Re: [PATCH] blk-cgroup: fix missing pd_online_fn() while activating policy

From: Michal Koutný
Date: Thu Jan 05 2023 - 05:46:22 EST


On Thu, Jan 05, 2023 at 09:43:02AM +0800, Yu Kuai <yukuai1@xxxxxxxxxxxxxxx> wrote:
> This is based only on code review, currently the only negative effects
> is that root blkg from blk-throtl won't call pd_online_fn().

Good, that's a NOP and there are no other uses of pd_online_fn.

I wonder are the separate pd_init_fn and pd_online_fn callbacks
necessary today?
(IOW your fixup is a good catch and looks correct to me; I'd suggest
more of a clean up. Shall I look into that?)

> No, this is not true, before blkcg_activate_policy() is called,
> blkg_create() won't see this policy, hence pd_init_fn/pd_online_fn won't
> be called from blkg_create().

Thanks, I missed the q->blkcg_pols bit.

Michal

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