[PATCH net-next 1/3] i40: optimize for XDP_REDIRECT in xsk path

[Magnus Karlsson]

From: Magnus Karlsson <magnus.karls...@intel.com>

Optimize i40e_run_xdp_zc() for the XDP program verdict being
XDP_REDIRECT in the zsk zero-copy path. This path is only used when
having AF_XDP zero-copy on and in that case most packets will be
directed to user space. This provides a little over 100k extra packets
in throughput on my server when running l2fwd in xdpsock.

Signed-off-by: Magnus Karlsson <magnus.karls...@intel.com>
---
 drivers/net/ethernet/intel/i40e/i40e_xsk.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/net/ethernet/intel/i40e/i40e_xsk.c 
b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
index 67febc7b6798..fbf76c67d77d 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_xsk.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_xsk.c
@@ -159,6 +159,13 @@ static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, 
struct xdp_buff *xdp)
        xdp_prog = READ_ONCE(rx_ring->xdp_prog);
        act = bpf_prog_run_xdp(xdp_prog, xdp);
 
+       if (likely(act == XDP_REDIRECT)) {
+               err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
+               result = !err ? I40E_XDP_REDIR : I40E_XDP_CONSUMED;
+               rcu_read_unlock();
+               return result;
+       }
+
        switch (act) {
        case XDP_PASS:
                break;
@@ -166,10 +173,6 @@ static int i40e_run_xdp_zc(struct i40e_ring *rx_ring, 
struct xdp_buff *xdp)
                xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->queue_index];
                result = i40e_xmit_xdp_tx_ring(xdp, xdp_ring);
                break;
-       case XDP_REDIRECT:
-               err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
-               result = !err ? I40E_XDP_REDIR : I40E_XDP_CONSUMED;
-               break;
        default:
                bpf_warn_invalid_xdp_action(act);
                fallthrough;
-- 
2.29.0