Re: [PATCH v2 2/2] i40e: add support for XDP_REDIRECT

2018-03-22 12:58 GMT+01:00 Jesper Dangaard Brouer [off-list ref]:

On Thu, 22 Mar 2018 10:03:07 +0100 Björn Töpel [off-list ref] wrote:

quoted

+/**
+ * i40e_xdp_xmit - Implements ndo_xdp_xmit
+ * @dev: netdev
+ * @xdp: XDP buffer
+ *
+ * Returns Zero if sent, else an error code
+ **/
+int i40e_xdp_xmit(struct net_device *dev, struct xdp_buff *xdp)
+{

The return code is used by the XDP redirect tracepoint... this is the
only way we have to debug/troubleshoot runtime issues with XDP. Thus,
these need to be consistent across drives and distinguishable.

Thanks for pointing this out! I'll address all your comments and do a
respin (but I'll wait for Alex' comments, if any).


Björn

quoted

+     struct i40e_netdev_priv *np = netdev_priv(dev);
+     unsigned int queue_index = smp_processor_id();
+     struct i40e_vsi *vsi = np->vsi;
+     int err;
+
+     if (test_bit(__I40E_VSI_DOWN, vsi->state))
+             return -EINVAL;

Should be: -ENETDOWN

quoted

+
+     if (!i40e_enabled_xdp_vsi(vsi) || queue_index >= vsi->num_queue_pairs)
+             return -EINVAL;

Should be: -ENXIO

quoted

+     err = i40e_xmit_xdp_ring(xdp, vsi->xdp_rings[queue_index]);
+     if (err != I40E_XDP_TX)
+             return -ENOMEM;

Should be: -ENOSPC

The ENOSPC return code is important, as this can be used as a feedback
to a XDP_REDIRECT load-balancer facility.

--
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer