tuntap: XDP_TX can use native XDP

Now we have ndo_xdp_xmit, switch to use it instead of the slow generic
XDP TX routine. XDP_TX on TAP gets ~20% improvements from ~1.5Mpps to
~1.8Mpps on 2.60GHz Core(TM) i7-5600U.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index 475088f947bb700105f271e75c936c04c9ff76bb..baeafa00446375d21315692a6f347df6834c0eb0 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -1613,7 +1613,6 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
        unsigned int delta = 0;
        char *buf;
        size_t copied;
-       bool xdp_xmit = false;
        int err, pad = TUN_RX_PAD;
 
        rcu_read_lock();
@@ -1671,8 +1670,14 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
                        preempt_enable();
                        return NULL;
                case XDP_TX:
-                       xdp_xmit = true;
-                       /* fall through */
+                       get_page(alloc_frag->page);
+                       alloc_frag->offset += buflen;
+                       if (tun_xdp_xmit(tun->dev, &xdp))
+                               goto err_redirect;
+                       tun_xdp_flush(tun->dev);
+                       rcu_read_unlock();
+                       preempt_enable();
+                       return NULL;
                case XDP_PASS:
                        delta = orig_data - xdp.data;
                        break;
@@ -1699,14 +1704,6 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun,
        get_page(alloc_frag->page);
        alloc_frag->offset += buflen;
 
-       if (xdp_xmit) {
-               skb->dev = tun->dev;
-               generic_xdp_tx(skb, xdp_prog);
-               rcu_read_unlock();
-               preempt_enable();
-               return NULL;
-       }
-
        rcu_read_unlock();
        preempt_enable();