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?
J
> 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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