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

Richard Weinberger
2014-07-21T06:55:16Z

Yie,

Am 21.07.2014 04:44, schrieb Yue Zhang (OSTC DEV):
>> From: Richard Weinberger [mailto:richard.weinberger@gmail.com]
>> Why 10? Is this a random number which works by accident for ifplugd?
>> What about other networking implementations, is 10 also ok for them?
>> --
>> Thanks,
>> //richard
>
> Hi, Richard
>
> I checked ifplugd's code. The deferring time is 5 seconds. That's how comes
> the "10s". I agree with you this is a magic number and should be avoid. However,
> this is the only feasible solution right now. If there is a better solution, I will be
> glad to switch to it.
>
> I tested the fix in Redhat, Ubuntu and SUSE and it works in all of them.

The problem I see is that there is no good way to trigger a DHCP renew from
a network device drivers. You're on the wrong layer.
10 seconds may work but this is IMHO a hack which can easily break.
There are also more networking implementations than ifplugd.
Specially the systemd implementation looks promising.

Can't you propagate the RNDIS_STATUS_NETWORK_CHANGE event to userspace?
IIRC on HyperV guests already have a guest daemon. Let the daemon handle
the event such that distros can install their own hooks...

Thanks,
//richard