[PATCH v11 1/8] power: reset: reboot-mode: Add device tree node-based registration

[Dmitry Baryshkov]

On Thu, Jul 17, 2025 at 06:16:47PM +0530, Shivendra Pratap wrote:
> The reboot-mode driver does not have a strict requirement for
> device-based registration. It primarily uses the device's of_node
> to read mode-<cmd> properties and the device pointer for logging.
> 
> Remove the dependency on struct device and introduce support for
> Device Tree (DT) node-based registration. This enables drivers
> that are not associated with a struct device to leverage the
> reboot-mode framework.
> 
> Signed-off-by: Shivendra Pratap <shivendra.pratap at oss.qualcomm.com>
> ---
>  drivers/power/reset/reboot-mode.c | 29 +++++++++++++++++++----------
>  include/linux/reboot-mode.h       |  2 +-
>  2 files changed, 20 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/power/reset/reboot-mode.c b/drivers/power/reset/reboot-mode.c
> index fba53f638da04655e756b5f8b7d2d666d1379535..0269ec55106472cf2f2b12bd65704dd0114bf4a3 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/list.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/reboot.h>
>  #include <linux/reboot-mode.h>
> +#include <linux/slab.h>
>  
>  #define PREFIX "mode-"
>  
> @@ -65,33 +69,35 @@ static int reboot_mode_notify(struct notifier_block *this,
>  /**
>   * reboot_mode_register - register a reboot mode driver
>   * @reboot: reboot mode driver
> + * @np: Pointer to device tree node
>   *
>   * Returns: 0 on success or a negative error code on failure.
>   */
> -int reboot_mode_register(struct reboot_mode_driver *reboot)
> +int reboot_mode_register(struct reboot_mode_driver *reboot, struct device_node *np)
>  {
>  	struct mode_info *info;
>  	struct property *prop;
> -	struct device_node *np = reboot->dev->of_node;
>  	size_t len = strlen(PREFIX);
>  	int ret;
>  
> +	if (!np)
> +		return -EINVAL;
> +
>  	INIT_LIST_HEAD(&reboot->head);
>  
>  	for_each_property_of_node(np, prop) {
>  		if (strncmp(prop->name, PREFIX, len))
>  			continue;
>  
> -		info = devm_kzalloc(reboot->dev, sizeof(*info), GFP_KERNEL);
> +		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);
> +			pr_err("reboot mode %s without magic number\n", info->mode);
> +			kfree(info);
>  			continue;
>  		}
>  
> @@ -102,8 +108,7 @@ 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;
>  		}
>  
> @@ -130,11 +135,15 @@ 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) {

This feels liks a missing lock.

>  		kfree_const(info->mode);
> +		list_del(&info->list);

list_del should come before kfree, otherwise it's possible to access
freed memory while traversing the list.

> +		kfree(info);
> +	}
>  
>  	return 0;
>  }
> @@ -162,7 +171,7 @@ int devm_reboot_mode_register(struct device *dev,
>  	if (!dr)
>  		return -ENOMEM;
>  
> -	rc = reboot_mode_register(reboot);
> +	rc = reboot_mode_register(reboot, reboot->dev->of_node);
>  	if (rc) {
>  		devres_free(dr);
>  		return rc;
> diff --git a/include/linux/reboot-mode.h b/include/linux/reboot-mode.h
> index 4a2abb38d1d612ec0fdf05eb18c98b210f631b7f..36f071f4b82e1fc255d8dd679a18e537655c3179 100644
> --- a/include/linux/reboot-mode.h
> +++ b/include/linux/reboot-mode.h
> @@ -9,7 +9,7 @@ struct reboot_mode_driver {
>  	struct notifier_block reboot_notifier;
>  };
>  
> -int reboot_mode_register(struct reboot_mode_driver *reboot);
> +int reboot_mode_register(struct reboot_mode_driver *reboot, struct device_node *np);
>  int reboot_mode_unregister(struct reboot_mode_driver *reboot);
>  int devm_reboot_mode_register(struct device *dev,
>  			      struct reboot_mode_driver *reboot);
> 
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry