[PATCH 6.19 118/342] ipv6: Remove permanent routes from tb6_gc_hlist when all exceptions expire.

Greg Kroah-Hartman
2026-03-31T16:36:24Z

From: Kuniyuki Iwashima <kuniyu@google.com>

[ Upstream commit 6af51e9f31336632263c4680b2a3712295103e1f ]

Commit 5eb902b8e719 ("net/ipv6: Remove expired routes with a
separated list of routes.") introduced a per-table GC list and
changed GC to iterate over that list instead of traversing
the entire route table.

However, it forgot to add permanent routes to tb6_gc_hlist
when exception routes are added.

Commit cfe82469a00f ("ipv6: add exception routes to GC list
in rt6_insert_exception") fixed that issue but introduced
another one.

Even after all exception routes expire, the permanent routes
remain in tb6_gc_hlist, potentially negating the performance
benefits intended by the initial change.

Let's count gc_args->more before and after rt6_age_exceptions()
and remove the permanent route when the delta is 0.

Note that the next patch will reuse fib6_age_exceptions().

Fixes: cfe82469a00f ("ipv6: add exception routes to GC list in rt6_insert_exception")
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20260320072317.2561779-2-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv6/ip6_fib.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index cc149227b49f4..a22af1c8f93ac 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -2348,6 +2348,17 @@ 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)
+{
+ bool may_expire = rt->fib6_flags & RTF_EXPIRES && rt->expires;
+ int old_more = gc_args->more;
+
+ rt6_age_exceptions(rt, gc_args, now);
+
+ if (!may_expire && old_more == gc_args->more)
+ fib6_remove_gc_list(rt);
+}

static int fib6_age(struct fib6_info *rt, struct fib6_gc_args *gc_args)
{
@@ -2370,7 +2381,7 @@ static int fib6_age(struct fib6_info *rt, struct fib6_gc_args *gc_args)
* Note, that clones are aged out
* only if they are not in use now.
*/
- rt6_age_exceptions(rt, gc_args, now);
+ fib6_age_exceptions(rt, gc_args, now);

return 0;
}
--
2.51.0