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

From: Jay Vosburgh <[email-masked]>
Date: Mon, 17 Nov 2014 17:38:49 -0800

Wengang <[email-masked]> wrote:

>Hi,
>
>Could anybody please review this patch?

	I don't see that the original of this ever came through netdev.

>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.

>> 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()".

	-J

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