Subject: Re: [PATCH] [bonding]: clear header_ops when last slave detached

From: Wengang <[email-masked]>
Date: Tue, 18 Nov 2014 09:56:22 +0800

Hi Jay,

于 2014年11月18日 09:38, Jay Vosburgh 写道:
> Wengang <[email-masked]> wrote:
>
>> Hi,
>>
>> Could anybody please review this patch?
> 	I don't see that the original of this ever came through netdev.

Oh, that' bad. I sent this to [email-masked]. The mail address 
is wrong?

>> thanks,
>> wengang
>>
>> 于 2014年11月13日 10:19, Wengang Wang 写道:
>>> When last slave of a bonding master is removed, the bonding then does not work.
>>> When packet_snd is called against with a master net_device, it accesses
>>> header_ops. In case the header_ops is not valid any longer(say module unloaded)
>>> it will then access an invalid memory address.
>>> This patch try to fix this issue by clearing header_ops when last slave
>>> detached.
> 	Am I correct in presuming that this behavior is limited to ipoib
> slaves only?  I don't see that this could occur with ethernet slaves, as
> eth_header_ops isn't part of a module.  This needs to be mentioned in
> the commit log.
Yes, the problem is found with ipoib slaves.
>>> Signed-off-by: Wengang Wang <[email-masked]>
>>> ---
>>>    drivers/net/bonding/bond_main.c | 2 ++
>>>    1 file changed, 2 insertions(+)
>>>
>>> diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c
>>> index c9ac06c..84a34fc 100644
>>> --- a/drivers/net/bonding/bond_main.c
>>> +++ b/drivers/net/bonding/bond_main.c
>>> @@ -1728,6 +1728,8 @@ static int __bond_release_one(struct net_device *bond_dev,
>>>    	unblock_netpoll_tx();
>>>    	synchronize_rcu();
>>>    	bond->slave_cnt--;
>>> +	if (!bond->slave_cnt)
>>> +		bond->dev->header_ops = NULL;
>>>      	if (!bond_has_slaves(bond)) {
>>>    		call_netdevice_notifiers(NETDEV_CHANGEADDR, bond->dev);
> 	I believe your addition could be moved into the block for the
> next if, as "!bond->slave_cnt" is essentially "!bond_has_slaves()".

Yes, Agree.
I will send the second prompt soon with commit message mentioning ipoib.

thanks,
wengang

> 	-J
>
> ---
> 	-Jay Vosburgh, [email-masked]