Merge branch 'rtnetlink-dev-notification-fixes'

Xin Long says:

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rtnetlink: a bunch of fixes for userspace notifications in changing dev properties

Whenever any property of a link, address, route, etc. changes by whatever way,
kernel should notify the programs that listen for such events in userspace.

The patchet "rtnetlink: Cleanup user notifications for netdev events" tried to
fix a redundant notifications issue, but it also introduced a side effect.

After that, user notifications could only be sent when changing dev properties
via netlink api. As it removed some events process in rtnetlink_event where
the notifications was sent to users.

It resulted in no notification generated when dev properties are changed via
other ways, like ioctl, sysfs, etc. It may cause some user programs doesn't
work as expected because of the missing notifications.

This patchset will fix it by bringing some of these netdev events back and
also fix the old redundant notifications issue with a proper way.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>