[PATCH net-next 0/5] ipv6: Stop /128 route from disappearing after pmtu update

[PATCH net-next 0/5] ipv6: Stop /128 route from disappearing after pmtu update

[Martin KaFai Lau]

The series is separated from another patch series,
'ipv6: Only create RTF_CACHE route after encountering pmtu exception',
which can be found here:
http://thread.gmane.org/gmane.linux.network/359140

This series focus on fixing the /128 route issues.  It is currently targeted
for net-next due to the number of code churn but it is also applicable
to net (should be without conflict).  The original reported problem can be
found here:
http://thread.gmane.org/gmane.linux.network/348138

Patch 01 and 02 are to prepare the fib6 search to expect both the
RTF_CACHE clone and its original route exist at the same fib6_node.

Patch 03 fixes the /128 route disappearing bug.

Patch 04 and 05 stop rt6_info from using the inet_peer's metrics to
avoid the /128 routes (like the /128 clone and its original route)
from stepping on each others' metrics.

The second patch is by 'Steffen Klassert <steffen.klassert@secunet.com>'
which I pulled off from netdev.  The third patch is also mostly by
Steffen with one minor optimization.

Many thanks to Hannes Frederic Sowa <hannes@stressinduktion.org> on
reviewing the patches and giving advice.

--Martin

[PATCH net-next 1/5] ipv6: Consider RTF_CACHE when searching the fib6 tree

[Martin KaFai Lau]

It is a prep work for the later bug-fix patch which will stop /128 route
from disappearing after pmtu update.

The later bug-fix patch will allow a /128 route and its RTF_CACHE clone
both exist at the same fib6_node.  To do this, we need to prepare the
existing fib6 tree search to expect RTF_CACHE for /128 route.

Note that the fn->leaf is sorted by rt6i_metric.  Hence,
RTF_CACHE (if there is any) is always at the front.  This property
leads to the following:

1. When doing ip6_route_del(), it should honor the RTF_CACHE flag which
   the caller is used to ask for deleting clone or non-clone.
   The rtm_to_fib6_config() should also check the RTM_F_CLONED and
   then set RTF_CACHE accordingly so that:
   - 'ip -6 r del...' will make ip6_route_del() to delete a route
     and all its clones. Note that its clones is flushed by fib6_del()
   - 'ip -6 r flush table cache' will make ip6_route_del() to
      only delete clone(s).

2. Exclude RTF_CACHE from addrconf_get_prefix_route() which
   should not configure on a cloned route.

3. No change is need for rt6_device_match() since it currently could
   return a RTF_CACHE clone route, so the later bug-fix patch will not
   affect it.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/ipv6/addrconf.c | 2 ++
 net/ipv6/route.c    | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 37b70e8..21c2c81 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2121,6 +2121,8 @@ static struct rt6_info *addrconf_get_prefix_route(const struct in6_addr *pfx,
 	fn = fib6_locate(&table->tb6_root, pfx, plen, NULL, 0);
 	if (!fn)
 		goto out;
+
+	noflags |= RTF_CACHE;
 	for (rt = fn->leaf; rt; rt = rt->dst.rt6_next) {
 		if (rt->dst.dev->ifindex != dev->ifindex)
 			continue;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 5c48293..4774f13 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1785,6 +1785,9 @@ static int ip6_route_del(struct fib6_config *cfg)
 
 	if (fn) {
 		for (rt = fn->leaf; rt; rt = rt->dst.rt6_next) {
+			if ((rt->rt6i_flags & RTF_CACHE) &&
+			    !(cfg->fc_flags & RTF_CACHE))
+				continue;
 			if (cfg->fc_ifindex &&
 			    (!rt->dst.dev ||
 			     rt->dst.dev->ifindex != cfg->fc_ifindex))
@@ -2433,6 +2436,9 @@ static int rtm_to_fib6_config(struct sk_buff *skb, struct nlmsghdr *nlh,
 	if (rtm->rtm_type == RTN_LOCAL)
 		cfg->fc_flags |= RTF_LOCAL;
 
+	if (rtm->rtm_flags & RTM_F_CLONED)
+		cfg->fc_flags |= RTF_CACHE;
+
 	cfg->fc_nlinfo.portid = NETLINK_CB(skb).portid;
 	cfg->fc_nlinfo.nlh = nlh;
 	cfg->fc_nlinfo.nl_net = sock_net(skb->sk);
-- 
1.8.1

[PATCH net-next 2/5] ipv6: Extend the route lookups to low priority metrics.

[Martin KaFai Lau]

From: Steffen Klassert <steffen.klassert@secunet.com>

We search only for routes with highest priority metric in
find_rr_leaf(). However if one of these routes is marked
as invalid, we may fail to find a route even if there is
a appropriate route with lower priority. Then we loose
connectivity until the garbage collector deletes the
invalid route. This typically happens if a host route
expires afer a pmtu event. Fix this by searching also
for routes with a lower priority metric.

Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 net/ipv6/route.c | 28 +++++++++++++++++++++++-----
 1 file changed, 23 insertions(+), 5 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 4774f13..07562a2 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -652,15 +652,33 @@ static struct rt6_info *find_rr_leaf(struct fib6_node *fn,
 				     u32 metric, int oif, int strict,
 				     bool *do_rr)
 {
-	struct rt6_info *rt, *match;
+	struct rt6_info *rt, *match, *cont;
 	int mpri = -1;
 
 	match = NULL;
-	for (rt = rr_head; rt && rt->rt6i_metric == metric;
-	     rt = rt->dst.rt6_next)
+	cont = NULL;
+	for (rt = rr_head; rt; rt = rt->dst.rt6_next) {
+		if (rt->rt6i_metric != metric) {
+			cont = rt;
+			break;
+		}
+
+		match = find_match(rt, oif, strict, &mpri, match, do_rr);
+	}
+
+	for (rt = fn->leaf; rt && rt != rr_head; rt = rt->dst.rt6_next) {
+		if (rt->rt6i_metric != metric) {
+			cont = rt;
+			break;
+		}
+
 		match = find_match(rt, oif, strict, &mpri, match, do_rr);
-	for (rt = fn->leaf; rt && rt != rr_head && rt->rt6i_metric == metric;
-	     rt = rt->dst.rt6_next)
+	}
+
+	if (match || !cont)
+		return match;
+
+	for (rt = cont; rt; rt = rt->dst.rt6_next)
 		match = find_match(rt, oif, strict, &mpri, match, do_rr);
 
 	return match;
-- 
1.8.1

[PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Martin KaFai Lau]

This patch is mostly from Steffen Klassert <steffen.klassert@secunet.com>.
I only removed the (rt6->rt6i_dst.plen == 128) check from
ip6_rt_update_pmtu() because the (rt6->rt6i_flags & RTF_CACHE) test
has already implied it.

