ice: optimize for XDP_REDIRECT in xsk path

Optimize ice_run_xdp_zc() for the XDP program verdict being
XDP_REDIRECT in the xsk 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.karlsson@intel.com>
Tested-by: George Kuruvinakunnel <george.kuruvinakunnel@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>

drivers/net/ethernet/intel/ice/ice_xsk.c

@@ -473,6 +473,14 @@ ice_run_xdp_zc(struct ice_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 ? ICE_XDP_REDIR : ICE_XDP_CONSUMED;
+		rcu_read_unlock();
+		return result;
+	}
+
 	switch (act) {
 	case XDP_PASS:
 		break;
@@ -480,10 +488,6 @@ ice_run_xdp_zc(struct ice_ring *rx_ring, struct xdp_buff *xdp)
 		xdp_ring = rx_ring->vsi->xdp_rings[rx_ring->q_index];
 		result = ice_xmit_xdp_buff(xdp, xdp_ring);
 		break;
-	case XDP_REDIRECT:
-		err = xdp_do_redirect(rx_ring->netdev, xdp, xdp_prog);
-		result = !err ? ICE_XDP_REDIR : ICE_XDP_CONSUMED;
-		break;
 	default:
 		bpf_warn_invalid_xdp_action(act);
 		fallthrough;