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-rw-r--r--include/linux/if_packet.h2
-rw-r--r--net/packet/af_packet.c33
2 files changed, 35 insertions, 0 deletions
diff --git a/include/linux/if_packet.h b/include/linux/if_packet.h
index dea7d6b7cf9..e5d200f53fc 100644
--- a/include/linux/if_packet.h
+++ b/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
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index d7ecca0a0c0..d398a9bf690 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -524,6 +524,31 @@ static inline unsigned int run_filter(struct sk_buff *skb, struct sock *sk,
}
/*
+ * 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 @@ drop:
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.