Merge branch 'neigh-fwd-grat' into next

Danielle Ratson  says:

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The existing neighbor suppression unconditionally suppresses gratuitous
ARP and unsolicited Neighbor Advertisements, which breaks legitimate use
cases like Multi-Homing and EVPN where these announcements need to
propagate across the VXLAN fabric.

This series adds a new neigh_forward_grat option that provides
independent control of gratuitous ARP and unsolicited NA forwarding.
When neigh_suppress is enabled and neigh_forward_grat is also enabled,
regular neighbor discovery is suppressed while gratuitous announcements
are forwarded.

Both port-level control (via IFLA_BRPORT_NEIGH_FORWARD_GRAT) and
per-VLAN control (via BRIDGE_VLANDB_ENTRY_NEIGH_FORWARD_GRAT) are
provided. The default value of OFF preserves existing behavior.

The new attributes use NLA_U8, although the kernel netlink guideline
recommends NLA_U32 as the minimum integer type on the grounds that
alignment makes smaller types equivalent on the wire. For a simple
on/off attribute there is no technical advantage to u32 over u8, and
keeping u8 preserves consistency with all surrounding bridge port
attributes and avoids introducing new helpers alongside the existing
infrastructure.

====================

Signed-off-by: David Ahern <dsahern@kernel.org>