header_fast(skb, 0);
>  	if (unlikely(skb_gro_header_hard(skb, hlen))) {
>  		eth = skb_gro_header_slow(skb, hlen, 0);
> -		if (unlikely(!eth)) {
> +		if (WARN_ON(!eth)) {
>  			napi_reuse_skb(napi, skb);
>  			return NULL;
>  		}

It's generally a good idea to use
WARN_ON_RATELIMIT or WARN_ON_ONCE.