On Mon, Aug 19, 2019 at 03:37:07PM -0500, minyard@xxxxxxx wrote:
> From: Corey Minyard <cminyard@xxxxxxxxxx>
>
> Add a way to tell the watchdog what to do on a timeout and on
> a pretimeout. This is to support the IPMI watchdog's ability
> to do this.
>
> Signed-off-by: Corey Minyard <cminyard@xxxxxxxxxx>
> ---
> Documentation/watchdog/watchdog-api.rst | 40 ++++++++++++
> drivers/watchdog/watchdog_dev.c | 82 +++++++++++++++++++++++++
> include/linux/watchdog.h | 4 ++
> include/uapi/linux/watchdog.h | 14 +++++
> 4 files changed, 140 insertions(+)
>
> diff --git a/Documentation/watchdog/watchdog-api.rst b/Documentation/watchdog/watchdog-api.rst
> index c6c1e9fa9f73..927be9e56b5d 100644
> --- a/Documentation/watchdog/watchdog-api.rst
> +++ b/Documentation/watchdog/watchdog-api.rst
> @@ -112,6 +112,24 @@ current timeout using the GETTIMEOUT ioctl::
> ioctl(fd, WDIOC_GETTIMEOUT, &timeout);
> printf("The timeout was is %d seconds\n", timeout);
>
> +Actions
> +=======
> +
> +Some watchdog timers can perform different actions when they time out.
> +Most will only reset. The values are::
> +
> + WDIOA_RESET - Reset the system
> + WDIOA_POWER_OFF - Power off the system
> + WDIOA_POWER_CYCLE - Power off the system then power it back on
> +
> +The value can be set::
> +
> + ioctl(fd, WDIOC_SETACTION, &action);
> +
> +and queried::
> +
> + ioctl(fd, WDIOC_GETACTION, &action);
> +
> Pretimeouts
> ===========
>
> @@ -137,6 +155,28 @@ There is also a get function for getting the pretimeout::
>
> Not all watchdog drivers will support a pretimeout.
>
> +Preactions
> +==========
> +
> +Like actions some watchdog timers can perform different actions when
> +they pretimeout. The values are::
> +
> + WDIOP_NONE - Don't do anything on a pretimeout
> + WDIOP_NMI - Issue an NMI
> + WDIOP_SMI - Issue a system management interrupt
> + WDIOP_INTERRUPT - Issue a normal interrupt
> +
> +The value can be set::
> +
> + ioctl(fd, WDIOC_SETPREACTION, &preaction);
> +
> +and queried::
> +
> + ioctl(fd, WDIOC_GETPREACTION, &preaction);
> +
> +Note that the pretimeout governor that reads data is not compatible with
> +the NMI preaction. The NMI preaction can only do nothing or panic.
> +
I find this quite confusing. We would now have this ioctl, and then we
have the pretimeout sysfs attributes which are also supposed to set
pretimeout actions. This will require a bit more discussion for a
more concise and less confusing interface/API/ABI.
Guenter
> Get the number of seconds before reboot
> =======================================
>
> diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c
> index 8e8304607a8c..0e70f510a491 100644
> --- a/drivers/watchdog/watchdog_dev.c
> +++ b/drivers/watchdog/watchdog_dev.c
> @@ -423,6 +423,48 @@ static int watchdog_set_pretimeout(struct watchdog_device *wdd,
> return err;
> }
>
> +/*
> + * watchdog_set_action: set the action the watchdog performs.
> + * @wdd: the watchdog device to set the timeout for
> + * @action: The action, one of WDIOA_xxx
> + *
> + * The caller must hold wd_data->lock.
> + */
> +
> +static int watchdog_set_action(struct watchdog_device *wdd,
> + unsigned int action)
> +{
> + int err = 0;
> +
> + if (wdd->ops->set_action)
> + err = wdd->ops->set_action(wdd, action);
> + else if (action != WDIOA_RESET)
> + err = -EINVAL;
> +
> + return err;
> +}
> +
> +/*
> + * watchdog_set_preaction: set the action the watchdog pretimeout performs.
> + * @wdd: the watchdog device to set the timeout for
> + * @action: The action, one of WDIOP_xxx
> + *
> + * The caller must hold wd_data->lock.