This patch:
1. Create RTF_CACHE route for /128 non local route
2. After (1), all routes that allow pmtu update should have a RTF_CACHE
   clone.  Hence, stop updating MTU for any non RTF_CACHE route.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 net/ipv6/route.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 07562a2..aa4cfdd 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -977,7 +977,7 @@ redo_rt6_select:
 
 	if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY)))
 		nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
-	else if (!(rt->dst.flags & DST_HOST))
+	else if (!(rt->dst.flags & DST_HOST) || !(rt->dst.flags & RTF_LOCAL))
 		nrt = rt6_alloc_clone(rt, &fl6->daddr);
 	else
 		goto out2;
@@ -1172,7 +1172,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 	struct rt6_info *rt6 = (struct rt6_info *)dst;
 
 	dst_confirm(dst);
-	if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) {
+	if (mtu < dst_mtu(dst) && (rt6->rt6i_flags & RTF_CACHE)) {
 		struct net *net = dev_net(dst->dev);
 
 		rt6->rt6i_flags |= RTF_MODIFIED;
-- 
1.8.1

[PATCH net-next 4/5] ipv6: Stop rt6_info from using inet_peer's metrics

[Martin KaFai Lau]

inet_peer is indexed by the dst address alone.  However, the fib6 tree
could have multiple routing entries (rt6_info) for the same dst. For
example,
1. A /128 dst via multiple gateways.
2. A RTF_CACHE route cloned from a /128 route.

In the above cases, all of them will share the same metrics and
step on each other.

This patch will steer away from inet_peer's metrics and use
dst_cow_metrics_generic() for everything.

Change Highlights:
1. Remove rt6_cow_metrics() which currently acquires metrics from
   inet_peer for DST_HOST route (i.e. /128 route).
2. Add rt6i_pmtu to take care of the pmtu update to avoid creating a
   full size metrics just to override the RTAX_MTU.
3. After (2), the RTF_CACHE route can also share the metrics with its
   dst.from route, by:
   dst_init_metrics(&cache_rt->dst, dst_metrics_ptr(cache_rt->dst.from), true);
4. Stop creating RTF_CACHE route by cloning another RTF_CACHE route.  Instead,
   directly clone from rt->dst.

   [ Currently, cloning from another RTF_CACHE is only possible during
     rt6_do_redirect().  Also, the old clone is removed from the tree
     immediately after the new clone is added. ]

   In case of cloning from an older redirect RTF_CACHE, it should work as
   before.

   In case of cloning from an older pmtu RTF_CACHE, this patch will forget
   the pmtu and re-learn it (if there is any) from the redirected route.

The _rt6i_peer and DST_METRICS_FORCE_OVERWRITE will be removed
in the next cleanup patch.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
---
 include/net/ip6_fib.h |  10 +----
 net/ipv6/route.c      | 102 +++++++++++++++++++++++++++++---------------------
 2 files changed, 60 insertions(+), 52 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 20e80fa..7383a8c 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -124,6 +124,7 @@ struct rt6_info {
 	unsigned long			_rt6i_peer;
 
 	u32				rt6i_metric;
+	u32				rt6i_pmtu;
 	/* more non-fragment space at head required */
 	unsigned short			rt6i_nfheader_len;
 	u8				rt6i_protocol;
@@ -189,15 +190,6 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout)
 	rt0->rt6i_flags |= RTF_EXPIRES;
 }
 
-static inline void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
-{
-	struct dst_entry *new = (struct dst_entry *) from;
-
-	rt->rt6i_flags &= ~RTF_EXPIRES;
-	dst_hold(new);
-	rt->dst.from = new;
-}
-
 static inline void ip6_rt_put(struct rt6_info *rt)
 {
 	/* dst_release() accepts a NULL parameter.
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index aa4cfdd..4d6eb5d 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -92,6 +92,7 @@ static void		ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 					   struct sk_buff *skb, u32 mtu);
 static void		rt6_do_redirect(struct dst_entry *dst, struct sock *sk,
 					struct sk_buff *skb);
+static void		rt6_dst_from_metrics_check(struct rt6_info *rt);
 static int rt6_score_route(struct rt6_info *rt, int oif, int strict);
 
 #ifdef CONFIG_IPV6_ROUTE_INFO
@@ -136,33 +137,12 @@ static struct inet_peer *rt6_get_peer_create(struct rt6_info *rt)
 
 static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)
 {
-	struct rt6_info *rt = (struct rt6_info *) dst;
-	struct inet_peer *peer;
-	u32 *p = NULL;
+	struct rt6_info *rt = (struct rt6_info *)dst;
 
-	if (!(rt->dst.flags & DST_HOST))
+	if (rt->rt6i_flags & RTF_CACHE)
+		return NULL;
+	else
 		return dst_cow_metrics_generic(dst, old);
-
-	peer = rt6_get_peer_create(rt);
-	if (peer) {
-		u32 *old_p = __DST_METRICS_PTR(old);
-		unsigned long prev, new;
-
-		p = peer->metrics;
-		if (inet_metrics_new(peer) ||
-		    (old & DST_METRICS_FORCE_OVERWRITE))
-			memcpy(p, old_p, sizeof(u32) * RTAX_MAX);
-
-		new = (unsigned long) p;
-		prev = cmpxchg(&dst->_metrics, old, new);
-
-		if (prev != old) {
-			p = __DST_METRICS_PTR(prev);
-			if (prev & DST_METRICS_READ_ONLY)
-				p = NULL;
-		}
-	}
-	return p;
 }
 
 static inline const void *choose_neigh_daddr(struct rt6_info *rt,
@@ -323,8 +303,7 @@ static void ip6_dst_destroy(struct dst_entry *dst)
 	struct inet6_dev *idev = rt->rt6i_idev;
 	struct dst_entry *from = dst->from;
 
-	if (!(rt->dst.flags & DST_HOST))
-		dst_destroy_metrics_generic(dst);
+	dst_destroy_metrics_generic(dst);
 
 	if (idev) {
 		rt->rt6i_idev = NULL;
@@ -333,11 +312,6 @@ static void ip6_dst_destroy(struct dst_entry *dst)
 
 	dst->from = NULL;
 	dst_release(from);
-
-	if (rt6_has_peer(rt)) {
-		struct inet_peer *peer = rt6_peer_ptr(rt);
-		inet_putpeer(peer);
-	}
 }
 
 static void ip6_dst_ifdown(struct dst_entry *dst, struct net_device *dev,
@@ -1003,6 +977,7 @@ redo_rt6_select:
 	goto redo_fib6_lookup_lock;
 
 out2:
+	rt6_dst_from_metrics_check(rt);
 	rt->dst.lastuse = jiffies;
 	rt->dst.__use++;
 
@@ -1111,6 +1086,13 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
  *	Destination cache support functions
  */
 
