netdev - Re: Requirements for a shutdown function?

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Message-ID: <1efae594-427b-58e5-fd48-bac9f686bb52@codeaurora.org>
Date:   Wed, 10 May 2017 15:17:25 -0500
From:   Timur Tabi <timur@...eaurora.org>
To:     Florian Fainelli <f.fainelli@...il.com>, netdev@...r.kernel.org
Subject: Re: Requirements for a shutdown function?

On 05/09/2017 02:06 PM, Florian Fainelli wrote:
> On 05/09/2017 11:51 AM, Timur Tabi wrote:

>> Is it possible that the network stack detects a kexec and automatically
>> stops all network devices?
> 
> No. why would it? However the device driver model does call into your
> driver's remove function and that one does a right job already because
> it does an network device unregister, and so on.

I ran some more tests.  When I launch kexec, the driver's
net_device_ops.ndo_stop function is called, which already stops the interface.

So it looks to me as if the network stack does close the interface during a
kexec.  With the interface closed, there's no point in having a shutdown
function, is there?

>> My in-house driver stops the RX and TX queues.  I'm guessing that's good
>> enough, but I don't have a failing test case to prove it.
>>
> 
> That's probably good enough, yes.

Except that it turns out that the queues are already stopped by then because
the emac_close() function has already been called.

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