[PATCH net-next v4 03/10] ipv6: record the reason for kernel-initiated route deletions

[Yuyang Huang <sigefriedhyy@gmail.com>]

Record why the kernel deletes an IPv6 route on its own:

- RTA_DEL_REASON_EXPIRED for routes reaped by the FIB6 garbage
  collector after their RTF_EXPIRES lifetime ran out.
- RTA_DEL_REASON_RA_WITHDRAWN for default routes, prefix routes and
  RFC 4191 route information routes withdrawn by a zero-lifetime
  Router Advertisement.

Deleting a default route because its metric changed is not a
withdrawal, so it keeps RTA_DEL_REASON_UNSPEC.

Signed-off-by: Yuyang Huang <sigefriedhyy@gmail.com>
---
 net/ipv6/addrconf.c | 3 ++-
 net/ipv6/ip6_fib.c  | 2 +-
 net/ipv6/ndisc.c    | 4 +++-
 net/ipv6/route.c    | 2 +-
 4 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index f1fe9ede1edb..1ca9d82b5721 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2874,7 +2874,8 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
 		if (rt) {
 			/* Autoconf prefix route */
 			if (valid_lft == 0) {
-				ip6_del_rt(net, rt, false);
+				ip6_del_rt_reason(net, rt, false,
+						  RTA_DEL_REASON_RA_WITHDRAWN);
 				rt = NULL;
 			} else {
 				table = rt->fib6_table;
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index b6e3bdd20cd0..d77c61f53155 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -2402,7 +2402,7 @@ static void fib6_gc_table(struct net *net,
 
 	hlist_for_each_entry_safe(rt, n, &tb6->tb6_gc_hlist, gc_link)
 		if (fib6_age(rt, gc_args) == -1)
-			fib6_del(rt, &info, RTA_DEL_REASON_UNSPEC);
+			fib6_del(rt, &info, RTA_DEL_REASON_EXPIRED);
 }
 
 static void fib6_gc_all(struct net *net, struct fib6_gc_args *gc_args)
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index f867ec8d3d90..713db9089d5e 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -1361,7 +1361,9 @@ static enum skb_drop_reason ndisc_router_discovery(struct sk_buff *skb)
 	defrtr_usr_metric = in6_dev->cnf.ra_defrtr_metric;
 	/* delete the route if lifetime is 0 or if metric needs change */
 	if (rt && (lifetime == 0 || rt->fib6_metric != defrtr_usr_metric)) {
-		ip6_del_rt(net, rt, false);
+		ip6_del_rt_reason(net, rt, false,
+				  lifetime == 0 ? RTA_DEL_REASON_RA_WITHDRAWN :
+						  RTA_DEL_REASON_UNSPEC);
 		rt = NULL;
 	}
 
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 7574c385105f..d2b9f9a899cf 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1020,7 +1020,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,
 					gwaddr, dev);
 
 	if (rt && !lifetime) {
-		ip6_del_rt(net, rt, false);
+		ip6_del_rt_reason(net, rt, false, RTA_DEL_REASON_RA_WITHDRAWN);
 		rt = NULL;
 	}
 
-- 
2.43.0