> + */
> +
> +static int watchdog_set_preaction(struct watchdog_device *wdd,
> + unsigned int action)
> +{
> + int err;
> +
> + if (wdd->ops->set_preaction)
> + err = wdd->ops->set_preaction(wdd, action);
> + else
> + err = -EOPNOTSUPP;
> +
> + return err;
> +}
> +
> /*
> * watchdog_get_timeleft: wrapper to get the time left before a reboot
> * @wdd: the watchdog device to get the remaining time from
> @@ -516,6 +558,24 @@ static ssize_t pretimeout_show(struct device *dev,
> }
> static DEVICE_ATTR_RO(pretimeout);
>
> +static ssize_t action_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct watchdog_device *wdd = dev_get_drvdata(dev);
> +
> + return sprintf(buf, "%u\n", wdd->action);
> +}
> +static DEVICE_ATTR_RO(action);
> +
> +static ssize_t preaction_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + struct watchdog_device *wdd = dev_get_drvdata(dev);
> +
> + return sprintf(buf, "%u\n", wdd->preaction);
> +}
> +static DEVICE_ATTR_RO(preaction);
> +
> static ssize_t identity_show(struct device *dev, struct device_attribute *attr,
> char *buf)
> {
> @@ -592,6 +652,8 @@ static struct attribute *wdt_attrs[] = {
> &dev_attr_identity.attr,
> &dev_attr_timeout.attr,
> &dev_attr_pretimeout.attr,
> + &dev_attr_action.attr,
> + &dev_attr_preaction.attr,
> &dev_attr_timeleft.attr,
> &dev_attr_bootstatus.attr,
> &dev_attr_status.attr,
> @@ -784,6 +846,26 @@ static long watchdog_ioctl(struct file *file, unsigned int cmd,
> case WDIOC_GETPRETIMEOUT:
> err = put_user(wdd->pretimeout, p);
> break;
> + case WDIOC_SETACTION:
> + if (get_user(val, p)) {
> + err = -EFAULT;
> + break;
> + }
> + err = watchdog_set_action(wdd, val);
> + break;
> + case WDIOC_GETACTION:
> + err = put_user(wdd->action, p);
> + break;
> + case WDIOC_SETPREACTION:
> + if (get_user(val, p)) {
> + err = -EFAULT;
> + break;
> + }
> + err = watchdog_set_preaction(wdd, val);
> + break;
> + case WDIOC_GETPREACTION:
> + err = put_user(wdd->preaction, p);
> + break;
> default:
> err = -ENOTTY;
> break;
> diff --git a/include/linux/watchdog.h b/include/linux/watchdog.h
> index e34501a822f0..d4644994106e 100644
> --- a/include/linux/watchdog.h
> +++ b/include/linux/watchdog.h
> @@ -53,6 +53,8 @@ struct watchdog_ops {
> unsigned int (*get_timeleft)(struct watchdog_device *);
> int (*restart)(struct watchdog_device *, unsigned long, void *);
> long (*ioctl)(struct watchdog_device *, unsigned int, unsigned long);
> + int (*set_action)(struct watchdog_device *wdd, unsigned int val);
> + int (*set_preaction)(struct watchdog_device *wdd, unsigned int val);
> };
>
> /** struct watchdog_device - The structure that defines a watchdog device
> @@ -101,6 +103,8 @@ struct watchdog_device {
> unsigned int bootstatus;
> unsigned int timeout;
> unsigned int pretimeout;
> + unsigned int action;
> + unsigned int preaction;
> unsigned int min_timeout;
> unsigned int max_timeout;
> unsigned int min_hw_heartbeat_ms;
> diff --git a/include/uapi/linux/watchdog.h b/include/uapi/linux/watchdog.h
> index b15cde5c9054..bf13cf25f9e0 100644
> --- a/include/uapi/linux/watchdog.h
> +++ b/include/uapi/linux/watchdog.h
> @@ -32,6 +32,10 @@ struct watchdog_info {
> #define WDIOC_SETPRETIMEOUT _IOWR(WATCHDOG_IOCTL_BASE, 8, int)
> #define WDIOC_GETPRETIMEOUT _IOR(WATCHDOG_IOCTL_BASE, 9, int)
> #define WDIOC_GETTIMELEFT _IOR(WATCHDOG_IOCTL_BASE, 10, int)
> +#define WDIOC_SETACTION _IOWR(WATCHDOG_IOCTL_BASE, 11, int)
> +#define WDIOC_GETACTION _IOR(WATCHDOG_IOCTL_BASE, 12, int)
> +#define WDIOC_SETPREACTION _IOWR(WATCHDOG_IOCTL_BASE, 13, int)
> +#define WDIOC_GETPREACTION _IOR(WATCHDOG_IOCTL_BASE, 14, int)
>
> #define WDIOF_UNKNOWN -1 /* Unknown flag error */
> #define WDIOS_UNKNOWN -1 /* Unknown status error */
> @@ -54,5 +58,15 @@ struct watchdog_info {
> #define WDIOS_ENABLECARD 0x0002 /* Turn on the watchdog timer */
> #define WDIOS_TEMPPANIC 0x0004 /* Kernel panic on temperature trip */
>
> +/* Actions for WDIOC_xxxACTION ioctls. */
> +#define WDIOA_RESET 0 /* Reset the system. */
> +#define WDIOA_POWER_OFF 1 /* Power off the system. */
> +#define WDIOA_POWER_CYCLE 2 /* Power cycle the system. */
> +
> +/* Actions for WDIOC_xxxPREACTION ioctls. */
> +#define WDIOP_NONE 0 /* Do nothing. */
> +#define WDIOP_NMI 1 /* Issue an NMI. */
> +#define WDIOP_SMI 2 /* Issue a system management irq. */
> +#define WDIOP_INTERRUPT 3 /* Issue a normal irq. */
>
> #endif /* _UAPI_LINUX_WATCHDOG_H */
> --
> 2.17.1
>
