neigh: Better handling of transition to NUD_PROBE state

[1] When entering NUD_PROBE state via neigh_update(), perhaps received
    from userspace, correctly (re)initialize the probes count to zero.

    This is useful for forcing revalidation of a neighbor (for example
    if the host is attempting to do DNA [IPv4 4436, IPv6 6059]).

[2] Notify listeners when a neighbor goes into NUD_PROBE state.

    By sending notifications on entry to NUD_PROBE state listeners get
    more timely warnings of imminent connectivity issues.

    The current notifications on entry to NUD_STALE have somewhat
    limited usefulness: NUD_STALE is a perfectly normal state, as is
    NUD_DELAY, whereas notifications on entry to NUD_FAILURE come after
    a neighbor reachability problem has been confirmed (typically after
    three probes).

Change-Id: I5b27b806736bad50723d6c48262da82bef760b71
Signed-off-by: Erik Kline <ek@google.com>
Acked-By: Lorenzo Colitti <lorenzo@google.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Erik Kline 2015-05-18 19:44:41 +09:00 committed by Lorenzo Colitti
parent 86e3b85a50
commit 80c68458dc

View file

@ -935,6 +935,7 @@ static void neigh_timer_handler(unsigned long arg)
neigh->nud_state = NUD_PROBE;
neigh->updated = jiffies;
atomic_set(&neigh->probes, 0);
notify = 1;
next = now + neigh->parms->retrans_time;
}
} else {
@ -1162,6 +1163,8 @@ int neigh_update(struct neighbour *neigh, const u8 *lladdr, u8 new,
if (new != old) {
neigh_del_timer(neigh);
if (new & NUD_PROBE)
atomic_set(&neigh->probes, 0);
if (new & NUD_IN_TIMER)
neigh_add_timer(neigh, (jiffies +
((new & NUD_REACHABLE) ?