Re: [RFC PATCH v1.0] af_packet: don't emit packet on orig fanout group

From: Eric Leblond <redacted>
Date: Thu, 16 Aug 2012 17:44:50 +0200

If a packet is emitted on one socket in one group of fanout sockets,
it is transmitted again. It is thus read again on one of the sockets
of the fanout group. This result in a loop for software which
generate packets when receiving one.
This retransmission is not the intended behavior: a fanout group
must behave like a single socket. The packet should not be
transmitted on a socket if it originates from a socket belonging
to the same fanout group.

This patch fixes the issue by changing the transmission check to
take fanout group info account.

This looks mostly fine, thanks for fixing this.

I wonder if it wouldn't be better to simply have a callback?  That
would eliminate all of the ifdefs:

	if (ptype->id_match) {
		if (ptype->id_match(ptype, skb->sk))
			return true;
	} else if (ptype->af_packet_priv == skb->sk)
		return true;

It's a shame that we have a user of af_packet_priv outside of
AF_PACKET, in TIPC.  If we could get rid of that we could simplify
things even futher.