netdev - Re: [net-next PATCH v4 12/16] net: sched: rcu'ify cls

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Date:	Fri, 12 Sep 2014 08:16:04 -0700
From:	John Fastabend <john.fastabend@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
CC:	xiyou.wangcong@...il.com, davem@...emloft.net, jhs@...atatu.com,
	netdev@...r.kernel.org, paulmck@...ux.vnet.ibm.com,
	brouer@...hat.com
Subject: Re: [net-next PATCH v4 12/16] net: sched: rcu'ify cls_bpf

On 09/10/2014 07:28 PM, Eric Dumazet wrote:
> On Wed, 2014-09-10 at 08:51 -0700, John Fastabend wrote:
>> This patch makes the cls_bpf classifier RCU safe. The tcf_lock
>> was being used to protect a list of cls_bpf_prog now this list
>> is RCU safe and updates occur with rcu_replace.
>>
>> Signed-off-by: John Fastabend <john.r.fastabend@...el.com>
>
> ...

[...]

>> @@ -281,15 +280,17 @@ static int cls_bpf_change(struct net *net, struct sk_buff *in_skb,
>>   	if (ret < 0)
>>   		goto errout;
>>
>> -	tcf_tree_lock(tp);
>> -	list_add(&prog->link, &head->plist);
>> -	tcf_tree_unlock(tp);
>> +	if (oldprog) {
>> +		list_replace_rcu(&prog->link, &oldprog->link);
>> +		call_rcu(&oldprog->rcu, __cls_bpf_delete_prog);
>> +	} else {
>> +		list_add_rcu(&prog->link, &head->plist);
>> +	}
>>
>>   	*arg = (unsigned long) prog;
>> -
>>   	return 0;
>>   errout:
>> -	if (*arg == 0UL && prog)
>> +	if (prog)
>>   		kfree(prog);
>>
>
> nit, you can directly call kfree(prog) even if prog == NULL
>

Yep, made the change.

-- 
John Fastabend         Intel Corporation
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