Re: [PATCH] Hyperv: Trigger DHCP renew after host hibernation

[Dan Williams <dcbw@redhat.com>]

On Mon, 2014-07-21 at 15:11 +0200, Lennart Poettering wrote:
> On Mon, 21.07.14 10:21, Yue Zhang (OSTC DEV) (yuezha@microsoft.com) wrote:
> 
> > Some network monitoring daemon, like ifplugd has a deferring mechanism.
> > When it detects carriers is offline, it doesn't trigger DHCP renew immediately. 
> > Instead it will wait for another 5 seconds to check whether carrier is back to 
> > online status. In that case, it will avoid renew DHCP lease.
> 
> ifplugd doesn't renew DHCP leases anyway, one of the scripts it invokes
> does.
> 
> ifplugd is obsolete software. I wrote it more than 10 years ago, and
> haven't really updated it since. it's sounds seriously wrong to add
> multi-second waits to the kernel just to make this crappy, obsolete
> software work.
> 
> Please fix this properly, and work with the PM guys, so that we get a
> sane userspace how the kernel can notify userspace about
> suspends/hibernations triggered from the outside, so that userspace
> daemons can subscribe to that and then refresh the DHCP leases on their
> own.

Yeah, like I've said before, there have been other cases where a "hey,
my L3 address might be wrong now, so please confirm it" message would be
useful.  Carrier on/off doesn't necessarily mean that, but even if it
did, the off interval is a really bad mechanism for that too.  So I'd
really like some kind of event for this that's distinct from carrier
that userspace could use.

Dan