Re: [PATCH] Xen watchdog driver

["Jan Beulich" <JBeulich@novell.com>]

 >>> On 30.09.10 at 18:16, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> On 09/30/2010 07:01 AM, Jan Beulich wrote:
>> While the hypervisor change adding SCHEDOP_watchdog support included a
>> daemon to make use of the new functionality, having a kernel driver
>> for /dev/watchdog so that user space code doesn't need to distinguish
>> non-Xen and Xen seems to be preferable.
> 
> Looks good.  Are you going to submit this upstream?

By sending it to you I thought I did.

Confused, Jan

>> Signed-off-by: Jan Beulich <jbeulich@novell.com>
>>
>> ---
>>  drivers/watchdog/Kconfig      |   10 +
>>  drivers/watchdog/Makefile     |    3 
>>  drivers/watchdog/xen_wdt.c    |  359 
> ++++++++++++++++++++++++++++++++++++++++++
>>  include/xen/interface/sched.h |   34 +++
>>  4 files changed, 406 insertions(+)
>>
>> --- linux-2.6.36-rc6/drivers/watchdog/Kconfig
>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Kconfig
>> @@ -1043,6 +1043,16 @@ config WATCHDOG_RIO
>>  
>>  # XTENSA Architecture
>>  
>> +# Xen Architecture
>> +
>> +config XEN_WDT
>> +	tristate "Xen Watchdog support"
>> +	depends on XEN
>> +	help
>> +	  Say Y here to support the hypervisor watchdog capability provided
>> +	  by Xen 4.0 and newer.  The watchdog timeout period is normally one
>> +	  minute but can be changed with a boot-time parameter.
>> +
>>  #
>>  # ISA-based Watchdog Cards
>>  #
>> --- linux-2.6.36-rc6/drivers/watchdog/Makefile
>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/Makefile
>> @@ -145,6 +145,9 @@ obj-$(CONFIG_WATCHDOG_CP1XXX)		+= cpwd.o
>>  
>>  # XTENSA Architecture
>>  
>> +# Xen
>> +obj-$(CONFIG_XEN_WDT) += xen_wdt.o
>> +
>>  # Architecture Independant
>>  obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
>>  obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
>> --- linux-2.6.36-rc6/drivers/watchdog/xen_wdt.c
>> +++ 2.6.36-rc6-xen-watchdog/drivers/watchdog/xen_wdt.c
>> @@ -0,0 +1,359 @@
>> +/*
>> + *	Xen Watchdog Driver
>> + *
>> + *	(c) Copyright 2010 Novell, Inc.
>> + *
>> + *	This program is free software; you can redistribute it and/or
>> + *	modify it under the terms of the GNU General Public License
>> + *	as published by the Free Software Foundation; either version
>> + *	2 of the License, or (at your option) any later version.
>> + */
>> +
>> +#define DRV_NAME	"wdt"
>> +#define DRV_VERSION	"0.01"
>> +#define PFX		DRV_NAME ": "
>> +
>> +#include <linux/bug.h>
>> +#include <linux/errno.h>
>> +#include <linux/fs.h>
>> +#include <linux/hrtimer.h>
>> +#include <linux/kernel.h>
>> +#include <linux/ktime.h>
>> +#include <linux/init.h>
>> +#include <linux/miscdevice.h>
>> +#include <linux/module.h>
>> +#include <linux/moduleparam.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/spinlock.h>
>> +#include <linux/uaccess.h>
>> +#include <linux/watchdog.h>
>> +#include <xen/xen.h>
>> +#include <asm/xen/hypercall.h>
>> +#include <xen/interface/sched.h>
>> +
>> +static struct platform_device *platform_device;
>> +static DEFINE_SPINLOCK(wdt_lock);
>> +static struct sched_watchdog wdt;
>> +static __kernel_time_t wdt_expires;
>> +static bool is_active, expect_release;
>> +
>> +#define WATCHDOG_TIMEOUT 60 /* in seconds */
>> +static unsigned int timeout = WATCHDOG_TIMEOUT;
>> +module_param(timeout, uint, S_IRUGO);
