[PATCH] PM: domains: Fix return value of API dev_pm_get_subsys_data()

[Zijun Hu <zijun_hu@icloud.com>]

From: Zijun Hu <quic_zijuhu@quicinc.com>

dev_pm_get_subsys_data() has below 2 issues under condition
(@dev->power.subsys_data != NULL):

- it will do unnecessary kzalloc() and kfree().
- it will return -ENOMEM if the kzalloc() fails, that is wrong
  since the kzalloc() is not needed.

Fixed by not doing kzalloc() and returning 0 for the condition.

Fixes: ef27bed1870d ("PM: Reference counting of power.subsys_data")
Cc: stable@vger.kernel.org
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
---
 drivers/base/power/common.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/base/power/common.c b/drivers/base/power/common.c
index 8c34ae1cd8d5..13cb1f2a06e7 100644
--- a/drivers/base/power/common.c
+++ b/drivers/base/power/common.c
@@ -26,6 +26,14 @@ int dev_pm_get_subsys_data(struct device *dev)
 {
 	struct pm_subsys_data *psd;
 
+	spin_lock_irq(&dev->power.lock);
+	if (dev->power.subsys_data) {
+		dev->power.subsys_data->refcount++;
+		spin_unlock_irq(&dev->power.lock);
+		return 0;
+	}
+	spin_unlock_irq(&dev->power.lock);
+
 	psd = kzalloc(sizeof(*psd), GFP_KERNEL);
 	if (!psd)
 		return -ENOMEM;

---
base-commit: 9852d85ec9d492ebef56dc5f229416c925758edc
change-id: 20241010-fix_dev_pm_get_subsys_data-2478bb200fde

Best regards,
-- 
Zijun Hu <quic_zijuhu@quicinc.com>