Message-ID: <d2859be7-a1e4-9f6a-5df3-e050e42061b9@roeck-us.net>
Date:   Sun, 13 Feb 2022 07:34:04 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Daniel Bristot de Oliveira <bristot@...nel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>
Cc:     Randy Dunlap <rdunlap@...radead.org>,
        linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] watchdog: Improve watchdog_dev function documentation

On 2/11/22 06:30, Daniel Bristot de Oliveira wrote:
> Adjust function comments to the kernel doc format. It
> also adjusts some variable names and adds return values.
> 
> No functional change.
> 
> Changes from V1:
>    Change "Returns" to "Return:" (Randy Dunlap)
> 
> Cc: Wim Van Sebroeck <wim@...ux-watchdog.org>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Randy Dunlap <rdunlap@...radead.org>
> Cc: linux-watchdog@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Daniel Bristot de Oliveira <bristot@...nel.org>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>   drivers/watchdog/watchdog_dev.c | 244 ++++++++++++++++----------------
>   1 file changed, 125 insertions(+), 119 deletions(-)
> 
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 3a3d8b5c7ad5..54903f3c851e 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -171,17 +171,17 @@ static int __watchdog_ping(struct watchdog_device *wdd)
>   }
>   
>   /*
> - *	watchdog_ping: ping the watchdog.
> - *	@wdd: the watchdog device to ping
> + * watchdog_ping - ping the watchdog
> + * @wdd: The watchdog device to ping
>    *
> - *	The caller must hold wd_data->lock.
> + * If the watchdog has no own ping operation then it needs to be
> + * restarted via the start operation. This wrapper function does
> + * exactly that.
> + * We only ping when the watchdog device is running.
> + * The caller must hold wd_data->lock.
>    *
> - *	If the watchdog has no own ping operation then it needs to be
> - *	restarted via the start operation. This wrapper function does
> - *	exactly that.
> - *	We only ping when the watchdog device is running.
> + * Return: 0 on success, error otherwise.
>    */
> -
>   static int watchdog_ping(struct watchdog_device *wdd)
>   {
>   	struct watchdog_core_data *wd_data = wdd->wd_data;
> @@ -231,16 +231,14 @@ static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer)
>   }
>   
>   /*
> - *	watchdog_start: wrapper to start the watchdog.
> - *	@wdd: the watchdog device to start
> + * watchdog_start - wrapper to start the watchdog
> + * @wdd: The watchdog device to start
>    *
> - *	The caller must hold wd_data->lock.
> + * Start the watchdog if it is not active and mark it active.
> + * The caller must hold wd_data->lock.
>    *
> - *	Start the watchdog if it is not active and mark it active.
> - *	This function returns zero on success or a negative errno code for
> - *	failure.
> + * Return: 0 on success or a negative errno code for failure.
>    */
> -
>   static int watchdog_start(struct watchdog_device *wdd)
>   {
>   	struct watchdog_core_data *wd_data = wdd->wd_data;
> @@ -274,17 +272,15 @@ static int watchdog_start(struct watchdog_device *wdd)
>   }
>   
>   /*
> - *	watchdog_stop: wrapper to stop the watchdog.
> - *	@wdd: the watchdog device to stop
> + * watchdog_stop - wrapper to stop the watchdog
> + * @wdd: The watchdog device to stop
>    *
> - *	The caller must hold wd_data->lock.
> + * Stop the watchdog if it is still active and unmark it active.
> + * If the 'nowayout' feature was set, the watchdog cannot be stopped.
> + * The caller must hold wd_data->lock.
>    *
> - *	Stop the watchdog if it is still active and unmark it active.
> - *	This function returns zero on success or a negative errno code for
> - *	failure.
> - *	If the 'nowayout' feature was set, the watchdog cannot be stopped.
> + * Return: 0 on success or a negative errno code for failure.
>    */
> -
>   static int watchdog_stop(struct watchdog_device *wdd)
>   {
>   	int err = 0;
> @@ -315,14 +311,14 @@ static int watchdog_stop(struct watchdog_device *wdd)
>   }
>   
>   /*
> - *	watchdog_get_status: wrapper to get the watchdog status
> - *	@wdd: the watchdog device to get the status from
> + * watchdog_get_status - wrapper to get the watchdog status
> + * @wdd: The watchdog device to get the status from
>    *
> - *	The caller must hold wd_data->lock.