+static void rt6_dst_from_metrics_check(struct rt6_info *rt)
+{
+	if (rt->dst.from &&
+	    dst_metrics_ptr(&rt->dst) != dst_metrics_ptr(rt->dst.from))
+		dst_init_metrics(&rt->dst, dst_metrics_ptr(rt->dst.from), true);
+}
+
 static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
 {
 	struct rt6_info *rt;
@@ -1127,6 +1109,8 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
 	if (rt6_check_expired(rt))
 		return NULL;
 
+	rt6_dst_from_metrics_check(rt);
+
 	return dst;
 }
 
@@ -1179,7 +1163,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 		if (mtu < IPV6_MIN_MTU)
 			mtu = IPV6_MIN_MTU;
 
-		dst_metric_set(dst, RTAX_MTU, mtu);
+		rt6->rt6i_pmtu = mtu;
 		rt6_update_expires(rt6, net->ipv6.sysctl.ip6_rt_mtu_expires);
 	}
 }
@@ -1359,12 +1343,17 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst)
 
 static unsigned int ip6_mtu(const struct dst_entry *dst)
 {
+	const struct rt6_info *rt = (const struct rt6_info *)dst;
+	unsigned int mtu = rt->rt6i_pmtu;
 	struct inet6_dev *idev;
-	unsigned int mtu = dst_metric_raw(dst, RTAX_MTU);
 
 	if (mtu)
 		goto out;
 
+	mtu = dst_metric_raw(dst, RTAX_MTU);
+	if (mtu)
+		goto out;
+
 	mtu = IPV6_MIN_MTU;
 
 	rcu_read_lock();
@@ -1947,12 +1936,27 @@ out:
  *	Misc support functions
  */
 
+static void rt6_set_from(struct rt6_info *rt, struct rt6_info *from)
+{
+	BUG_ON(from->dst.from);
+
+	rt->rt6i_flags &= ~RTF_EXPIRES;
+	dst_hold(&from->dst);
+	rt->dst.from = &from->dst;
+	dst_init_metrics(&rt->dst, dst_metrics_ptr(&from->dst), true);
+}
+
 static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
 				    const struct in6_addr *dest)
 {
 	struct net *net = dev_net(ort->dst.dev);
-	struct rt6_info *rt = ip6_dst_alloc(net, ort->dst.dev, 0,
-					    ort->rt6i_table);
+	struct rt6_info *rt;
+
+	if (ort->rt6i_flags & RTF_CACHE)
+		ort = (struct rt6_info *)ort->dst.from;
+
+	rt = ip6_dst_alloc(net, ort->dst.dev, 0,
+			   ort->rt6i_table);
 
 	if (rt) {
 		rt->dst.input = ort->dst.input;
@@ -1961,7 +1965,6 @@ static struct rt6_info *ip6_rt_copy(struct rt6_info *ort,
 
 		rt->rt6i_dst.addr = *dest;
 		rt->rt6i_dst.plen = 128;
-		dst_copy_metrics(&rt->dst, &ort->dst);
 		rt->dst.error = ort->dst.error;
 		rt->rt6i_idev = ort->rt6i_idev;
 		if (rt->rt6i_idev)
@@ -2393,11 +2396,20 @@ static int rt6_mtu_change_route(struct rt6_info *rt, void *p_arg)
 	   PMTU discouvery.
 	 */
 	if (rt->dst.dev == arg->dev &&
-	    !dst_metric_locked(&rt->dst, RTAX_MTU) &&
-	    (dst_mtu(&rt->dst) >= arg->mtu ||
-	     (dst_mtu(&rt->dst) < arg->mtu &&
-	      dst_mtu(&rt->dst) == idev->cnf.mtu6))) {
-		dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu);
+	    !dst_metric_locked(&rt->dst, RTAX_MTU)) {
+		if (rt->rt6i_flags & RTF_CACHE) {
+			/* For RTF_CACHE with rt6i_pmtu == 0
+			 * (i.e. a redirected route),
+			 * the metrics of its rt->dst.from has already
+			 * been updated.
+			 */
+			if (rt->rt6i_pmtu && rt->rt6i_pmtu > arg->mtu)
+				rt->rt6i_pmtu = arg->mtu;
+		} else if (dst_mtu(&rt->dst) >= arg->mtu ||
+			   (dst_mtu(&rt->dst) < arg->mtu &&
+			    dst_mtu(&rt->dst) == idev->cnf.mtu6)) {
+			dst_metric_set(&rt->dst, RTAX_MTU, arg->mtu);
+		}
 	}
 	return 0;
 }
@@ -2627,6 +2639,7 @@ static int rt6_fill_node(struct net *net,
 			 int iif, int type, u32 portid, u32 seq,
 			 int prefix, int nowait, unsigned int flags)
 {
+	u32 metrics[RTAX_MAX];
 	struct rtmsg *rtm;
 	struct nlmsghdr *nlh;
 	long expires;
@@ -2740,7 +2753,10 @@ static int rt6_fill_node(struct net *net,
 			goto nla_put_failure;
 	}
 
-	if (rtnetlink_put_metrics(skb, dst_metrics_ptr(&rt->dst)) < 0)
+	memcpy(metrics, dst_metrics_ptr(&rt->dst), sizeof(metrics));
+	if (rt->rt6i_pmtu)
+		metrics[RTAX_MTU - 1] = rt->rt6i_pmtu;
+	if (rtnetlink_put_metrics(skb, metrics) < 0)
 		goto nla_put_failure;
 
 	if (rt->rt6i_flags & RTF_GATEWAY) {
-- 
1.8.1

[PATCH net-next 5/5] ipv6: Remove DST_METRICS_FORCE_OVERWRITE and _rt6i_peer

[Martin KaFai Lau]

_rt6i_peer is no longer needed after the last patch,
'ipv6: Stop rt6_info from using inet_peer's metrics'.

DST_METRICS_FORCE_OVERWRITE is added by
commit e5fd387ad5b3 ("ipv6: do not overwrite inetpeer metrics prematurely").
Since inetpeer is no longer used for metrics, this bit is also not needed.

Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Reviewed-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Michal Kubeček <mkubecek@suse.cz>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
---
 include/net/dst.h       |  6 ------
 include/net/ip6_fib.h   | 31 -------------------------------
 net/ipv6/route.c        | 36 +-----------------------------------
 net/ipv6/xfrm6_policy.c | 14 --------------
 4 files changed, 1 insertion(+), 86 deletions(-)

diff --git a/include/net/dst.h b/include/net/dst.h
index 0fb99a2..22aa93f 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -109,7 +109,6 @@ u32 *dst_cow_metrics_generic(struct dst_entry *dst, unsigned long old);
 extern const u32 dst_default_metrics[];
 
 #define DST_METRICS_READ_ONLY		0x1UL
-#define DST_METRICS_FORCE_OVERWRITE	0x2UL
 #define DST_METRICS_FLAGS		0x3UL
 #define __DST_METRICS_PTR(Y)	\
 	((u32 *)((Y) & ~DST_METRICS_FLAGS))
@@ -120,11 +119,6 @@ static inline bool dst_metrics_read_only(const struct dst_entry *dst)
 	return dst->_metrics & DST_METRICS_READ_ONLY;
 }
 
-static inline void dst_metrics_set_force_overwrite(struct dst_entry *dst)
-{
-	dst->_metrics |= DST_METRICS_FORCE_OVERWRITE;
-}
-
 void __dst_destroy_metrics_generic(struct dst_entry *dst, unsigned long old);
 
 static inline void dst_destroy_metrics_generic(struct dst_entry *dst)
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 7383a8c..e000180 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -121,7 +121,6 @@ struct rt6_info {
 	struct rt6key			rt6i_prefsrc;
 
 	struct inet6_dev		*rt6i_idev;
-	unsigned long			_rt6i_peer;
 
 	u32				rt6i_metric;
 	u32				rt6i_pmtu;
@@ -130,36 +129,6 @@ struct rt6_info {
 	u8				rt6i_protocol;
 };
 
-static inline struct inet_peer *rt6_peer_ptr(struct rt6_info *rt)
-{
-	return inetpeer_ptr(rt->_rt6i_peer);
-}
-
-static inline bool rt6_has_peer(struct rt6_info *rt)
-{
-	return inetpeer_ptr_is_peer(rt->_rt6i_peer);
-}
-
-static inline void __rt6_set_peer(struct rt6_info *rt, struct inet_peer *peer)
-{
-	__inetpeer_ptr_set_peer(&rt->_rt6i_peer, peer);
-}
-
-static inline bool rt6_set_peer(struct rt6_info *rt, struct inet_peer *peer)
-{
-	return inetpeer_ptr_set_peer(&rt->_rt6i_peer, peer);
-}
-
-static inline void rt6_init_peer(struct rt6_info *rt, struct inet_peer_base *base)
-{
-	inetpeer_init_ptr(&rt->_rt6i_peer, base);
-}
-
-static inline void rt6_transfer_peer(struct rt6_info *rt, struct rt6_info *ort)
-{
-	inetpeer_transfer_peer(&rt->_rt6i_peer, &ort->_rt6i_peer);
-}
-
 static inline struct inet6_dev *ip6_dst_idev(struct dst_entry *dst)
 {
 	return ((struct rt6_info *)dst)->rt6i_idev;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 4d6eb5d..3522711 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -105,36 +105,6 @@ static struct rt6_info *rt6_get_route_info(struct net *net,
 					   const struct in6_addr *gwaddr, int ifindex);
 #endif
 
-static void rt6_bind_peer(struct rt6_info *rt, int create)
-{
-	struct inet_peer_base *base;
-	struct inet_peer *peer;
-
-	base = inetpeer_base_ptr(rt->_rt6i_peer);
-	if (!base)
-		return;
-
-	peer = inet_getpeer_v6(base, &rt->rt6i_dst.addr, create);
-	if (peer) {
-		if (!rt6_set_peer(rt, peer))
-			inet_putpeer(peer);
-	}
-}
-
-static struct inet_peer *__rt6_get_peer(struct rt6_info *rt, int create)
-{
-	if (rt6_has_peer(rt))
-		return rt6_peer_ptr(rt);
-
-	rt6_bind_peer(rt, create);
-	return (rt6_has_peer(rt) ? rt6_peer_ptr(rt) : NULL);
-}
-
-static struct inet_peer *rt6_get_peer_create(struct rt6_info *rt)
-{
-	return __rt6_get_peer(rt, 1);
-}
-
 static u32 *ipv6_cow_metrics(struct dst_entry *dst, unsigned long old)
 {
 	struct rt6_info *rt = (struct rt6_info *)dst;
@@ -291,7 +261,6 @@ static inline struct rt6_info *ip6_dst_alloc(struct net *net,
 		struct dst_entry *dst = &rt->dst;
 
 		memset(dst + 1, 0, sizeof(*rt) - sizeof(*dst));
-		rt6_init_peer(rt, table ? &table->tb6_peers : net->ipv6.peers);
 		INIT_LIST_HEAD(&rt->rt6i_siblings);
 	}
 	return rt;
@@ -1052,7 +1021,6 @@ struct dst_entry *ip6_blackhole_route(struct net *net, struct dst_entry *dst_ori
 		new = &rt->dst;
 
 		memset(new + 1, 0, sizeof(*rt) - sizeof(*new));
-		rt6_init_peer(rt, net->ipv6.peers);
 
 		new->__use = 1;
 		new->input = dst_discard;
@@ -1597,10 +1565,8 @@ int ip6_route_add(struct fib6_config *cfg)
 
 	ipv6_addr_prefix(&rt->rt6i_dst.addr, &cfg->fc_dst, cfg->fc_dst_len);
 	rt->rt6i_dst.plen = cfg->fc_dst_len;
-	if (rt->rt6i_dst.plen == 128) {
+	if (rt->rt6i_dst.plen == 128)
 		rt->dst.flags |= DST_HOST;
-		dst_metrics_set_force_overwrite(&rt->dst);
-	}
 
 #ifdef CONFIG_IPV6_SUBTREES
 	ipv6_addr_prefix(&rt->rt6i_src.addr, &cfg->fc_src, cfg->fc_src_len);
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index f337a90..6ae256b 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -71,13 +71,6 @@ static int xfrm6_get_tos(const struct flowi *fl)
 	return 0;
 }
 
-static void xfrm6_init_dst(struct net *net, struct xfrm_dst *xdst)
-{
-	struct rt6_info *rt = (struct rt6_info *)xdst;
-
-	rt6_init_peer(rt, net->ipv6.peers);
-}
-
 static int xfrm6_init_path(struct xfrm_dst *path, struct dst_entry *dst,
 			   int nfheader_len)
 {
@@ -106,8 +99,6 @@ static int xfrm6_fill_dst(struct xfrm_dst *xdst, struct net_device *dev,
 		return -ENODEV;
 	}
 
-	rt6_transfer_peer(&xdst->u.rt6, rt);
-
 	/* Sheit... I remember I did this right. Apparently,
 	 * it was magically lost, so this code needs audit */
 	xdst->u.rt6.rt6i_flags = rt->rt6i_flags & (RTF_ANYCAST |
@@ -255,10 +246,6 @@ static void xfrm6_dst_destroy(struct dst_entry *dst)
 	if (likely(xdst->u.rt6.rt6i_idev))
 		in6_dev_put(xdst->u.rt6.rt6i_idev);
 	dst_destroy_metrics_generic(dst);
-	if (rt6_has_peer(&xdst->u.rt6)) {
-		struct inet_peer *peer = rt6_peer_ptr(&xdst->u.rt6);
-		inet_putpeer(peer);
-	}
 	xfrm_dst_destroy(xdst);
 }
 
@@ -308,7 +295,6 @@ static struct xfrm_policy_afinfo xfrm6_policy_afinfo = {
 	.get_saddr =		xfrm6_get_saddr,
 	.decode_session =	_decode_session6,
 	.get_tos =		xfrm6_get_tos,
-	.init_dst =		xfrm6_init_dst,
 	.init_path =		xfrm6_init_path,
 	.fill_dst =		xfrm6_fill_dst,
 	.blackhole_route =	ip6_blackhole_route,
-- 
1.8.1

Re: [PATCH net-next 0/5] ipv6: Stop /128 route from disappearing after pmtu update

[David Miller]

From: Martin KaFai Lau <kafai@fb.com>
Date: Tue, 28 Apr 2015 13:03:02 -0700

> The series is separated from another patch series,
> 'ipv6: Only create RTF_CACHE route after encountering pmtu exception',
> which can be found here:

Looks good, and the divorce of inetpeer from ipv6 routes is
especially nice to see.

