linux-kernel - Re: [PATCH] regulator: core: Clean up on enable failure

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Date:   Fri, 19 Aug 2022 16:46:22 -0400
From:   Brian Masney <bmasney@...hat.com>
To:     Andrew Halaney <ahalaney@...hat.com>
Cc:     lgirdwood@...il.com, broonie@...nel.org,
        linux-kernel@...r.kernel.org, dianders@...omium.org
Subject: Re: [PATCH] regulator: core: Clean up on enable failure

On Fri, Aug 19, 2022 at 02:43:36PM -0500, Andrew Halaney wrote:
> If regulator_enable() fails, enable_count is incremented still.
> A consumer, assuming no matching regulator_disable() is necessary on
> failure, will then get this error message upon regulator_put()
> since enable_count is non-zero:
> 
>     [    1.277418] WARNING: CPU: 3 PID: 1 at drivers/regulator/core.c:2304 _regulator_put.part.0+0x168/0x170
> 
> The consumer could try to fix this in their driver by cleaning up on
> error from regulator_enable() (i.e. call regulator_disable()), but that
> results in the following since regulator_enable() failed and didn't
> increment user_count:
> 
>     [    1.258112] unbalanced disables for vreg_l17c
>     [    1.262606] WARNING: CPU: 4 PID: 1 at drivers/regulator/core.c:2899 _regulator_disable+0xd4/0x190
> 
> Fix this by decrementing enable_count upon failure to enable.
> 
> With this in place, just the reason for failure to enable is printed
> as expected and developers can focus on the root cause of their issue
> instead of thinking their usage of the regulator consumer api is
> incorrect. For example, in my case:
> 
>     [    1.240426] vreg_l17c: invalid input voltage found
> 
> Fixes: 5451781dadf8 ("regulator: core: Only count load for enabled consumers")
> Signed-off-by: Andrew Halaney <ahalaney@...hat.com>

Reviewed-by: Brian Masney <bmasney@...hat.com>