[PATCH] hwrng: exynos - fix reference leak in exynos_trng_probe

[PATCH] hwrng: exynos - fix reference leak in exynos_trng_probe

[Qinglang Miao]

pm_runtime_get_sync will increment pm usage counter even it
failed. Forgetting to putting operation will result in a
reference leak here.

A new function pm_runtime_resume_and_get is introduced in
[0] to keep usage counter balanced. So We fix the reference
leak by replacing it with new funtion.

[0] dd8088d5a896 ("PM: runtime: Add  pm_runtime_resume_and_get to deal with usage counter")

Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
---
 drivers/char/hw_random/exynos-trng.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
index 8e1fe3f8d..666246bc8 100644
--- a/drivers/char/hw_random/exynos-trng.c
+++ b/drivers/char/hw_random/exynos-trng.c
@@ -132,7 +132,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
 		return PTR_ERR(trng->mem);
 
 	pm_runtime_enable(&pdev->dev);
-	ret = pm_runtime_get_sync(&pdev->dev);
+	ret = pm_runtime_resume_and_get(&pdev->dev);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "Could not get runtime PM.\n");
 		goto err_pm_get;
-- 
2.23.0

Re: [PATCH] hwrng: exynos - fix reference leak in exynos_trng_probe

[Krzysztof Kozlowski]

On Fri, Nov 27, 2020 at 05:44:46PM +0800, Qinglang Miao wrote:
> pm_runtime_get_sync will increment pm usage counter even it
> failed. Forgetting to putting operation will result in a
> reference leak here.
> 
> A new function pm_runtime_resume_and_get is introduced in
> [0] to keep usage counter balanced. So We fix the reference
> leak by replacing it with new funtion.
> 
> [0] dd8088d5a896 ("PM: runtime: Add  pm_runtime_resume_and_get to deal with usage counter")

Do not put such dependencies into the commit message - it does not bring
useful information to the history. Store it under '---' separator.

> 
> Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
> ---
>  drivers/char/hw_random/exynos-trng.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
> index 8e1fe3f8d..666246bc8 100644
> --- a/drivers/char/hw_random/exynos-trng.c
> +++ b/drivers/char/hw_random/exynos-trng.c
> @@ -132,7 +132,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
>  		return PTR_ERR(trng->mem);
>  
>  	pm_runtime_enable(&pdev->dev);
> -	ret = pm_runtime_get_sync(&pdev->dev);
> +	ret = pm_runtime_resume_and_get(&pdev->dev);

This cannot be applied. Fix it by replacing err_clock label with this
one.

Best regards,
Krzysztof

Re: [PATCH] hwrng: exynos - fix reference leak in exynos_trng_probe

[Qinglang Miao]

在 2020/11/27 17:44, Krzysztof Kozlowski 写道:
> On Fri, Nov 27, 2020 at 05:44:46PM +0800, Qinglang Miao wrote:
>> pm_runtime_get_sync will increment pm usage counter even it
>> failed. Forgetting to putting operation will result in a
>> reference leak here.
>>
>> A new function pm_runtime_resume_and_get is introduced in
>> [0] to keep usage counter balanced. So We fix the reference
>> leak by replacing it with new funtion.
>>
>> [0] dd8088d5a896 ("PM: runtime: Add  pm_runtime_resume_and_get to deal with usage counter")
> 
> Do not put such dependencies into the commit message - it does not bring
> useful information to the history. Store it under '---' separator.
> 
>>
>> Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
>> ---
>>   drivers/char/hw_random/exynos-trng.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
>> index 8e1fe3f8d..666246bc8 100644
>> --- a/drivers/char/hw_random/exynos-trng.c
>> +++ b/drivers/char/hw_random/exynos-trng.c
>> @@ -132,7 +132,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
>>   		return PTR_ERR(trng->mem);
>>   
>>   	pm_runtime_enable(&pdev->dev);
>> -	ret = pm_runtime_get_sync(&pdev->dev);
>> +	ret = pm_runtime_resume_and_get(&pdev->dev);
> 
> This cannot be applied. Fix it by replacing err_clock label with this
> one. >
> Best regards,
> Krzysztof
> 
> .
Hi Krzysztof,

I realize that there's a mistake in this patch through your reply.

