netdev - Re: [PATCH v19 bpf-next 23/23] xdp: disable XDP

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Date:   Mon, 6 Dec 2021 20:24:12 +0100
From:   Lorenzo Bianconi <lorenzo.bianconi@...hat.com>
To:     Jesper Dangaard Brouer <jbrouer@...hat.com>
Cc:     Lorenzo Bianconi <lorenzo@...nel.org>, bpf@...r.kernel.org,
        netdev@...r.kernel.org, brouer@...hat.com, davem@...emloft.net,
        kuba@...nel.org, ast@...nel.org, daniel@...earbox.net,
        shayagr@...zon.com, john.fastabend@...il.com, dsahern@...nel.org,
        echaudro@...hat.com, jasowang@...hat.com,
        alexander.duyck@...il.com, saeed@...nel.org,
        maciej.fijalkowski@...el.com, magnus.karlsson@...el.com,
        tirthendu.sarkar@...el.com, toke@...hat.com
Subject: Re: [PATCH v19 bpf-next 23/23] xdp: disable XDP_REDIRECT for xdp
 multi-buff

> On 30/11/2021 12.53, Lorenzo Bianconi wrote:
> > XDP_REDIRECT is not fully supported yet for xdp multi-buff since not
> > all XDP capable drivers can map non-linear xdp_frame in ndo_xdp_xmit
> > so disable it for the moment.
> > 
> > Signed-off-by: Lorenzo Bianconi <lorenzo@...nel.org>
> > ---
> >   net/core/filter.c | 7 +++++++
> >   1 file changed, 7 insertions(+)
> > 
> > diff --git a/net/core/filter.c b/net/core/filter.c
> > index b70725313442..a87d835d1122 100644
> > --- a/net/core/filter.c
> > +++ b/net/core/filter.c
> > @@ -4189,6 +4189,13 @@ int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp,
> >   	struct bpf_map *map;
> >   	int err;
> > +	/* XDP_REDIRECT is not fully supported yet for xdp multi-buff since
> > +	 * not all XDP capable drivers can map non-linear xdp_frame in
> > +	 * ndo_xdp_xmit.
> > +	 */
> > +	if (unlikely(xdp_buff_is_mb(xdp)))
> > +		return -EOPNOTSUPP;
> > +
> 
> This approach also exclude 'cpumap' use-case, which you AFAIK have added MB
> support for in this patchset.

ack, right. We can exclude CPUMAPs here.

> 
> Generally this check is hopefully something we can remove again, once
> drivers add MB ndo_xdp_xmit support.

right.

Regards,
Lorenzo

> 
> 
> >   	ri->map_id = 0; /* Valid map id idr range: [1,INT_MAX[ */
> >   	ri->map_type = BPF_MAP_TYPE_UNSPEC;
> > 
> 

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