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From: Tejun Heo <tj@kernel.org>
To: Yu Kuai <yukuai1@huaweicloud.com>
Cc: axboe@kernel.dk, linux-block@vger.kernel.org,
	linux-kernel@vger.kernel.org, yukuai3@huawei.com,
	yi.zhang@huawei.com
Subject: Re: [PATCH -next 3/5] blk-iocost: prevent configuration update concurrent with io throttling
Date: Tue, 11 Oct 2022 07:03:13 -1000	[thread overview]
Message-ID: <Y0Wh0fQBkKlhEiYi@slm.duckdns.org> (raw)
In-Reply-To: <20221011083547.1831389-4-yukuai1@huaweicloud.com>

On Tue, Oct 11, 2022 at 04:35:45PM +0800, Yu Kuai wrote:
> From: Yu Kuai <yukuai3@huawei.com>
> 
> This won't cause any severe problem currently, however, this doesn't
> seems appropriate:
> 
> 1) 'ioc->params' is read from multiple places without holding
> 'ioc->lock', unexpected value might be read if writing it concurrently.
> 
> 2) If configuration is changed while io is throttling, the functionality
> might be affected. For example, if module params is updated and cost
> becomes smaller, waiting for timer that is caculated under old
> configuration is not appropriate.
> 
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>

Acked-by: Tejun Heo <tj@kernel.org>

Thanks.

-- 
tejun

  reply	other threads:[~2022-10-11 17:03 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-11  8:35 [PATCH -next 0/5] blk-iocost: some random patches to improve iocost Yu Kuai
2022-10-11  8:35 ` [PATCH -next 1/5] blk-iocost: disable writeback throttling Yu Kuai
2022-10-11 16:54   ` Tejun Heo
2022-10-11  8:35 ` [PATCH -next 2/5] blk-iocost: don't release 'ioc->lock' while updating params Yu Kuai
2022-10-11 16:56   ` Tejun Heo
2022-10-11  8:35 ` [PATCH -next 3/5] blk-iocost: prevent configuration update concurrent with io throttling Yu Kuai
2022-10-11 17:03   ` Tejun Heo [this message]
2022-10-11  8:35 ` [PATCH -next 4/5] blk-iocost: bypass if only one cgroup issues io Yu Kuai
2022-10-11 17:02   ` Tejun Heo
2022-10-12  1:33     ` Yu Kuai
2022-10-12  8:04       ` Tejun Heo
2022-10-11  8:35 ` [PATCH -next 5/5] blk-iocost: read 'ioc->params' inside 'ioc->lock' in ioc_timer_fn() Yu Kuai
2022-10-11 17:01   ` Tejun Heo

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