linux-kernel - Re: [PATCH] regulator: core: Only increment use_count when enable

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Date:   Fri, 3 Nov 2023 12:51:20 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Rui Zhang <zr.zhang@...o.com>
Cc:     Douglas Anderson <dianders@...omium.org>,
        opensource.kernel@...o.com, Liam Girdwood <lgirdwood@...il.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: core: Only increment use_count when
 enable_count changes

On Fri, Nov 03, 2023 at 03:42:31PM +0800, Rui Zhang wrote:

> The use_count of a regulator should only be incremented when the
> enable_count changes from 0 to 1. Similarly, the use_count should
> only be decremented when the enable_count changes from 1 to 0.

Why?

> In the previous implementation, use_count was sometimes decremented
> to 0 when some consumer called unbalanced disable,
> leading to unexpected disable even the regulator is enabled by
> other consumers. With this change, the use_count accurately reflects
> the number of users which the regulator is enabled.

If a consumer does an unbalanced disable the consumer is buggy and the
reference counting is wrong overall.  The bug is in the consumer driver
doing the unbalanced disable.

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