Series applied, thanks Martin!

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Hajime Tazaki]

Hi Martin, Dave,

# I'm not a policeman though..

a regression is detected by my nightly test (below) and
quick bisecting with LibOS (ns-3/DCE) gave me this commit.

http://ns-3-dce.cloud.wide.ad.jp/jenkins/job/daily-net-next-sim/878/

At Tue, 28 Apr 2015 13:03:05 -0700,
Martin KaFai Lau wrote:
> ---
>  net/ipv6/route.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> index 07562a2..aa4cfdd 100644
> --- a/net/ipv6/route.c
> +++ b/net/ipv6/route.c
> @@ -977,7 +977,7 @@ redo_rt6_select:
>  
>  	if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY)))
>  		nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
> -	else if (!(rt->dst.flags & DST_HOST))
> +	else if (!(rt->dst.flags & DST_HOST) || !(rt->dst.flags & RTF_LOCAL))
>  		nrt = rt6_alloc_clone(rt, &fl6->daddr);
>  	else
>  		goto out2;
> @@ -1172,7 +1172,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
>  	struct rt6_info *rt6 = (struct rt6_info *)dst;
>  
>  	dst_confirm(dst);
> -	if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) {
> +	if (mtu < dst_mtu(dst) && (rt6->rt6i_flags & RTF_CACHE)) {
>  		struct net *net = dev_net(dst->dev);
>  
>  		rt6->rt6i_flags |= RTF_MODIFIED;

- how to reproduce it

the test is simply sending an IPv6 packet to a node on the
same subnet to verify the connectivity (e.g., ping6
2001:1::2 from 2001:1::1) and echo packets didn't get back.

reverting this commit fixes the issue.

please take a look at it: I'm glad to know if this only
happens in my local environment.

-- Hajime

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Martin KaFai Lau]

Hi Hajime,

On Sun, May 03, 2015 at 07:41:57AM +0900, Hajime Tazaki wrote:
> a regression is detected by my nightly test (below) and
> quick bisecting with LibOS (ns-3/DCE) gave me this commit.
> 
> https://urldefense.proofpoint.com/v1/url?u=http://ns-3-dce.cloud.wide.ad.jp/jenkins/job/daily-net-next-sim/878/&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=%2Faj1ZOQObwbmtLwlDw3XzQ%3D%3D%0A&m=%2B4tL0PwkB3R%2BcCJxbDDg3rbrKM%2Fq3CKnwlsp5XsSwqg%3D%0A&s=07d84598efaff9b3d5df8d42779e0753f0cc007daaf1aaf9c0ca6bd8999192b9
> 
> At Tue, 28 Apr 2015 13:03:05 -0700,
> Martin KaFai Lau wrote:
> > ---
> >  net/ipv6/route.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/net/ipv6/route.c b/net/ipv6/route.c
> > index 07562a2..aa4cfdd 100644
> > --- a/net/ipv6/route.c
> > +++ b/net/ipv6/route.c
> > @@ -977,7 +977,7 @@ redo_rt6_select:
> >  
> >  	if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY)))
> >  		nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
> > -	else if (!(rt->dst.flags & DST_HOST))
> > +	else if (!(rt->dst.flags & DST_HOST) || !(rt->dst.flags & RTF_LOCAL))
> >  		nrt = rt6_alloc_clone(rt, &fl6->daddr);
> >  	else
> >  		goto out2;
> > @@ -1172,7 +1172,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
> >  	struct rt6_info *rt6 = (struct rt6_info *)dst;
> >  
> >  	dst_confirm(dst);
> > -	if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) {
> > +	if (mtu < dst_mtu(dst) && (rt6->rt6i_flags & RTF_CACHE)) {
> >  		struct net *net = dev_net(dst->dev);
> >  
> >  		rt6->rt6i_flags |= RTF_MODIFIED;
> 
> - how to reproduce it
> 
> the test is simply sending an IPv6 packet to a node on the
> same subnet to verify the connectivity (e.g., ping6
> 2001:1::2 from 2001:1::1) and echo packets didn't get back.
> 
> reverting this commit fixes the issue.
> 
> please take a look at it: I'm glad to know if this only
> happens in my local environment.
Thanks for reporting.

I cannot reproduce in my environment.

15:58:30.658360 6a:aa:e6:a1:ce:f9 > 52:54:00:12:34:56, ethertype IPv6 (0x86dd), length 118: 2001:1::2 > 2001:1::1: ICMP6, echo request, seq 1, length 64
15:58:30.658479 52:54:00:12:34:56 > 6a:aa:e6:a1:ce:f9, ethertype IPv6 (0x86dd), length 118: 2001:1::1 > 2001:1::2: ICMP6, echo reply, seq 1, length 64
15:58:31.658093 6a:aa:e6:a1:ce:f9 > 52:54:00:12:34:56, ethertype IPv6 (0x86dd), length 118: 2001:1::2 > 2001:1::1: ICMP6, echo request, seq 2, length 64
15:58:31.658214 52:54:00:12:34:56 > 6a:aa:e6:a1:ce:f9, ethertype IPv6 (0x86dd), length 118: 2001:1::1 > 2001:1::2: ICMP6, echo reply, seq 2, length 64
15:58:32.657977 6a:aa:e6:a1:ce:f9 > 52:54:00:12:34:56, ethertype IPv6 (0x86dd), length 118: 2001:1::2 > 2001:1::1: ICMP6, echo request, seq 3, length 64
15:58:32.658079 52:54:00:12:34:56 > 6a:aa:e6:a1:ce:f9, ethertype IPv6 (0x86dd), length 118: 2001:1::1 > 2001:1::2: ICMP6, echo reply, seq 3, length 64
15:58:33.658104 6a:aa:e6:a1:ce:f9 > 52:54:00:12:34:56, ethertype IPv6 (0x86dd), length 118: 2001:1::2 > 2001:1::1: ICMP6, echo request, seq 4, length 64
15:58:33.658243 52:54:00:12:34:56 > 6a:aa:e6:a1:ce:f9, ethertype IPv6 (0x86dd), length 118: 2001:1::1 > 2001:1::2: ICMP6, echo reply, seq 4, length 64
15:58:34.658150 6a:aa:e6:a1:ce:f9 > 52:54:00:12:34:56, ethertype IPv6 (0x86dd), length 118: 2001:1::2 > 2001:1::1: ICMP6, echo request, seq 5, length 64
15:58:34.658275 52:54:00:12:34:56 > 6a:aa:e6:a1:ce:f9, ethertype IPv6 (0x86dd), length 118: 2001:1::1 > 2001:1::2: ICMP6, echo reply, seq 5, length 64

I suspect there is a RTF_LOCAL route getting a ICMPv6 too-big packet.

