Commit 8164f1b7 authored by Ben Greear's avatar Ben Greear Committed by David S. Miller
Browse files

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: default avatarBen Greear <>
Signed-off-by: default avatarDavid S. Miller <>
parent 6ea7ae1d
...@@ -818,18 +818,18 @@ static int arp_process(struct sk_buff *skb) ...@@ -818,18 +818,18 @@ static int arp_process(struct sk_buff *skb)
addr_type = rt->rt_type; addr_type = rt->rt_type;
if (addr_type == RTN_LOCAL) { if (addr_type == RTN_LOCAL) {
n = neigh_event_ns(&arp_tbl, sha, &sip, dev); int dont_send = 0;
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)
neigh_release(n); 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) {
n = neigh_event_ns(&arp_tbl, sha, &sip, dev);
if (n) {
} }
goto out; goto out;
} else if (IN_DEV_FORWARD(in_dev)) { } else if (IN_DEV_FORWARD(in_dev)) {
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