net: l2tp_eth: provide tx_dropped counter

Change l2tp_xmit_skb() to return NET_XMIT_DROP in case skb is dropped.

Use kfree_skb() instead dev_kfree_skb() for drop_monitor pleasure.

Support tx_dropped counter for l2tp_eth

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: James Chapman <jchapman@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 16 insertions, 10 deletions

diff --git a/net/l2tp/l2tp_core.c b/net/l2tp/l2tp_core.c
index 32b2155e7ab4..393355d37b47 100644
--- a/net/l2tp/l2tp_core.c
+++ b/net/l2tp/l2tp_core.c
@@ -1128,6 +1128,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
         int headroom;
         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
         int udp_len;
+        int ret = NET_XMIT_SUCCESS;
 
         /* Check that there's enough headroom in the skb to insert IP,
          * UDP and L2TP headers. If not enough, expand it to
@@ -1137,8 +1138,8 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
                 uhlen + hdr_len;
         old_headroom = skb_headroom(skb);
         if (skb_cow_head(skb, headroom)) {
-                dev_kfree_skb(skb);
-                goto abort;
+                kfree_skb(skb);
+                return NET_XMIT_DROP;
         }
 
         new_headroom = skb_headroom(skb);
@@ -1156,7 +1157,8 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
 
         bh_lock_sock(sk);
         if (sock_owned_by_user(sk)) {
-                dev_kfree_skb(skb);
+                kfree_skb(skb);
+                ret = NET_XMIT_DROP;
                 goto out_unlock;
         }
 
@@ -1215,8 +1217,7 @@ int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len
 out_unlock:
         bh_unlock_sock(sk);
 
-abort:
-        return 0;
+        return ret;
 }
 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
 
diff --git a/net/l2tp/l2tp_eth.c b/net/l2tp/l2tp_eth.c
index 47b259fccd27..f9ee74deeac2 100644
--- a/net/l2tp/l2tp_eth.c
+++ b/net/l2tp/l2tp_eth.c
@@ -44,6 +44,7 @@ struct l2tp_eth {
         struct list_head        list;
         atomic_long_t           tx_bytes;
         atomic_long_t           tx_packets;
+        atomic_long_t           tx_dropped;
         atomic_long_t           rx_bytes;
         atomic_long_t           rx_packets;
         atomic_long_t           rx_errors;
@@ -92,12 +93,15 @@ static int l2tp_eth_dev_xmit(struct sk_buff *skb, struct net_device *dev)
 {
         struct l2tp_eth *priv = netdev_priv(dev);
         struct l2tp_session *session = priv->session;
+        unsigned int len = skb->len;
+        int ret = l2tp_xmit_skb(session, skb, session->hdr_len);
 
-        atomic_long_add(skb->len, &priv->tx_bytes);
-        atomic_long_inc(&priv->tx_packets);
-
-        l2tp_xmit_skb(session, skb, session->hdr_len);
-
+        if (likely(ret == NET_XMIT_SUCCESS)) {
+                atomic_long_add(len, &priv->tx_bytes);
+                atomic_long_inc(&priv->tx_packets);
+        } else {
+                atomic_long_inc(&priv->tx_dropped);
+        }
         return NETDEV_TX_OK;
 }
 
@@ -108,6 +112,7 @@ static struct rtnl_link_stats64 *l2tp_eth_get_stats64(struct net_device *dev,
 
         stats->tx_bytes   = atomic_long_read(&priv->tx_bytes);
         stats->tx_packets = atomic_long_read(&priv->tx_packets);
+        stats->tx_dropped = atomic_long_read(&priv->tx_dropped);
         stats->rx_bytes   = atomic_long_read(&priv->rx_bytes);
         stats->rx_packets = atomic_long_read(&priv->rx_packets);
         stats->rx_errors  = atomic_long_read(&priv->rx_errors);