linux-kernel - Re: [PATCH bpf-next v2 1/6] cgroup: Prepare for using css_task_iter

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Date:   Mon, 18 Sep 2023 10:42:37 -1000
From:   Tejun Heo <tj@...nel.org>
To:     Chuyi Zhou <zhouchuyi@...edance.com>
Cc:     bpf@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        andrii@...nel.org, martin.lau@...nel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH bpf-next v2 1/6] cgroup: Prepare for using
 css_task_iter_*() in BPF

On Tue, Sep 12, 2023 at 03:01:44PM +0800, Chuyi Zhou wrote:
> This patch makes some preparations for using css_task_iter_*() in BPF
> Program.
> 
> 1. Flags CSS_TASK_ITER_* are #define-s and it's not easy for bpf prog to
> use them. Convert them to enum so bpf prog can take them from vmlinux.h.
> 
> 2. In the next patch we will add css_task_iter_*() in common kfuncs which
> is not safe. Since css_task_iter_*() does spin_unlock_irq() which might
> screw up irq flags depending on the context where bpf prog is running.
> So we should use irqsave/irqrestore here and the switching is harmless.
> 
> Signed-off-by: Chuyi Zhou <zhouchuyi@...edance.com>

Acked-by: Tejun Heo <tj@...nel.org>

Thanks.

-- 
tejun