linux-kernel - 回复: [PATCH v2] regulator: core: fix use

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Date:   Thu, 1 Dec 2022 03:06:00 +0000
From:   张睿-拍照技术开发部 
        <zr.zhang@...o.com>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: 回复: [PATCH v2] regulator: core: fix use_count leakage when handling boot-on

> I found a use_count leakage towards supply regulator of rdev with
> boot-on option.
> 
> ┌───────────────────┐           ┌───────────────────┐
> │  regulator_dev A  │           │  regulator_dev B  │
> │     (boot-on)     │           │     (boot-on)     │
> │    use_count=0    │◀──supply──│    use_count=1    │
> │                   │           │                   │
> └───────────────────┘           └───────────────────┘
> 
> In case of rdev(A) configured with `regulator-boot-on', the use_count
> of supplying regulator(B) will increment inside
> regulator_enable(rdev->supply).
> 
> Thus, B will acts like always-on, and further balanced
> regulator_enable/disable cannot actually disable it anymore.
> 
> However, B was also configured with `regulator-boot-on', we wish it
> could be disabled afterwards.
> 
> Signed-off-by: Rui Zhang <zr.zhang@...o.com>
> ---
>  drivers/regulator/core.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
> index e8c00a884f1f..1cfac32121c0 100644
> --- a/drivers/regulator/core.c
> +++ b/drivers/regulator/core.c
> @@ -1596,7 +1596,13 @@ static int set_machine_constraints(struct regulator_dev *rdev)
>                 if (rdev->supply_name && !rdev->supply)
>                         return -EPROBE_DEFER;
> 
> -               if (rdev->supply) {
> +               /* If supplying regulator has already been enabled,
> +                * it's not intended to have use_count increment
> +                * when rdev is only boot-on.
> +                */
> +               if (rdev->supply &&
> +                   (rdev->constraints->always_on ||
> +                    !regulator_is_enabled(rdev->supply))) {
>                         ret = regulator_enable(rdev->supply);
>                         if (ret < 0) {
>                                 _regulator_put(rdev->supply);
> 
> base-commit: 01f856ae6d0ca5ad0505b79bf2d22d7ca439b2a1
> --
> 2.34.1
> 
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> 
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> Thank you

Sorry, please ignore the mail above. The unexpected `tail' was appended due to organization policy. I will resend the patch later when the issue is resolved.