hsr: broadcast netlink notifications in the device's net namespace

hsr: broadcast netlink notifications in the device's net namespace

The HSR generic netlink family sets .netnsok = true. HSR devices can
live in network namespaces other than init_net.

Two async notifiers broadcast events with genlmsg_multicast(). They
are hsr_nl_ringerror() and hsr_nl_nodedown(). That helper delivers
only on the default genl socket in init_net. So the events always land
in init_net. The network namespace of the device does not matter.

This has two effects. A listener in the device's own namespace never
sees its own ring error and node down events. A privileged listener in
init_net receives events from HSR devices in other namespaces. The
payload carries the peer node MAC (HSR_A_NODE_ADDR) and the slave port
ifindex (HSR_A_IFINDEX).

Switch both callers to genlmsg_multicast_netns(). Other families with
.netnsok = true already do this. Examples are gtp, ovpn, team,
batman-adv, netdev-genl, ethtool and handshake.

hsr_nl_ringerror() already has the slave port. It uses
dev_net(port->dev). hsr_nl_nodedown() takes the namespace from the
master port via hsr_port_get_hsr().

Reviewed-by: Fernando Fernandez Mancera <fmancera@suse.de>
Signed-off-by: Maoyi Xie <maoyixie.tju@gmail.com>
Link: https://patch.msgid.link/20260604054949.2999304-1-maoyixie.tju@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>