netdev - Re: [PATCH net-next v2 2/2] bpf: let bpf_warn_invalid_xdp

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Date:   Fri, 26 Nov 2021 19:57:19 +0100
From:   Paolo Abeni <pabeni@...hat.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, bpf@...r.kernel.org,
        Toke Høiland-Jørgensen <toke@...hat.com>
Subject: Re: [PATCH net-next v2 2/2] bpf: let bpf_warn_invalid_xdp_action()
 report more info

On Fri, 2021-11-26 at 10:19 -0800, Jakub Kicinski wrote:
> On Fri, 26 Nov 2021 12:19:11 +0100 Paolo Abeni wrote:
> > -void bpf_warn_invalid_xdp_action(u32 act)
> > +void bpf_warn_invalid_xdp_action(struct net_device *dev, struct bpf_prog *prog, u32 act)
> >  {
> >  	const u32 act_max = XDP_REDIRECT;
> >  
> > -	pr_warn_once("%s XDP return value %u, expect packet loss!\n",
> > +	pr_warn_once("%s XDP return value %u on prog %s (id %d) dev %s, expect packet loss!\n",
> >  		     act > act_max ? "Illegal" : "Driver unsupported",
> > -		     act);
> > +		     act, prog->aux->name, prog->aux->id, dev->name ? dev->name : "");
> >  }
> 
> Since we have to touch all the drivers each time the prototype of this
> function is changed - would it make sense to pass in rxq instead? It has
> more info which may become useful at some point.

I *think* for this specific scenario the device name provides all the
necessary info - the users need to know the driver causing the issue.

Others similar xdp helpers - e.g. trace_xdp_exception() - have the same
arguments list used here. If the rxq is useful I guess we will have to
change even them, and touch all the drivers anyway.

Cheers,

Paolo