Re: [PATCH net 1/2] vxlan: keep reserved_bits across changelink

[Petr Machata]

Hannes Laimer <h.laimer@xxxxxxxxxxx> writes:

> vxlan_nl2conf() derives reserved_bits from the extension attributes
> set in the netlink message if IFLA_VXLAN_RESERVED_BITS is absent. A
> changelink having it set is rejected, so this means that every
> changelink will reset all extension bits and reserve them again.
> vxlan_nl2flag() rejects setting a flag on an attribute that is
> create-only on changelink. So also setting an extension attribute will
> fail before it can un-reserve its fields.

> Keeping the reserved_bits on changelink is safe because anything a
> changelink accepts leaves the header bits enabled extensions use
> unchanged.

> Fixes: e4f8647767cf ("vxlan: Track reserved bits explicitly as part of the configuration")
> Link: https://lore.proxmox.com/pve-devel/20260828134708.692354-1-h.laimer@xxxxxxxxxxx/
> Signed-off-by: Hannes Laimer <h.laimer@xxxxxxxxxxx>

Reviewed-by: Petr Machata <petrm@xxxxxxxxxx>