From fe070690841b7a7a4957366676844f2b985d952a Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@google.com>
Date: Thu, 28 Jul 2022 09:37:18 +0200
Subject: [PATCH] Revert "thermal/drivers/core: Use a char pointer for the
 cooling device name"

This reverts commit dcf5ffc91c91cf58c5f172e83daa34d5ea6b69fc which is
commit 58483761810087e5ffdf36e84ac1bf26df909097 upstream.

It breaks the Android kernel ABI and is not needed for Android devices,
so it is safe to revert for now.  If it is determined that it is needed
in the future, it can be brought back in an abi-preserving way.

Bug: 161946584
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I1554f3e0e4972d5553d62dc7b994303708c617b5
---
 .../ethernet/mellanox/mlxsw/core_thermal.c    |  2 +-
 drivers/thermal/thermal_core.c                | 38 ++++++++-----------
 include/linux/thermal.h                       |  2 +-
 3 files changed, 18 insertions(+), 24 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
index ecd1856bef5e..7ec1d0ee9bee 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/core_thermal.c
@@ -133,7 +133,7 @@ static int mlxsw_get_cooling_device_idx(struct mlxsw_thermal *thermal,
 	/* Allow mlxsw thermal zone binding to an external cooling device */
 	for (i = 0; i < ARRAY_SIZE(mlxsw_thermal_external_allowed_cdev); i++) {
 		if (strnstr(cdev->type, mlxsw_thermal_external_allowed_cdev[i],
-			    strlen(cdev->type)))
+			    sizeof(cdev->type)))
 			return 0;
 	}
 
diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index e8da2cd61e77..48a993d2236a 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -1095,7 +1095,10 @@ __thermal_cooling_device_register(struct device_node *np,
 {
 	struct thermal_cooling_device *cdev;
 	struct thermal_zone_device *pos = NULL;
-	int ret;
+	int result;
+
+	if (type && strlen(type) >= THERMAL_NAME_LENGTH)
+		return ERR_PTR(-EINVAL);
 
 	if (!ops || !ops->get_max_state || !ops->get_cur_state ||
 	    !ops->set_cur_state)
@@ -1105,17 +1108,14 @@ __thermal_cooling_device_register(struct device_node *np,
 	if (!cdev)
 		return ERR_PTR(-ENOMEM);
 
-	ret = ida_simple_get(&thermal_cdev_ida, 0, 0, GFP_KERNEL);
-	if (ret < 0)
-		goto out_kfree_cdev;
-	cdev->id = ret;
-
-	cdev->type = kstrdup(type ? type : "", GFP_KERNEL);
-	if (!cdev->type) {
-		ret = -ENOMEM;
-		goto out_ida_remove;
+	result = ida_simple_get(&thermal_cdev_ida, 0, 0, GFP_KERNEL);
+	if (result < 0) {
+		kfree(cdev);
+		return ERR_PTR(result);
 	}
 
+	cdev->id = result;
+	strlcpy(cdev->type, type ? : "", sizeof(cdev->type));
 	mutex_init(&cdev->lock);
 	INIT_LIST_HEAD(&cdev->thermal_instances);
 	cdev->np = np;
@@ -1125,9 +1125,12 @@ __thermal_cooling_device_register(struct device_node *np,
 	cdev->devdata = devdata;
 	thermal_cooling_device_setup_sysfs(cdev);
 	dev_set_name(&cdev->device, "cooling_device%d", cdev->id);
-	ret = device_register(&cdev->device);
-	if (ret)
-		goto out_kfree_type;
+	result = device_register(&cdev->device);
+	if (result) {
+		ida_simple_remove(&thermal_cdev_ida, cdev->id);
+		put_device(&cdev->device);
+		return ERR_PTR(result);
+	}
 
 	/* Add 'this' new cdev to the global cdev list */
 	mutex_lock(&thermal_list_lock);
@@ -1145,14 +1148,6 @@ __thermal_cooling_device_register(struct device_node *np,
 	mutex_unlock(&thermal_list_lock);
 
 	return cdev;
-
-out_kfree_type:
-	kfree(cdev->type);
-	put_device(&cdev->device);
-out_ida_remove:
-	ida_simple_remove(&thermal_cdev_ida, cdev->id);
-out_kfree_cdev:
-	return ERR_PTR(ret);
 }
 
 /**
@@ -1311,7 +1306,6 @@ void thermal_cooling_device_unregister(struct thermal_cooling_device *cdev)
 	ida_simple_remove(&thermal_cdev_ida, cdev->id);
 	device_del(&cdev->device);
 	thermal_cooling_device_destroy_sysfs(cdev);
-	kfree(cdev->type);
 	put_device(&cdev->device);
 }
 EXPORT_SYMBOL_GPL(thermal_cooling_device_unregister);
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index e78c34314ec6..a8b81be94a81 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -96,7 +96,7 @@ struct thermal_cooling_device_ops {
 
 struct thermal_cooling_device {
 	int id;
-	char *type;
+	char type[THERMAL_NAME_LENGTH];
 	struct device device;
 	struct device_node *np;
 	void *devdata;