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Date:   Wed, 4 Jan 2023 16:12:41 +0100
From:   Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>
To:     Yu Kuai <yukuai1@huaweicloud.com>
Cc:     tj@kernel.org, josef@toxicpanda.com, axboe@kernel.dk,
        cgroups@vger.kernel.org, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org, yukuai3@huawei.com,
        yi.zhang@huawei.com, yangerkun@huawei.com
Subject: Re: [PATCH] blk-cgroup: fix missing pd_online_fn() while activating
 policy
Message-ID: <20230104151241.GA13268@blackbody.suse.cz>
References: <20230103112833.2013432-1-yukuai1@huaweicloud.com>
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Hello.

On Tue, Jan 03, 2023 at 07:28:33PM +0800, Yu Kuai <yukuai1@huaweicloud.com>=
 wrote:
> If the policy defines pd_online_fn(), it should be called after
> pd_init_fn(), like blkg_create().

Is this based only on code review or has it some negative effects?

I assume this would affect hot-plugged (read after cgroup creation) devices.

I took a cursory look at:

	blkcg_init_disk
	  blkg_create
	    pol->pd_init_fn(blkg->pd[i]);
	    pol->pd_online_fn(blkg->pd[i]);
	  blk_throtl_init
	    blkcg_activate_policy
	      pol->pd_init_fn(blkg->pd[i]);
	      ?? pol->pd_online_fn(blkg->pd[i]);

I.e. the pd_online_fn is already called and pd_init_fn is called 2nd
time?=20

Thanks,
Michal

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