Re: [net PATCH v3 3/5] virtio_net: factor out xdp handler for readability

On 17-01-12 11:40 PM, Jason Wang wrote:

On 2017年01月13日 10:51, John Fastabend wrote:

quoted

At this point the do_xdp_prog is mostly if/else branches handling
the different modes of virtio_net. So remove it and handle running
the program in the per mode handlers.

Signed-off-by: John Fastabend <redacted>
---
  drivers/net/virtio_net.c |   76 +++++++++++++++++-----------------------------
  1 file changed, 28 insertions(+), 48 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 43cb2e0..ec54644 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -388,49 +388,6 @@ static void virtnet_xdp_xmit(struct virtnet_info *vi,
      virtqueue_kick(sq->vq);
  }
  

[...]

quoted

            /* This happens when rx buffer size is underestimated */

@@ -598,8 +570,10 @@ static struct sk_buff *receive_mergeable(struct

net_device *dev,
          if (unlikely(hdr->hdr.gso_type))
              goto err_xdp;
  -        act = do_xdp_prog(vi, rq, xdp_prog,
-                  page_address(xdp_page) + offset, len);
+        data = page_address(xdp_page) + offset;
+        xdp.data = data + desc_room;
+        xdp.data_end = xdp.data + (len - vi->hdr_len);

It looks desc_room is always vi->hdr_len.

Seems to be the case I'll just use vi->hdr_len and remove the variable.

Thanks.

quoted

+        act = bpf_prog_run_xdp(xdp_prog, &xdp);
          switch (act) {
          case XDP_PASS:
              /* We can only create skb based on xdp_page. */

@@ -613,13 +587,19 @@ static struct sk_buff *receive_mergeable(struct

net_device *dev,
              }
              break;
          case XDP_TX:
+            qp = vi->curr_queue_pairs -
+                vi->xdp_queue_pairs +
+                smp_processor_id();
+            virtnet_xdp_xmit(vi, rq, &vi->sq[qp], &xdp, data);
              ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);
              if (unlikely(xdp_page != page))
                  goto err_xdp;
              rcu_read_unlock();
              goto xdp_xmit;
-        case XDP_DROP:
          default:
+            bpf_warn_invalid_xdp_action(act);
+        case XDP_ABORTED:
+        case XDP_DROP:
              if (unlikely(xdp_page != page))
                  __free_pages(xdp_page, 0);
              ewma_pkt_len_add(&rq->mrg_avg_pkt_len, len);