netdev - Re: [PATCH] net: remove the unnecessary list

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Date:	Mon, 25 Feb 2013 16:01:24 +0800
From:	Gao feng <gaofeng@...fujitsu.com>
To:	David Miller <davem@...emloft.net>
CC:	netdev@...r.kernel.org
Subject: Re: [PATCH] net: remove the unnecessary list_del

On 2013/02/25 13:39, David Miller wrote:
> From: Gao feng <gaofeng@...fujitsu.com>
> Date: Mon, 25 Feb 2013 13:03:04 +0800
> 
>> On 2013/02/25 12:54, David Miller wrote:
>>> From: Gao feng <gaofeng@...fujitsu.com>
>>> Date: Mon, 25 Feb 2013 12:41:56 +0800
>>>
>>>> These lists are used by unregister_netdevice_many,
>>>> they are local variables,will not be seen by others.
>>>> there is no need to delete them.
>>>>
>>>> Signed-off-by: Gao feng <gaofeng@...fujitsu.com>
>>>
>>> What about the devices on the list?  The ones at the front and the
>>> rear of the list will have list pointers that point into no longer
>>> valid stack frame locations.
>>
>> These lists are only used by unregister_netdevice_many,
>> we don't access these lists again after unregister_netdevice_many,
>> so I think it doesn't have invalid stack frame locations problems.
> 
> I do not see unregister_netdevice_many() list_del()'ing the devices
> on the list, therefore those netdevice objects have pointers into
> the stale stack frame.
> 

Yes, I agree that this will make the netdevice objects have pointers
into the stale stack frame.

I check the codes,and found there are tons of codes that don't call
list_del after unregister_netdevice_many(). such as mroute_clean_tables,
ip6_tnl_destroy_tunnels...

I think it's better to make sure netdevice objects have valid pointers
by calling list_del in unregister_netdevice_many.

> You cannot make this change.
> 

Will send another patch.

Thanks
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