linux-kernel - Re: [char-misc-next 4/7] watchdog: mei

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Message-ID: <56743795.6090700@roeck-us.net>
Date:	Fri, 18 Dec 2015 08:43:01 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Tomas Winkler <tomas.winkler@...el.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Wim Van Sebroeck <wim@...ana.be>
Cc:	Alexander Usyskin <alexander.usyskin@...el.com>,
	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [char-misc-next 4/7] watchdog: mei_wdt: add status debugfs entry

On 12/17/2015 06:49 AM, Tomas Winkler wrote:
> Add entry for dumping current watchdog internal state
>
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> ---
>   drivers/watchdog/mei_wdt.c | 84 ++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 84 insertions(+)
>
> diff --git a/drivers/watchdog/mei_wdt.c b/drivers/watchdog/mei_wdt.c
> index 3c97deb70d90..a3f1c1613c32 100644
> --- a/drivers/watchdog/mei_wdt.c
> +++ b/drivers/watchdog/mei_wdt.c
> @@ -16,6 +16,7 @@
>   #include <linux/slab.h>
>   #include <linux/interrupt.h>
>   #include <linux/watchdog.h>
> +#include <linux/debugfs.h>
>
>   #include <linux/uuid.h>
>   #include <linux/mei_cl_bus.h>
> @@ -54,6 +55,19 @@ enum mei_wdt_state {
>   	MEI_WDT_STOPPING,
>   };
>
> +#if IS_ENABLED(CONFIG_DEBUG_FS)
> +static const char *mei_wdt_state_str(enum mei_wdt_state state)
> +{
> +	switch (state) {
> +	case MEI_WDT_IDLE: return "IDLE";
> +	case MEI_WDT_START: return "START";
> +	case MEI_WDT_RUNNING: return "RUNNING";
> +	case MEI_WDT_STOPPING: return "STOPPING";
> +	default: return "unknown";

Doesn't this cause checkpatch warnings ?

> +	}
> +}
> +#endif /* CONFIG_DEBUG_FS */
> +

Can you move this conditional code into the other #ifdef block below ?

Thanks,
Guenter

>   /**
>    * struct mei_wdt - mei watchdog driver
>    * @wdd: watchdog device
> @@ -62,6 +76,8 @@ enum mei_wdt_state {
>    * @state: watchdog internal state
>    * @cldev: mei watchdog client device
>    * @timeout: watchdog current timeout
> + *
> + * @dbgfs_dir: debugfs dir entry
>    */
>   struct mei_wdt {
>   	struct watchdog_device wdd;
> @@ -70,6 +86,10 @@ struct mei_wdt {
>   	struct mei_cl_device *cldev;
>   	enum mei_wdt_state state;
>   	u16 timeout;
> +
> +#if IS_ENABLED(CONFIG_DEBUG_FS)
> +	struct dentry *dbgfs_dir;
> +#endif /* CONFIG_DEBUG_FS */
>   };
>
>   /*
> @@ -296,6 +316,66 @@ static void mei_wdt_ops_unref(struct watchdog_device *wdd)
>   	kref_put(&wdt->refcnt, mei_wdt_release);
>   }
>
> +#if IS_ENABLED(CONFIG_DEBUG_FS)
> +
> +static ssize_t mei_dbgfs_read_state(struct file *file, char __user *ubuf,
> +				    size_t cnt, loff_t *ppos)
> +{
> +	struct mei_wdt *wdt = file->private_data;
> +	const size_t bufsz = 32;
> +	char buf[32];
> +	ssize_t pos = 0;
> +
> +	pos += scnprintf(buf + pos, bufsz - pos, "state: %s\n",
> +			 mei_wdt_state_str(wdt->state));
> +
> +	return simple_read_from_buffer(ubuf, cnt, ppos, buf, pos);
> +}
> +
> +static const struct file_operations dbgfs_fops_state = {
> +	.open = simple_open,
> +	.read = mei_dbgfs_read_state,
> +	.llseek = generic_file_llseek,
> +};
> +
> +static void dbgfs_deregister(struct mei_wdt *wdt)
> +{
> +	if (!wdt->dbgfs_dir)
> +		return;
> +	debugfs_remove_recursive(wdt->dbgfs_dir);
> +	wdt->dbgfs_dir = NULL;
> +}
> +
> +static int dbgfs_register(struct mei_wdt *wdt)
> +{
> +	struct dentry *dir, *f;
> +
> +	dir = debugfs_create_dir(KBUILD_MODNAME, NULL);
> +	if (!dir)
> +		return -ENOMEM;
> +
> +	wdt->dbgfs_dir = dir;
> +	f = debugfs_create_file("state", S_IRUSR, dir, wdt, &dbgfs_fops_state);
> +	if (!f)
> +		goto err;
> +
> +	return 0;
> +err:
> +	dbgfs_deregister(wdt);
> +	return -ENODEV;
> +}
> +
> +#else
> +
> +static inline void dbgfs_deregister(struct mei_wdt *wdt) {}
> +
> +static inline int dbgfs_register(struct mei_wdt *wdt)
> +{
> +	return 0;
> +}
> +#endif /* CONFIG_DEBUG_FS */
> +
> +
>   static const struct watchdog_ops wd_ops = {
>   	.owner       = THIS_MODULE,
>   	.start       = mei_wdt_ops_start,
> @@ -348,6 +428,8 @@ static int mei_wdt_probe(struct mei_cl_device *cldev,
>   	if (ret)
>   		goto err_disable;
>
> +	dbgfs_register(wdt);
> +
>   	return 0;
>
>   err_disable:
> @@ -367,6 +449,8 @@ static int mei_wdt_remove(struct mei_cl_device *cldev)
>
>   	kref_put(&wdt->refcnt, mei_wdt_release);
>
> +	dbgfs_deregister(wdt);
> +

This should probably come before the call to kref_put() since it uses wdt.

>   	mei_cldev_disable(cldev);
>
>   	return 0;
>

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