Can you provide a tcpdump at both ends?  Also, the output of
the 'ip -6 a' and 'ip -6 r show'.

Also, can you try the following change which is a partial revert.  If ping goes
through again, can you capture the 'ip -6 show' on both sides quickly after the
test.

Thanks,
--Martin

diff --git i/net/ipv6/route.c w/net/ipv6/route.c
index 3522711..60212d4 100644
--- i/net/ipv6/route.c
+++ w/net/ipv6/route.c
@@ -1124,7 +1124,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
 	struct rt6_info *rt6 = (struct rt6_info *)dst;

 	dst_confirm(dst);
-	if (mtu < dst_mtu(dst) && (rt6->rt6i_flags & RTF_CACHE)) {
+	if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) {
 		struct net *net = dev_net(dst->dev);

 		rt6->rt6i_flags |= RTF_MODIFIED;

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Hajime Tazaki]

Hello Martin,

thank you for your quick reply.

At Sat, 2 May 2015 16:20:40 -0700,
Martin KaFai Lau wrote:

> > - how to reproduce it
> > 
> > the test is simply sending an IPv6 packet to a node on the
> > same subnet to verify the connectivity (e.g., ping6
> > 2001:1::2 from 2001:1::1) and echo packets didn't get back.
> > 
> > reverting this commit fixes the issue.
> > 
> > please take a look at it: I'm glad to know if this only
> > happens in my local environment.
> Thanks for reporting.
> 
> I cannot reproduce in my environment.
(snip)
> 15:58:34.658150 6a:aa:e6:a1:ce:f9 > 52:54:00:12:34:56, ethertype IPv6 (0x86dd), length 118: 2001:1::2 > 2001:1::1: ICMP6, echo request, seq 5, length 64
> 15:58:34.658275 52:54:00:12:34:56 > 6a:aa:e6:a1:ce:f9, ethertype IPv6 (0x86dd), length 118: 2001:1::1 > 2001:1::2: ICMP6, echo reply, seq 5, length 64
> 
> I suspect there is a RTF_LOCAL route getting a ICMPv6 too-big packet.
> 
> Can you provide a tcpdump at both ends?  Also, the output of
> the 'ip -6 a' and 'ip -6 r show'.

- tcpdump -vvv
09:00:00.200000 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:1 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
          source link-address option (1), length 8 (1): 00:00:00:00:00:01
            0x0000:  0000 0000 0001
09:00:00.401092 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:2 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
          source link-address option (1), length 8 (1): 00:00:00:00:00:02
            0x0000:  0000 0000 0002
09:00:01.000000 IP6 (hlim 64, next-header ICMPv6 (58) payload length: 1008) 2001:1::1 > 2001:1::2: [icmp6 sum ok] ICMP6, echo request, seq 1
09:00:02.000000 IP6 (hlim 64, next-header ICMPv6 (58) payload length: 1008) 2001:1::1 > 2001:1::2: [icmp6 sum ok] ICMP6, echo request, seq 2
09:00:03.000000 IP6 (hlim 64, next-header ICMPv6 (58) payload length: 1008) 2001:1::1 > 2001:1::2: [icmp6 sum ok] ICMP6, echo request, seq 3
09:00:04.000000 IP6 (hlim 64, next-header ICMPv6 (58) payload length: 1008) 2001:1::1 > 2001:1::2: [icmp6 sum ok] ICMP6, echo request, seq 4
09:00:04.200000 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:1 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
          source link-address option (1), length 8 (1): 00:00:00:00:00:01
            0x0000:  0000 0000 0001
09:00:04.401092 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:2 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
          source link-address option (1), length 8 (1): 00:00:00:00:00:02            0x0000:  0000 0000 0002
(snip)

- 'ip -6 a' at the ping6 sender
7: sim0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qlen 1000
    inet6 2001:1::1/64 scope global 
       valid_lft forever preferred_lft forever
    inet6 fe80::200:ff:fe00:1/64 scope link 
       valid_lft forever preferred_lft forever

- 'ip -6 r show' at the ping6 sender
2001:1::/64 dev sim0  proto kernel  metric 256 
fe80::/64 dev sim0  proto kernel  metric 256 

# the results of ip command on receiver side are almost
  similar.

I found that the test uses non-ARP interface between nodes:
if I changed the interface to 'non-NOARP' NIC, the issue has
gone away without the revert.

I'm using the following scenario: just FYI.

https://gist.github.com/thehajime/26be8606ddbb924f357c

> Also, can you try the following change which is a partial revert.  If ping goes
> through again, can you capture the 'ip -6 show' on both sides quickly after the
> test.
> 
> Thanks,
> --Martin
> 
> diff --git i/net/ipv6/route.c w/net/ipv6/route.c
> index 3522711..60212d4 100644
> --- i/net/ipv6/route.c
> +++ w/net/ipv6/route.c
> @@ -1124,7 +1124,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
>  	struct rt6_info *rt6 = (struct rt6_info *)dst;
> 
>  	dst_confirm(dst);
> -	if (mtu < dst_mtu(dst) && (rt6->rt6i_flags & RTF_CACHE)) {
> +	if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) {
>  		struct net *net = dev_net(dst->dev);
> 
>  		rt6->rt6i_flags |= RTF_MODIFIED;

this partial revert didn't change my situation.


