From: Bart Van Assche <bvanassche@acm.org>
To: Yu Kuai <yukuai3@huawei.com>,
axboe@kernel.dk, josef@toxicpanda.com, ming.lei@redhat.com
Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org,
nbd@other.debian.org, yi.zhang@huawei.com
Subject: Re: [PATCH 1/2] blk-mq: add two interfaces to lock/unlock blk_mq_tags->lock
Date: Sun, 8 Aug 2021 09:44:40 -0700 [thread overview]
Message-ID: <1e6b1a1e-eb45-f6c7-a8ce-e534b8cda710@acm.org> (raw)
In-Reply-To: <20210808031752.579882-2-yukuai3@huawei.com>
On 8/7/21 8:17 PM, Yu Kuai wrote:
> +void blk_mq_tags_lock(struct blk_mq_tags *tags, unsigned long *flags)
> +{
> + spin_lock_irqsave(&tags->lock, *flags);
> +}
> +EXPORT_SYMBOL(blk_mq_tags_lock);
> +
> +void blk_mq_tags_unlock(struct blk_mq_tags *tags, unsigned long *flags)
> +{
> + spin_unlock_irqrestore(&tags->lock, *flags);
> +}
> +EXPORT_SYMBOL(blk_mq_tags_unlock);
The tag map lock is an implementation detail and hence this lock must
not be used directly by block drivers. I propose to introduce and export
a new function to block drivers that does the following:
* Lock tags->lock.
* Call blk_mq_tag_to_rq().
* Check whether the request is in the started state. If so, increment
its reference count.
* Unlock tags->lock.
Thanks,
Bart.
next prev parent reply other threads:[~2021-08-08 16:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-08-08 3:17 [PATCH 0/2] fix request uaf in nbd_read_stat() Yu Kuai
2021-08-08 3:17 ` [PATCH 1/2] blk-mq: add two interfaces to lock/unlock blk_mq_tags->lock Yu Kuai
2021-08-08 16:44 ` Bart Van Assche [this message]
2021-08-09 1:11 ` yukuai (C)
2021-08-08 3:17 ` [PATCH 2/2] nbd: hold tags->lock to prevent access freed request through blk_mq_tag_to_rq() Yu Kuai
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