Commit 8164f1b7 authored Nov 16, 2008 by Ben Greear Committed by David S. Miller Nov 16, 2008

ipv4: Fix ARP behavior with many mac-vlans

Ben Greear wrote:
> I have 500 mac-vlans on a system talking to 500 other
> mac-vlans.  My problem is that the arp-table gets extremely
> huge because every time an arp-request comes in on all mac-vlans,
> a stale arp entry is added for each mac-vlan.  I have filtering
> turned on, but that doesn't help because the neigh_event_ns call
> below will cause a stale neighbor entry to be created regardless
> of whether a replay will be sent or not.
> Maybe the neigh_event code should be below the checks for dont_send,
> and only create check neigh_event_ns if we are !dont_send?

The attached patch makes it work much better for me.  The patch
will cause the code to NOT create a stale neighbor entry if we
are not going to respond to the ARP request.  The old code
*would* create a stale entry even if we are not going to respond.

Signed-off-by: Ben Greear <greearb@candelatech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 6ea7ae1d

net/ipv4/arp.c

+11 −11

Original line number	Diff line number	Diff line
		@@ -818,19 +818,19 @@ static int arp_process(struct sk_buff *skb)
		addr_type = rt->rt_type;

		if (addr_type == RTN_LOCAL) {
		n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
		if (n) {
		int dont_send = 0;

		if (!dont_send)
		dont_send \|= arp_ignore(in_dev,sip,tip);
		if (!dont_send && IN_DEV_ARPFILTER(in_dev))
		dont_send \|= arp_filter(sip,tip,dev);
		if (!dont_send)
		if (!dont_send) {
		n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
		if (n) {
		arp_send(ARPOP_REPLY,ETH_P_ARP,sip,dev,tip,sha,dev->dev_addr,sha);

		neigh_release(n);
		}
		}
		goto out;
		} else if (IN_DEV_FORWARD(in_dev)) {
		if (addr_type == RTN_UNICAST && rt->u.dst.dev != dev &&

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