[PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[Yu Kuai]

pm_runtime_get_sync will increment pm usage counter even it failed.
Forgetting to putting operation will result in reference leak here.
Fix it by replacing it with pm_runtime_resume_and_get to keep usage
counter balanced.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
 drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 0cd8f40fb690..305489d48c16 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2478,7 +2478,7 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
 	clk_prepare_enable(clk);
 
 	pm_runtime_enable(dev);
-	ret = pm_runtime_get_sync(dev);
+	ret = pm_runtime_resume_and_get(dev);
 	if (ret < 0) {
 		dev_err(dev, "pm_runtime_get_sync failed\n");
 		pm_runtime_disable(dev);
-- 
2.25.4

Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[Robert Foss]

Hey Yu,

On Mon, 17 May 2021 at 10:08, Yu Kuai <yukuai3@huawei.com> wrote:
>
> pm_runtime_get_sync will increment pm usage counter even it failed.
> Forgetting to putting operation will result in reference leak here.
> Fix it by replacing it with pm_runtime_resume_and_get to keep usage
> counter balanced.
>
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
>  drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> index 0cd8f40fb690..305489d48c16 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> @@ -2478,7 +2478,7 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
>         clk_prepare_enable(clk);
>
>         pm_runtime_enable(dev);
> -       ret = pm_runtime_get_sync(dev);
> +       ret = pm_runtime_resume_and_get(dev);
>         if (ret < 0) {
>                 dev_err(dev, "pm_runtime_get_sync failed\n");
>                 pm_runtime_disable(dev);

The code is correct as it is. If pm_runtime_get_sync() fails and
increments[1] the pm.usage_count variable, that isn't a problem since
pm_runtime_disable() disables pm, and resets pm.usage_count variable
to zero[2].

[1] https://elixir.bootlin.com/linux/latest/source/include/linux/pm_runtime.h#L384
[2] https://elixir.bootlin.com/linux/latest/source/drivers/base/power/runtime.c#L1383

Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[yukuai (C)]

On 2021/05/17 17:27, Robert Foss wrote:
> Hey Yu,
> 
> On Mon, 17 May 2021 at 10:08, Yu Kuai <yukuai3@huawei.com> wrote:
>>
>> pm_runtime_get_sync will increment pm usage counter even it failed.
>> Forgetting to putting operation will result in reference leak here.
>> Fix it by replacing it with pm_runtime_resume_and_get to keep usage
>> counter balanced.
>>
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> ---
>>   drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> index 0cd8f40fb690..305489d48c16 100644
>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> @@ -2478,7 +2478,7 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
>>          clk_prepare_enable(clk);
>>
>>          pm_runtime_enable(dev);
>> -       ret = pm_runtime_get_sync(dev);
>> +       ret = pm_runtime_resume_and_get(dev);
>>          if (ret < 0) {
>>                  dev_err(dev, "pm_runtime_get_sync failed\n");
>>                  pm_runtime_disable(dev);
> 
> The code is correct as it is. If pm_runtime_get_sync() fails and
> increments[1] the pm.usage_count variable, that isn't a problem since
> pm_runtime_disable() disables pm, and resets pm.usage_count variable
> to zero[2].
> 
> [1] https://elixir.bootlin.com/linux/latest/source/include/linux/pm_runtime.h#L384
> [2] https://elixir.bootlin.com/linux/latest/source/drivers/base/power/runtime.c#L1383
> .
> 
Hi,

Thank you very much for your explanation

Yu Kuai

Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[Johan Hovold]

On Mon, May 17, 2021 at 11:27:38AM +0200, Robert Foss wrote:
> Hey Yu,
> 
> On Mon, 17 May 2021 at 10:08, Yu Kuai <yukuai3@huawei.com> wrote:
> >
> > pm_runtime_get_sync will increment pm usage counter even it failed.
> > Forgetting to putting operation will result in reference leak here.
> > Fix it by replacing it with pm_runtime_resume_and_get to keep usage
> > counter balanced.
> >
> > Reported-by: Hulk Robot <hulkci@huawei.com>
> > Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> > ---
> >  drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > index 0cd8f40fb690..305489d48c16 100644
> > --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > @@ -2478,7 +2478,7 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
> >         clk_prepare_enable(clk);
> >
> >         pm_runtime_enable(dev);
> > -       ret = pm_runtime_get_sync(dev);
> > +       ret = pm_runtime_resume_and_get(dev);
> >         if (ret < 0) {
> >                 dev_err(dev, "pm_runtime_get_sync failed\n");
> >                 pm_runtime_disable(dev);
> 
> The code is correct as it is. If pm_runtime_get_sync() fails and
> increments[1] the pm.usage_count variable, that isn't a problem since
> pm_runtime_disable() disables pm, and resets pm.usage_count variable
> to zero[2].