-- Hajime

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Martin KaFai Lau]

On Sun, May 03, 2015 at 09:19:47AM +0900, Hajime Tazaki wrote:
> At Sat, 2 May 2015 16:20:40 -0700,
> Martin KaFai Lau wrote:
> > Can you provide a tcpdump at both ends?  Also, the output of
> > the 'ip -6 a' and 'ip -6 r show'.
>
> - tcpdump -vvv
> 09:00:00.200000 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:1 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
>           source link-address option (1), length 8 (1): 00:00:00:00:00:01
>             0x0000:  0000 0000 0001
> 09:00:00.401092 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:2 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
>           source link-address option (1), length 8 (1): 00:00:00:00:00:02
>             0x0000:  0000 0000 0002
> 09:00:01.000000 IP6 (hlim 64, next-header ICMPv6 (58) payload length: 1008) 2001:1::1 > 2001:1::2: [icmp6 sum ok] ICMP6, echo request, seq 1
> 09:00:02.000000 IP6 (hlim 64, next-header ICMPv6 (58) payload length: 1008) 2001:1::1 > 2001:1::2: [icmp6 sum ok] ICMP6, echo request, seq 2
> 09:00:03.000000 IP6 (hlim 64, next-header ICMPv6 (58) payload length: 1008) 2001:1::1 > 2001:1::2: [icmp6 sum ok] ICMP6, echo request, seq 3
> 09:00:04.000000 IP6 (hlim 64, next-header ICMPv6 (58) payload length: 1008) 2001:1::1 > 2001:1::2: [icmp6 sum ok] ICMP6, echo request, seq 4
> 09:00:04.200000 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:1 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
>           source link-address option (1), length 8 (1): 00:00:00:00:00:01
>             0x0000:  0000 0000 0001
> 09:00:04.401092 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:2 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
>           source link-address option (1), length 8 (1): 00:00:00:00:00:02            0x0000:  0000 0000 0002
Was it captured at the sender side?
Did the receiver (2001:1::2) get the echo request?

> (snip)
> 
> - 'ip -6 a' at the ping6 sender
> 7: sim0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qlen 1000
>     inet6 2001:1::1/64 scope global 
>        valid_lft forever preferred_lft forever
>     inet6 fe80::200:ff:fe00:1/64 scope link 
>        valid_lft forever preferred_lft forever
> 
> - 'ip -6 r show' at the ping6 sender
> 2001:1::/64 dev sim0  proto kernel  metric 256 
> fe80::/64 dev sim0  proto kernel  metric 256 
> 
hmm...It is weird.  It is a /64 route, so it should have
failed the (rt->dst.flags & DST_HOST) test anyway...

> # the results of ip command on receiver side are almost
>   similar.
> 
> I found that the test uses non-ARP interface between nodes:
> if I changed the interface to 'non-NOARP' NIC, the issue has
> gone away without the revert.
> 
> I'm using the following scenario: just FYI.
> 
> https://gist.github.com/thehajime/26be8606ddbb924f357c
> 
You meant without 'arp off'?  Can you grep those IP from 'ip -6 neigh'?

Can you try this patch just to confirm:

Thanks
--Martin

diff --git i/net/ipv6/route.c w/net/ipv6/route.c
index 3522711..c0ae180 100644
--- i/net/ipv6/route.c
+++ w/net/ipv6/route.c
@@ -920,7 +920,7 @@ redo_rt6_select:

 	if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY)))
 		nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
-	else if (!(rt->dst.flags & DST_HOST) || !(rt->dst.flags & RTF_LOCAL))
+	else if (!(rt->dst.flags & DST_HOST)))
 		nrt = rt6_alloc_clone(rt, &fl6->daddr);
 	else
 		goto out2;

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Martin KaFai Lau]

On Sat, May 02, 2015 at 06:00:55PM -0700, Martin KaFai Lau wrote:
> Can you try this patch just to confirm:
> 
> Thanks
> --Martin
> 
> diff --git i/net/ipv6/route.c w/net/ipv6/route.c
> index 3522711..c0ae180 100644
> --- i/net/ipv6/route.c
> +++ w/net/ipv6/route.c
> @@ -920,7 +920,7 @@ redo_rt6_select:
> 
>  	if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY)))
>  		nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
> -	else if (!(rt->dst.flags & DST_HOST) || !(rt->dst.flags & RTF_LOCAL))
> +	else if (!(rt->dst.flags & DST_HOST)))
>  		nrt = rt6_alloc_clone(rt, &fl6->daddr);
>  	else
>  		goto out2;

Sorry for the noise, try this one instead

diff --git i/net/ipv6/route.c w/net/ipv6/route.c
index 3522711..f81b321 100644
--- i/net/ipv6/route.c
+++ w/net/ipv6/route.c
@@ -920,7 +920,7 @@ redo_rt6_select:

 	if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY)))
 		nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
-	else if (!(rt->dst.flags & DST_HOST) || !(rt->dst.flags & RTF_LOCAL))
+	else if (!(rt->dst.flags & DST_HOST))
 		nrt = rt6_alloc_clone(rt, &fl6->daddr);
 	else
 		goto out2;

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Martin KaFai Lau]

On Sun, May 03, 2015 at 09:19:47AM +0900, Hajime Tazaki wrote:
> - 'ip -6 r show' at the ping6 sender
> 2001:1::/64 dev sim0  proto kernel  metric 256 
> fe80::/64 dev sim0  proto kernel  metric 256 
> 
> # the results of ip command on receiver side are almost
>   similar.
> 
> I found that the test uses non-ARP interface between nodes:
> if I changed the interface to 'non-NOARP' NIC, the issue has
> gone away without the revert.
I have given a little more thoughts.  With the below partial patch
ruled out and together with a /64 route in your test,
I failed to see how another line change could have broken.

Can you share some more details on your test and
can you reproduce it with some basic iproute2 commands?

--Martin


> 
> I'm using the following scenario: just FYI.
> 
> https://gist.github.com/thehajime/26be8606ddbb924f357c
> 
> > Also, can you try the following change which is a partial revert.  If ping goes
> > through again, can you capture the 'ip -6 show' on both sides quickly after the
> > test.
> > 
> > Thanks,
> > --Martin
> > 
> > diff --git i/net/ipv6/route.c w/net/ipv6/route.c
> > index 3522711..60212d4 100644
> > --- i/net/ipv6/route.c
> > +++ w/net/ipv6/route.c
> > @@ -1124,7 +1124,7 @@ static void ip6_rt_update_pmtu(struct dst_entry *dst, struct sock *sk,
> >  	struct rt6_info *rt6 = (struct rt6_info *)dst;
> > 
> >  	dst_confirm(dst);
> > -	if (mtu < dst_mtu(dst) && (rt6->rt6i_flags & RTF_CACHE)) {
> > +	if (mtu < dst_mtu(dst) && rt6->rt6i_dst.plen == 128) {
> >  		struct net *net = dev_net(dst->dev);
> > 
> >  		rt6->rt6i_flags |= RTF_MODIFIED;
> 
> this partial revert didn't change my situation.
> 
> 
> -- Hajime

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Hajime Tazaki]

At Sat, 2 May 2015 18:00:55 -0700,
Martin KaFai Lau wrote:

> > 09:00:04.401092 IP6 (hlim 255, next-header ICMPv6 (58) payload length: 16) fe80::200:ff:fe00:2 > ff02::2: [icmp6 sum ok] ICMP6, router solicitation, length 16
> >           source link-address option (1), length 8 (1): 00:00:00:00:00:02            0x0000:  0000 0000 0002
> Was it captured at the sender side?
> Did the receiver (2001:1::2) get the echo request?

the capture was on the sender side.

the receiver got the echo request: I will detail the next
email but since two nodes connected back to back via
point-to-point data link, the receiver side also has exactly
the same pcap.