> + * Get the watchdog's status flags.
> + * The caller must hold wd_data->lock.
>    *
> - *	Get the watchdog's status flags.
> + * Return: watchdog's status flags.
>    */
> -
>   static unsigned int watchdog_get_status(struct watchdog_device *wdd)
>   {
>   	struct watchdog_core_data *wd_data = wdd->wd_data;
> @@ -352,13 +348,14 @@ static unsigned int watchdog_get_status(struct watchdog_device *wdd)
>   }
>   
>   /*
> - *	watchdog_set_timeout: set the watchdog timer timeout
> - *	@wdd: the watchdog device to set the timeout for
> - *	@timeout: timeout to set in seconds
> + * watchdog_set_timeout - set the watchdog timer timeout
> + * @wdd:	The watchdog device to set the timeout for
> + * @timeout:	Timeout to set in seconds
> + *
> + * The caller must hold wd_data->lock.
>    *
> - *	The caller must hold wd_data->lock.
> + * Return: 0 if successful, error otherwise.
>    */
> -
>   static int watchdog_set_timeout(struct watchdog_device *wdd,
>   							unsigned int timeout)
>   {
> @@ -385,11 +382,12 @@ static int watchdog_set_timeout(struct watchdog_device *wdd,
>   }
>   
>   /*
> - *	watchdog_set_pretimeout: set the watchdog timer pretimeout
> - *	@wdd: the watchdog device to set the timeout for
> - *	@timeout: pretimeout to set in seconds
> + * watchdog_set_pretimeout - set the watchdog timer pretimeout
> + * @wdd:	The watchdog device to set the timeout for
> + * @timeout:	pretimeout to set in seconds
> + *
> + * Return: 0 if successful, error otherwise.
>    */
> -
>   static int watchdog_set_pretimeout(struct watchdog_device *wdd,
>   				   unsigned int timeout)
>   {
> @@ -410,15 +408,15 @@ static int watchdog_set_pretimeout(struct watchdog_device *wdd,
>   }
>   
>   /*
> - *	watchdog_get_timeleft: wrapper to get the time left before a reboot
> - *	@wdd: the watchdog device to get the remaining time from
> - *	@timeleft: the time that's left
> + * watchdog_get_timeleft - wrapper to get the time left before a reboot
> + * @wdd:	The watchdog device to get the remaining time from
> + * @timeleft:	The time that's left
>    *
> - *	The caller must hold wd_data->lock.
> + * Get the time before a watchdog will reboot (if not pinged).
> + * The caller must hold wd_data->lock.
>    *
> - *	Get the time before a watchdog will reboot (if not pinged).
> + * Return: 0 if successful, error otherwise.
>    */
> -
>   static int watchdog_get_timeleft(struct watchdog_device *wdd,
>   							unsigned int *timeleft)
>   {
> @@ -635,14 +633,15 @@ __ATTRIBUTE_GROUPS(wdt);
>   #endif
>   
>   /*
> - *	watchdog_ioctl_op: call the watchdog drivers ioctl op if defined
> - *	@wdd: the watchdog device to do the ioctl on
> - *	@cmd: watchdog command
> - *	@arg: argument pointer
> + * watchdog_ioctl_op - call the watchdog drivers ioctl op if defined
> + * @wdd: The watchdog device to do the ioctl on
> + * @cmd: Watchdog command
> + * @arg: Argument pointer
>    *
> - *	The caller must hold wd_data->lock.
> + * The caller must hold wd_data->lock.
> + *
> + * Return: 0 if successful, error otherwise.
>    */
> -
>   static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
>   							unsigned long arg)
>   {
> @@ -653,17 +652,18 @@ static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd,
>   }
>   
>   /*
> - *	watchdog_write: writes to the watchdog.
> - *	@file: file from VFS
> - *	@data: user address of data
> - *	@len: length of data
> - *	@ppos: pointer to the file offset
> + * watchdog_write - writes to the watchdog
> + * @file:	File from VFS
> + * @data:	User address of data
> + * @len:	Length of data
> + * @ppos:	Pointer to the file offset
>    *
> - *	A write to a watchdog device is defined as a keepalive ping.
