netdev - Re: [patch net-next] tc: add BPF based action

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Date:	Thu, 8 Jan 2015 16:01:36 +0100
From:	Jiri Pirko <jiri@...nulli.us>
To:	Hannes Frederic Sowa <hannes@...hat.com>
Cc:	netdev@...r.kernel.org, davem@...emloft.net, jhs@...atatu.com,
	stephen@...workplumber.org
Subject: Re: [patch net-next] tc: add BPF based action

Thu, Jan 08, 2015 at 03:55:37PM CET, hannes@...hat.com wrote:
>On Mi, 2015-01-07 at 17:43 +0100, Jiri Pirko wrote:
>> +static int tcf_bpf(struct sk_buff *skb, const struct tc_action *a,
>> +		   struct tcf_result *res)
>> +{
>> +	struct tcf_bpf *b = a->priv;
>> +	int action;
>> +	int filter_res;
>> +
>> +	spin_lock(&b->tcf_lock);
>> +	b->tcf_tm.lastuse = jiffies;
>> +	bstats_update(&b->tcf_bstats, skb);
>> +	action = b->tcf_action;
>> +
>> +	filter_res = BPF_PROG_RUN(b->filter, skb);
>> +	if (filter_res == -1)
>> +		goto drop;
>> +
>> +	goto unlock;
>> +
>> +drop:
>> +	action = TC_ACT_SHOT;
>> +	b->tcf_qstats.drops++;
>> +unlock:
>> +	spin_unlock(&b->tcf_lock);
>> +	return action;
>> +}
>
>In theory this could be like:
>
>filter_res = BPF_PROG_RUN(b->filter, skb);
>
>spin_lock(&b->tcf_lock);
><update stats...>
>
>if (filter_res == -1)
>  goto drop;
>
>action = b->tcf_action;
>...
>
>to keep BPF_PROG_RUN out of the spin_lock?

Okay. That makes sense. Will include this change into v2.

Thanks.

>
>Bye,
>Hannes
>
>
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