On Tue, 10 Nov 2020 12:23:05 -0500 Jeff Dike wrote:
> Commit 58956317c8de ("neighbor: Improve garbage collection")
> guarantees neighbour table entries a five-second lifetime. Processes
> which make heavy use of multicast can fill the neighour table with
> multicast addresses in five seconds. At that point, neighbour entries
> can't be GC-ed because they aren't five seconds old yet, the kernel
> log starts to fill up with "neighbor table overflow!" messages, and
> sends start to fail.
>
> This patch allows multicast addresses to be thrown out before they've
> lived out their five seconds. This makes room for non-multicast
> addresses and makes messages to all addresses more reliable in these
> circumstances.
We should add
Fixes: 58956317c8de ("neighbor: Improve garbage collection")
right?
> Signed-off-by: Jeff Dike <jd...@akamai.com>
> diff --git a/net/ipv4/arp.c b/net/ipv4/arp.c
> index 687971d83b4e..097aa8bf07ee 100644
> --- a/net/ipv4/arp.c
> +++ b/net/ipv4/arp.c
> @@ -125,6 +125,7 @@ static int arp_constructor(struct neighbour *neigh);
> static void arp_solicit(struct neighbour *neigh, struct sk_buff *skb);
> static void arp_error_report(struct neighbour *neigh, struct sk_buff *skb);
> static void parp_redo(struct sk_buff *skb);
> +static int arp_is_multicast(const void *pkey);
>
> static const struct neigh_ops arp_generic_ops = {
> .family = AF_INET,
> @@ -156,6 +157,7 @@ struct neigh_table arp_tbl = {
> .key_eq = arp_key_eq,
> .constructor = arp_constructor,
> .proxy_redo = parp_redo,
> + .is_multicast = arp_is_multicast,
extreme nit pick - please align the = sign using tabs like the
surrounding code does.
> .id = "arp_cache",
> .parms = {
> .tbl = &arp_tbl,
> @@ -928,6 +930,10 @@ static void parp_redo(struct sk_buff *skb)
> arp_process(dev_net(skb->dev), NULL, skb);
> }
>
> +static int arp_is_multicast(const void *pkey)
> +{
> + return ipv4_is_multicast(*((__be32 *)pkey));
> +}
>
> /*
> * Receive an arp request from the device layer.
> diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
> index 27f29b957ee7..67457cfadcd2 100644
> --- a/net/ipv6/ndisc.c
> +++ b/net/ipv6/ndisc.c
> @@ -81,6 +81,7 @@ static void ndisc_error_report(struct neighbour *neigh,
> struct sk_buff *skb);
> static int pndisc_constructor(struct pneigh_entry *n);
> static void pndisc_destructor(struct pneigh_entry *n);
> static void pndisc_redo(struct sk_buff *skb);
> +static int ndisc_is_multicast(const void *pkey);
>
> static const struct neigh_ops ndisc_generic_ops = {
> .family = AF_INET6,
> @@ -115,6 +116,7 @@ struct neigh_table nd_tbl = {
> .pconstructor = pndisc_constructor,
> .pdestructor = pndisc_destructor,
> .proxy_redo = pndisc_redo,
> + .is_multicast = ndisc_is_multicast,
looks like the character after = is expected to be a tab, for better or
worse
> .allow_add = ndisc_allow_add,
> .id = "ndisc_cache",
> .parms = {
> @@ -1706,6 +1708,11 @@ static void pndisc_redo(struct sk_buff *skb)
> kfree_skb(skb);
> }
>
> +static int ndisc_is_multicast(const void *pkey)
> +{
> + return ipv6_addr_is_multicast((struct in6_addr *)pkey);
> +}
> +
> static bool ndisc_suppress_frag_ndisc(struct sk_buff *skb)
> {
> struct inet6_dev *idev = __in6_dev_get(skb->dev);
