linux-kernel - Re: [PATCH v2] watchdog: core: Make use of devm_register_reboot

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Date:   Sat, 15 Apr 2017 23:11:16 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Andrey Smirnov <andrew.smirnov@...il.com>,
        linux-watchdog@...r.kernel.org
Cc:     cphealy@...il.com, linux-kernel@...r.kernel.org,
        Wim Van Sebroeck <wim@...ana.be>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v2] watchdog: core: Make use of
 devm_register_reboot_notifier()

On 04/11/2017 09:06 AM, Andrey Smirnov wrote:
> Save a bit of cleanup code by leveraging newly added
> devm_register_reboot_notifier().
>
> Cc: cphealy@...il.com
> Cc: linux-kernel@...r.kernel.org
> Cc: Wim Van Sebroeck <wim@...ana.be>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Andy Shevchenko <andy.shevchenko@...il.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>

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

> ---
>
> Guenter, Andy:
>
> Here's the second version of the patch originally submitted in
> [v1]. This time I tried to follow Guenter's suggestion of moving this
> bit on initialization in watchdog_dev_register().
>
> If I missed something obvious why this patch wouldn't work, again,
> please let me know.
>
> Patch introducting devm_register_reboot_notifier() can be found in
> [other-patch]
>
> Thanks,
> Andrey Smirnov
>
> [v1] https://lkml.org/lkml/2017/4/4/388
> [other-patch] https://lkml.org/lkml/2017/3/20/671
>
>
>  drivers/watchdog/watchdog_core.c | 35 -----------------------------------
>  drivers/watchdog/watchdog_dev.c  | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 32 insertions(+), 35 deletions(-)
>
> diff --git a/drivers/watchdog/watchdog_core.c b/drivers/watchdog/watchdog_core.c
> index 74265b2..8a8d952 100644
> --- a/drivers/watchdog/watchdog_core.c
> +++ b/drivers/watchdog/watchdog_core.c
> @@ -137,25 +137,6 @@ int watchdog_init_timeout(struct watchdog_device *wdd,
>  }
>  EXPORT_SYMBOL_GPL(watchdog_init_timeout);
>
> -static int watchdog_reboot_notifier(struct notifier_block *nb,
> -				    unsigned long code, void *data)
> -{
> -	struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
> -						   reboot_nb);
> -
> -	if (code == SYS_DOWN || code == SYS_HALT) {
> -		if (watchdog_active(wdd)) {
> -			int ret;
> -
> -			ret = wdd->ops->stop(wdd);
> -			if (ret)
> -				return NOTIFY_BAD;
> -		}
> -	}
> -
> -	return NOTIFY_DONE;
> -}
> -
>  static int watchdog_restart_notifier(struct notifier_block *nb,
>  				     unsigned long action, void *data)
>  {
> @@ -244,19 +225,6 @@ static int __watchdog_register_device(struct watchdog_device *wdd)
>  		}
>  	}
>
> -	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
> -		wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
> -
> -		ret = register_reboot_notifier(&wdd->reboot_nb);
> -		if (ret) {
> -			pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
> -			       wdd->id, ret);
> -			watchdog_dev_unregister(wdd);
> -			ida_simple_remove(&watchdog_ida, wdd->id);
> -			return ret;
> -		}
> -	}
> -
>  	if (wdd->ops->restart) {
>  		wdd->restart_nb.notifier_call = watchdog_restart_notifier;
>
> @@ -302,9 +270,6 @@ static void __watchdog_unregister_device(struct watchdog_device *wdd)
>  	if (wdd->ops->restart)
>  		unregister_restart_handler(&wdd->restart_nb);
>
> -	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status))
> -		unregister_reboot_notifier(&wdd->reboot_nb);
> -
>  	watchdog_dev_unregister(wdd);
>  	ida_simple_remove(&watchdog_ida, wdd->id);
>  }
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 32930a0..9a52990 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -42,6 +42,7 @@
>  #include <linux/miscdevice.h>	/* For handling misc devices */
>  #include <linux/module.h>	/* For module stuff/... */
>  #include <linux/mutex.h>	/* For mutexes */
> +#include <linux/reboot.h>	/* For reboot notifier */
>  #include <linux/slab.h>		/* For memory functions */
>  #include <linux/types.h>	/* For standard types (like size_t) */
>  #include <linux/watchdog.h>	/* For watchdog specific items */
> @@ -998,6 +999,25 @@ static struct class watchdog_class = {
>  	.dev_groups =	wdt_groups,
>  };
>
> +static int watchdog_reboot_notifier(struct notifier_block *nb,
> +				    unsigned long code, void *data)
> +{
> +	struct watchdog_device *wdd = container_of(nb, struct watchdog_device,
> +						   reboot_nb);
> +
> +	if (code == SYS_DOWN || code == SYS_HALT) {
> +		if (watchdog_active(wdd)) {
> +			int ret;
> +
> +			ret = wdd->ops->stop(wdd);
> +			if (ret)
> +				return NOTIFY_BAD;
> +		}
> +	}
> +
> +	return NOTIFY_DONE;
> +}
> +
>  /*
>   *	watchdog_dev_register: register a watchdog device
>   *	@wdd: watchdog device
> @@ -1031,6 +1051,18 @@ int watchdog_dev_register(struct watchdog_device *wdd)
>  	if (ret) {
>  		device_destroy(&watchdog_class, devno);
>  		watchdog_cdev_unregister(wdd);
> +		return ret;
> +	}
> +
> +	if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) {
> +		wdd->reboot_nb.notifier_call = watchdog_reboot_notifier;
> +
> +		ret = devm_register_reboot_notifier(dev, &wdd->reboot_nb);
> +		if (ret) {
> +			pr_err("watchdog%d: Cannot register reboot notifier (%d)\n",
> +			       wdd->id, ret);
> +			watchdog_dev_unregister(wdd);
> +		}
>  	}
>
>  	return ret;
>