There's two way to fix this one:
1) replace err_pm_get with err_clock label when pm_runtime_get_sync fails.
2) replace pm_runtime_get_sync with pm_runtime_resume_and_get and remove
redundant label(err_clock).

I take 2) on v2 for it makes codes more clearer in a way.

Thanks.

> 

Re: [PATCH] hwrng: exynos - fix reference leak in exynos_trng_probe

[Lukasz Stelmach]

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It was <2020-11-27 pią 17:44>, when Qinglang Miao wrote:
> pm_runtime_get_sync will increment pm usage counter even it
> failed. Forgetting to putting operation will result in a
> reference leak here.
>
> A new function pm_runtime_resume_and_get is introduced in
> [0] to keep usage counter balanced. So We fix the reference
> leak by replacing it with new funtion.
>
> [0] dd8088d5a896 ("PM: runtime: Add  pm_runtime_resume_and_get to deal with usage counter")
>
> Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
> ---
>  drivers/char/hw_random/exynos-trng.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
> index 8e1fe3f8d..666246bc8 100644
> --- a/drivers/char/hw_random/exynos-trng.c
> +++ b/drivers/char/hw_random/exynos-trng.c
> @@ -132,7 +132,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
>  		return PTR_ERR(trng->mem);
>  
>  	pm_runtime_enable(&pdev->dev);
> -	ret = pm_runtime_get_sync(&pdev->dev);
> +	ret = pm_runtime_resume_and_get(&pdev->dev);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "Could not get runtime PM.\n");
>  		goto err_pm_get;

Thanks. I suppose you may use the new function exynos_trng_resume(),
remove everything and leave only

return pm_runtime_resume_and_get(dev);

-- 
Łukasz Stelmach
Samsung R&D Institute Poland
Samsung Electronics

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Re: [PATCH] hwrng: exynos - fix reference leak in exynos_trng_probe

[Qinglang Miao]

在 2020/11/27 22:26, Lukasz Stelmach 写道:
> It was <2020-11-27 pią 17:44>, when Qinglang Miao wrote:
>> pm_runtime_get_sync will increment pm usage counter even it
>> failed. Forgetting to putting operation will result in a
>> reference leak here.
>>
>> A new function pm_runtime_resume_and_get is introduced in
>> [0] to keep usage counter balanced. So We fix the reference
>> leak by replacing it with new funtion.
>>
>> [0] dd8088d5a896 ("PM: runtime: Add  pm_runtime_resume_and_get to deal with usage counter")
>>
>> Fixes: 6cd225cc5d8a ("hwrng: exynos - add Samsung Exynos True RNG driver")
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
>> ---
>>   drivers/char/hw_random/exynos-trng.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/char/hw_random/exynos-trng.c b/drivers/char/hw_random/exynos-trng.c
>> index 8e1fe3f8d..666246bc8 100644
>> --- a/drivers/char/hw_random/exynos-trng.c
>> +++ b/drivers/char/hw_random/exynos-trng.c
>> @@ -132,7 +132,7 @@ static int exynos_trng_probe(struct platform_device *pdev)
>>   		return PTR_ERR(trng->mem);
>>   
>>   	pm_runtime_enable(&pdev->dev);
>> -	ret = pm_runtime_get_sync(&pdev->dev);
>> +	ret = pm_runtime_resume_and_get(&pdev->dev);
>>   	if (ret < 0) {
>>   		dev_err(&pdev->dev, "Could not get runtime PM.\n");
>>   		goto err_pm_get;
> 
> Thanks. I suppose you may use the new function exynos_trng_resume(),
> remove everything and leave only
> 
> return pm_runtime_resume_and_get(dev);
Hi, Lukasz

I sent a v2 on this one.

But I'm not really sure about what does 'remove everything' mean. for 
example, should I remove exynos_trng_resume in this patch?

Thanks.
>