[PATCH] ipv6: preserve insertion order for same-scope addresses

[PATCH] ipv6: preserve insertion order for same-scope addresses

[Yumei Huang]

IPv6 addresses with the same scope were returned in reverse insertion
order, unlike IPv4. For example, when adding a -> b -> c, the list was
reported as c -> b -> a, while IPv4 preserved the original order.

This patch aligns IPv6 address ordering with IPv4 for consistency.

Signed-off-by: Yumei Huang <yuhuang@redhat.com>
---
 net/ipv6/addrconf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 40e9c336f6c5..ca998bf46863 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1013,7 +1013,7 @@ ipv6_link_dev_addr(struct inet6_dev *idev, struct inet6_ifaddr *ifp)
 	list_for_each(p, &idev->addr_list) {
 		struct inet6_ifaddr *ifa
 			= list_entry(p, struct inet6_ifaddr, if_list);
-		if (ifp_scope >= ipv6_addr_src_scope(&ifa->addr))
+		if (ifp_scope > ipv6_addr_src_scope(&ifa->addr))
 			break;
 	}
 
-- 
2.51.1

Re: [PATCH] ipv6: preserve insertion order for same-scope addresses

[Jakub Kicinski]

On Wed, 26 Nov 2025 16:37:14 +0800 Yumei Huang wrote:
> IPv6 addresses with the same scope were returned in reverse insertion
> order, unlike IPv4. For example, when adding a -> b -> c, the list was
> reported as c -> b -> a, while IPv4 preserved the original order.
> 
> This patch aligns IPv6 address ordering with IPv4 for consistency.

This breaks the ioam6.sh test:
https://netdev-3.bots.linux.dev/vmksft-net-dbg/results/402461/16-ioam6-sh/stdout
https://netdev-3.bots.linux.dev/vmksft-net/results/402461/14-ioam6-sh/stdout
-- 
pw-bot: cr

Re: [PATCH] ipv6: preserve insertion order for same-scope addresses

[Yumei Huang]

On Wed, Nov 26, 2025 at 10:58 PM Jakub Kicinski <kuba@kernel.org> wrote:
>
> On Wed, 26 Nov 2025 16:37:14 +0800 Yumei Huang wrote:
> > IPv6 addresses with the same scope were returned in reverse insertion
> > order, unlike IPv4. For example, when adding a -> b -> c, the list was
> > reported as c -> b -> a, while IPv4 preserved the original order.
> >
> > This patch aligns IPv6 address ordering with IPv4 for consistency.
>
> This breaks the ioam6.sh test:
> https://netdev-3.bots.linux.dev/vmksft-net-dbg/results/402461/16-ioam6-sh/stdout
> https://netdev-3.bots.linux.dev/vmksft-net/results/402461/14-ioam6-sh/stdout

Thanks for catching this. The error can be fixed by just swaping the
two lines of adding addresses for veth0 in ioam_node_alpha netns. I
will fix it in v2. Thanks!
> --
> pw-bot: cr
>


-- 
Thanks,

Yumei Huang