1 files changed, 112 insertions, 100 deletions

diff --git a/drivers/watchdog/softdog.c b/drivers/watchdog/softdog.c
index b68b1e519d53..0820e35ad2e3 100644
--- a/drivers/watchdog/softdog.c
+++ b/drivers/watchdog/softdog.c
@@ -1,14 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0+
 /*
  *	SoftDog:	A Software Watchdog Device
  *
  *	(c) Copyright 1996 Alan Cox <alan@lxorguk.ukuu.org.uk>,
  *							All Rights Reserved.
  *
- *	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.
- *
  *	Neither Alan Cox nor CymruNet Ltd. admit liability nor provide
  *	warranty for any of this software. This material is provided
  *	"AS-IS" and at no charge.
@@ -17,38 +13,20 @@
  *
  *	Software only watchdog driver. Unlike its big brother the WDT501P
  *	driver this won't always recover a failed machine.
- *
- *  03/96: Angelo Haritsis <ah@doc.ic.ac.uk> :
- *	Modularised.
- *	Added soft_margin; use upon insmod to change the timer delay.
- *	NB: uses same minor as wdt (WATCHDOG_MINOR); we could use separate
- *	    minors.
- *
- *  19980911 Alan Cox
- *	Made SMP safe for 2.3.x
- *
- *  20011127 Joel Becker (jlbec@evilplan.org>
- *	Added soft_noboot; Allows testing the softdog trigger without
- *	requiring a recompile.
- *	Added WDIOC_GETTIMEOUT and WDIOC_SETTIMOUT.
- *
- *  20020530 Joel Becker <joel.becker@oracle.com>
- *	Added Matt Domsch's nowayout module option.
  */
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/hrtimer.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
+#include <linux/reboot.h>
 #include <linux/types.h>
-#include <linux/timer.h>
-#include <linux/miscdevice.h>
 #include <linux/watchdog.h>
-#include <linux/notifier.h>
-#include <linux/reboot.h>
-#include <linux/init.h>
-#include <linux/jiffies.h>
-#include <linux/kernel.h>
+#include <linux/workqueue.h>
 
 #define TIMER_MARGIN	60		/* Default is 60 seconds */
 static unsigned int soft_margin = TIMER_MARGIN;	/* in seconds */
@@ -63,7 +41,7 @@ MODULE_PARM_DESC(nowayout,
 		"Watchdog cannot be stopped once started (default="
 				__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
 
-static int soft_noboot = 0;
+static int soft_noboot;
 module_param(soft_noboot, int, 0);
 MODULE_PARM_DESC(soft_noboot,
 	"Softdog action, set to 1 to ignore reboots, 0 to reboot (default=0)");
@@ -73,138 +51,172 @@ module_param(soft_panic, int, 0);
 MODULE_PARM_DESC(soft_panic,
 	"Softdog action, set to 1 to panic, 0 to reboot (default=0)");
 
-/*
- *	Our timer
- */
+static char *soft_reboot_cmd;
+module_param(soft_reboot_cmd, charp, 0000);
+MODULE_PARM_DESC(soft_reboot_cmd,
+	"Set reboot command. Emergency reboot takes place if unset");
 
-static void watchdog_fire(unsigned long);
+static bool soft_active_on_boot;
+module_param(soft_active_on_boot, bool, 0000);
+MODULE_PARM_DESC(soft_active_on_boot,
+	"Set to true to active Softdog on boot (default=false)");
 
-static struct timer_list watchdog_ticktock =
-		TIMER_INITIALIZER(watchdog_fire, 0, 0);
+static struct hrtimer softdog_ticktock;
+static struct hrtimer softdog_preticktock;
 
-/*
- *	If the timer expires..
- */
+static int reboot_kthread_fn(void *data)
+{
+	kernel_restart(soft_reboot_cmd);
+	return -EPERM; /* Should not reach here */
+}
+
+static void reboot_work_fn(struct work_struct *unused)
+{
+	kthread_run(reboot_kthread_fn, NULL, "softdog_reboot");
+}
 
-static void watchdog_fire(unsigned long data)
+static enum hrtimer_restart softdog_fire(struct hrtimer *timer)
 {
-	if (soft_noboot)
+	static bool soft_reboot_fired;
+
+	module_put(THIS_MODULE);
+	if (soft_noboot) {
 		pr_crit("Triggered - Reboot ignored\n");
-	else if (soft_panic) {
+	} else if (soft_panic) {
 		pr_crit("Initiating panic\n");
 		panic("Software Watchdog Timer expired");
 	} else {
 		pr_crit("Initiating system reboot\n");
+		if (!soft_reboot_fired && soft_reboot_cmd != NULL) {
+			static DECLARE_WORK(reboot_work, reboot_work_fn);
+			/*
+			 * The 'kernel_restart' is a 'might-sleep' operation.
+			 * Also, executing it in system-wide workqueues blocks
+			 * any driver from using the same workqueue in its
+			 * shutdown callback function. Thus, we should execute
+			 * the 'kernel_restart' in a standalone kernel thread.
+			 * But since starting a kernel thread is also a
+			 * 'might-sleep' operation, so the 'reboot_work' is
+			 * required as a launcher of the kernel thread.
+			 *
+			 * After request the reboot, restart the timer to
+			 * schedule an 'emergency_restart' reboot after
+			 * 'TIMER_MARGIN' seconds. It's because if the softdog
+			 * hangs, it might be because of scheduling issues. And
+			 * if that is the case, both 'schedule_work' and
+			 * 'kernel_restart' may possibly be malfunctional at the
+			 * same time.
+			 */
+			soft_reboot_fired = true;
+			schedule_work(&reboot_work);
+			hrtimer_add_expires_ns(timer,
+					(u64)TIMER_MARGIN * NSEC_PER_SEC);
+
+			return HRTIMER_RESTART;
+		}
 		emergency_restart();
 		pr_crit("Reboot didn't ?????\n");
 	}
+
+	return HRTIMER_NORESTART;
 }
 
