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On Sun, Oct 20, 2013 at 10:11:16AM +0300, Julian Anastasov wrote:
>
> Hello,
>
> On Sun, 20 Oct 2013, Hannes Frederic Sowa wrote:
>
> > > Hm, maybe. I don't have too much insight into netfilter stack and
> > > what are the differences between OUTPUT and FORWARD path but plan to
> > > investigate. ;)
> >
> > It seems tables are processed with bh disabled, so no preemption while
> > recursing. So I guess the use of tee_active is safe for breaking the
> > tie here.
>
> May be, I'll check it again, for now I see only
> rcu_read_lock() in nf_hook_slow() which is preemptable.
> Looking at rcu_preempt_note_context_switch, many levels of
> RCU locks are preemptable too.
The caller I found was ip6t_do_table which does deactivate bottom halves.
Maybe there are others I did not see, so double checking is better.
> In my test I used link route to local subnet, --gateway to IP
> that is not present. I'll try other variants.
Is your kernel compiled with CONFIG_IPV6_ROUTER_PREF?
> > The more I review the patch the more I think it is ok. But we could actually
> > try to just always return rt6i_gateway, as we should always be handed a
> > cloned
> > rt6_info where the gateway is already filled in, no?
>
> Yes, this patch is ok and after spending the whole
> saturday I'm preparing a new patch that will convert
> rt6_nexthop() to return just rt6i_gateway, without daddr.
> This can happen after filling rt6i_gateway in all places.
>
> For your concern for loopback, I don't see problem,
> local/anycast route will have rt6i_gateway=IP, they are
> simple DST_HOST routes. I'm preparing now the patches and
> will post them in following hours.
Ok, that's a nice simplification. I'll have a look tomorrow.
I cannot test my patch today any more, so I just leave it here. It is only
compile tested. Maybe you can make use of it:
Btw: I cannot put a reference to the rt6_info into __rt6_probe_work because we
are not supposed to use rt6_info reference counters outside of ip6_fib
because the deletion from the fib will break otherwise.
Maybe we should also create a seperate ipv6 workqueue. Will check later.
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index c3130ff..6c539bc 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -476,6 +476,40 @@ out:
}
#ifdef CONFIG_IPV6_ROUTER_PREF
+struct __rt6_probe_work {
+ struct work_struct work;
+ struct in6_addr target;
+ struct net_device *dev;
+};
+
+static void rt6_probe_deferred(struct work_struct *w)
+{
+ struct in6_addr mcaddr;
+ struct __rt6_probe_work *work =
+ container_of(w, struct __rt6_probe_work, work);
+
+ addrconf_addr_solict_mult(&work->target, &mcaddr);
+ ndisc_send_ns(work->dev, NULL, &work->target, &mcaddr, NULL);
+ dev_put(work->dev);
+ kfree(w);
+}
+
+static bool rt6_probe_later(struct rt6_info *rt)
+{
+ struct __rt6_probe_work *work;
+
+ work = kmalloc(sizeof(*work), GFP_ATOMIC);
+ if (!work)
+ return false;
+
+ INIT_WORK(&work->work, rt6_probe_deferred);
+ work->target = rt->rt6i_gateway;
+ dev_hold(rt->dst.dev);
+ work->dev = rt->dst.dev;
+ schedule_work(&work->work);
+ return true;
+}
+
static void rt6_probe(struct rt6_info *rt)
{
struct neighbour *neigh;
@@ -499,17 +533,10 @@ static void rt6_probe(struct rt6_info *rt)
if (!neigh ||
time_after(jiffies, neigh->updated +
rt->rt6i_idev->cnf.rtr_probe_interval)) {
- struct in6_addr mcaddr;
- struct in6_addr *target;
-
- if (neigh) {
- neigh->updated = jiffies;
+ if (neigh)
write_unlock(&neigh->lock);
- }
-
- target = (struct in6_addr *)&rt->rt6i_gateway;
- addrconf_addr_solict_mult(target, &mcaddr);
- ndisc_send_ns(rt->dst.dev, NULL, target, &mcaddr, NULL);
+ if (rt6_probe_later(rt) && neigh)
+ neigh->updated = jiffies;
} else {
out:
write_unlock(&neigh->lock);
Greetings,
Hannes
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