netdev - Re: [PATCH net-next 1/5] bonding: convert to list API and replace bond's custom list

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Date:	Wed, 31 Jul 2013 20:44:49 +0200
From:	Nikolay Aleksandrov <nikolay@...hat.com>
To:	Stephen Hemminger <stephen@...workplumber.org>
CC:	netdev@...r.kernel.org, andy@...yhouse.net, davem@...emloft.net,
	fubar@...ibm.com
Subject: Re: [PATCH net-next 1/5] bonding: convert to list API and replace
 bond's custom list

On 07/31/2013 08:37 PM, Stephen Hemminger wrote:
> On Wed, 31 Jul 2013 17:12:29 +0200
> Nikolay Aleksandrov <nikolay@...hat.com> wrote:
> 
>> diff --git a/drivers/net/bonding/bond_3ad.c b/drivers/net/bonding/bond_3ad.c
>> index 390061d..80e288c 100644
>> --- a/drivers/net/bonding/bond_3ad.c
>> +++ b/drivers/net/bonding/bond_3ad.c
>> @@ -143,10 +143,13 @@ static inline struct bonding *__get_bond_by_port(struct port *port)
>>   */
>>  static inline struct port *__get_first_port(struct bonding *bond)
>>  {
>> +	struct slave *first_slave;
>> +
>>  	if (bond->slave_cnt == 0)
>>  		return NULL;
>> +	first_slave = bond_first_slave(bond);
> 
> As Jay said, it would be be better to have bond_first_slave return
> NULL (if no slaves), and eliminate slave_cnt. It would also fix
> a race here between slave_cnt and all slave's being removed.
> 
Hi Stephen,
First off - thank you for the review.

What do you mean by eliminate slave_cnt ?
We need it for various calculations throughout the bonding.
There's no race here because read_lock(&bond->lock) is held every time this
is called and slave_cnt can change only under write_lock of the same lock,
the 3ad code is not yet converted to RCU.

Nik
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