netdev - [PATCH v3 1/2] PM: runtime: Add pm_runtime_resume_and

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Date:   Tue, 10 Nov 2020 17:29:32 +0800
From:   Zhang Qilong <zhangqilong3@...wei.com>
To:     <rjw@...ysocki.net>, <fugang.duan@....com>, <davem@...emloft.net>,
        <kuba@...nel.org>
CC:     <linux-pm@...r.kernel.org>, <netdev@...r.kernel.org>
Subject: [PATCH v3 1/2] PM: runtime: Add pm_runtime_resume_and_get to deal with usage counter

In many case, we need to check return value of pm_runtime_get_sync, but
it brings a trouble to the usage counter processing. Many callers forget
to decrease the usage counter when it failed, which could resulted in
reference leak. It has been discussed a lot[0][1]. So we add a function
to deal with the usage counter for better coding.

[0]https://lkml.org/lkml/2020/6/14/88
[1]https://patchwork.ozlabs.org/project/linux-tegra/list/?series=178139
Signed-off-by: Zhang Qilong <zhangqilong3@...wei.com>
---
 include/linux/pm_runtime.h | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/include/linux/pm_runtime.h b/include/linux/pm_runtime.h
index 4b708f4e8eed..b492ae00cc90 100644
--- a/include/linux/pm_runtime.h
+++ b/include/linux/pm_runtime.h
@@ -386,6 +386,27 @@ static inline int pm_runtime_get_sync(struct device *dev)
 	return __pm_runtime_resume(dev, RPM_GET_PUT);
 }
 
+/**
+ * pm_runtime_resume_and_get - Bump up usage counter of a device and resume it.
+ * @dev: Target device.
+ *
+ * Resume @dev synchronously and if that is successful, increment its runtime
+ * PM usage counter. Return 0 if the runtime PM usage counter of @dev has been
+ * incremented or a negative error code otherwise.
+ */
+static inline int pm_runtime_resume_and_get(struct device *dev)
+{
+	int ret;
+
+	ret = __pm_runtime_resume(dev, RPM_GET_PUT);
+	if (ret < 0) {
+		pm_runtime_put_noidle(dev);
+		return ret;
+	}
+
+	return 0;
+}
+
 /**
  * pm_runtime_put - Drop device usage counter and queue up "idle check" if 0.
  * @dev: Target device.
-- 
2.25.4