[PATCH v21 01/13] power: reset: reboot-mode: Remove devres based allocations

Shivendra Pratap
2026-04-27T17:35:34Z

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.

Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
Signed-off-by: Shivendra Pratap <shivendra.pratap@oss.qualcomm.com>
---
drivers/power/reset/reboot-mode.c | 32 ++++++++++++++++++++------------
1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
index d20e44db053256d87ad8034ddab233e49d36072d..7a74f72a8313b73c3e0930a426ebcf7ef6eed99b 100644
--- a/drivers/power/reset/reboot-mode.c
+++ b/drivers/power/reset/reboot-mode.c
@@ -3,6 +3,8 @@
* Copyright (c) 2016, Fuzhou Rockchip Electronics Co., Ltd
*/

+#define pr_fmt(fmt) "reboot-mode: " fmt
+
#include <linux/device.h>
#include <linux/err.h>
#include <linux/init.h>
@@ -10,6 +12,7 @@
#include <linux/list.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>
@@ -168,10 +171,11 @@ static int reboot_mode_create_device(struct reboot_mode_driver *reboot)
*/
int reboot_mode_register(struct reboot_mode_driver *reboot)
{
- struct mode_info *info;
+ struct mode_info *info = NULL;
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);
@@ -180,19 +184,18 @@ 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;
@@ -200,12 +203,12 @@ 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;
}

list_add_tail(&info->list, &reboot->head);
+ info = NULL;
}

reboot->reboot_notifier.notifier_call = reboot_mode_notify;
@@ -218,6 +221,7 @@ int reboot_mode_register(struct reboot_mode_driver *reboot)
return 0;

error:
+ kfree(info);
reboot_mode_unregister(reboot);
return ret;
}
@@ -261,12 +265,16 @@ static inline void reboot_mode_unregister_device(struct reboot_mode_driver *rebo
int reboot_mode_unregister(struct reboot_mode_driver *reboot)
{
struct mode_info *info;
+ struct mode_info *next;

unregister_reboot_notifier(&reboot->reboot_notifier);
reboot_mode_unregister_device(reboot);

- 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