> - *	Writing the magic 'V' sequence allows the next close to turn
> - *	off the watchdog (if 'nowayout' is not set).
> + * A write to a watchdog device is defined as a keepalive ping.
> + * Writing the magic 'V' sequence allows the next close to turn
> + * off the watchdog (if 'nowayout' is not set).
> + *
> + * Return: @len if successful, error otherwise.
>    */
> -
>   static ssize_t watchdog_write(struct file *file, const char __user *data,
>   						size_t len, loff_t *ppos)
>   {
> @@ -706,13 +706,15 @@ static ssize_t watchdog_write(struct file *file, const char __user *data,
>   }
>   
>   /*
> - *	watchdog_ioctl: handle the different ioctl's for the watchdog device.
> - *	@file: file handle to the device
> - *	@cmd: watchdog command
> - *	@arg: argument pointer
> + * watchdog_ioctl - handle the different ioctl's for the watchdog device
> + * @file:	File handle to the device
> + * @cmd:	Watchdog command
> + * @arg:	Argument pointer
>    *
> - *	The watchdog API defines a common set of functions for all watchdogs
> - *	according to their available features.
> + * The watchdog API defines a common set of functions for all watchdogs
> + * according to their available features.
> + *
> + * Return: 0 if successful, error otherwise.
>    */
>   
>   static long watchdog_ioctl(struct file *file, unsigned int cmd,
> @@ -819,15 +821,16 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
>   }
>   
>   /*
> - *	watchdog_open: open the /dev/watchdog* devices.
> - *	@inode: inode of device
> - *	@file: file handle to device
> + * watchdog_open - open the /dev/watchdog* devices
> + * @inode:	Inode of device
> + * @file:	File handle to device
> + *
> + * When the /dev/watchdog* device gets opened, we start the watchdog.
> + * Watch out: the /dev/watchdog device is single open, so we make sure
> + * it can only be opened once.
>    *
> - *	When the /dev/watchdog* device gets opened, we start the watchdog.
> - *	Watch out: the /dev/watchdog device is single open, so we make sure
> - *	it can only be opened once.
> + * Return: 0 if successful, error otherwise.
>    */
> -
>   static int watchdog_open(struct inode *inode, struct file *file)
>   {
>   	struct watchdog_core_data *wd_data;
> @@ -896,15 +899,16 @@ static void watchdog_core_data_release(struct device *dev)
>   }
>   
>   /*
> - *	watchdog_release: release the watchdog device.
> - *	@inode: inode of device
> - *	@file: file handle to device
> + * watchdog_release - release the watchdog device
> + * @inode:	Inode of device
> + * @file:	File handle to device
> + *
> + * This is the code for when /dev/watchdog gets closed. We will only
> + * stop the watchdog when we have received the magic char (and nowayout
> + * was not set), else the watchdog will keep running.
>    *
> - *	This is the code for when /dev/watchdog gets closed. We will only
> - *	stop the watchdog when we have received the magic char (and nowayout
> - *	was not set), else the watchdog will keep running.
> + * Always returns 0.
>    */
> -
>   static int watchdog_release(struct inode *inode, struct file *file)
>   {
>   	struct watchdog_core_data *wd_data = file->private_data;
> @@ -977,14 +981,15 @@ static struct class watchdog_class = {
>   };
>   
>   /*
> - *	watchdog_cdev_register: register watchdog character device
> - *	@wdd: watchdog device
> + * watchdog_cdev_register - register watchdog character device
> + * @wdd: Watchdog device
> + *
> + * Register a watchdog character device including handling the legacy
> + * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
> + * thus we set it up like that.
>    *
> - *	Register a watchdog character device including handling the legacy
> - *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
> - *	thus we set it up like that.
> + * Return: 0 if successful, error otherwise.
>    */
> -
>   static int watchdog_cdev_register(struct watchdog_device *wdd)
>   {
>   	struct watchdog_core_data *wd_data;
> @@ -1074,13 +1079,12 @@ static int watchdog_cdev_register(struct watchdog_device *wdd)
>   }
>   
>   /*
> - *	watchdog_cdev_unregister: unregister watchdog character device
> - *	@watchdog: watchdog device
> + * watchdog_cdev_unregister - unregister watchdog character device
> + * @wdd: Watchdog device
>    *
> - *	Unregister watchdog character device and if needed the legacy
> - *	/dev/watchdog device.
