linux-kernel - [PATCH] thermal/core: cooling device duplicate creation check

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Date:   Wed, 26 Oct 2022 20:03:21 +0800
From:   Qibo Huang <huangqibo.tech@...il.com>
To:     rafael@...nel.org, daniel.lezcano@...aro.org, amitk@...nel.org,
        rui.zhang@...el.com
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        huangqibo <huangqibo@...omi.com>
Subject: [PATCH] thermal/core: cooling device duplicate creation check

From: huangqibo <huangqibo@...omi.com>

Because creating a cooling device may have duplicate names.
When creating, first check thermal_cdev_list whether
there is a device with the same name. If it has the same name,
it returns a reference to the cooling device.

Signed-off-by: huangqibo <huangqibo@...omi.com>
---
 drivers/thermal/thermal_core.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index 117eeaf7dd24..092c7732a294 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -873,6 +873,12 @@ __thermal_cooling_device_register(struct device_node *np,
 	    !ops->set_cur_state)
 		return ERR_PTR(-EINVAL);
 
+	if (type)
+		cdev = thermal_cdev_get_zone_by_name(type);
+
+	if (!IS_ERR_OR_NULL(cdev))
+		return cdev;
+
 	cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
 	if (!cdev)
 		return ERR_PTR(-ENOMEM);
@@ -1435,6 +1441,34 @@ struct thermal_zone_device *thermal_zone_get_zone_by_name(const char *name)
 }
 EXPORT_SYMBOL_GPL(thermal_zone_get_zone_by_name);
 
+struct thermal_cooling_device *thermal_cdev_get_zone_by_name(const char *name)
+{
+	struct thermal_cooling_device *pos = NULL, *ref = ERR_PTR(-EINVAL);
+	unsigned int found = 0;
+
+	if (!name)
+		goto exit;
+
+	mutex_lock(&thermal_list_lock);
+	list_for_each_entry(pos, &thermal_cdev_list, node)
+		if (!strncasecmp(name, pos->type, THERMAL_NAME_LENGTH)) {
+			found++;
+			ref = pos;
+		}
+	mutex_unlock(&thermal_list_lock);
+
+	/* nothing has been found, thus an error code for it */
+	if (found == 0)
+		ref = ERR_PTR(-ENODEV);
+	else if (found > 1)
+	/* Success only when an unique zone is found */
+		ref = ERR_PTR(-EEXIST);
+
+exit:
+	return ref;
+}
+EXPORT_SYMBOL_GPL(thermal_cdev_get_zone_by_name);
+
 static int thermal_pm_notify(struct notifier_block *nb,
 			     unsigned long mode, void *_unused)
 {
-- 
2.36.1