tun: fix missing dropped counter in tun_xdp_act

The commit 8ae1aff0 ("tuntap: split out XDP logic") includes
dropped counter for XDP_DROP, XDP_ABORTED, and invalid XDP actions.
Unfortunately, that commit missed the dropped counter when error
occurs during XDP_TX and XDP_REDIRECT actions. This patch fixes
this issue.

Fixes: 8ae1aff0 ("tuntap: split out XDP logic")
Signed-off-by: Yunjian Wang <wangyunjian@huawei.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/tun.c

@@ -1630,13 +1630,17 @@ static int tun_xdp_act(struct tun_struct *tun, struct bpf_prog *xdp_prog,
 	switch (act) {
 	case XDP_REDIRECT:
 		err = xdp_do_redirect(tun->dev, xdp, xdp_prog);
-		if (err)
+		if (err) {
+			dev_core_stats_rx_dropped_inc(tun->dev);
 			return err;
+		}
 		break;
 	case XDP_TX:
 		err = tun_xdp_tx(tun->dev, xdp);
-		if (err < 0)
+		if (err < 0) {
+			dev_core_stats_rx_dropped_inc(tun->dev);
 			return err;
+		}
 		break;
 	case XDP_PASS:
 		break;