Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.36 as permitted sender) client-ip=23.128.96.36;
Message-ID: <5cf3d2a8-563e-4fe5-a1a2-7af417bd8043@bytedance.com>
Date:   Mon, 30 Oct 2023 10:32:05 +0800
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [RESEND PATCH bpf-next v6 2/8] bpf: Introduce css_task open-coded
 iterator kfuncs
To:     Guenter Roeck <linux@roeck-us.net>
Cc:     bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
        andrii@kernel.org, martin.lau@kernel.org, tj@kernel.org,
        linux-kernel@vger.kernel.org
References: <20231018061746.111364-1-zhouchuyi@bytedance.com>
 <20231018061746.111364-3-zhouchuyi@bytedance.com>
 <bf2add1f-a9e4-46ac-b1ac-5b6ad9f0ed86@roeck-us.net>
From:   Chuyi Zhou <zhouchuyi@bytedance.com>
In-Reply-To: <bf2add1f-a9e4-46ac-b1ac-5b6ad9f0ed86@roeck-us.net>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

Hello,

在 2023/10/30 01:09, Guenter Roeck 写道:
> On Wed, Oct 18, 2023 at 02:17:40PM +0800, Chuyi Zhou wrote:
>> This patch adds kfuncs bpf_iter_css_task_{new,next,destroy} which allow
>> creation and manipulation of struct bpf_iter_css_task in open-coded
>> iterator style. These kfuncs actually wrapps css_task_iter_{start,next,
>> end}. BPF programs can use these kfuncs through bpf_for_each macro for
>> iteration of all tasks under a css.
>>
>> css_task_iter_*() would try to get the global spin-lock *css_set_lock*, so
>> the bpf side has to be careful in where it allows to use this iter.
>> Currently we only allow it in bpf_lsm and bpf iter-s.
>>
>> Signed-off-by: Chuyi Zhou <zhouchuyi@bytedance.com>
>> Acked-by: Tejun Heo <tj@kernel.org>
> 
> With this patch in linux-next:
> 
> Building m68k:defconfig ... failed
> --------------
> Error log:
> kernel/bpf/task_iter.c: In function 'bpf_iter_css_task_new':
> kernel/bpf/task_iter.c:917:14: error: 'CSS_TASK_ITER_PROCS' undeclared (first use in this function)
>    917 |         case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED:
>        |              ^~~~~~~~~~~~~~~~~~~
> kernel/bpf/task_iter.c:917:14: note: each undeclared identifier is reported only once for each function it appears in
> kernel/bpf/task_iter.c:917:36: error: 'CSS_TASK_ITER_THREADED' undeclared (first use in this function)
>    917 |         case CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED:
> 
> My apologies for the noise if this has already been reported and/or fixed.
> 
> Guenter

Here is the previous discussion link:
https://lore.kernel.org/lkml/20231020132749.1398012-1-arnd@kernel.org/

We can talk this issue on that maillist.

thanks.