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SubjectRE: [PATCH net-next] hv_netvsc: Increase delay for RNDIS_STATUS_NETWORK_CHANGE

> -----Original Message-----
> From: David Miller []
> Sent: Tuesday, February 9, 2016 5:05 AM
> To: Haiyang Zhang <>
> Cc:; KY Srinivasan <>;
> Subject: Re: [PATCH net-next] hv_netvsc: Increase delay for
> From: Haiyang Zhang <>
> Date: Tue, 2 Feb 2016 16:15:56 -0800
> > We simulates a link down period for RNDIS_STATUS_NETWORK_CHANGE
> > message to trigger DHCP renew. User daemons may need multiple seconds
> > to trigger the link down event. (e.g. ifplugd: 5sec, network-manager:
> > 4sec.) So update this link down period to 10 sec to properly trigger DHCP
> renew.
> >
> > Signed-off-by: Haiyang Zhang <>
> Two things look really bad about this to me:
> 1) Any value you choose is arbitrary. If some new network configuration
> daemon
> is slower, you will have to change this value again.
> This is _NOT_ sustainable in the long term.
> 2) It is completely unclear to me why this driver needs to delay at all or
> wait for anything. I see no other driver having to deal with this issue.
> Until you address both of these points I am not going to apply this patch.

1) I share your concern as well. Is there a universal way to immediately trigger
DHCP renew of all current and future daemons with a single event from kernel?
If not, can we put the delay (RNDIS_STATUS_NETWORK_CHANGE only) into a
tunable variable of this driver?

2) We used to have the call_usermodehelper "/etc/init.d/network restart" to
trigger DHCP renew. In commit 27a70af3f4, Vitaly has replaced it with the current
code that updates the link status with at least 2 seconds interval, so that the
"link_watch infrastructure" can send notification out. link_watch infrastructure
only sends one notification per second.

- Haiyang

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