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

[Xiangwu Lai]

stm32_dma_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: 05f8740a0e6f ("dmaengine: stm32-dma: add suspend/resume power management support")
Signed-off-by: Xiangwu Lai <laixiangwu at cmss.chinamobile.com>
---
 drivers/dma/stm32/stm32-dma.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/dma/stm32/stm32-dma.c b/drivers/dma/stm32/stm32-dma.c
index d3ad78562..2abe846a9 100644
--- a/drivers/dma/stm32/stm32-dma.c
+++ b/drivers/dma/stm32/stm32-dma.c
@@ -1743,6 +1743,7 @@ static int stm32_dma_pm_suspend(struct device *dev)
 		scr = stm32_dma_read(dmadev, STM32_DMA_SCR(id));
 		if (scr & STM32_DMA_SCR_EN) {
 			dev_warn(dev, "Suspend is prevented by Chan %i\n", id);
+			pm_runtime_put_sync(dev);
 			return -EBUSY;
 		}
 	}