-/*
- *	Softdog operations
- */
+static struct watchdog_device softdog_dev;
 
-static int softdog_ping(struct watchdog_device *w)
+static enum hrtimer_restart softdog_pretimeout(struct hrtimer *timer)
 {
-	mod_timer(&watchdog_ticktock, jiffies+(w->timeout*HZ));
-	return 0;
-}
+	watchdog_notify_pretimeout(&softdog_dev);
 
-static int softdog_stop(struct watchdog_device *w)
-{
-	del_timer(&watchdog_ticktock);
-	return 0;
+	return HRTIMER_NORESTART;
 }
 
-static int softdog_set_timeout(struct watchdog_device *w, unsigned int t)
+static int softdog_ping(struct watchdog_device *w)
 {
-	w->timeout = t;
+	if (!hrtimer_active(&softdog_ticktock))
+		__module_get(THIS_MODULE);
+	hrtimer_start(&softdog_ticktock, ktime_set(w->timeout, 0),
+		      HRTIMER_MODE_REL);
+
+	if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) {
+		if (w->pretimeout)
+			hrtimer_start(&softdog_preticktock,
+				      ktime_set(w->timeout - w->pretimeout, 0),
+				      HRTIMER_MODE_REL);
+		else
+			hrtimer_cancel(&softdog_preticktock);
+	}
+
 	return 0;
 }
 
-/*
- *	Notifier for system down
- */
-
-static int softdog_notify_sys(struct notifier_block *this, unsigned long code,
-	void *unused)
+static int softdog_stop(struct watchdog_device *w)
 {
-	if (code == SYS_DOWN || code == SYS_HALT)
-		/* Turn the WDT off */
-		softdog_stop(NULL);
-	return NOTIFY_DONE;
-}
+	if (hrtimer_cancel(&softdog_ticktock))
+		module_put(THIS_MODULE);
 
-/*
- *	Kernel Interfaces
- */
+	if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT))
+		hrtimer_cancel(&softdog_preticktock);
 
-static struct notifier_block softdog_notifier = {
-	.notifier_call	= softdog_notify_sys,
-};
+	return 0;
+}
 
 static struct watchdog_info softdog_info = {
 	.identity = "Software Watchdog",
 	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
 };
 
-static struct watchdog_ops softdog_ops = {
+static const struct watchdog_ops softdog_ops = {
 	.owner = THIS_MODULE,
 	.start = softdog_ping,
 	.stop = softdog_stop,
-	.set_timeout = softdog_set_timeout,
 };
 
 static struct watchdog_device softdog_dev = {
 	.info = &softdog_info,
 	.ops = &softdog_ops,
 	.min_timeout = 1,
-	.max_timeout = 0xFFFF
+	.max_timeout = 65535,
+	.timeout = TIMER_MARGIN,
 };
 
-static int __init watchdog_init(void)
+static int __init softdog_init(void)
 {
 	int ret;
 
-	/* Check that the soft_margin value is within it's range;
-	   if not reset to the default */
-	if (soft_margin < 1 || soft_margin > 65535) {
-		pr_info("soft_margin must be 0 < soft_margin < 65536, using %d\n",
-			TIMER_MARGIN);
-		return -EINVAL;
-	}
-	softdog_dev.timeout = soft_margin;
-
+	watchdog_init_timeout(&softdog_dev, soft_margin, NULL);
 	watchdog_set_nowayout(&softdog_dev, nowayout);
+	watchdog_stop_on_reboot(&softdog_dev);
 
-	ret = register_reboot_notifier(&softdog_notifier);
-	if (ret) {
-		pr_err("cannot register reboot notifier (err=%d)\n", ret);
-		return ret;
+	hrtimer_setup(&softdog_ticktock, softdog_fire, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+
+	if (IS_ENABLED(CONFIG_SOFT_WATCHDOG_PRETIMEOUT)) {
+		softdog_info.options |= WDIOF_PRETIMEOUT;
+		hrtimer_setup(&softdog_preticktock, softdog_pretimeout, CLOCK_MONOTONIC,
+			      HRTIMER_MODE_REL);
 	}
 
+	if (soft_active_on_boot)
+		softdog_ping(&softdog_dev);
+
 	ret = watchdog_register_device(&softdog_dev);
-	if (ret) {
-		unregister_reboot_notifier(&softdog_notifier);
+	if (ret)
 		return ret;
-	}
 
-	pr_info("Software Watchdog Timer: 0.08 initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
-		soft_noboot, soft_margin, soft_panic, nowayout);
+	pr_info("initialized. soft_noboot=%d soft_margin=%d sec soft_panic=%d (nowayout=%d)\n",
+		soft_noboot, softdog_dev.timeout, soft_panic, nowayout);
+	pr_info("             soft_reboot_cmd=%s soft_active_on_boot=%d\n",
+		soft_reboot_cmd ?: "<not set>", soft_active_on_boot);
 
 	return 0;
 }
+module_init(softdog_init);
 
-static void __exit watchdog_exit(void)
+static void __exit softdog_exit(void)
 {
 	watchdog_unregister_device(&softdog_dev);
-	unregister_reboot_notifier(&softdog_notifier);
 }
-
-module_init(watchdog_init);
-module_exit(watchdog_exit);
+module_exit(softdog_exit);
 
 MODULE_AUTHOR("Alan Cox");
 MODULE_DESCRIPTION("Software Watchdog Device Driver");
 MODULE_LICENSE("GPL");
-MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);