Revert "af_packet: add interframe drop cmsg (v6)"

This reverts commit 977750076d98c7ff6cbda51858bb5a5894a9d9ab.

Neil is reimplementing this generically, outside of AF_PACKET.

Signed-off-by: David S. Miller <[e-mail]>

include/linux/if_packet.h

···
 #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

net/packet/af_packet.c

···
 }
 
 /*
- * 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.
 
···
 
 	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);
···
 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:
···
 
 ring_is_full:
 	po->stats.tp_drops++;
-	po->stats.tp_gap++;
 	spin_unlock(&sk->sk_receive_queue.lock);
 
 	sk->sk_data_ready(sk, 0);
···
 	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))
···
 
 		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