[PATCH] dmaengine: qcom_hidma: Fix runtime PM leak in hidma_issue_task()

[Wentao Liang]

hidma_issue_task() bumps the device usage counter with
pm_runtime_get_sync() without checking the return value. The counter
is incremented even when the resume fails, e.g. when runtime PM has
been disabled or the device is suspending, and nothing drops it in
that case, so each failure leaves the device with an elevated usage
count and it can no longer runtime suspend.

Bail out and drop the leaked increment with pm_runtime_put_noidle()
when the resume fails, and only start the transfer when the device is
actually resumed. The counter for a successful resume is still
dropped by hidma_callback() as before.

Fixes: 67a2003e0607 ("dmaengine: add Qualcomm Technologies HIDMA channel driver")
Cc: stable at vger.kernel.org
Signed-off-by: Wentao Liang <vulab at iscas.ac.cn>
---
 drivers/dma/qcom/hidma.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/qcom/hidma.c b/drivers/dma/qcom/hidma.c
index 5a8dca8db5ce..03a73dc9b066 100644
--- a/drivers/dma/qcom/hidma.c
+++ b/drivers/dma/qcom/hidma.c
@@ -220,7 +220,10 @@ static void hidma_issue_task(struct tasklet_struct *t)
 {
 	struct hidma_dev *dmadev = from_tasklet(dmadev, t, task);
 
-	pm_runtime_get_sync(dmadev->ddev.dev);
+	if (pm_runtime_get_sync(dmadev->ddev.dev) < 0) {
+		pm_runtime_put_noidle(dmadev->ddev.dev);
+		return;
+	}
 	hidma_ll_start(dmadev->lldev);
 }
 
-- 
2.34.1