[PATCH v2 3/6] watchdog: starfive: balance PM refcount and disable in probe error paths

[William Theesfeld]

The probe path takes a runtime PM reference via
pm_runtime_resume_and_get() (or enables the clocks directly when
runtime PM is unavailable), but several error paths after that point
do not release that reference before returning, and the two earliest
error paths return without calling pm_runtime_disable() at all even
though pm_runtime_enable() has already run.

Restructure the error handling into three labels so every failure
path balances exactly the resources it has acquired:

  err_pm_disable: pm_runtime_enable() ran but no clock/refcount was
                  taken yet (resume_and_get / enable_clock failed).
  err_put_pm:     clock or PM refcount is held; release it, then
                  fall through to disable runtime PM.
  err_unregister_wdt: watchdog_register_device() succeeded; unregister
                  before releasing the refcount.

Update the in-function goto targets to use these labels and remove
the early "return ret;" paths so pm_runtime_disable() is always run
once pm_runtime_enable() has been called.

Signed-off-by: William Theesfeld <william@xxxxxxxxxxxxx>
---
 drivers/watchdog/starfive-wdt.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/watchdog/starfive-wdt.c b/drivers/watchdog/starfive-wdt.c
index c821b38d2..6539bf089 100644
--- a/drivers/watchdog/starfive-wdt.c
+++ b/drivers/watchdog/starfive-wdt.c
@@ -460,17 +460,17 @@ static int starfive_wdt_probe(struct platform_device *pdev)
 	if (pm_runtime_enabled(&pdev->dev)) {
 		ret = pm_runtime_resume_and_get(&pdev->dev);
 		if (ret < 0)
-			return ret;
+			goto err_pm_disable;
 	} else {
 		/* runtime PM is disabled but clocks need to be enabled */
 		ret = starfive_wdt_enable_clock(wdt);
 		if (ret)
-			return ret;
+			goto err_pm_disable;
 	}
 
 	ret = starfive_wdt_reset_init(&pdev->dev);
 	if (ret)
-		goto err_exit;
+		goto err_put_pm;
 
 	watchdog_set_drvdata(&wdt->wdd, wdt);
 	wdt->wdd.info = &starfive_wdt_info;
@@ -482,7 +482,7 @@ static int starfive_wdt_probe(struct platform_device *pdev)
 	if (!wdt->freq) {
 		dev_err(&pdev->dev, "get clock rate failed.\n");
 		ret = -EINVAL;
-		goto err_exit;
+		goto err_put_pm;
 	}
 
 	wdt->wdd.min_timeout = 1;
@@ -498,7 +498,7 @@ static int starfive_wdt_probe(struct platform_device *pdev)
 	if (early_enable) {
 		ret = starfive_wdt_start(wdt);
 		if (ret)
-			goto err_exit;
+			goto err_put_pm;
 		set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
 	} else {
 		starfive_wdt_stop(wdt);
@@ -506,7 +506,7 @@ static int starfive_wdt_probe(struct platform_device *pdev)
 
 	ret = watchdog_register_device(&wdt->wdd);
 	if (ret)
-		goto err_exit;
+		goto err_put_pm;
 
 	if (!early_enable) {
 		if (pm_runtime_enabled(&pdev->dev)) {
@@ -520,8 +520,12 @@ static int starfive_wdt_probe(struct platform_device *pdev)
 
 err_unregister_wdt:
 	watchdog_unregister_device(&wdt->wdd);
-err_exit:
-	starfive_wdt_disable_clock(wdt);
+err_put_pm:
+	if (pm_runtime_enabled(&pdev->dev))
+		pm_runtime_put_sync(&pdev->dev);
+	else
+		starfive_wdt_disable_clock(wdt);
+err_pm_disable:
 	pm_runtime_disable(&pdev->dev);
 
 	return ret;
-- 
2.54.0