Xen project Mailing List

[Xen-devel] [PATCH] Xen watchdog driver

To: "Jeremy Fitzhardinge" <jeremy@xxxxxxxx>

From: "Jan Beulich" <JBeulich@xxxxxxxxxx>

Date: Thu, 30 Sep 2010 15:01:06 +0100

Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>

Delivery-date: Thu, 30 Sep 2010 07:01:59 -0700

List-id: Xen developer discussion <xen-devel.lists.xensource.com>

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. 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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