linux-kernel - [PATCH] thermal: core: Save a few bytes of memory when registering a cooling device

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Date: Fri,  5 Jan 2024 14:45:11 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: "Rafael J. Wysocki" <rafael@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Lukasz Luba <lukasz.luba@....com>
Cc: alexis.lothore@...tlin.com,
	linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	linux-pm@...r.kernel.org
Subject: [PATCH] thermal: core: Save a few bytes of memory when registering a cooling device

Some *thermal_cooling_device_register() calls pass a string literal as the
'type' parameter.

So kstrdup_const() can be used instead of kfree() to avoid a memory
allocation in such cases.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
 drivers/thermal/thermal_core.c | 6 +++---
 include/linux/thermal.h        | 2 +-
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/thermal/thermal_core.c b/drivers/thermal/thermal_core.c
index fa88d8707241..d21225ddbf10 100644
--- a/drivers/thermal/thermal_core.c
+++ b/drivers/thermal/thermal_core.c
@@ -846,7 +846,7 @@ static void thermal_release(struct device *dev)
 			    sizeof("cooling_device") - 1)) {
 		cdev = to_cooling_device(dev);
 		thermal_cooling_device_destroy_sysfs(cdev);
-		kfree(cdev->type);
+		kfree_const(cdev->type);
 		ida_free(&thermal_cdev_ida, cdev->id);
 		kfree(cdev);
 	}
@@ -918,7 +918,7 @@ __thermal_cooling_device_register(struct device_node *np,
 	cdev->id = ret;
 	id = ret;
 
-	cdev->type = kstrdup(type ? type : "", GFP_KERNEL);
+	cdev->type = kstrdup_const(type ? type : "", GFP_KERNEL);
 	if (!cdev->type) {
 		ret = -ENOMEM;
 		goto out_ida_remove;
@@ -969,7 +969,7 @@ __thermal_cooling_device_register(struct device_node *np,
 out_cooling_dev:
 	thermal_cooling_device_destroy_sysfs(cdev);
 out_cdev_type:
-	kfree(cdev->type);
+	kfree_const(cdev->type);
 out_ida_remove:
 	ida_free(&thermal_cdev_ida, id);
 out_kfree_cdev:
diff --git a/include/linux/thermal.h b/include/linux/thermal.h
index bf84595a4e86..052c72c0fa17 100644
--- a/include/linux/thermal.h
+++ b/include/linux/thermal.h
@@ -102,7 +102,7 @@ struct thermal_cooling_device_ops {
 
 struct thermal_cooling_device {
 	int id;
-	char *type;
+	const char *type;
 	unsigned long max_state;
 	struct device device;
 	struct device_node *np;
-- 
2.34.1