> + * Unregister watchdog character device and if needed the legacy
> + * /dev/watchdog device.
>    */
> -
>   static void watchdog_cdev_unregister(struct watchdog_device *wdd)
>   {
>   	struct watchdog_core_data *wd_data = wdd->wd_data;
> @@ -1109,15 +1113,16 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd)
>   	put_device(&wd_data->dev);
>   }
>   
> -/*
> - *	watchdog_dev_register: register a watchdog device
> - *	@wdd: watchdog device
> +/**
> + * watchdog_dev_register - register a watchdog device
> + * @wdd: Watchdog device
> + *
> + * Register a watchdog device including handling the legacy
> + * /dev/watchdog node. /dev/watchdog is actually a miscdevice and
> + * thus we set it up like that.
>    *
> - *	Register a watchdog device including handling the legacy
> - *	/dev/watchdog node. /dev/watchdog is actually a miscdevice and
> - *	thus we set it up like that.
> + * Return: 0 if successful, error otherwise.
>    */
> -
>   int watchdog_dev_register(struct watchdog_device *wdd)
>   {
>   	int ret;
> @@ -1133,30 +1138,31 @@ int watchdog_dev_register(struct watchdog_device *wdd)
>   	return ret;
>   }
>   
> -/*
> - *	watchdog_dev_unregister: unregister a watchdog device
> - *	@watchdog: watchdog device
> +/**
> + * watchdog_dev_unregister - unregister a watchdog device
> + * @wdd: watchdog device
>    *
> - *	Unregister watchdog device and if needed the legacy
> - *	/dev/watchdog device.
> + * Unregister watchdog device and if needed the legacy
> + * /dev/watchdog device.
>    */
> -
>   void watchdog_dev_unregister(struct watchdog_device *wdd)
>   {
>   	watchdog_unregister_pretimeout(wdd);
>   	watchdog_cdev_unregister(wdd);
>   }
>   
> -/*
> - *	watchdog_set_last_hw_keepalive: set last HW keepalive time for watchdog
> - *	@wdd: watchdog device
> - *	@last_ping_ms: time since last HW heartbeat
> +/**
> + * watchdog_set_last_hw_keepalive - set last HW keepalive time for watchdog
> + * @wdd:		Watchdog device
> + * @last_ping_ms:	Time since last HW heartbeat
>    *
> - *	Adjusts the last known HW keepalive time for a watchdog timer.
> - *	This is needed if the watchdog is already running when the probe
> - *	function is called, and it can't be pinged immediately. This
> - *	function must be called immediately after watchdog registration,
> - *	and min_hw_heartbeat_ms must be set for this to be useful.
> + * Adjusts the last known HW keepalive time for a watchdog timer.
> + * This is needed if the watchdog is already running when the probe
> + * function is called, and it can't be pinged immediately. This
> + * function must be called immediately after watchdog registration,
> + * and min_hw_heartbeat_ms must be set for this to be useful.
> + *
> + * Return: 0 if successful, error otherwise.
>    */
>   int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
>   				   unsigned int last_ping_ms)
> @@ -1180,12 +1186,13 @@ int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
>   }
>   EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
>   
> -/*
> - *	watchdog_dev_init: init dev part of watchdog core
> +/**
> + * watchdog_dev_init - init dev part of watchdog core
>    *
> - *	Allocate a range of chardev nodes to use for watchdog devices
> + * Allocate a range of chardev nodes to use for watchdog devices.
> + *
> + * Return: 0 if successful, error otherwise.
>    */
> -
>   int __init watchdog_dev_init(void)
>   {
>   	int err;
> @@ -1218,12 +1225,11 @@ int __init watchdog_dev_init(void)
>   	return err;
>   }
>   
> -/*
> - *	watchdog_dev_exit: exit dev part of watchdog core
> +/**
> + * watchdog_dev_exit - exit dev part of watchdog core
>    *
> - *	Release the range of chardev nodes used for watchdog devices
> + * Release the range of chardev nodes used for watchdog devices.
>    */
> -
>   void __exit watchdog_dev_exit(void)
>   {
>   	unregister_chrdev_region(watchdog_devt, MAX_DOGS);

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