-----Original Message-----
From: Xin Long <lucien.xin@gmail.com>
Sent: Wednesday, July 16, 2025 11:14 AM
To: Simon Horman <horms@kernel.org>
Cc: Li Tian <redacted>; netdev@vger.kernel.org; linux-
hyperv@vger.kernel.org; linux-kernel@vger.kernel.org; Haiyang Zhang
[off-list ref]; Dexuan Cui [off-list ref]; Stephen
Hemminger [off-list ref]; Long Li [off-list ref]
Subject: [EXTERNAL] Re: [PATCH v3] hv_netvsc: Set VF priv_flags to
IFF_NO_ADDRCONF before open to prevent IPv6 addrconf

On Wed, Jul 16, 2025 at 5:29 AM Simon Horman [off-list ref] wrote:

quoted

+ Xin Long

Thanks for Ccing me.

quoted

On Wed, Jul 16, 2025 at 08:26:05AM +0800, Li Tian wrote:

quoted

Set an additional flag IFF_NO_ADDRCONF to prevent ipv6 addrconf.

Commit under Fixes added a new flag change that was not made
to hv_netvsc resulting in the VF being assinged an IPv6.

Fixes: 8a321cf7becc ("net: add IFF_NO_ADDRCONF and use it in bonding

to prevent ipv6 addrconf")

quoted

quoted

Suggested-by: Cathy Avery <redacted>
Signed-off-by: Li Tian <redacted>
---
v3:
  - only fixes commit message.
v2:

https://lore.ker/
nel.org%2Fnetdev%2F20250710024603.10162-1-
litian%40redhat.com%2F&data=05%7C02%7Chaiyangz%40microsoft.com%7C80485948c
b344b12f2dd08ddc47b7c6e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63888
2756868249313%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAu
MDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdat
a=1ljWIFtnhAiGjdIEgNNlQZGK%2F%2FZHdgHVkvyCWY9%2BKxI%3D&reserved=0

quoted

quoted

  - instead of replacing flag, add it.
v1:

https://lore.ker/
nel.org%2Fnetdev%2F20250710024603.10162-1-
litian%40redhat.com%2F&data=05%7C02%7Chaiyangz%40microsoft.com%7C80485948c
b344b12f2dd08ddc47b7c6e%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C63888
2756868272381%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAu
MDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdat
a=o%2B2BM9YEi3O2zcqQu9KfPae6PZerBWO%2FhL5KCIeJ9xI%3D&reserved=0

quoted

quoted

---
 drivers/net/hyperv/netvsc_drv.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

Hi Li Tian,

Thanks for addressing earlier feedback.

I don't think you need to repost because of this, but for future

reference:

quoted

1. Because this is a fix for a commit that is present in net
   it should be targeted at that tree.

   Subject: [PATCH net vX] ...

2. Please use get_maintainers.pl this.patch to generate the CC list. In
   this case Xin Long (now CCed) should be included as he is the author

of the

quoted

   patch cited in the Fixes tag.

   b4 can help you with this and other aspects of patch management.

quoted

diff --git a/drivers/net/hyperv/netvsc_drv.c

b/drivers/net/hyperv/netvsc_drv.c

quoted

quoted

index c41a025c66f0..8be9bce66a4e 100644

--- a/drivers/net/hyperv/netvsc_drv.c
+++ b/drivers/net/hyperv/netvsc_drv.c

@@ -2317,8 +2317,11 @@ static int netvsc_prepare_bonding(struct

net_device *vf_netdev)

quoted

quoted

      if (!ndev)
              return NOTIFY_DONE;

-     /* set slave flag before open to prevent IPv6 addrconf */
+     /* Set slave flag and no addrconf flag before open
+      * to prevent IPv6 addrconf.
+      */
      vf_netdev->flags |= IFF_SLAVE;
+     vf_netdev->priv_flags |= IFF_NO_ADDRCONF;

If it is only to prevent IPv6 addrconf, I think you can replace IFF_SLAVE
with IFF_NO_ADDRCONF.

IFF_SLAVE normally comes with IFF_MASTER, like bonding and eql.
I don't see IFF_MASTER used in netvsc_drv.c, so IFF_SLAVE probably
should be dropped, including the one in __netvsc_vf_setup()?

The IFF_SLAVE is not just for ipv6, the comment should be updated.
IFF_SLAVE is also used by udev and our other user mode daemons, so it needs
to stay.

- Haiyang