On 03/29/2017 03:11 PM, David Ahern wrote: > On 3/29/17 11:05 AM, Vlad Yasevich wrote: >> On 03/29/2017 12:37 PM, Roopa Prabhu wrote: >>> On 3/29/17, 5:23 AM, Vlad Yasevich wrote: >>>> [ resending to list. hit the wrong reply button last time ] >>>> >>>> On 03/27/2017 06:58 PM, David Miller wrote: >>>>> From: Vladislav Yasevich <vyasev...@gmail.com> >>>>> Date: Sat, 25 Mar 2017 21:59:47 -0400 >>>>> >>>>>> RTNL currently generates notifications on some netdev notifier events. >>>>>> However, user space has no idea what changed. All it sees is the >>>>>> data and has to infer what has changed. For some events that is not >>>>>> possible. >>>>>> >>>>>> This patch adds a new field to RTM_NEWLINK message called IFLA_EVENT >>>>>> that would have an encoding of the which event triggered this >>>>>> notification. Currectly, only 2 events (NETDEV_NOTIFY_PEERS and >>>>>> NETDEV_MTUCHANGED) are supported. These events could be interesting >>>>>> in the virt space to trigger additional configuration commands to VMs. >>>>>> Other events of interest may be added later. >>>>>> >>>>>> Signed-off-by: Vladislav Yasevich <vyase...@redhat.com> >>>>> At what point do we start providing the metadata for the changed >>>>> values as well? You'd probably need to provide both the old and >>>>> new values to cover all cases. >>>> I don't think if that would be possible because of when events are >>>> triggered. >>>> We send these notifications after all the changes have already been made, >>>> so >>>> it might be tough to carry old data. >>>> >>>> Looking at just the two events I am supporting in this patch, we could >>>> actually >>>> supply the old mtu data through a NETDEV_PRECHANGEMTU event, if it is >>>> necessary. >>> >>> But, NETDEV_PRECHANGEMTU will be a unnecessary notification to userspace >>> without >>> changes. There are already enough notifications generated for links (I know >>> you are not >>> suggesting adding it here) >> >> Actually, this one already triggers a link notification to userspace. It >> just has >> no event data in it to tell you that. :) > > Is it intentional or unintentional? perhaps rtnetlink_event should be a > whitelist -- events that userspace should be notified about. Seems like > NETDEV_ events have been added without rtnetlink_event getting updated.
I think a 'whitelist' was attempted, but as you mentioned, it hasn't been updated... I'll defer the definitive answer to someone else. It seems Patrick added a comment in commit a2835763 to update the white list and it's been a few times. > For example, does userspace care about NETDEV_UDP_TUNNEL_PUSH_INFO or > NETDEV_CHANGE_TX_QUEUE_LEN? > Probably not the first, but possibly the second. If txquelen is changed on a device, some apps might want to know about it. -vlad
