Commit 70978182 authored Dec 20, 2010 by Eric Dumazet Committed by David S. Miller Dec 21, 2010

net: timestamp cloned packet in dev_queue_xmit_nit



Le vendredi 17 décembre 2010 à 10:26 +0100, Eric Dumazet a écrit :

>
> I think we can add this after latest Changli patch :
>
> He does one skb_clone() before calling the sniffers.
> We could set timestamp on this clone, instead of original skb.
>
> Problem solved.
>

[PATCH net-next-2.6] net: timestamp cloned packet in dev_queue_xmit_nit

Now we do one clone of skb if at least one sniffer might take packet,
we also can do the skb timestamping on the clone and let original packet
unchanged.

This is a generalization of commit 8caf1539 (net: sch_netem: Fix an
inconsistency in ingress netem timestamps.)

This way, we can have a good idea when packets are delivered to our
stack (tcpdump -i ifb0), while a tcpdump on original device gives
timestamps right before ingressing.

This also speedup our stack, avoiding taking timestamps if not needed.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Changli Gao <xiaosuo@gmail.com>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Jarek Poplawski <jarkao2@gmail.com>
Acked-by: Changli Gao <xiaosuo@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 356f0398

net/core/dev.c

+2 −7

Original line number	Diff line number	Diff line
		@@ -1547,13 +1547,6 @@ static void dev_queue_xmit_nit(struct sk_buff skb, struct net_device dev)
		struct sk_buff *skb2 = NULL;
		struct packet_type *pt_prev = NULL;

		#ifdef CONFIG_NET_CLS_ACT
		if (!(skb->tstamp.tv64 && (G_TC_FROM(skb->tc_verd) & AT_INGRESS)))
		net_timestamp_set(skb);
		#else
		net_timestamp_set(skb);
		#endif

		rcu_read_lock();
		list_for_each_entry_rcu(ptype, &ptype_all, list) {
		/* Never send packets back to the socket
		@@ -1572,6 +1565,8 @@ static void dev_queue_xmit_nit(struct sk_buff skb, struct net_device dev)
		if (!skb2)
		break;

		net_timestamp_set(skb2);

		/* skb->nh should be correctly
		set by sender, so that the second statement is
		just protection against buggy protocols.

Admin message