>> +MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds "
>> +	"(default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")");
>> +
>> +static bool nowayout = WATCHDOG_NOWAYOUT;
>> +module_param(nowayout, bool, S_IRUGO);
>> +MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
>> +	"(default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
>> +
>> +static inline __kernel_time_t set_timeout(void)
>> +{
>> +	wdt.timeout = timeout;
>> +	return ktime_to_timespec(ktime_get()).tv_sec + timeout;
>> +}
>> +
>> +static int xen_wdt_start(void)
>> +{
>> +	__kernel_time_t expires;
>> +	int err;
>> +
>> +	spin_lock(&wdt_lock);
>> +
>> +	expires = set_timeout();
>> +	if (!wdt.id)
>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>> +	else
>> +		err = -EBUSY;
>> +	if (err > 0) {
>> +		wdt.id = err;
>> +		wdt_expires = expires;
>> +		err = 0;
>> +	} else
>> +		BUG_ON(!err);
>> +
>> +	spin_unlock(&wdt_lock);
>> +
>> +	return err;
>> +}
>> +
>> +static int xen_wdt_stop(void)
>> +{
>> +	int err = 0;
>> +
>> +	spin_lock(&wdt_lock);
>> +
>> +	wdt.timeout = 0;
>> +	if (wdt.id)
>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>> +	if (!err)
>> +		wdt.id = 0;
>> +
>> +	spin_unlock(&wdt_lock);
>> +
>> +	return err;
>> +}
>> +
>> +static int xen_wdt_kick(void)
>> +{
>> +	__kernel_time_t expires;
>> +	int err;
>> +
>> +	spin_lock(&wdt_lock);
>> +
>> +	expires = set_timeout();
>> +	if (wdt.id)
>> +		err = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wdt);
>> +	else
>> +		err = -ENXIO;
>> +	if (!err)
>> +		wdt_expires = expires;
>> +
>> +	spin_unlock(&wdt_lock);
>> +
>> +	return err;
>> +}
>> +
>> +static int xen_wdt_open(struct inode *inode, struct file *file)
>> +{
>> +	int err;
>> +
>> +	/* /dev/watchdog can only be opened once */
>> +	if (xchg(&is_active, true))
>> +		return -EBUSY;
>> +
>> +	err = xen_wdt_start();
>> +	if (err == -EBUSY)
>> +		err = xen_wdt_kick();
>> +	return err ?: nonseekable_open(inode, file);
>> +}
>> +
>> +static int xen_wdt_release(struct inode *inode, struct file *file)
>> +{
>> +	if (expect_release)
>> +		xen_wdt_stop();
>> +	else {
>> +		printk(KERN_CRIT PFX
>> +		       "unexpected close, not stopping watchdog!\n");
>> +		xen_wdt_kick();
>> +	}
>> +	is_active = false;
>> +	expect_release = false;
>> +	return 0;
>> +}
>> +
>> +static ssize_t xen_wdt_write(struct file *file, const char __user *data,
>> +			     size_t len, loff_t *ppos)
>> +{
>> +	/* See if we got the magic character 'V' and reload the timer */
>> +	if (len) {
>> +		if (!nowayout) {
>> +			size_t i;
>> +
>> +			/* in case it was set long ago */
>> +			expect_release = false;
>> +
>> +			/* scan to see whether or not we got the magic
>> +			   character */
>> +			for (i = 0; i != len; i++) {
>> +				char c;
>> +				if (get_user(c, data + i))
>> +					return -EFAULT;
>> +				if (c == 'V')
>> +					expect_release = true;
>> +			}
>> +		}
>> +
>> +		/* someone wrote to us, we should reload the timer */
>> +		xen_wdt_kick();
>> +	}
>> +	return len;
>> +}
>> +
>> +static long xen_wdt_ioctl(struct file *file, unsigned int cmd,
>> +			  unsigned long arg)
>> +{
>> +	int new_options, retval = -EINVAL;
>> +	int new_timeout;
>> +	int __user *argp = (void __user *)arg;
>> +	static const struct watchdog_info ident = {
>> +		.options =		WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE,
>> +		.firmware_version =	0,
