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From: Tejun Heo <tj@kernel.org>
To: Yu Kuai <yukuai3@huawei.com>
Cc: hch@infradead.org, axboe@kernel.dk, cgroups@vger.kernel.org,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
	yi.zhang@huawei.com
Subject: Re: [PATCH v2 2/2] block: cancel all throttled bios in del_gendisk()
Date: Tue, 30 Nov 2021 06:26:18 -1000	[thread overview]
Message-ID: <YaZQqjjygHGFEdbx@slm.duckdns.org> (raw)
In-Reply-To: <20211130011730.2584339-3-yukuai3@huawei.com>

Hello,

On Tue, Nov 30, 2021 at 09:17:30AM +0800, Yu Kuai wrote:
> +void blk_throtl_cancel_bios(struct request_queue *q)
> +{
> +	struct throtl_data *td = q->td;
> +	struct blkcg_gq *blkg;
> +	struct cgroup_subsys_state *pos_css;
> +	struct bio *bio;
> +	int rw;
> +
> +	rcu_read_lock();

So, all of the draining is being performed without holding the q lock, which
*might* be okay given that we're in the del_gendisk path but is likely risky
- ie. there can still be timers or whatever racing against it.

Thanks.

-- 
tejun

  parent reply	other threads:[~2021-11-30 16:26 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-30  1:17 [PATCH v2 0/2] cancel all throttled bios in del_gendisk() Yu Kuai
2021-11-30  1:17 ` [PATCH v2 1/2] blk-throtl: move WARN_ON_ONCE() from throtl_rb_first() to it's caller Yu Kuai
2021-11-30  6:43   ` Christoph Hellwig
2021-11-30  1:17 ` [PATCH v2 2/2] block: cancel all throttled bios in del_gendisk() Yu Kuai
2021-11-30  6:43   ` Christoph Hellwig
2021-11-30 16:26   ` Tejun Heo [this message]
2021-12-01  9:26     ` yukuai (C)

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