[PATCH v20 01/10] power: reset: reboot-mode: Remove devres based allocations

[Shivendra Pratap]

Devres APIs are intended for use in drivers, where the managed lifetime
of resources is tied directly to the driver attach/detach cycle. In
shared subsystem code, there is no guarantee that the subsystem
functions will only be called after a driver has been attached, nor that
they will not be referenced after the managed resources have been
released during driver detach.

To ensure correct lifetime handling, avoid using devres-based
allocations in the reboot-mode and explicitly handle allocation and
cleanup of resources.

Fixes: 4fcd504edbf7 ("power: reset: add reboot mode driver")
Signed-off-by: Shivendra Pratap <shivendra.pratap@xxxxxxxxxxxxxxxx>
---
 drivers/power/reset/reboot-mode.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
index fba53f638da04655e756b5f8b7d2d666d1379535..d033043f5250a4de152a7786ef37e88a0ace3bbb 100644
--- a/drivers/power/reset/reboot-mode.c
+++ b/drivers/power/reset/reboot-mode.c
@@ -3,13 +3,17 @@
  * Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
  */
 
+#define pr_fmt(fmt)	"reboot-mode: " fmt
+
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/property.h>
 #include <linux/reboot.h>
 #include <linux/reboot-mode.h>
+#include <linux/slab.h>
 
 #define PREFIX "mode-"
 
@@ -74,6 +78,7 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
 	struct property *prop;
 	struct device_node *np = reboot->dev->of_node;
 	size_t len = strlen(PREFIX);
+	u32 magic;
 	int ret;
 
 	INIT_LIST_HEAD(&reboot->head);
@@ -82,19 +87,18 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
 		if (strncmp(prop->name, PREFIX, len))
 			continue;
 
-		info = devm_kzalloc(reboot->dev, sizeof(*info), GFP_KERNEL);
+		if (device_property_read_u32(reboot->dev, prop->name, &magic)) {
+			pr_debug("reboot mode %s without magic number\n", prop->name);
+			continue;
+		}
+
+		info = kzalloc(sizeof(*info), GFP_KERNEL);
 		if (!info) {
 			ret = -ENOMEM;
 			goto error;
 		}
 
-		if (of_property_read_u32(np, prop->name, &info->magic)) {
-			dev_err(reboot->dev, "reboot mode %s without magic number\n",
-				info->mode);
-			devm_kfree(reboot->dev, info);
-			continue;
-		}
-
+		info->magic = magic;
 		info->mode = kstrdup_const(prop->name + len, GFP_KERNEL);
 		if (!info->mode) {
 			ret =  -ENOMEM;
@@ -102,8 +106,7 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
 		} else if (info->mode[0] == '\0') {
 			kfree_const(info->mode);
 			ret = -EINVAL;
-			dev_err(reboot->dev, "invalid mode name(%s): too short!\n",
-				prop->name);
+			pr_err("invalid mode name(%s): too short!\n", prop->name);
 			goto error;
 		}
 
@@ -116,8 +119,8 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
 	return 0;
 
 error:
-	list_for_each_entry(info, &reboot->head, list)
-		kfree_const(info->mode);
+	kfree(info);
+	reboot_mode_unregister(reboot);
 
 	return ret;
 }
@@ -130,11 +133,15 @@ EXPORT_SYMBOL_GPL(reboot_mode_register);
 int reboot_mode_unregister(struct reboot_mode_driver *reboot)
 {
 	struct mode_info *info;
+	struct mode_info *next;
 
 	unregister_reboot_notifier(&reboot->reboot_notifier);
 
-	list_for_each_entry(info, &reboot->head, list)
+	list_for_each_entry_safe(info, next, &reboot->head, list) {
+		list_del(&info->list);
 		kfree_const(info->mode);
+		kfree(info);
+	}
 
 	return 0;
 }

-- 
2.34.1