From: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6•org>
To: Jens Rosenboom <me@jayr•de>
Cc: Linux Network Developers <netdev@vger•kernel.org>,
YOSHIFUJI Hideaki <yoshfuji@linux-ipv6•org>
Subject: Re: [RFC] net/core: Delay neighbor only if it has been used after confirmed
Date: Wed, 02 Sep 2009 21:22:51 +0900 [thread overview]
Message-ID: <4A9E639B.20907@linux-ipv6.org> (raw)
In-Reply-To: <1251883079.5813.18.camel@fnki-nb00130>
Hello.
Jens Rosenboom wrote:
> When doing some IPv6 testing with the router advertising a small (e.g. 5
> seconds) reachable time, I noticed that after the traffic has stopped,
> hosts continue to exchange ND packets every 10 seconds. This is due to
> neigh_timer_handler() only checking neigh->used and puts a neighbor into
> NUD_DELAY state even if neigh->confirmed may be >= neigh->used.
Well, as you can see in neigh_periodic_timer():
| if (time_before(n->used, n->confirmed))
| n->used = n->confirmed;
time_after_eq(n->used, n->confirmed) should be taken valid;
confirmed <= used <= now <= jiffies
> The following patch for net-next-2.6 fixes this behaviour for my IPv6
> setup, however I would like to hear some opinion on whether this might
> have some negative influence on other protocols that use this code.
>
> I also think that it would make more sense to compute the time for the
> delay timer starting from neigh->used instead of using now (second part
> of the patch).
okay, but I would rather have this in another patch.
> diff --git a/net/core/neighbour.c b/net/core/neighbour.c
> index 5bc4ad5..ca20162 100644
> --- a/net/core/neighbour.c
> +++ b/net/core/neighbour.c
> @@ -820,12 +820,13 @@ static void neigh_timer_handler(unsigned long arg)
> NEIGH_PRINTK2("neigh %p is still alive.\n", neigh);
> next = neigh->confirmed + neigh->parms->reachable_time;
> } else if (time_before_eq(now,
> - neigh->used + neigh->parms->delay_probe_time)) {
> + neigh->used + neigh->parms->delay_probe_time) &&
> + time_after(neigh->confirmed, neigh->used)) {
> NEIGH_PRINTK2("neigh %p is delayed.\n", neigh);
> neigh->nud_state = NUD_DELAY;
I think your change should be
| time_after(neigh->used, neigh->confirmed)
or
| time_before(neigh->confirmed, neigh->used)
("_eq" is removed because there is a little chance
that the neighbor had been confirmed just before it was
used. It is not interesting for us at this moment.)
No?
And, this "if" for REACHABLE->DELAY may be completely needless.
Timer in REACHABLE is only for state transition for toward REACHABLE
or STALE.
--yoshfuji
next prev parent reply other threads:[~2009-09-02 12:31 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-02 9:17 [RFC] net/core: Delay neighbor only if it has been used after confirmed Jens Rosenboom
2009-09-02 12:22 ` YOSHIFUJI Hideaki [this message]
2009-09-02 13:03 ` Jens Rosenboom
2009-09-10 16:21 ` Jens Rosenboom
2009-09-15 10:07 ` Jens Rosenboom
2009-09-15 10:13 ` David Miller
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