netdev - Re: [PATCH net-next v11 3/4] net sched actions: dump more than TCA_ACT_MAX

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Date:   Tue, 25 Jul 2017 13:33:52 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     Jamal Hadi Salim <jhs@...atatu.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        xiyou.wangcong@...il.com, dsahern@...il.com,
        eric.dumazet@...il.com, mrv@...atatu.com,
        simon.horman@...ronome.com, alex.aring@...il.com
Subject: Re: [PATCH net-next v11 3/4] net sched actions: dump more than
 TCA_ACT_MAX_PRIO actions per batch

Tue, Jul 25, 2017 at 01:22:44PM CEST, jhs@...atatu.com wrote:
>On 17-07-24 07:27 AM, Jiri Pirko wrote:
>> Mon, Jul 24, 2017 at 03:35:45AM CEST, jhs@...atatu.com wrote:
>> > From: Jamal Hadi Salim <jhs@...atatu.com>
>[..]
>> 
>> This helper should be part of the previous patch.
>> 
>
>Will do next update.
>> 
>
>>> @@ -1157,8 +1164,18 @@ static int tc_dump_action(struct sk_buff *skb,
>struct netlink_callback *cb)
>>> 	struct tc_action_ops *a_o;
>>> 	int ret = 0;
>>> 	struct tcamsg *t = (struct tcamsg *) nlmsg_data(cb->nlh);
>>> -	struct nlattr *kind = find_dump_kind(cb->nlh);
>>> +	struct nla_bitfield_32 fb;
>>> +	struct nlattr *count_attr = NULL;
>>> +	struct nlattr *tb[TCA_ROOT_MAX + 1];
>>> +	struct nlattr *kind = NULL;
>>
>> Reverse christmas tree :D
>>
>
>There were already 2 christmas trees in place;->
>I will re-arrange this.
>
>> > 
>> > +	if (tb[TCA_ROOT_FLAGS])
>> > +		fb = nla_get_bitfield_32(tb[TCA_ROOT_FLAGS]);
>> 
>> fb? bf? nbf? Please make this synced within the patchset.
>> 
>> 
>
>Ok, what do you like best? ;->

"bf"


>
>> Don't you need to mask value with selector? In fact, I think that
>> nla_get_bitfield_32 could just return u32 which would be (value&selector).
>> The validation takes care of unsupported bits.
>
>For my use case I dont need any of the above since I dont need to
>unset things. In other use cases you will need both selector and
>value in case someone wants a bit to be set to 0.
>Infact I think i will rename that helper to "nla_get_bitvalue_32"
>to be more precise.

The getter should contain name of the type, so "nla_get_bitfield32_val"
is much better.

What if I pass val 0x1 and selector 0x0 from userspace. I don't have the
bit selected, so you should not process it in kernel, no?


>
>cheers,
>jamal