Re: [RFC PATCH v3 2/3] blk-mq: Freeze and quiesce all queues for tagset in elevator_exit()

To: John Garry <john.garry@xxxxxxxxxx>, hare@xxxxxxx, ming.lei@xxxxxxxxxx, axboe@xxxxxxxxx, hch@xxxxxx
Subject: Re: [RFC PATCH v3 2/3] blk-mq: Freeze and quiesce all queues for tagset in elevator_exit()
From: Bart Van Assche <bvanassche@xxxxxxx>
Date: Mon, 8 Mar 2021 11:35:11 -0800
Cc: linux-block@xxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, pragalla@xxxxxxxxxxxxxx, kashyap.desai@xxxxxxxxxxxx, yuyufen@xxxxxxxxxx
In-reply-to: <3c6cbe11-ac31-9a47-0096-17fbd584b83e@huawei.com>
References: <1614957294-188540-1-git-send-email-john.garry@huawei.com> <1614957294-188540-3-git-send-email-john.garry@huawei.com> <52618092-07ca-ecb5-320f-957af26ab146@acm.org> <3c6cbe11-ac31-9a47-0096-17fbd584b83e@huawei.com>
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On 3/8/21 2:50 AM, John Garry wrote:

Please let me know further thoughts.


Hi John,

My guess is that it is safe to nest these two locks. I was askingbecause I had not found any information about the nesting in the patchdescription.


Bart.

References:
- [RFC PATCH v3 0/3] blk-mq: Avoid use-after-free for accessing old requests
  - From: John Garry
- [RFC PATCH v3 2/3] blk-mq: Freeze and quiesce all queues for tagset in elevator_exit()
  - From: John Garry
- Re: [RFC PATCH v3 2/3] blk-mq: Freeze and quiesce all queues for tagset in elevator_exit()
  - From: Bart Van Assche
- Re: [RFC PATCH v3 2/3] blk-mq: Freeze and quiesce all queues for tagset in elevator_exit()
  - From: John Garry