[PATCH] dmaengine: stm32-mdma: Fix runtime PM reference leak in pm_suspend

[PATCH] dmaengine: stm32-mdma: Fix runtime PM reference leak in pm_suspend

[Xiangwu Lai]

stm32_mdma_pm_suspend() increments the runtime PM usage counter with
pm_runtime_resume_and_get(), but when a channel is still enabled it
returns -EBUSY directly without dropping the reference.  The matching
pm_runtime_put_sync() only runs on the success path.

Each failed suspend attempt therefore leaks one runtime PM reference,
so the device can never runtime suspend afterwards.  Drop the
reference before returning -EBUSY.

Fixes: 7cb819c856d9 ("dmaengine: stm32-mdma: add suspend/resume power management support")
Signed-off-by: Xiangwu Lai <laixiangwu@cmss.chinamobile.com>
---
 drivers/dma/stm32/stm32-mdma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/stm32/stm32-mdma.c b/drivers/dma/stm32/stm32-mdma.c
index e3bbdc9ee..fe1ff4a00 100644
--- a/drivers/dma/stm32/stm32-mdma.c
+++ b/drivers/dma/stm32/stm32-mdma.c
@@ -1785,6 +1785,7 @@ static int stm32_mdma_pm_suspend(struct device *dev)
 		ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(id));
 		if (ccr & STM32_MDMA_CCR_EN) {
 			dev_warn(dev, "Suspend is prevented by Chan %i\n", id);
+			pm_runtime_put_sync(dev);
 			return -EBUSY;
 		}
 	}

Re: [PATCH] dmaengine: stm32-mdma: Fix runtime PM reference leak in pm_suspend

[Amelie Delaunay]

On 11/2/26 11:44, Xiangwu Lai wrote:
> stm32_mdma_pm_suspend() increments the runtime PM usage counter with
> pm_runtime_resume_and_get(), but when a channel is still enabled it
> returns -EBUSY directly without dropping the reference.  The matching
> pm_runtime_put_sync() only runs on the success path.
> 
> Each failed suspend attempt therefore leaks one runtime PM reference,
> so the device can never runtime suspend afterwards.  Drop the
> reference before returning -EBUSY.
> 
> Fixes: 7cb819c856d9 ("dmaengine: stm32-mdma: add suspend/resume power management support")
> Signed-off-by: Xiangwu Lai <laixiangwu@cmss.chinamobile.com>

Thanks for your patch,
Reviewed-by: Amelie Delaunay <amelie.delaunay@foss.st.com>

> ---
>   drivers/dma/stm32/stm32-mdma.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/dma/stm32/stm32-mdma.c b/drivers/dma/stm32/stm32-mdma.c
> index e3bbdc9ee..fe1ff4a00 100644
> --- a/drivers/dma/stm32/stm32-mdma.c
> +++ b/drivers/dma/stm32/stm32-mdma.c
> @@ -1785,6 +1785,7 @@ static int stm32_mdma_pm_suspend(struct device *dev)
>   		ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(id));
>   		if (ccr & STM32_MDMA_CCR_EN) {
>   			dev_warn(dev, "Suspend is prevented by Chan %i\n", id);
> +			pm_runtime_put_sync(dev);
>   			return -EBUSY;
>   		}
>   	}
> 
> 
> 

Re: [PATCH] dmaengine: stm32-mdma: Fix runtime PM reference leak in pm_suspend

[Frank Li]

On Mon, Nov 02, 2026 at 06:44:31PM +0800, Xiangwu Lai wrote:
> [You don't often get email from laixiangwu@cmss.chinamobile.com. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ]
>
> stm32_mdma_pm_suspend() increments the runtime PM usage counter with
> pm_runtime_resume_and_get(), but when a channel is still enabled it
> returns -EBUSY directly without dropping the reference.  The matching
> pm_runtime_put_sync() only runs on the success path.
>
> Each failed suspend attempt therefore leaks one runtime PM reference,
> so the device can never runtime suspend afterwards.  Drop the
> reference before returning -EBUSY.
>
> Fixes: 7cb819c856d9 ("dmaengine: stm32-mdma: add suspend/resume power management support")
> Signed-off-by: Xiangwu Lai <laixiangwu@cmss.chinamobile.com>

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> ---
>  drivers/dma/stm32/stm32-mdma.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/dma/stm32/stm32-mdma.c b/drivers/dma/stm32/stm32-mdma.c
> index e3bbdc9ee..fe1ff4a00 100644
> --- a/drivers/dma/stm32/stm32-mdma.c
> +++ b/drivers/dma/stm32/stm32-mdma.c
> @@ -1785,6 +1785,7 @@ static int stm32_mdma_pm_suspend(struct device *dev)
>                 ccr = stm32_mdma_read(dmadev, STM32_MDMA_CCR(id));
>                 if (ccr & STM32_MDMA_CCR_EN) {
>                         dev_warn(dev, "Suspend is prevented by Chan %i\n", id);
> +                       pm_runtime_put_sync(dev);
>                         return -EBUSY;
>                 }
>         }
>
>
>