>> +		.identity =		DRV_NAME,
>> +	};
>> +
>> +	switch (cmd) {
>> +	case WDIOC_GETSUPPORT:
>> +		return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0;
>> +
>> +	case WDIOC_GETSTATUS:
>> +	case WDIOC_GETBOOTSTATUS:
>> +		return put_user(0, argp);
>> +
>> +	case WDIOC_SETOPTIONS:
>> +		if (get_user(new_options, argp))
>> +			return -EFAULT;
>> +
>> +		if (new_options & WDIOS_DISABLECARD)
>> +			retval = xen_wdt_stop();
>> +		if (new_options & WDIOS_ENABLECARD) {
>> +			retval = xen_wdt_start();
>> +			if (retval == -EBUSY)
>> +				retval = xen_wdt_kick();
>> +		}
>> +		return retval;
>> +
>> +	case WDIOC_KEEPALIVE:
>> +		xen_wdt_kick();
>> +		return 0;
>> +
>> +	case WDIOC_SETTIMEOUT:
>> +		if (get_user(new_timeout, argp))
>> +			return -EFAULT;
>> +		if (!new_timeout)
>> +			return -EINVAL;
>> +		timeout = new_timeout;
>> +		xen_wdt_kick();
>> +		/* fall through */
>> +	case WDIOC_GETTIMEOUT:
>> +		return put_user(timeout, argp);
>> +
>> +	case WDIOC_GETTIMELEFT:
>> +		retval = wdt_expires - ktime_to_timespec(ktime_get()).tv_sec;
>> +		return put_user(retval, argp);
>> +	}
>> +
>> +	return -ENOTTY;
>> +}
>> +
>> +static const struct file_operations xen_wdt_fops = {
>> +	.owner =		THIS_MODULE,
>> +	.llseek =		no_llseek,
>> +	.write =		xen_wdt_write,
>> +	.unlocked_ioctl =	xen_wdt_ioctl,
>> +	.open =			xen_wdt_open,
>> +	.release =		xen_wdt_release,
>> +};
>> +
>> +static struct miscdevice xen_wdt_miscdev = {
>> +	.minor =	WATCHDOG_MINOR,
>> +	.name =		"watchdog",
>> +	.fops =		&xen_wdt_fops,
>> +};
>> +
>> +static int __devinit xen_wdt_probe(struct platform_device *dev)
>> +{
>> +	struct sched_watchdog wd = { .id = ~0 };
>> +	int ret = HYPERVISOR_sched_op(SCHEDOP_watchdog, &wd);
>> +
>> +	switch (ret) {
>> +	case -EINVAL:
>> +		if (!timeout) {
>> +			timeout = WATCHDOG_TIMEOUT;
>> +			printk(KERN_INFO PFX
>> +			       "timeout value invalid, using %d\n", timeout);
>> +		}
>> +
>> +		ret = misc_register(&xen_wdt_miscdev);
>> +		if (ret) {
>> +			printk(KERN_ERR PFX
>> +			       "cannot register miscdev on minor=%d (%d)\n",
>> +			       WATCHDOG_MINOR, ret);
>> +			break;
>> +		}
>> +
>> +		printk(KERN_INFO PFX
>> +		       "initialized (timeout=%ds, nowayout=%d)\n",
>> +		       timeout, nowayout);
>> +		break;
>> +
>> +	case -ENOSYS:
>> +		printk(KERN_INFO PFX "not supported\n");
>> +		ret = -ENODEV;
>> +		break;
>> +
>> +	default:
>> +		printk(KERN_INFO PFX "bogus return value %d\n", ret);
>> +		break;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static int __devexit xen_wdt_remove(struct platform_device *dev)
>> +{
>> +	/* Stop the timer before we leave */
>> +	if (!nowayout)
>> +		xen_wdt_stop();
>> +
>> +	misc_deregister(&xen_wdt_miscdev);
>> +
>> +	return 0;
>> +}
>> +
>> +static void xen_wdt_shutdown(struct platform_device *dev)
>> +{
>> +	xen_wdt_stop();
>> +}
>> +
>> +static int xen_wdt_suspend(struct platform_device *dev, pm_message_t state)
>> +{
>> +	return xen_wdt_stop();
>> +}
>> +
>> +static int xen_wdt_resume(struct platform_device *dev)
>> +{
>> +	return xen_wdt_start();
>> +}
>> +
>> +static struct platform_driver xen_wdt_driver = {
>> +	.probe          = xen_wdt_probe,
>> +	.remove         = __devexit_p(xen_wdt_remove),
>> +	.shutdown       = xen_wdt_shutdown,
>> +	.suspend        = xen_wdt_suspend,
>> +	.resume         = xen_wdt_resume,
>> +	.driver         = {
