netdev - Re: [PATCH net-next] hyperv: Add handler for RNDIS_STATUS_NETWORK

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Date:	Fri, 30 Oct 2015 23:10:55 +0100
From:	Richard Weinberger <richard@....at>
To:	Haiyang Zhang <haiyangz@...rosoft.com>,
	Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:	David Miller <davem@...emloft.net>,
	"olaf@...fle.de" <olaf@...fle.de>,
	"jasowang@...hat.com" <jasowang@...hat.com>,
	"driverdev-devel@...uxdriverproject.org" 
	<driverdev-devel@...uxdriverproject.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next] hyperv: Add handler for
 RNDIS_STATUS_NETWORK_CHANGE event

Am 30.10.2015 um 23:03 schrieb Haiyang Zhang:
> 
> 
>> -----Original Message-----
>> From: Vitaly Kuznetsov [mailto:vkuznets@...hat.com]
>> Sent: Friday, October 30, 2015 6:56 AM
>> To: Haiyang Zhang <haiyangz@...rosoft.com>
>> Cc: Richard Weinberger <richard.weinberger@...il.com>; David Miller
>> <davem@...emloft.net>; olaf@...fle.de; jasowang@...hat.com; driverdev-
>> devel@...uxdriverproject.org; LKML <linux-kernel@...r.kernel.org>;
>> netdev@...r.kernel.org
>> Subject: Re: [PATCH net-next] hyperv: Add handler for
>> RNDIS_STATUS_NETWORK_CHANGE event
>>
>> Haiyang Zhang <haiyangz@...rosoft.com> writes:
>>
>>>> -----Original Message-----
>>>> From: Richard Weinberger [mailto:richard.weinberger@...il.com]
>>>> Sent: Tuesday, October 27, 2015 6:36 PM
>>>> To: David Miller <davem@...emloft.net>
>>>> Cc: Haiyang Zhang <haiyangz@...rosoft.com>; olaf@...fle.de; Greg
>> Kroah-
>>>> Hartman <greg@...ah.com>; netdev@...r.kernel.org; jasowang@...hat.com;
>>>> driverdev-devel@...uxdriverproject.org; LKML <linux-
>>>> kernel@...r.kernel.org>
>>>> 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@...emloft.net>
>>>> wrote:
>>>>> From: Haiyang Zhang <haiyangz@...rosoft.com>
>>>>> 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.

Can't you propagate the event to userspace and let it take an appropriate
action?

Thanks,
//richard
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