| Message ID | 1268912902-27050-1-git-send-email-timo.teras@iki.fi |
|---|---|
| State | Changes Requested, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, Mar 18, 2010 at 01:48:22PM +0200, Timo Teras wrote: > Xfrm_dst keeps a reference to ipv4 rtable entries on each > cached bundle. The only we to renew xfrm_dst when the underlying > route has changed, is to implement dst_check for this. This is > what ipv6 side does too. > > The problems started after 87c1e12b5eeb7b30b4b41291bef8e0b41fc3dde9 > which fixed a bug causing xfrm_dst to not get reused, until that all > lookups always generated new xfrm_dst with new route reference > and path mtu worked. But after the fix, the old routes started > to get reused even after they were expired causing pmtu to break > (well it would occationally work if the rtable gc has ran recently > and marked the route obsolete causing dst_check to get called). > > Signed-off-by: Timo Teras <timo.teras@iki.fi> I completely agree with your assessment and patch. The null dst_check only worked when we purged IPv4 route cache entries synchronously. So this should've be done when asynchronous deletion through genid was introduced. > @@ -1726,7 +1726,9 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu) > > static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie) > { > - return NULL; > + if (dst && dst->dev && rt_is_expired((struct rtable *) dst)) > + return NULL; > + return dst; > } Can dst->dev ever be NULL? I'm pretty sure that we disallow that from ever happening through the use of the loopback device. A quick grep also fails to find any other dst->dev NULL checks in this file. Otherwise Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Cheers,
From: Herbert Xu <herbert@gondor.apana.org.au> Date: Thu, 18 Mar 2010 20:11:46 +0800 > On Thu, Mar 18, 2010 at 01:48:22PM +0200, Timo Teras wrote: >> @@ -1726,7 +1726,9 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu) >> >> static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie) >> { >> - return NULL; >> + if (dst && dst->dev && rt_is_expired((struct rtable *) dst)) >> + return NULL; >> + return dst; >> } > > Can dst->dev ever be NULL? I'm pretty sure that we disallow that > from ever happening through the use of the loopback device. A > quick grep also fails to find any other dst->dev NULL checks in > this file. Timo please respin with the NULL check removed, it just creates confusion if one spot has the NULL check and not only is it not needed, but also no other spots make this check. Please remember to add in Herbert's ACK when reposting. Thanks. -- 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 Thu, Mar 18, 2010 at 10:16:49PM -0700, David Miller wrote: > From: Herbert Xu <herbert@gondor.apana.org.au> > Date: Thu, 18 Mar 2010 20:11:46 +0800 > > > On Thu, Mar 18, 2010 at 01:48:22PM +0200, Timo Teras wrote: > >> @@ -1726,7 +1726,9 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu) > >> > >> static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie) > >> { > >> - return NULL; > >> + if (dst && dst->dev && rt_is_expired((struct rtable *) dst)) ^ While you're at it, please delete this space to preemptively stop anyone from sending a checkpatch patch :) Thanks,
diff --git a/net/ipv4/route.c b/net/ipv4/route.c index a770df2..59449a3 100644 --- a/net/ipv4/route.c +++ b/net/ipv4/route.c @@ -1441,7 +1441,7 @@ void ip_rt_redirect(__be32 old_gw, __be32 daddr, __be32 new_gw, dev_hold(rt->u.dst.dev); if (rt->idev) in_dev_hold(rt->idev); - rt->u.dst.obsolete = 0; + rt->u.dst.obsolete = -1; rt->u.dst.lastuse = jiffies; rt->u.dst.path = &rt->u.dst; rt->u.dst.neighbour = NULL; @@ -1506,7 +1506,7 @@ static struct dst_entry *ipv4_negative_advice(struct dst_entry *dst) struct dst_entry *ret = dst; if (rt) { - if (dst->obsolete) { + if (dst->obsolete > 0) { ip_rt_put(rt); ret = NULL; } else if ((rt->rt_flags & RTCF_REDIRECTED) || @@ -1726,7 +1726,9 @@ static void ip_rt_update_pmtu(struct dst_entry *dst, u32 mtu) static struct dst_entry *ipv4_dst_check(struct dst_entry *dst, u32 cookie) { - return NULL; + if (dst && dst->dev && rt_is_expired((struct rtable *) dst)) + return NULL; + return dst; } static void ipv4_dst_destroy(struct dst_entry *dst) @@ -1888,7 +1890,8 @@ static int ip_route_input_mc(struct sk_buff *skb, __be32 daddr, __be32 saddr, if (!rth) goto e_nobufs; - rth->u.dst.output= ip_rt_bug; + rth->u.dst.output = ip_rt_bug; + rth->u.dst.obsolete = -1; atomic_set(&rth->u.dst.__refcnt, 1); rth->u.dst.flags= DST_HOST; @@ -2054,6 +2057,7 @@ static int __mkroute_input(struct sk_buff *skb, rth->fl.oif = 0; rth->rt_spec_dst= spec_dst; + rth->u.dst.obsolete = -1; rth->u.dst.input = ip_forward; rth->u.dst.output = ip_output; rth->rt_genid = rt_genid(dev_net(rth->u.dst.dev)); @@ -2218,6 +2222,7 @@ local_input: goto e_nobufs; rth->u.dst.output= ip_rt_bug; + rth->u.dst.obsolete = -1; rth->rt_genid = rt_genid(net); atomic_set(&rth->u.dst.__refcnt, 1); @@ -2444,6 +2449,7 @@ static int __mkroute_output(struct rtable **result, rth->rt_spec_dst= fl->fl4_src; rth->u.dst.output=ip_output; + rth->u.dst.obsolete = -1; rth->rt_genid = rt_genid(dev_net(dev_out)); RT_CACHE_STAT_INC(out_slow_tot);
Xfrm_dst keeps a reference to ipv4 rtable entries on each cached bundle. The only we to renew xfrm_dst when the underlying route has changed, is to implement dst_check for this. This is what ipv6 side does too. The problems started after 87c1e12b5eeb7b30b4b41291bef8e0b41fc3dde9 which fixed a bug causing xfrm_dst to not get reused, until that all lookups always generated new xfrm_dst with new route reference and path mtu worked. But after the fix, the old routes started to get reused even after they were expired causing pmtu to break (well it would occationally work if the rtable gc has ran recently and marked the route obsolete causing dst_check to get called). Signed-off-by: Timo Teras <timo.teras@iki.fi> Cc: Herbert Xu <herbert@gondor.apana.org.au> --- net/ipv4/route.c | 14 ++++++++++---- 1 files changed, 10 insertions(+), 4 deletions(-)