Re: [PATCH v2 1/2] blk-iocost: add refcounting for iocg

[Tejun Heo]

Hello,

On Wed, Jan 11, 2023 at 09:36:25AM +0800, Yu Kuai wrote:
> I'm not sure, of course this can fix the problem, but two spinlock
> 'blkcg->lock' and 'q->queue_lock' are used to protect blkg_destroy()
> currently, add a mutex（disk level?) requires a refactor, which seems
> complex to me.

The fact that the two paths can race each other already seems buggy. e.g.
What prevents them from running pd_free on the same pd twice? So, it needs
to be fixed anyway and the intention always has been that these callbacks
are called in the correct traversal order.

Thanks.

-- 
tejun