linux-kernel - [PATCH RESEND] PM: domains: Fix return value of API dev_pm_get_subsys

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Message-Id: <20241028-fix_dev_pm_get_subsys_data-v1-1-20385f4b1e17@quicinc.com>
Date: Mon, 28 Oct 2024 20:31:11 +0800
From: Zijun Hu <zijun_hu@...oud.com>
To: "Rafael J. Wysocki" <rafael@...nel.org>, Pavel Machek <pavel@....cz>, 
 Len Brown <len.brown@...el.com>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Zijun Hu <zijun_hu@...oud.com>, linux-pm@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Zijun Hu <quic_zijuhu@...cinc.com>, 
 stable@...r.kernel.org
Subject: [PATCH RESEND] PM: domains: Fix return value of API
 dev_pm_get_subsys_data()

From: Zijun Hu <quic_zijuhu@...cinc.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@...r.kernel.org
Signed-off-by: Zijun Hu <quic_zijuhu@...cinc.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@...cinc.com>