2022-01-17 06:39:59

by Yongzhi Liu

Subject: [PATCH] dmaengine: ti: Fix runtime PM imbalance on error

pm_runtime_get_sync() increments the runtime PM usage counter even
when it returns an error code, thus a matching decrement is needed on
the error handling path to keep the counter balanced.

Signed-off-by: Yongzhi Liu <[email protected]>
---
drivers/dma/ti/edma.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/ti/edma.c b/drivers/dma/ti/edma.c
index 08e47f4..a73f779 100644
--- a/drivers/dma/ti/edma.c
+++ b/drivers/dma/ti/edma.c
@@ -2398,9 +2398,9 @@ static int edma_probe(struct platform_device *pdev)
platform_set_drvdata(pdev, ecc);

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);
return ret;
}
--
2.7.4

2022-01-23 14:51:42

by Péter Ujfalusi

Subject: Re: [PATCH] dmaengine: ti: Fix runtime PM imbalance on error

On 1/16/22 13:31, Yongzhi Liu wrote:
> pm_runtime_get_sync() increments the runtime PM usage counter even
> when it returns an error code, thus a matching decrement is needed on
> the error handling path to keep the counter balanced.

The patch is correct, however the commit message is a bit incorrect.

We are not adding any visible matching decrement, we are switching to
pm_runtime_resume_and_get() which only increments the usage counter if
pm_runtime_resume() is successful.
Granted internally it does a pm_runtime_put_noidle() if resume call fails.

Switch to pm_runtime_resume_and_get() to keep the device's use caunt
balanced?

>
> Signed-off-by: Yongzhi Liu <[email protected]>
> ---
> drivers/dma/ti/edma.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/dma/ti/edma.c b/drivers/dma/ti/edma.c
> index 08e47f4..a73f779 100644
> --- a/drivers/dma/ti/edma.c
> +++ b/drivers/dma/ti/edma.c
> @@ -2398,9 +2398,9 @@ static int edma_probe(struct platform_device *pdev)
> platform_set_drvdata(pdev, ecc);
>
> 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);
> return ret;
> }

--
Péter

2022-01-23 14:54:27

by Yongzhi Liu

Subject: Re: [PATCH] dmaengine: ti: Fix runtime PM imbalance on error

> -----原始邮件-----
> 发件人: "Péter Ujfalusi" <[email protected]>
> 发送时间: 2022-01-22 16:09:53 (星期六)
> 收件人: "Yongzhi Liu" <[email protected]>, [email protected]
> 抄送: [email protected], [email protected]
> 主题: Re: [PATCH] dmaengine: ti: Fix runtime PM imbalance on error
>
>
>
> On 1/16/22 13:31, Yongzhi Liu wrote:
> > pm_runtime_get_sync() increments the runtime PM usage counter even
> > when it returns an error code, thus a matching decrement is needed on
> > the error handling path to keep the counter balanced.
>
> The patch is correct, however the commit message is a bit incorrect.
>
> We are not adding any visible matching decrement, we are switching to
> pm_runtime_resume_and_get() which only increments the usage counter if
> pm_runtime_resume() is successful.
> Granted internally it does a pm_runtime_put_noidle() if resume call fails.
>
> Switch to pm_runtime_resume_and_get() to keep the device's use caunt
> balanced?
>

Thanks for your reply. I agree with your change and rewrite the commit message as follows.

[why]
pm_runtime_get_sync() increments the runtime PM usage counter even
when it returns an error code, however pm_runtime_resume_and_get()
only increments the usage counter if pm_runtime_resume() is successful,
which granted internally does a pm_runtime_put_noidle() if resume call fails.

[how]
Fix this by switching to pm_runtime_resume_and_get() to keep the device's use count
balanced.


> >
> > Signed-off-by: Yongzhi Liu <[email protected]>
> > ---
> > drivers/dma/ti/edma.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/dma/ti/edma.c b/drivers/dma/ti/edma.c
> > index 08e47f4..a73f779 100644
> > --- a/drivers/dma/ti/edma.c
> > +++ b/drivers/dma/ti/edma.c
> > @@ -2398,9 +2398,9 @@ static int edma_probe(struct platform_device *pdev)
> > platform_set_drvdata(pdev, ecc);
> >
> > 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);
> > return ret;
> > }
>
> --
> Péter