Re: [PATCH net-next 1/3] net: gre_demux: add skb drop reasons to gre_rcv()

[Jakub Kicinski]

On Tue, 15 Mar 2022 21:49:01 -0600 David Ahern wrote:
> >>  	ver = skb->data[1]&0x7f;
> >> -	if (ver >= GREPROTO_MAX)
> >> +	if (ver >= GREPROTO_MAX) {
> >> +		reason = SKB_DROP_REASON_GRE_VERSION;  
> > 
> > TBH I'm still not sure what level of granularity we should be shooting
> > for with the reasons. I'd throw all unexpected header values into one 
> > bucket, not go for a reason per field, per protocol. But as I'm said
> > I'm not sure myself, so we can keep what you have..  
> 
> I have stated before I do not believe every single drop point in the
> kernel needs a unique reason code. This is overkill. The reason augments
> information we already have -- the IP from kfree_skb tracepoint.

That's certainly true. I wonder if there is a systematic way of
approaching these additions that'd help us picking the points were 
we add reasons less of a judgment call.