netdev - Re: [PATCHv12 bpf-next 1/6] bpf: run devmap xdp_prog on flush instead of bulk enqueue

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Message-ID: <20201218094302.GN273186@localhost.localdomain>
Date:   Fri, 18 Dec 2020 17:43:02 +0800
From:   Hangbin Liu <haliu@...hat.com>
To:     David Ahern <dsahern@...il.com>
Cc:     Hangbin Liu <liuhangbin@...il.com>, bpf@...r.kernel.org,
        netdev@...r.kernel.org,
        Toke Høiland-Jørgensen <toke@...hat.com>,
        Jiri Benc <jbenc@...hat.com>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        Eelco Chaudron <echaudro@...hat.com>, ast@...nel.org,
        Daniel Borkmann <daniel@...earbox.net>,
        Lorenzo Bianconi <lorenzo.bianconi@...hat.com>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Alexei Starovoitov <alexei.starovoitov@...il.com>
Subject: Re: [PATCHv12 bpf-next 1/6] bpf: run devmap xdp_prog on flush
 instead of bulk enqueue

Hi David,

Thanks for the comment.

On Thu, Dec 17, 2020 at 09:07:03AM -0700, David Ahern wrote:
> > +	return n - nframes; /* dropped frames count */
> 
> just return nframes here, since ...
> 
> > +		xdp_drop = dev_map_bpf_prog_run(bq->xdp_prog, bq->q, cnt, dev);
> > +		cnt -= xdp_drop;
> 
> ... that is apparently what you really want.

I will fix this

> > +	if (dst && dst->xdp_prog && !bq->xdp_prog)
> > +		bq->xdp_prog = dst->xdp_prog;
> 
> 
> if you pass in xdp_prog through __xdp_enqueue you can reduce that to just:
> 
> 	if (!bq->xdp_prog)
> 		bq->xdp_prog = xdp_prog;

And this in the next PATCH version.

Thanks
Hangbin