[PATCH 6.12 086/244] ipv6: Dont remove permanent routes with exceptions from tb6_gc_hlist.

Greg Kroah-Hartman
2026-03-31T16:49:45Z

From: Kuniyuki Iwashima <kuniyu@google.com>

[ Upstream commit 4be7b99c253f0c85a255cc1db7127ba3232dfa30 ]

The cited commit mechanically put fib6_remove_gc_list()
just after every fib6_clean_expires() call.

When a temporary route is promoted to a permanent route,
there may already be exception routes tied to it.

If fib6_remove_gc_list() removes the route from tb6_gc_hlist,
such exception routes will no longer be aged.

Let's replace fib6_remove_gc_list() with a new helper
fib6_may_remove_gc_list() and use fib6_age_exceptions() there.

Note that net->ipv6 is only compiled when CONFIG_IPV6 is
enabled, so fib6_{add,remove,may_remove}_gc_list() are guarded.

Fixes: 5eb902b8e719 ("net/ipv6: Remove expired routes with a separated list of routes.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20260320072317.2561779-3-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/net/ip6_fib.h | 21 ++++++++++++++++++++-
net/ipv6/addrconf.c | 4 ++--
net/ipv6/ip6_fib.c | 6 +++---
net/ipv6/route.c | 2 +-
4 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 6cb867ce48784..74b78c80af71d 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -506,12 +506,14 @@ void fib6_rt_update(struct net *net, struct fib6_info *rt,
void inet6_rt_notify(int event, struct fib6_info *rt, struct nl_info *info,
unsigned int flags);

+void fib6_age_exceptions(struct fib6_info *rt, struct fib6_gc_args *gc_args,
+ unsigned long now);
void fib6_run_gc(unsigned long expires, struct net *net, bool force);
-
void fib6_gc_cleanup(void);

int fib6_init(void);

+#if IS_ENABLED(CONFIG_IPV6)
/* Add the route to the gc list if it is not already there
*
* The callers should hold f6i->fib6_table->tb6_lock.
@@ -544,6 +546,23 @@ static inline void fib6_remove_gc_list(struct fib6_info *f6i)
hlist_del_init(&f6i->gc_link);
}

+static inline void fib6_may_remove_gc_list(struct net *net,
+ struct fib6_info *f6i)
+{
+ struct fib6_gc_args gc_args;
+
+ if (hlist_unhashed(&f6i->gc_link))
+ return;
+
+ gc_args.timeout = READ_ONCE(net->ipv6.sysctl.ip6_rt_gc_interval);
+ gc_args.more = 0;
+
+ rcu_read_lock();
+ fib6_age_exceptions(f6i, &gc_args, jiffies);
+ rcu_read_unlock();
+}
+#endif
+
struct ipv6_route_iter {
struct seq_net_private p;
struct fib6_walker w;
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index e57a2b1841616..63ada312061c6 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -2860,7 +2860,7 @@ void addrconf_prefix_rcv(struct net_device *dev, u8 *opt, int len, bool sllao)
fib6_add_gc_list(rt);
} else {
fib6_clean_expires(rt);
- fib6_remove_gc_list(rt);
+ fib6_may_remove_gc_list(net, rt);
}

spin_unlock_bh(&table->tb6_lock);
@@ -4850,7 +4850,7 @@ static int modify_prefix_route(struct net *net, struct inet6_ifaddr *ifp,

if (!(flags & RTF_EXPIRES)) {
fib6_clean_expires(f6i);
- fib6_remove_gc_list(f6i);
+ fib6_may_remove_gc_list(net, f6i);
} else {
fib6_set_expires(f6i, expires);
fib6_add_gc_list(f6i);
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index fca68fb1b74c2..2072c788c912a 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -1133,7 +1133,7 @@ static int fib6_add_rt2node(struct fib6_node *fn, struct fib6_info *rt,
return -EEXIST;
if (!(rt->fib6_flags & RTF_EXPIRES)) {
fib6_clean_expires(iter);
- fib6_remove_gc_list(iter);
+ fib6_may_remove_gc_list(info->nl_net, iter);
} else {
fib6_set_expires(iter, rt->expires);
fib6_add_gc_list(iter);
@@ -2314,8 +2314,8 @@ static void fib6_flush_trees(struct net *net)
/*
* Garbage collection
*/
-static void fib6_age_exceptions(struct fib6_info *rt, struct fib6_gc_args *gc_args,
- unsigned long now)
+void fib6_age_exceptions(struct fib6_info *rt, struct fib6_gc_args *gc_args,
+ unsigned long now)
{
bool may_expire = rt->fib6_flags & RTF_EXPIRES && rt->expires;
int old_more = gc_args->more;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 36324d1905f81..31c9e3b73f2da 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1034,7 +1034,7 @@ int rt6_route_rcv(struct net_device *dev, u8 *opt, int len,

if (!addrconf_finite_timeout(lifetime)) {
fib6_clean_expires(rt);
- fib6_remove_gc_list(rt);
+ fib6_may_remove_gc_list(net, rt);
} else {
fib6_set_expires(rt, jiffies + HZ * lifetime);
fib6_add_gc_list(rt);
--
2.51.0