Re: [PATCH net-next v7 08/10] virtio_net: xsk: rx: support fill with xsk buffer

[Xuan Zhuo <xuanzhuo@linux.alibaba.com>]

On Mon, 8 Jul 2024 14:49:35 +0800, Jason Wang <jasowang@redhat.com> wrote:
> On Fri, Jul 5, 2024 at 3:37 PM Xuan Zhuo <xuanzhuo@linux.alibaba.com> wrote:
> >
> > Implement the logic of filling rq with XSK buffers.
> >
> > Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
> > ---
> >
> > v7:
> >    1. some small fixes
> >
> >  drivers/net/virtio_net.c | 70 +++++++++++++++++++++++++++++++++++++---
> >  1 file changed, 66 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 29fa25ce1a7f..2b27f5ada64a 100644
> > --- a/drivers/net/virtio_net.c
> > +++ b/drivers/net/virtio_net.c
> > @@ -354,6 +354,8 @@ struct receive_queue {
> >
> >         /* xdp rxq used by xsk */
> >         struct xdp_rxq_info xsk_rxq_info;
> > +
> > +       struct xdp_buff **xsk_buffs;
> >  };
> >
> >  /* This structure can contain rss message with maximum settings for indirection table and keysize
> > @@ -1054,6 +1056,53 @@ static void check_sq_full_and_disable(struct virtnet_info *vi,
> >         }
> >  }
> >
> > +static void sg_fill_dma(struct scatterlist *sg, dma_addr_t addr, u32 len)
> > +{
> > +       sg->dma_address = addr;
> > +       sg->length = len;
> > +}
> > +
> > +static int virtnet_add_recvbuf_xsk(struct virtnet_info *vi, struct receive_queue *rq,
> > +                                  struct xsk_buff_pool *pool, gfp_t gfp)
> > +{
> > +       struct xdp_buff **xsk_buffs;
> > +       dma_addr_t addr;
> > +       int err = 0;
> > +       u32 len, i;
> > +       int num;
> > +
> > +       xsk_buffs = rq->xsk_buffs;
> > +
> > +       num = xsk_buff_alloc_batch(pool, xsk_buffs, rq->vq->num_free);
> > +       if (!num)
> > +               return -ENOMEM;
> > +
> > +       len = xsk_pool_get_rx_frame_size(pool) + vi->hdr_len;
> > +
> > +       for (i = 0; i < num; ++i) {
> > +               /* use the part of XDP_PACKET_HEADROOM as the virtnet hdr space */
>
> It's better to also say we assume hdr->len is larger than
> XDP_PACKET_HEADROOM. (see function xyz).
>
> > +               addr = xsk_buff_xdp_get_dma(xsk_buffs[i]) - vi->hdr_len;
> > +
> > +               sg_init_table(rq->sg, 1);
> > +               sg_fill_dma(rq->sg, addr, len);
> > +
> > +               err = virtqueue_add_inbuf(rq->vq, rq->sg, 1, xsk_buffs[i], gfp);
> > +               if (err)
> > +                       goto err;
> > +       }
> > +
> > +       return num;
> > +
> > +err:
> > +       if (i)
> > +               err = i;
>
> Any reason to assign an index to err here?

I tried to return the num of bufs added to the ring.

But rethink this, we should return the error of virtqueue_add_inbuf() directly.

Will fix.

Thanks.

>
> Others look good.
>
> Thanks
>