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@oss.qualcomm.com>
---
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;
}
--
2.34.1On 04/03/2026 19:03, Shivendra Pratap wrote:
> 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")
I don't think this is correct tag.
That commit added code which was a driver, not subsystem level things.
Using devres, as you pointed out, in platform_driver is correct.
Otherwise please specify what bug from that commit is being fixed.
Best regards,
Krzysztof
On 01-04-2026 20:49, Krzysztof Kozlowski wrote:
> On 04/03/2026 19:03, Shivendra Pratap wrote:
>> 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")
>
> I don't think this is correct tag.
>
> That commit added code which was a driver, not subsystem level things.
> Using devres, as you pointed out, in platform_driver is correct.
sure. thanks. will remove the Fixes tag.
thanks,
Shivendra
Hi,
On Wed, Mar 04, 2026 at 11:33:01PM +0530, Shivendra Pratap wrote:
> 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@oss.qualcomm.com>
> ---
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
The patch does not apply, though.
-- Sebastian
> 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
>
On 11-03-2026 14:51, Sebastian Reichel wrote:
> Hi,
>
> On Wed, Mar 04, 2026 at 11:33:01PM +0530, Shivendra Pratap wrote:
>> 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@oss.qualcomm.com>
>> ---
>
> Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
>
> The patch does not apply, though.
thanks. Will re-base it.
thanks,
Shivendra
On Wed, 4 Mar 2026 19:03:01 +0100, Shivendra Pratap
<shivendra.pratap@oss.qualcomm.com> said:
> 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@oss.qualcomm.com>
> ---
Reviewed-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
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