RE: [PATCH net-next] hyperv: Add handler for RNDIS_STATUS_NETWORK_CHANGE event

[Haiyang Zhang]

> -----Original Message-----
> From: Vitaly Kuznetsov [mailto:vkuznets@xxxxxxxxxx]
> Sent: Friday, October 30, 2015 6:56 AM
> To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Cc: Richard Weinberger <richard.weinberger@xxxxxxxxx>; David Miller
> <davem@xxxxxxxxxxxxx>; olaf@xxxxxxxxx; jasowang@xxxxxxxxxx; driverdev-
> devel@xxxxxxxxxxxxxxxxxxxxxx; LKML <linux-kernel@xxxxxxxxxxxxxxx>;
> netdev@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH net-next] hyperv: Add handler for
> RNDIS_STATUS_NETWORK_CHANGE event
> 
> Haiyang Zhang <haiyangz@xxxxxxxxxxxxx> writes:
> 
> >> -----Original Message-----
> >> From: Richard Weinberger [mailto:richard.weinberger@xxxxxxxxx]
> >> Sent: Tuesday, October 27, 2015 6:36 PM
> >> To: David Miller <davem@xxxxxxxxxxxxx>
> >> Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; olaf@xxxxxxxxx; Greg
> Kroah-
> >> Hartman <greg@xxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; jasowang@xxxxxxxxxx;
> >> driverdev-devel@xxxxxxxxxxxxxxxxxxxxxx; LKML <linux-
> >> kernel@xxxxxxxxxxxxxxx>
> >> Subject: Re: [PATCH net-next] hyperv: Add handler for
> >> RNDIS_STATUS_NETWORK_CHANGE event
> >>
> >> On Mon, Jun 23, 2014 at 10:10 PM, David Miller <davem@xxxxxxxxxxxxx>
> >> wrote:
> >> > From: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> >> > Date: Mon, 23 Jun 2014 16:09:59 +0000
> >> >
> >> >> So, what's the equivalent or similar command to "network restart"
> on
> >> SLES12? Could
> >> >> you update the command line for the usermodehelper when porting
> this
> >> patch to SLES
> >> >> 12?
> >> >
> >> > No, you are not going to keep the usermodehelper invocation in your
> >> driver
> >> > please remove it.  It is absolutely inappropriate, and I strictly
> do
> >> not want
> >> > to keep it in there because other people will copy it and then
> we'll
> >> have a
> >> > real mess on our hands.
> >>
> >> Sorry for digging up this old thread.
> >> While talking with some guys about usermodehelper abuses I came
> across
> >> this gem.
> >> Mainline still contains that "/etc/init.d/network restart" code.
> >> Haiyang, care to cleanup?
> >
> > Hi Richard and others,
> >
> > Thanks for the reminder. I will clean up the usermode helper.
> >
> > Do you have suggestions of trigger DHCP refresh from kernel mode? Any
> > sample code in the existing kernel code?
> >
> 
> I think it's wrong to call dhcp refresh from kernel. What happens when
> we reconnect normal hardware adapter to another network? Link goes down
> and then up and userspace is supposed to react accordingly. I think we
> should emulate something similar for RNDIS_STATUS_NETWORK_CHANGE.

When link is down physically for a few seconds, the DHCP will automatically 
refresh. I will add code to emulate this. There were some discussions around 
this and other possibilities previously... I agree emulating what happens 
with physically plug/unplug a cable is a reasonable way to trigger the DHCP 
refresh.

Thanks,
- Haiyang



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