netdev - Re: [PATCH net] net/sched: cls_flower: allocate mask dynamically in fl

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Date:   Wed, 16 Jan 2019 16:49:03 +0100
From:   Ivan Vecera <ivecera@...hat.com>
To:     Jiri Pirko <jiri@...nulli.us>
Cc:     netdev@...r.kernel.org, Petr Oros <poros@...hat.com>,
        Paul Blakey <paulb@...lanox.com>
Subject: Re: [PATCH net] net/sched: cls_flower: allocate mask dynamically in
 fl_change()

On 16. 01. 19 16:24, Jiri Pirko wrote:
> Wed, Jan 16, 2019 at 04:02:10PM CET, ivecera@...hat.com wrote:
>> Recent changes (especially 05cd271fd61a ("cls_flower: Support multiple
>> masks per priority")) in the fl_flow_mask structure grow it and its
>> current size e.g. on x86_64 with defconfig is 760 bytes and more than
>> 1024 bytes with some debug options enabled. Prior the mentioned commit
>> its size was 176 bytes (using defconfig on x86_64).
>> With regard to this fact it's reasonable to allocate this structure
>> dynamically in fl_change() to reduce its stack size.
>>
>> Fixes: 05cd271fd61a ("cls_flower: Support multiple masks per priority")
> 
> Not sure this is -net material. But I don't mind.
> 
> 
>> Cc: Jiri Pirko <jiri@...nulli.us>
>> Cc: Paul Blakey <paulb@...lanox.com>
>> Signed-off-by: Ivan Vecera <ivecera@...hat.com>
>> ---
>> net/sched/cls_flower.c | 19 ++++++++++++++-----
>> 1 file changed, 14 insertions(+), 5 deletions(-)
>>
>> diff --git a/net/sched/cls_flower.c b/net/sched/cls_flower.c
>> index dad04e710493..47ac88cc34fb 100644
>> --- a/net/sched/cls_flower.c
>> +++ b/net/sched/cls_flower.c
>> @@ -1291,16 +1291,22 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
>> 	struct cls_fl_filter *fold = *arg;
>> 	struct cls_fl_filter *fnew;
>> 	struct nlattr **tb;
>> -	struct fl_flow_mask mask = {};
>> +	struct fl_flow_mask *mask;
>> 	int err;
>>
>> 	if (!tca[TCA_OPTIONS])
>> 		return -EINVAL;
>>
>> -	tb = kcalloc(TCA_FLOWER_MAX + 1, sizeof(struct nlattr *), GFP_KERNEL);
>> -	if (!tb)
>> +	mask = kcalloc(1, sizeof(struct fl_flow_mask), GFP_KERNEL);
> 
> kzalloc?
Sure.. excuse.

> Otherwise this looks fine.
> Acked-by: Jiri Pirko <jiri@...lanox.com>
Thx.

> 
> 
> 
>> +	if (!mask)
>> 		return -ENOBUFS;
>>
>> +	tb = kcalloc(TCA_FLOWER_MAX + 1, sizeof(struct nlattr *), GFP_KERNEL);
>> +	if (!tb) {
>> +		err = -ENOBUFS;
>> +		goto errout_mask_alloc;
>> +	}
>> +
>> 	err = nla_parse_nested(tb, TCA_FLOWER_MAX, tca[TCA_OPTIONS],
>> 			       fl_policy, NULL);
>> 	if (err < 0)
>> @@ -1343,12 +1349,12 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
>> 		}
>> 	}
>>
>> -	err = fl_set_parms(net, tp, fnew, &mask, base, tb, tca[TCA_RATE], ovr,
>> +	err = fl_set_parms(net, tp, fnew, mask, base, tb, tca[TCA_RATE], ovr,
>> 			   tp->chain->tmplt_priv, extack);
>> 	if (err)
>> 		goto errout_idr;
>>
>> -	err = fl_check_assign_mask(head, fnew, fold, &mask);
>> +	err = fl_check_assign_mask(head, fnew, fold, mask);
>> 	if (err)
>> 		goto errout_idr;
>>
>> @@ -1392,6 +1398,7 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
>> 	}
>>
>> 	kfree(tb);
>> +	kfree(mask);
>> 	return 0;
>>
>> errout_mask:
>> @@ -1405,6 +1412,8 @@ static int fl_change(struct net *net, struct sk_buff *in_skb,
>> 	kfree(fnew);
>> errout_tb:
>> 	kfree(tb);
>> +errout_mask_alloc:
>> +	kfree(mask);
>> 	return err;
>> }
>>
>> -- 
>> 2.19.2
>>