linux/net/8021q
Eric Dumazet 0287587884 net: better IFF_XMIT_DST_RELEASE support
Testing xmit_more support with netperf and connected UDP sockets,
I found strange dst refcount false sharing.

Current handling of IFF_XMIT_DST_RELEASE is not optimal.

Dropping dst in validate_xmit_skb() is certainly too late in case
packet was queued by cpu X but dequeued by cpu Y

The logical point to take care of drop/force is in __dev_queue_xmit()
before even taking qdisc lock.

As Julian Anastasov pointed out, need for skb_dst() might come from some
packet schedulers or classifiers.

This patch adds new helper to cleanly express needs of various drivers
or qdiscs/classifiers.

Drivers that need skb_dst() in their ndo_start_xmit() should call
following helper in their setup instead of the prior :

	dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
->
	netif_keep_dst(dev);

Instead of using a single bit, we use two bits, one being
eventually rebuilt in bonding/team drivers.

The other one, is permanent and blocks IFF_XMIT_DST_RELEASE being
rebuilt in bonding/team. Eventually, we could add something
smarter later.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
2014-10-07 13:22:11 -04:00
..
Kconfig 8021q: update description 2014-01-21 17:01:25 -08:00
Makefile net/8021q: Implement Multiple VLAN Registration Protocol (MVRP) 2013-02-10 20:37:22 -05:00
vlan.c vlan: fail early when creating netdev named config 2014-07-29 11:43:50 -07:00
vlan.h 8021q: Convert uses of __constant_<foo> to <foo> 2014-03-12 15:28:06 -04:00
vlan_core.c net: Always untag vlan-tagged traffic on input. 2014-08-11 12:16:51 -07:00
vlan_dev.c net: better IFF_XMIT_DST_RELEASE support 2014-10-07 13:22:11 -04:00
vlan_gvrp.c net: vlan: prepare for 802.1ad support 2013-04-19 14:45:27 -04:00
vlan_mvrp.c net: vlan: prepare for 802.1ad support 2013-04-19 14:45:27 -04:00
vlan_netlink.c 8021q: Convert uses of __constant_<foo> to <foo> 2014-03-12 15:28:06 -04:00
vlanproc.c vlan: fail early when creating netdev named config 2014-07-29 11:43:50 -07:00
vlanproc.h [VLAN]: Add a net argument to proc init and cleanup calls. 2008-04-16 00:51:12 -07:00