No it doesn't; pm_runtime_disable() does not reset the counter and you
still need to decrement the usage count when pm_runtime_get_sync()
fails.

> [1] https://elixir.bootlin.com/linux/latest/source/include/linux/pm_runtime.h#L384
> [2] https://elixir.bootlin.com/linux/latest/source/drivers/base/power/runtime.c#L1383

Johan

Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[Robert Foss]

On Tue, 18 May 2021 at 09:42, Johan Hovold <johan@kernel.org> wrote:
>
> On Mon, May 17, 2021 at 11:27:38AM +0200, Robert Foss wrote:
> > Hey Yu,
> >
> > On Mon, 17 May 2021 at 10:08, Yu Kuai <yukuai3@huawei.com> wrote:
> > >
> > > pm_runtime_get_sync will increment pm usage counter even it failed.
> > > Forgetting to putting operation will result in reference leak here.
> > > Fix it by replacing it with pm_runtime_resume_and_get to keep usage
> > > counter balanced.
> > >
> > > Reported-by: Hulk Robot <hulkci@huawei.com>
> > > Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> > > ---
> > >  drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > > index 0cd8f40fb690..305489d48c16 100644
> > > --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > > +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> > > @@ -2478,7 +2478,7 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
> > >         clk_prepare_enable(clk);
> > >
> > >         pm_runtime_enable(dev);
> > > -       ret = pm_runtime_get_sync(dev);
> > > +       ret = pm_runtime_resume_and_get(dev);
> > >         if (ret < 0) {
> > >                 dev_err(dev, "pm_runtime_get_sync failed\n");

This error message is a bit confusing now, could you update it.

> > >                 pm_runtime_disable(dev);
> >
> > The code is correct as it is. If pm_runtime_get_sync() fails and
> > increments[1] the pm.usage_count variable, that isn't a problem since
> > pm_runtime_disable() disables pm, and resets pm.usage_count variable
> > to zero[2].
>
> No it doesn't; pm_runtime_disable() does not reset the counter and you
> still need to decrement the usage count when pm_runtime_get_sync()
> fails.

Thanks for chiming in Johan, you're absolutely right and I must have
misread something.

With the above fix, feel free to add my r-b.

Reviewed-by: Robert Foss <robert.foss@linaro.org>

Re: [PATCH] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[yukuai (C)]

ping ...

On 2021/05/18 20:58, Robert Foss wrote:
> On Tue, 18 May 2021 at 09:42, Johan Hovold <johan@kernel.org> wrote:
>>
>> On Mon, May 17, 2021 at 11:27:38AM +0200, Robert Foss wrote:
>>> Hey Yu,
>>>
>>> On Mon, 17 May 2021 at 10:08, Yu Kuai <yukuai3@huawei.com> wrote:
>>>>
>>>> pm_runtime_get_sync will increment pm usage counter even it failed.
>>>> Forgetting to putting operation will result in reference leak here.
>>>> Fix it by replacing it with pm_runtime_resume_and_get to keep usage
>>>> counter balanced.
>>>>
>>>> Reported-by: Hulk Robot <hulkci@huawei.com>
>>>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>>>> ---
>>>>   drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 2 +-
>>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>>>> index 0cd8f40fb690..305489d48c16 100644
>>>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>>>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>>>> @@ -2478,7 +2478,7 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
>>>>          clk_prepare_enable(clk);
>>>>
>>>>          pm_runtime_enable(dev);
>>>> -       ret = pm_runtime_get_sync(dev);
>>>> +       ret = pm_runtime_resume_and_get(dev);
>>>>          if (ret < 0) {
>>>>                  dev_err(dev, "pm_runtime_get_sync failed\n");
> 
> This error message is a bit confusing now, could you update it.
> 
>>>>                  pm_runtime_disable(dev);
>>>
>>> The code is correct as it is. If pm_runtime_get_sync() fails and
>>> increments[1] the pm.usage_count variable, that isn't a problem since
>>> pm_runtime_disable() disables pm, and resets pm.usage_count variable
>>> to zero[2].
>>
>> No it doesn't; pm_runtime_disable() does not reset the counter and you
>> still need to decrement the usage count when pm_runtime_get_sync()
>> fails.
> 
> Thanks for chiming in Johan, you're absolutely right and I must have
> misread something.
> 
> With the above fix, feel free to add my r-b.
> 
> Reviewed-by: Robert Foss <robert.foss@linaro.org>
> .
> 

