| Message ID | 1251883079.5813.18.camel@fnki-nb00130 |
|---|---|
| State | RFC, archived |
| Delegated to: | David Miller |
| Headers | show |
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 -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 2009-09-02 at 21:22 +0900, YOSHIFUJI Hideaki wrote: > 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 Isn't there a chance that neigh_timer_handler() is run before the periodic timer fixes this? Otherwise I agree that the test could just say (n->used != n->confirmed). > > 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? Yes, you are right, this test should be reversed. But together with your remarks above, this probably means that the whole stuff also works fine if we completely remove this if-branch. > And, this "if" for REACHABLE->DELAY may be completely needless. > Timer in REACHABLE is only for state transition for toward REACHABLE > or STALE. Well, this part has been there for a long time, at least it looks pretty much the same in the first git version, so I would be a bit reluctant to completely remove it, but since that would probably also solve my problem, I also wouldn't object that proposition. ;-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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; neigh->updated = jiffies; neigh_suspect(neigh); - next = now + neigh->parms->delay_probe_time; + next = neigh->used + neigh->parms->delay_probe_time; } else { NEIGH_PRINTK2("neigh %p is suspected.\n", neigh); neigh->nud_state = NUD_STALE;