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[Xen-devel] Re: [PATCH] Xen watchdog driver



 On 09/30/2010 11:56 PM, Jan Beulich wrote:
>  >>> On 30.09.10 at 18:16, Jeremy Fitzhardinge <jeremy@xxxxxxxx> 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.

I'm not the exclusive path for upstream Xen; I'm happy to ack things and
let others submit them.  But I'm also happy to submit this too.

    J

> Confused, Jan
>
>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
>>>
>>> ---
>>>  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@xxxxxxxxxx>");
>>> +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__ */
>>>
>>>
>


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