vlan: adds drops accounting

Its hard to tell if vlans are dropping frames, since
every frame given to vlan_???_start_xmit() functions
is accounted as fully transmitted by lower device.

We can test dev_queue_xmit() return values to
properly account for dropped frames.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index 3938c3e50fb121404058b8df0456dc3bed057fd8..4198ec5c8abcae3fd1ca36e8e617c3c13e67ad1b 100644 (file)
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -294,6 +294,8 @@ static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb,
        int i = skb_get_queue_mapping(skb);
        struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
        struct vlan_ethhdr *veth = (struct vlan_ethhdr *)(skb->data);
+       unsigned int len;
+       int ret;
 
        /* Handle non-VLAN frames if they are sent to us, for example by DHCP.
         *
@@ -319,11 +321,17 @@ static netdev_tx_t vlan_dev_hard_start_xmit(struct sk_buff *skb,
                        vlan_dev_info(dev)->cnt_inc_headroom_on_tx++;
        }
 
-       txq->tx_packets++;
-       txq->tx_bytes += skb->len;
 
        skb->dev = vlan_dev_info(dev)->real_dev;
-       dev_queue_xmit(skb);
+       len = skb->len;
+       ret = dev_queue_xmit(skb);
+
+       if (likely(ret == NET_XMIT_SUCCESS)) {
+               txq->tx_packets++;
+               txq->tx_bytes += len;
+       } else
+               txq->tx_dropped++;
+
        return NETDEV_TX_OK;
 }
 
@@ -333,16 +341,23 @@ static netdev_tx_t vlan_dev_hwaccel_hard_start_xmit(struct sk_buff *skb,
        int i = skb_get_queue_mapping(skb);
        struct netdev_queue *txq = netdev_get_tx_queue(dev, i);
        u16 vlan_tci;
+       unsigned int len;
+       int ret;
 
        vlan_tci = vlan_dev_info(dev)->vlan_id;
        vlan_tci |= vlan_dev_get_egress_qos_mask(dev, skb);
        skb = __vlan_hwaccel_put_tag(skb, vlan_tci);
 
-       txq->tx_packets++;
-       txq->tx_bytes += skb->len;
-
        skb->dev = vlan_dev_info(dev)->real_dev;
-       dev_queue_xmit(skb);
+       len = skb->len;
+       ret = dev_queue_xmit(skb);
+
+       if (likely(ret == NET_XMIT_SUCCESS)) {
+               txq->tx_packets++;
+               txq->tx_bytes += len;
+       } else
+               txq->tx_dropped++;
+
        return NETDEV_TX_OK;
 }