[PATCH v3 1/6] watchdog: starfive: balance PM refcount when start operation fails

[William Theesfeld]

After pm_runtime_resume_and_get() succeeds in starfive_wdt_pm_start(),
the runtime PM usage counter is incremented.  If starfive_wdt_start()
subsequently fails, the function returns the error without releasing
that reference, leaking the usage counter.

Call pm_runtime_put_sync() on the start failure path so the counter
is balanced.

This also folds in the v1 conversion of pm_runtime_get_sync() to
pm_runtime_resume_and_get(), which was the original purpose of this
patch; both fixes together close the refcount-leak window in this
function as flagged by the maintainer on the v1 thread.

Signed-off-by: William Theesfeld <william@xxxxxxxxxxxxx>
---
 drivers/watchdog/starfive-wdt.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/starfive-wdt.c b/drivers/watchdog/starfive-wdt.c
index af55adc4a..ed8c5711a 100644
--- a/drivers/watchdog/starfive-wdt.c
+++ b/drivers/watchdog/starfive-wdt.c
@@ -371,12 +371,16 @@ static void starfive_wdt_stop(struct starfive_wdt *wdt)
 static int starfive_wdt_pm_start(struct watchdog_device *wdd)
 {
 	struct starfive_wdt *wdt = watchdog_get_drvdata(wdd);
-	int ret = pm_runtime_get_sync(wdd->parent);
+	int ret = pm_runtime_resume_and_get(wdd->parent);
 
 	if (ret < 0)
 		return ret;
 
-	return starfive_wdt_start(wdt);
+	ret = starfive_wdt_start(wdt);
+	if (ret)
+		pm_runtime_put_sync(wdd->parent);
+
+	return ret;
 }
 
 static int starfive_wdt_pm_stop(struct watchdog_device *wdd)
-- 
2.54.0