netdev - Re: [PATCH net-next 0/5] bonding: patchset for rcu use in bonding

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Date:	Mon, 21 Oct 2013 20:32:11 +0800
From:	Ding Tianhong <dingtianhong@...wei.com>
To:	Veaceslav Falico <vfalico@...hat.com>
CC:	Jay Vosburgh <fubar@...ibm.com>,
	Andy Gospodarek <andy@...yhouse.net>,
	"David S. Miller" <davem@...emloft.net>,
	Nikolay Aleksandrov <nikolay@...hat.com>,
	Netdev <netdev@...r.kernel.org>
Subject: Re: [PATCH net-next 0/5] bonding: patchset for rcu use in bonding

On 2013/10/21 17:35, Veaceslav Falico wrote:
> On Mon, Oct 21, 2013 at 05:27:51PM +0800, Ding Tianhong wrote:
>> On 2013/10/21 17:13, Veaceslav Falico wrote:
>>> On Mon, Oct 21, 2013 at 04:58:36PM +0800, Ding Tianhong wrote:
>>>> Hi:
>>>>
>>>> The Patch Set will remove the invalid lock for bond work queue and replace it
>>>> with rtnl lock, as read lock for bond could not protect slave list any more.
>>>
>>> rtnl lock is a lot more expensive than bond lock, and not only for bond,
>>> but for all the networking stack.
>>>
>>> Why is the bond->lock invalid? It correctly protects slaves from being
>>> modified concurrently.
>>>
>>> I don't see the point in this patchset.
>>>
>>
>> yes, rtnl lock is a big lock, but I think bond->lock could not protect
>> bond_for_each_slave any more, am I miss something?
> 
> Why can't it protect bond_for_each_slave()?
> 

bond_master_upper_dev_link() and bond_upper_dev_unlink() was only in rtnl lock,
bond_for_each_slave may changed while loop in bond read lock, but it sees that
nothing serious will happen yet.
Maybe I miss something.

Ding


>>
>> Ding
>>
>>>>
>>>> Ding Tianhong (5):
>>>>  bonding: remove bond read lock for bond_mii_monitor()
>>>>  bonding: remove bond read lock for bond_alb_monitor()
>>>>  bonding: remove bond read lock for bond_loadbalance_arp_mon()
>>>>  bonding: remove bond read lock for bond_activebackup_arp_mon()
>>>>  bonding: remove bond read lock for bond_3ad_state_machine_handler()
>>>>
>>>> drivers/net/bonding/bond_3ad.c  |   9 ++--
>>>> drivers/net/bonding/bond_alb.c  |  20 ++------
>>>> drivers/net/bonding/bond_main.c | 100 +++++++++++++---------------------------
>>>> 3 files changed, 40 insertions(+), 89 deletions(-)
>>>>
>>>> -- 
>>>> 1.8.2.1
>>>>
>>>>
>>>>
>>>
>>>
>>
>>
> 
> .
> 


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