From: Kuniyuki Iwashima <kuniyu@google.com>
Date: Fri, 20 Mar 2026 07:22:59 +0000 (+0000)
Subject: ipv6: Remove permanent routes from tb6_gc_hlist when all exceptions expire.
X-Git-Tag: v7.0-rc6~40^2~22^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6af51e9f31336632263c4680b2a3712295103e1f;p=thirdparty%2Fkernel%2Flinux.git

ipv6: Remove permanent routes from tb6_gc_hlist when all exceptions expire.

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>
---

diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 9058e71241dc..fadfca49d6b1 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;
 }