linux-kernel - Re: [PATCH 1/4] blkcg: Drop unnecessary RCU read [un]locks from blkg_conf

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Message-ID: <20230108170240.GA19165@lst.de>
Date:   Sun, 8 Jan 2023 18:02:40 +0100
From:   Christoph Hellwig <hch@....de>
To:     Tejun Heo <tj@...nel.org>
Cc:     axboe@...nel.dk, josef@...icpanda.com, hch@....de,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/4] blkcg: Drop unnecessary RCU read [un]locks from
 blkg_conf_prep/finish()

On Thu, Jan 05, 2023 at 11:24:29AM -1000, Tejun Heo wrote:
> Holding the queue lock now implies RCU read lock, so no need to use
> rcu_read_[un]lock() explicitly. This shouldn't cause any behavior changes.

How so?

> While at it, drop __acquires() annotation on the queue lock too. The
> __acquires() part was already out of sync and it doesn't catch anything that
> lockdep can't.

This makes sparse even more unhappy than it was before.  For now
please keep the annotation.