i40e: optimize for XDP_REDIRECT in xsk path

stable inclusion
from stable-5.10.43
commit fbae1a97ce342470dcf2c3f51e63faf2e8e557f0
bugzilla: 109284
CVE: NA

--------------------------------

[ Upstream commit 346497c7 ]

Optimize i40e_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: NMagnus Karlsson <magnus.karlsson@intel.com>
Tested-by: NGeorge Kuruvinakunnel <george.kuruvinakunnel@intel.com>
Signed-off-by: NTony Nguyen <anthony.l.nguyen@intel.com>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NChen Jun <chenjun102@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

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;