netdev - Re: [PATCH net-next v4 2/3] bpf: Add bpf_current_task_under

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Date:	Thu, 11 Aug 2016 21:50:48 -0700
From:	Sargun Dhillon <sargun@...gun.me>
To:	Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:	netdev <netdev@...r.kernel.org>,
	Daniel Borkmann <daniel@...earbox.net>, tj@...nel.org
Subject: Re: [PATCH net-next v4 2/3] bpf: Add bpf_current_task_under_cgroup helper

I realize that in_cgroup is more consistent, but under_cgroup makes
far more sense to me. I think it's more intuitive.

On Thu, Aug 11, 2016 at 9:48 PM, Alexei Starovoitov
<alexei.starovoitov@...il.com> wrote:
> On Thu, Aug 11, 2016 at 08:14:56PM -0700, Sargun Dhillon wrote:
>> This adds a bpf helper that's similar to the skb_in_cgroup helper to check
>> whether the probe is currently executing in the context of a specific
>> subset of the cgroupsv2 hierarchy. It does this based on membership test
>> for a cgroup arraymap. It is invalid to call this in an interrupt, and
>> it'll return an error. The helper is primarily to be used in debugging
>> activities for containers, where you may have multiple programs running in
>> a given top-level "container".
>>
>> Signed-off-by: Sargun Dhillon <sargun@...gun.me>
>> Cc: Alexei Starovoitov <ast@...nel.org>
>> Cc: Daniel Borkmann <daniel@...earbox.net>
>> Cc: Tejun Heo <tj@...nel.org>
>> ---
>> +     /**
>> +      * bpf_current_task_under_cgroup(map, index) - Check cgroup2 membership of current task
>> +      * @map: pointer to bpf_map in BPF_MAP_TYPE_CGROUP_ARRAY type
>> +      * @index: index of the cgroup in the bpf_map
>> +      * Return:
>> +      *   == 0 current failed the cgroup2 descendant test
>> +      *   == 1 current succeeded the cgroup2 descendant test
>> +      *    < 0 error
>> +      */
>> +     BPF_FUNC_current_task_under_cgroup,
> ..
>>       case BPF_MAP_TYPE_CGROUP_ARRAY:
>> -             if (func_id != BPF_FUNC_skb_in_cgroup)
>> +             if (func_id != BPF_FUNC_skb_in_cgroup &&
>> +                 func_id != BPF_FUNC_current_task_under_cgroup)
>>                       goto error;
> ...
>> +     case BPF_FUNC_current_task_under_cgroup:
>>       case BPF_FUNC_skb_in_cgroup:
>
> Tejun,
> do you feel strongly about 'under' ?
> It just looks inconsistent vs existing skb_in_cgroup...
> "in cgroup" - 4k google hits
> "under cgroup" - 2k google hits
>