netdev - Re: [PATCH 4/6] vlan: Optimize multiple unregistration

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Message-ID: <4AE9A554.8030207@trash.net>
Date:	Thu, 29 Oct 2009 15:23:16 +0100
From:	Patrick McHardy <kaber@...sh.net>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	"David S. Miller" <davem@...emloft.net>,
	Linux Netdev List <netdev@...r.kernel.org>
Subject: Re: [PATCH 4/6] vlan: Optimize multiple unregistration

Patrick McHardy wrote:
> Eric Dumazet wrote:
>> Patrick McHardy a écrit :
>>>> +{
>>>> +	LIST_HEAD(list);
>>>> +	int i;
>>>> +	struct net_device *vlandev;
>>>> +	struct vlan_group save;
>>>> +
>>>> +	memcpy(&save, grp, sizeof(save));
>>>> +	memset(&grp->vlan_devices_arrays, 0, sizeof(grp->vlan_devices_arrays));
>>> This shouldn't be necessary since the lower device is already in the
>>> process of being unregistered. If it was necessary, it could cause
>>> crashes since the individual pointers are not set to zero atomically.
>>> Or maybe I'm misunderstanding the purpose entirely :)
>> Very good point indeed, even if in practice memset() use long word transferts
>>
>> I'll make a cleanup patch, or do you want to do it ?
> 
> I can take care of this, patch will follow shortly.

How about this? I moved the code back into vlan_device_event() since
its now only a very minimal change to the original code.

vlan-orig.diff contains the diff between the original code and the
code after this patch for reference.


View attachment "vlan.diff" of type "text/x-patch" (2891 bytes)

View attachment "vlan-orig.diff" of type "text/x-patch" (1400 bytes)