From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Wed, 15 Apr 2009 12:41:01 +0200
From: Patrick McHardy <kaber@trash.net>
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Subject: Re: [Bridge] [PATCH 1/3] net: introduce a list of device addresses
	dev_addr_list
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To: David Miller <davem@davemloft.net>
Cc: ivecera@redhat.com, fubar@us.ibm.com, jpirko@redhat.com, netdev@vger.kernel.org, bridge@lists.linux-foundation.org, lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, mschmidt@redhat.com, dada1@cosmosbay.com, jgarzik@pobox.com, bonding-devel@lists.sourceforge.net

David Miller wrote:
> From: Patrick McHardy <kaber@trash.net>
> Date: Wed, 15 Apr 2009 12:13:57 +0200
> 
>> David Miller wrote:
>>> From: Eric Dumazet <dada1@cosmosbay.com>
>>> Date: Wed, 15 Apr 2009 11:27:50 +0200
>>>
>>>> Since you obviously need a write lock here to be sure following
>>>> can be done by one cpu only.
>>>>
>>>> You have same problem all over this patch.
>>> RTNL semaphore is held across all modification operations.
>> If this will also be used for multicast lists, changes can happen
>> (IPv6) without the RTNL.
> 
> Indeed, that is true :-/

Herbert (I think) suggested to make address list updates in softirq
context a two-step process, where addresses would first be added to
a temporary list and the final change would be done in process context
while holding the RTNL.

Given the complicated mess we currently have, this would be a very
worthwhile change IMO.