From mboxrd@z Thu Jan  1 00:00:00 1970
From: Tejun Heo <tj@kernel.org>
Subject: Re: [PATCH v3 cgroup/for-5.20] cgroup: Replace
 cgroup->ancestor_ids[] with ->ancestors[]
Date: Mon, 15 Aug 2022 11:17:16 -1000
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Sender: Tejun Heo <htejun@gmail.com>
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To: cgroups@vger.kernel.org, Zefan Li <lizefan.x@bytedance.com>, Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>, Christian Brauner <brauner@kernel.org>
Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, Namhyung Kim <namhyung@kernel.org>, Pablo Neira Ayuso <pablo@netfilter.org>

On Fri, Jul 29, 2022 at 01:10:16PM -1000, Tejun Heo wrote:
> Every cgroup knows all its ancestors through its ->ancestor_ids[]. There's
> no advantage to remembering the IDs instead of the pointers directly and
> this makes the array useless for finding an actual ancestor cgroup forcing
> cgroup_ancestor() to iteratively walk up the hierarchy instead. Let's
> replace cgroup->ancestor_ids[] with ->ancestors[] and remove the walking-up
> from cgroup_ancestor().
> 
> While at it, improve comments around cgroup_root->cgrp_ancestor_storage.
> 
> This patch shouldn't cause user-visible behavior differences.
> 
> v2: Update cgroup_ancestor() to use ->ancestors[].
> 
> v3: cgroup_root->cgrp_ancestor_storage's type is updated to match
>     cgroup->ancestors[]. Better comments.
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Acked-by: Namhyung Kim <namhyung@kernel.org>

Applied to cgroup/for-6.1.

-- 
tejun