netdev - RE: [PATCH net v4 00/12] Fix possbile memleaks when fail to register

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Date:   Wed, 3 May 2017 08:33:02 +0800
From:   "Gao Feng" <gfree.wind@...mail.com>
To:     "'David Miller'" <davem@...emloft.net>
Cc:     <jiri@...nulli.us>, <mareklindner@...mailbox.ch>,
        <sw@...onwunderlich.de>, <a@...table.cc>, <kuznet@....inr.ac.ru>,
        <jmorris@...ei.org>, <yoshfuji@...ux-ipv6.org>, <kaber@...sh.net>,
        <steffen.klassert@...unet.com>, <herbert@...dor.apana.org.au>,
        <netdev@...r.kernel.org>
Subject: RE: [PATCH net v4 00/12] Fix possbile memleaks when fail to register_netdevice

Hi David

> From: David Miller [mailto:davem@...emloft.net]
> Sent: Wednesday, May 3, 2017 3:30 AM
> From: gfree.wind@...mail.com
> Date: Tue,  2 May 2017 13:58:42 +0800
> 
[...]
> >
> > This solution doesn't only make sure free all resources in any case,
> > but also follows the original desgin that some resources could be kept
> > until the destructor executes normally after register the device
> > successfully.
> 
> I want to think about this some more.
> 
> It is really unfortunate that resources are allocated strictly from the
ndo_init()
> yet released in two different callbacks which are invoked only in certain
> (different) situations.
> 
> Just the fact that we have to make an internal netdev state test in the
> ndo_uninit callback to get this right is a big red flag to me.

Yes, I am very agree with you.
This fix is just like a workaround under current framework.

The root is that allocate in one spot, but free them at two spots.
It means all ndo_uninit need to handle this case if allocate some resource
and free them in the destructor.
It should be done by the framework.

I thought about if there was a better solution to fix it.
But I think it need to modify the framework of net_device, it seems not good
as a bug fix to net.git.

Best Regards
Feng