>> +		.owner  = THIS_MODULE,
>> +		.name   = DRV_NAME,
>> +	},
>> +};
>> +
>> +static int __init xen_wdt_init_module(void)
>> +{
>> +	int err;
>> +
>> +	if (!xen_domain())
>> +		return -ENODEV;
>> +
>> +	printk(KERN_INFO PFX "Xen WatchDog Timer Driver v%s\n", DRV_VERSION);
>> +
>> +	err = platform_driver_register(&xen_wdt_driver);
>> +	if (err)
>> +		return err;
>> +
>> +	platform_device = platform_device_register_simple(DRV_NAME,
>> +								  -1, NULL, 0);
>> +	if (IS_ERR(platform_device)) {
>> +		err = PTR_ERR(platform_device);
>> +		platform_driver_unregister(&xen_wdt_driver);
>> +	}
>> +
>> +	return err;
>> +}
>> +
>> +static void __exit xen_wdt_cleanup_module(void)
>> +{
>> +	platform_device_unregister(platform_device);
>> +	platform_driver_unregister(&xen_wdt_driver);
>> +	printk(KERN_INFO PFX "module unloaded\n");
>> +}
>> +
>> +module_init(xen_wdt_init_module);
>> +module_exit(xen_wdt_cleanup_module);
>> +
>> +MODULE_AUTHOR("Jen Beulich <jbeulich@novell.com>");
>> +MODULE_DESCRIPTION("Xen WatchDog Timer Driver");
>> +MODULE_VERSION(DRV_VERSION);
>> +MODULE_LICENSE("GPL");
>> +MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
>> --- linux-2.6.36-rc6/include/xen/interface/sched.h
>> +++ 2.6.36-rc6-xen-watchdog/include/xen/interface/sched.h
>> @@ -65,6 +65,39 @@ struct sched_poll {
>>  DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
>>  
>>  /*
>> + * Declare a shutdown for another domain. The main use of this function is
>> + * in interpreting shutdown requests and reasons for fully-virtualized
>> + * domains.  A para-virtualized domain may use SCHEDOP_shutdown directly.
>> + * @arg == pointer to sched_remote_shutdown structure.
>> + */
>> +#define SCHEDOP_remote_shutdown        4
>> +struct sched_remote_shutdown {
>> +    domid_t domain_id;         /* Remote domain ID */
>> +    unsigned int reason;       /* SHUTDOWN_xxx reason */
>> +};
>> +
>> +/*
>> + * Latch a shutdown code, so that when the domain later shuts down it
>> + * reports this code to the control tools.
>> + * @arg == as for SCHEDOP_shutdown.
>> + */
>> +#define SCHEDOP_shutdown_code 5
>> +
>> +/*
>> + * Setup, poke and destroy a domain watchdog timer.
>> + * @arg == pointer to sched_watchdog structure.
>> + * With id == 0, setup a domain watchdog timer to cause domain shutdown
>> + *               after timeout, returns watchdog id.
>> + * With id != 0 and timeout == 0, destroy domain watchdog timer.
>> + * With id != 0 and timeout != 0, poke watchdog timer and set new timeout.
>> + */
>> +#define SCHEDOP_watchdog    6
>> +struct sched_watchdog {
>> +    uint32_t id;                /* watchdog ID */
>> +    uint32_t timeout;           /* timeout */
>> +};
>> +
>> +/*
>>   * Reason codes for SCHEDOP_shutdown. These may be interpreted by control
>>   * software to determine the appropriate action. For the most part, Xen 
> does
>>   * not care about the shutdown code.
>> @@ -73,5 +106,6 @@ DEFINE_GUEST_HANDLE_STRUCT(sched_poll);
>>  #define SHUTDOWN_reboot     1  /* Clean up, kill, and then restart.         
>  */
>>  #define SHUTDOWN_suspend    2  /* Clean up, save suspend info, kill.        
>  */
>>  #define SHUTDOWN_crash      3  /* Tell controller we've crashed.            
>  */
>> +#define SHUTDOWN_watchdog   4  /* Restart because watchdog time expired.    
>  */
>>  
>>  #endif /* __XEN_PUBLIC_SCHED_H__ */
>>
>>