net: core: neighbour: Inline neigh_update_notify() calls

net: core: neighbour: Inline neigh_update_notify() calls

The obvious idea behind the helper is to keep together the two bits that
should be done either both or neither: the internal notifier chain message,
and the netlink notification.

To make sure that the notification sent reflects the change being made, the
netlink message needs to be send inside the critical section where the
neighbor is changed. But for the notifier chain, there is no such need: the
listeners do not assume lock, and often in fact just schedule a delayed
work to act on the neighbor later. At least one in fact also takes the
neighbor lock. Therefore these two items have each different locking needs.

Now we could unlock inside the helper, but I find that error prone, and the
fact that the notification is conditional in the first place does not help
to make the call site obvious.

So in this patch, the helper is instead removed and the body, which is just
these two calls, inlined. That way we can use each notifier independently.

Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/e65dce5882bc6f4aa2530b8a4877d0e003071a1a.1769012464.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>