> > (snip)
> > - 'ip -6 a' at the ping6 sender
> > 7: sim0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qlen 1000
> >     inet6 2001:1::1/64 scope global 
> >        valid_lft forever preferred_lft forever
> >     inet6 fe80::200:ff:fe00:1/64 scope link 
> >        valid_lft forever preferred_lft forever
> > 
> > - 'ip -6 r show' at the ping6 sender
> > 2001:1::/64 dev sim0  proto kernel  metric 256 
> > fe80::/64 dev sim0  proto kernel  metric 256 
> > 
> hmm...It is weird.  It is a /64 route, so it should have
> failed the (rt->dst.flags & DST_HOST) test anyway...
> 
> > # the results of ip command on receiver side are almost
> >   similar.
> > 
> > I found that the test uses non-ARP interface between nodes:
> > if I changed the interface to 'non-NOARP' NIC, the issue has
> > gone away without the revert.
> > 
> > I'm using the following scenario: just FYI.
> > 
> > https://gist.github.com/thehajime/26be8606ddbb924f357c
> > 
> You meant without 'arp off'? 

Yes, I meant that.

>  Can you grep those IP from 'ip -6 neigh'?

there is no output from 'ip -6 neigh' since the interfaces
is configured with IFF_NOARP.
 
> Can you try this patch just to confirm:

I applied the updated patch and the ping successfully got
replies.

-- Hajime

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Hajime Tazaki]

Hi,

At Sat, 2 May 2015 20:38:01 -0700,
Martin KaFai Lau wrote:
> 
> On Sun, May 03, 2015 at 09:19:47AM +0900, Hajime Tazaki wrote:
> > - 'ip -6 r show' at the ping6 sender
> > 2001:1::/64 dev sim0  proto kernel  metric 256 
> > fe80::/64 dev sim0  proto kernel  metric 256 
> > 
> > # the results of ip command on receiver side are almost
> >   similar.
> > 
> > I found that the test uses non-ARP interface between nodes:
> > if I changed the interface to 'non-NOARP' NIC, the issue has
> > gone away without the revert.
> I have given a little more thoughts.  With the below partial patch
> ruled out and together with a /64 route in your test,
> I failed to see how another line change could have broken.
> 
> Can you share some more details on your test and

the test uses two nodes (running on ns-3 network simulator
with net-next kernel), which is connected via a
point-to-point data link: payload is encapsulated by PPP
(RFC1661).

https://www.nsnam.org/docs/models/html/point-to-point.html

so there is no need of neighbor resolution (ARP, NS/NA) on
that link (dev->flags has IFF_NOARP and IFF_POINTOPOINT bits).

             point-to-point
   node 0  <---------------> node 1
2001:1::1/64               2001:1::2/64

let me know if you need further information.

> can you reproduce it with some basic iproute2 commands?

I'm going to create a real environment to figure out a
minimum-reproducible command set that we can try.

do you have any chance to create an interface with IFF_NOARP
and IFF_POINTOPOINT (some tunnel device ?) on the latest
net-next kernel ?


-- Hajime

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Martin KaFai Lau]

Hi Hajime,

On Sun, May 03, 2015 at 11:29:55PM +0900, Hajime Tazaki wrote:
> the test uses two nodes (running on ns-3 network simulator
> with net-next kernel), which is connected via a
> point-to-point data link: payload is encapsulated by PPP
> (RFC1661).
> 
> so there is no need of neighbor resolution (ARP, NS/NA) on
> that link (dev->flags has IFF_NOARP and IFF_POINTOPOINT bits).
> 
>              point-to-point
>    node 0  <---------------> node 1
> 2001:1::1/64               2001:1::2/64
> 
> let me know if you need further information.
Thanks for the details and confirming the last patch.  I think I may
know what could be wrong.  I am going to confirm it first by trying
to reproduce it.

> I'm going to create a real environment to figure out a
> minimum-reproducible command set that we can try.
That will be great!

> do you have any chance to create an interface with IFF_NOARP
> and IFF_POINTOPOINT (some tunnel device ?) on the latest
> net-next kernel ?
I am going to give it a try.

Thanks,
--Martin

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Martin KaFai Lau]

Hi Hajime,

On Sun, May 03, 2015 at 12:01:09PM -0700, Martin KaFai Lau wrote:
> Thanks for the details and confirming the last patch.  I think I may
> know what could be wrong.  I am going to confirm it first by trying
> to reproduce it.
I tried the sit and also the gre6 tunnel.  I cannot make it break as
the way you have observed.  The ping can still go through.  I am probably
missing something.

However, I did uncover a problem in this patch and posted a fix to
netdev.  I have also attached here.  Can you give it a try?

If there is still no luck, do you have a chance to
reproduce it with a simple setup by iproute2 commands?
Can you specify which POINTTOPOINT device and sim device you are using?
Are they in or out of kernel-tree driver?

Thanks,
--Martin

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 3522711..106dbe5 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -920,7 +920,7 @@ redo_rt6_select:

 	if (!(rt->rt6i_flags & (RTF_NONEXTHOP | RTF_GATEWAY)))
 		nrt = rt6_alloc_cow(rt, &fl6->daddr, &fl6->saddr);
-	else if (!(rt->dst.flags & DST_HOST) || !(rt->dst.flags & RTF_LOCAL))
+	else if (!(rt->dst.flags & DST_HOST) || !(rt->rt6i_flags & RTF_LOCAL))
 		nrt = rt6_alloc_clone(rt, &fl6->daddr);
 	else
 		goto out2;

Re: [PATCH net-next 3/5] ipv6: Stop /128 route from disappearing after pmtu update

[Hajime Tazaki]

Hi Martin,

At Sun, 3 May 2015 17:29:38 -0700,
Martin KaFai Lau wrote:

> On Sun, May 03, 2015 at 12:01:09PM -0700, Martin KaFai Lau wrote:
> > Thanks for the details and confirming the last patch.  I think I may
> > know what could be wrong.  I am going to confirm it first by trying
> > to reproduce it.
> I tried the sit and also the gre6 tunnel.  I cannot make it break as
> the way you have observed.  The ping can still go through.  I am probably
> missing something.
> 
> However, I did uncover a problem in this patch and posted a fix to
> netdev.  I have also attached here.  Can you give it a try?

tried it and it's perfect !
all other tests I have are also working fine.

> If there is still no luck, do you have a chance to
> reproduce it with a simple setup by iproute2 commands?
> Can you specify which POINTTOPOINT device and sim device you are using?
> Are they in or out of kernel-tree driver?

indeed, it's an out-of-tree driver of LibOS patchset (*1)

https://github.com/libos-nuse/net-next-nuse/blob/nuse/arch/lib/lib-device.c

this is not always P2P device: an application (e.g., ns-3)
can define the flags of the device.

I'll follow up to reproduce with sit or gre and let you know
once I got succeed.

thank you.

-- Hajime