[PATCH v2] regulator: core: fix use_count leakage when handling boot-on

[PATCH v2] regulator: core: fix use_count leakage when handling boot-on

[Rui Zhang]

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@vivo.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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Thank you

回复: [PATCH v2] regulator: core: fix use_count leakage when handling boot-on

[张睿-拍照技术开发部]

> 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@vivo.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
> 
> ________________________________
> 
> 本邮件及其附件内容可能含有机密和/或隐私信息，仅供指定个人或机构使用。若您非发件人指定收件人或其代理人，请勿使用、传播、复制或存储此邮件之任何内容或其附件。如您误收本邮件，请即以回复或电话方式通知发件人，并将原始邮件、附件及其所有复本删除。谢谢。
> The contents of this message and any attachments may contain confidential and/or privileged information and are intended exclusively for the addressee(s). If you are not the intended recipient of this message or their agent, please note that any use, dissemination, copying, or storage of this message or its attachments is not allowed. If you receive this message in error, please notify the sender by reply the message or phone and delete this message, any attachments and any copies immediately.
> 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.