---

yaml
---
r: 170420
b: refs/heads/master
c: 9777500
h: refs/heads/master
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 69ef9694099802f7feeb23182dfb869e7c5f76f0
+refs/heads/master: 977750076d98c7ff6cbda51858bb5a5894a9d9ab

trunk/include/linux/if_packet.h

@@ -48,11 +48,13 @@ struct sockaddr_ll
 #define PACKET_RESERVE			12
 #define PACKET_TX_RING			13
 #define PACKET_LOSS			14
+#define PACKET_GAPDATA			15
 
 struct tpacket_stats
 {
 	unsigned int	tp_packets;
 	unsigned int	tp_drops;
+	unsigned int    tp_gap;
 };
 
 struct tpacket_auxdata

trunk/net/packet/af_packet.c

@@ -523,6 +523,31 @@ static inline unsigned int run_filter(struct sk_buff *skb, struct sock *sk,
 	return res;
 }
 
+/*
+ * If we've lost frames since the last time we queued one to the
+ * sk_receive_queue, we need to record it here.
+ * This must be called under the protection of the socket lock
+ * to prevent racing with other softirqs and user space
+ */
+static inline void record_packet_gap(struct sk_buff *skb,
+					struct packet_sock *po)
+{
+	/*
+	 * We overload the mark field here, since we're about
+	 * to enqueue to a receive queue and no body else will
+	 * use this field at this point
+	 */
+	skb->mark = po->stats.tp_gap;
+	po->stats.tp_gap = 0;
+	return;
+
+}
+
+static inline __u32 check_packet_gap(struct sk_buff *skb)
+{
+	return skb->mark;
+}
+
 /*
    This function makes lazy skb cloning in hope that most of packets
    are discarded by BPF.
@@ -626,6 +651,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 
 	spin_lock(&sk->sk_receive_queue.lock);
 	po->stats.tp_packets++;
+	record_packet_gap(skb, po);
 	__skb_queue_tail(&sk->sk_receive_queue, skb);
 	spin_unlock(&sk->sk_receive_queue.lock);
 	sk->sk_data_ready(sk, skb->len);
@@ -634,6 +660,7 @@ static int packet_rcv(struct sk_buff *skb, struct net_device *dev,
 drop_n_acct:
 	spin_lock(&sk->sk_receive_queue.lock);
 	po->stats.tp_drops++;
+	po->stats.tp_gap++;
 	spin_unlock(&sk->sk_receive_queue.lock);
 
 drop_n_restore:
@@ -811,6 +838,7 @@ static int tpacket_rcv(struct sk_buff *skb, struct net_device *dev,
 
 ring_is_full:
 	po->stats.tp_drops++;
+	po->stats.tp_gap++;
 	spin_unlock(&sk->sk_receive_queue.lock);
 
 	sk->sk_data_ready(sk, 0);
@@ -1418,6 +1446,7 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
 	struct sk_buff *skb;
 	int copied, err;
 	struct sockaddr_ll *sll;
+	__u32 gap;
 
 	err = -EINVAL;
 	if (flags & ~(MSG_PEEK|MSG_DONTWAIT|MSG_TRUNC|MSG_CMSG_COMPAT))
@@ -1496,6 +1525,10 @@ static int packet_recvmsg(struct kiocb *iocb, struct socket *sock,
 		put_cmsg(msg, SOL_PACKET, PACKET_AUXDATA, sizeof(aux), &aux);
 	}
 
+	gap = check_packet_gap(skb);
+	if (gap)
+		put_cmsg(msg, SOL_PACKET, PACKET_GAPDATA, sizeof(__u32), &gap);
+
 	/*
 	 *	Free or return the buffer as appropriate. Again this
 	 *	hides all the races and re-entrancy issues from us.