[PATCH] dmaengine: xilinx: zynqmp_dma: fix autosuspend cleanup during teardown

[PATCH] dmaengine: xilinx: zynqmp_dma: fix autosuspend cleanup during teardown

[Guangshuo Li]

zynqmp_dma_probe() calls pm_runtime_use_autosuspend(), but its failure
paths and zynqmp_dma_remove() do not call the matching
pm_runtime_dont_use_autosuspend().

If the autosuspend delay is set to a negative value while autosuspend
is enabled, the runtime PM core increments usage_count to prevent
runtime suspend. Without calling pm_runtime_dont_use_autosuspend()
during teardown, this reference is not dropped and usage_count remains
unbalanced.

The documentation for pm_runtime_use_autosuspend() also notes that it
is important to undo it with pm_runtime_dont_use_autosuspend() at
driver exit time, unless runtime PM was initially enabled with
devm_pm_runtime_enable().

Add the missing pm_runtime_dont_use_autosuspend() calls to the probe
failure and remove paths.

This issue was found by manual code inspection.

Fixes: 64c6f7da8c2c ("dmaengine: zynqmp_dma: Add runtime pm support")
Cc: stable@vger.kernel.org
Signed-off-by: Guangshuo Li <lgs201920130244@gmail.com>
---
 drivers/dma/xilinx/zynqmp_dma.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/xilinx/zynqmp_dma.c b/drivers/dma/xilinx/zynqmp_dma.c
index f6a812e49ddc..635c3f6cc5c2 100644
--- a/drivers/dma/xilinx/zynqmp_dma.c
+++ b/drivers/dma/xilinx/zynqmp_dma.c
@@ -1116,8 +1116,10 @@ static int zynqmp_dma_probe(struct platform_device *pdev)
 	}
 	if (!pm_runtime_enabled(zdev->dev)) {
 		ret = zynqmp_dma_runtime_resume(zdev->dev);
-		if (ret)
+		if (ret) {
+			pm_runtime_dont_use_autosuspend(zdev->dev);
 			return ret;
+		}
 	}
 
 	ret = zynqmp_dma_chan_probe(zdev, pdev);
@@ -1152,6 +1154,7 @@ static int zynqmp_dma_probe(struct platform_device *pdev)
 err_disable_pm:
 	if (!pm_runtime_enabled(zdev->dev))
 		zynqmp_dma_runtime_suspend(zdev->dev);
+	pm_runtime_dont_use_autosuspend(zdev->dev);
 	pm_runtime_disable(zdev->dev);
 	return ret;
 }
@@ -1172,6 +1175,7 @@ static void zynqmp_dma_remove(struct platform_device *pdev)
 	zynqmp_dma_chan_remove(zdev->chan);
 	if (pm_runtime_active(zdev->dev))
 		zynqmp_dma_runtime_suspend(zdev->dev);
+	pm_runtime_dont_use_autosuspend(zdev->dev);
 	pm_runtime_disable(zdev->dev);
 }
 
-- 
2.43.0