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

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Message-Id: <20221027031648.2452-1-huangqibo.tech@gmail.com>
Date:   Thu, 27 Oct 2022 11:16:48 +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,
        Qibo Huang <huangqibo.tech@...il.com>
Subject: [PATCH] thermal/core: cooling device duplicate creation check

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: Qibo Huang <huangqibo.tech@...il.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 7e669b60a065..f38f9464e9f4 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -844,6 +844,34 @@ static void bind_cdev(struct thermal_cooling_device *cdev)
 	mutex_unlock(&thermal_list_lock);
 }
 
+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);
+
 /**
  * __thermal_cooling_device_register() - register a new thermal cooling device
  * @np:		a pointer to a device tree node.
@@ -873,6 +901,12 @@ __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(cdev))
+			return cdev;
+	}
+
 	cdev = kzalloc(sizeof(*cdev), GFP_KERNEL);
 	if (!cdev)
 		return ERR_PTR(-ENOMEM);
-- 
2.37.1