Re: [RFC PATCH v2 2/4] virtio/vsock: remove all data from sk_buff

[Stefano Garzarella]

On Mon, Mar 06, 2023 at 06:31:22PM +0300, Arseniy Krasnov wrote:
> On 06.03.2023 15:08, Stefano Garzarella wrote:
> > On Sun, Mar 05, 2023 at 11:07:37PM +0300, Arseniy Krasnov wrote:
> > > In case of SOCK_SEQPACKET all sk_buffs are used once - after read some
> > > data from it, it will be removed, so user will never read rest of the
> > > data. Thus we need to update credit parameters of the socket like whole
> > > sk_buff is read - so call 'skb_pull()' for the whole buffer.
> > >
> > > Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
> > > Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
> > > ---
> > > net/vmw_vsock/virtio_transport_common.c | 2 +-
> > > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > Maybe we could avoid this patch if we directly use pkt_len as I
> > suggested in the previous patch.
> Hm, may be we can avoid calling 'skb_pull()' here if 'virtio_transport_dec_rx_pkt()'
> will use integer argument?

Yep, exactly!

> Just call 'virtio_transport_dec_rx_pkt(skb->len)'. skb

It depends on how we call virtio_transport_inc_rx_pkt(). If we use
hdr->len there I would use the same to avoid confusion. Plus that's the
value the other peer sent us, so definitely the right value to increase
fwd_cnt with. But if skb->len always reflects it, then that's fine.

> is never returned to queue to read it again, so i think may be there is no sense for
> extra call 'skb_pull'?

Right!

Thanks,
Stefano