From: "yukuai (C)" <yukuai3@huawei.com>
To: Bart Van Assche <bvanassche@acm.org>, <axboe@kernel.dk>,
<ming.lei@redhat.com>
Cc: <yi.zhang@huawei.com>, <zhangxiaoxu5@huawei.com>,
<luoshijie1@huawei.com>, <linux-block@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] block: rename 'q->debugfs_dir' in blk_unregister_queue()
Date: Wed, 12 Feb 2020 12:20:50 +0800 [thread overview]
Message-ID: <18bf436a-9c6a-dba8-46a4-ef57132f467a@huawei.com> (raw)
In-Reply-To: <c57b050d-9ed7-9d6b-b1d0-628a197f6ea6@acm.org>
On 2020/2/12 11:27, Bart Van Assche wrote:
> What is the behavior of this loop if multiple block devices are being
> removed concurrently? Does it perhaps change remove block device removal
> from an O(1) into an O(n) operation?
Yes, there may be performance overhead.(I thought it's minimal) However,
I can change the name of dir form "read_to_remove_%d" to
"read_to_remove_%s(dev_name)_%d" to fix that.
>
> Since this scenario may only matter to syzbot tests: has it been
> considered to delay block device creation if the debugfs directory from
> a previous incarnation of the block device still exists?
>
I think it's a bug device creation succeed when the debugfs directory
exist. Of course delay block device creation can fix the problem, but I
haven't come up with a good solution. And by renaming the dir, there is
no need to delay cration.
Thanks!
Yu Kuai
next prev parent reply other threads:[~2020-02-12 4:21 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-11 3:51 [PATCH] block: rename 'q->debugfs_dir' in blk_unregister_queue() yu kuai
2020-02-12 3:27 ` Bart Van Assche
2020-02-12 4:20 ` yukuai (C) [this message]
2020-02-13 4:38 ` kbuild test robot
2020-02-13 11:39 ` kbuild test robot
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