[PATCH] drm/panfrost: fix reference leak in panfrost_job_hw_submit

[PATCH] drm/panfrost: fix reference leak in panfrost_job_hw_submit

[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: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
---
 drivers/gpu/drm/panfrost/panfrost_job.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
index 30e7b7196..04cf3bb67 100644
--- a/drivers/gpu/drm/panfrost/panfrost_job.c
+++ b/drivers/gpu/drm/panfrost/panfrost_job.c
@@ -147,7 +147,7 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
 
 	panfrost_devfreq_record_busy(&pfdev->pfdevfreq);
 
-	ret = pm_runtime_get_sync(pfdev->dev);
+	ret = pm_runtime_resume_and_get(pfdev->dev);
 	if (ret < 0)
 		return;
 
-- 
2.23.0

Re: [PATCH] drm/panfrost: fix reference leak in panfrost_job_hw_submit

[Steven Price]

On 27/11/2020 09:44, 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: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
> ---
>   drivers/gpu/drm/panfrost/panfrost_job.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index 30e7b7196..04cf3bb67 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -147,7 +147,7 @@ static void panfrost_job_hw_submit(struct panfrost_job *job, int js)
>   
>   	panfrost_devfreq_record_busy(&pfdev->pfdevfreq);
>   
> -	ret = pm_runtime_get_sync(pfdev->dev);
> +	ret = pm_runtime_resume_and_get(pfdev->dev);

Sorry, but in this case this change isn't correct. 
panfrost_job_hw_submit() is expected to be unbalanced (the PM reference 
count is expected to be incremented on return).

In the case where pm_runtime_get_sync() fails, the job will eventually 
timeout, and there's a corresponding pm_runtime_put_noidle() in 
panfrost_reset().

Potentially this could be handled better (e.g. without waiting for the 
timeout to occur), but equally this isn't something we expect to happen 
in normal operation).

Steve

>   	if (ret < 0)
>   		return;
>   
> 

Re: [PATCH] drm/panfrost: fix reference leak in panfrost_job_hw_submit

[Qinglang Miao]

在 2020/11/27 18:06, Steven Price 写道:
> On 27/11/2020 09:44, 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: f3ba91228e8e ("drm/panfrost: Add initial panfrost driver")
>> Reported-by: Hulk Robot <hulkci@huawei.com>
>> Signed-off-by: Qinglang Miao <miaoqinglang@huawei.com>
>> ---
>>   drivers/gpu/drm/panfrost/panfrost_job.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c 
>> b/drivers/gpu/drm/panfrost/panfrost_job.c
>> index 30e7b7196..04cf3bb67 100644
>> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
>> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
>> @@ -147,7 +147,7 @@ static void panfrost_job_hw_submit(struct 
>> panfrost_job *job, int js)
>>       panfrost_devfreq_record_busy(&pfdev->pfdevfreq);
>> -    ret = pm_runtime_get_sync(pfdev->dev);
>> +    ret = pm_runtime_resume_and_get(pfdev->dev);
> 
> Sorry, but in this case this change isn't correct. 
> panfrost_job_hw_submit() is expected to be unbalanced (the PM reference 
> count is expected to be incremented on return).
> 
> In the case where pm_runtime_get_sync() fails, the job will eventually 
> timeout, and there's a corresponding pm_runtime_put_noidle() in 
> panfrost_reset().
> 
> Potentially this could be handled better (e.g. without waiting for the 
> timeout to occur), but equally this isn't something we expect to happen 
> in normal operation).
> 
> Steve
Sorry, I didn't notice the pm_runtime_put_noidle() in 
panfrost_job_timedout() before.

Thanks for your reply.
> 
>>       if (ret < 0)
>>           return;
>>
> 
> .