[PATCH V2] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[Yu Kuai]

pm_runtime_get_sync will increment pm usage counter even it failed.
Forgetting to putting operation will result in reference leak here.
Fix it by replacing it with pm_runtime_resume_and_get to keep usage
counter balanced.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
---
changes in V2:
 - change error message.

 drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
index 0cd8f40fb690..eab959a59214 100644
--- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
+++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
@@ -2478,9 +2478,9 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
 	clk_prepare_enable(clk);
 
 	pm_runtime_enable(dev);
-	ret = pm_runtime_get_sync(dev);
+	ret = pm_runtime_resume_and_get(dev);
 	if (ret < 0) {
-		dev_err(dev, "pm_runtime_get_sync failed\n");
+		dev_err(dev, "pm_runtime_resume_and_get failed\n");
 		pm_runtime_disable(dev);
 		goto clk_disable;
 	}
-- 
2.25.4

Re: [PATCH V2] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[Robert Foss]

Hey Yu,

I'm not finding your this patch with the correct tags. I'd expect the subject:
[PATCH v2] drm: bridge: cdns-mhdp8546: Fix PM reference leak in
cdns_mhdp_probe()

Can you please resubmit using this title, just to be sure I merge the
right version of this code.

On Sat, 29 May 2021 at 11:46, Yu Kuai <yukuai3@huawei.com> wrote:
>
> pm_runtime_get_sync will increment pm usage counter even it failed.
> Forgetting to putting operation will result in reference leak here.
> Fix it by replacing it with pm_runtime_resume_and_get to keep usage
> counter balanced.
>
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
> ---
> changes in V2:
>  - change error message.
>
>  drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> index 0cd8f40fb690..eab959a59214 100644
> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
> @@ -2478,9 +2478,9 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
>         clk_prepare_enable(clk);
>
>         pm_runtime_enable(dev);
> -       ret = pm_runtime_get_sync(dev);
> +       ret = pm_runtime_resume_and_get(dev);
>         if (ret < 0) {
> -               dev_err(dev, "pm_runtime_get_sync failed\n");
> +               dev_err(dev, "pm_runtime_resume_and_get failed\n");
>                 pm_runtime_disable(dev);
>                 goto clk_disable;
>         }
> --
> 2.25.4
>

Re: [PATCH V2] drm: bridge: cdns-mhdp8546: Fix PM reference leak in cdns_mhdp_probe()

[yukuai (C)]

On 2021/05/31 18:54, Robert Foss wrote:
> Hey Yu,
> 
> I'm not finding your this patch with the correct tags. I'd expect the subject:
> [PATCH v2] drm: bridge: cdns-mhdp8546: Fix PM reference leak in
> cdns_mhdp_probe()
> 
> Can you please resubmit using this title, just to be sure I merge the
> right version of this code.
> 
Hi,

I just resubmit v2 patch.

Thanks
Yu Kuai
> On Sat, 29 May 2021 at 11:46, Yu Kuai <yukuai3@huawei.com> wrote:
>>
>> pm_runtime_get_sync will increment pm usage counter even it failed.
>> Forgetting to putting operation will result in reference leak here.
>> Fix it by replacing it with pm_runtime_resume_and_get to keep usage
>> counter balanced.
>>
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Yu Kuai <yukuai3@huawei.com>
>> ---
>> changes in V2:
>>   - change error message.
>>
>>   drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c | 4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> index 0cd8f40fb690..eab959a59214 100644
>> --- a/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> +++ b/drivers/gpu/drm/bridge/cadence/cdns-mhdp8546-core.c
>> @@ -2478,9 +2478,9 @@ static int cdns_mhdp_probe(struct platform_device *pdev)
>>          clk_prepare_enable(clk);
>>
>>          pm_runtime_enable(dev);
>> -       ret = pm_runtime_get_sync(dev);
>> +       ret = pm_runtime_resume_and_get(dev);
>>          if (ret < 0) {
>> -               dev_err(dev, "pm_runtime_get_sync failed\n");
>> +               dev_err(dev, "pm_runtime_resume_and_get failed\n");
>>                  pm_runtime_disable(dev);
>>                  goto clk_disable;
>>          }
>> --
>> 2.25.4
>>
> .
>