If the ipv6 dst cache which copy from the dst generated by ICMPV6 RA packet.
this dst cache will not check expire because it has no RTF_EXPIRES flag.
So this dst cache will always be used until the dst gc run.

Change the struct dst_entry,add a union contains new pointer from and expires.
When rt6_info.rt6i_flags has no RTF_EXPIRES flag,the dst.expires has no use.
we can use this field to point to where the dst cache copy from.
The dst.from is only used in IPV6.

In func rt6_check_expired check if rt6_info.dst.from is expired.

In func ip6_rt_copy only set dst.from when the ort has flag RTF_ADDRCONF
and RTF_DEFAULT.then hold the ort.

In func ip6_dst_destroy release the ort.

Add some functions to operate the RTF_EXPIRES flag and expires(from)
and change the code to use these new adding functions.

Signed-off-by: Gao feng <redacted>
---
 include/net/dst.h     |   11 ++++++++++-
 include/net/ip6_fib.h |   41 +++++++++++++++++++++++++++++++++++++++++
 net/ipv6/addrconf.c   |    9 +++------
 net/ipv6/ip6_fib.c    |    3 +--
 net/ipv6/route.c      |   49 +++++++++++++++++++++++++++++++------------------
 5 files changed, 86 insertions(+), 27 deletions(-)

diff --git a/include/net/dst.h b/include/net/dst.h
index 344c8dd..5147839 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h

@@ -35,7 +35,16 @@ struct dst_entry {
 	struct net_device       *dev;
 	struct  dst_ops	        *ops;
 	unsigned long		_metrics;
-	unsigned long		expires;
+
+	union {
+		unsigned long		expires;
+		/*
+		 * from is used only for dst cache witch copy form

+		 */
+		void			*from;
+	};
 	struct dst_entry	*path;
 	struct neighbour __rcu	*_neighbour;
 #ifdef CONFIG_XFRM

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index b26bb81..86cf1ac 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h

@@ -123,6 +123,47 @@ static inline struct inet6_dev *ip6_dst_idev(struct dst_entry *dst)
 	return ((struct rt6_info *)dst)->rt6i_idev;
 }
 
+static inline void rt6_clean_expires(struct rt6_info *rt)
+{
+	if (!(rt->rt6i_flags & RTF_EXPIRES) && rt->dst.from)
+		dst_release(&rt->dst);
+
+	rt->rt6i_flags &= ~RTF_EXPIRES;
+	rt->dst.expires = 0;
+}
+
+static inline void rt6_set_expires(struct rt6_info *rt, unsigned long expires)
+{
+	if (!(rt->rt6i_flags & RTF_EXPIRES) && rt->dst.from)
+		dst_release(&rt->dst);
+
+	rt->rt6i_flags |= RTF_EXPIRES;
+	rt->dst.expires = expires;
+}
+
+static inline void rt6_update_expires(struct rt6_info *rt, int timeout)
+{
+	if (!(rt->rt6i_flags & RTF_EXPIRES) && rt->dst.from)
+		dst_release(&rt->dst);
+
+	dst_set_expires(&rt->dst, timeout);
+	rt->rt6i_flags |= RTF_EXPIRES;
+}