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2023-12-11 072de836f53be56a70cecf70b43ae43b7ce17376 
 kernel/drivers/watchdog/watchdog_dev.c
....@@ -1,3 +1,4 @@
1
+// SPDX-License-Identifier: GPL-2.0+
12 /*
23  *	watchdog_dev.c
34  *
....@@ -19,11 +20,6 @@
1920  *	  Rusty Lynch <rusty@linux.co.intel.com>
2021  *	  Satyam Sharma <satyam@infradead.org>
2122  *	  Randy Dunlap <randy.dunlap@oracle.com>
22
- *
23
- *	This program is free software; you can redistribute it and/or
24
- *	modify it under the terms of the GNU General Public License
25
- *	as published by the Free Software Foundation; either version
26
- *	2 of the License, or (at your option) any later version.
2723  *
2824  *	Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw.
2925  *	admit liability nor provide warranty for any of this software.
....@@ -47,8 +43,6 @@
4743 #include <linux/watchdog.h>	/* For watchdog specific items */
4844 #include <linux/uaccess.h>	/* For copy_to_user/put_user/... */
4945 
50
-#include <uapi/linux/sched/types.h>	/* For struct sched_param */
51
-
5246 #include "watchdog_core.h"
5347 #include "watchdog_pretimeout.h"
5448 
....@@ -67,6 +61,7 @@
6761 	struct mutex lock;
6862 	ktime_t last_keepalive;
6963 	ktime_t last_hw_keepalive;
64
+	ktime_t open_deadline;
7065 	struct hrtimer timer;
7166 	struct kthread_work work;
7267 	unsigned long status;		/* Internal status bits */
....@@ -84,6 +79,19 @@
8479 
8580 static bool handle_boot_enabled =
8681 	IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED);
82
+
83
+static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT;
84
+
85
+static bool watchdog_past_open_deadline(struct watchdog_core_data *data)
86
+{
87
+	return ktime_after(ktime_get(), data->open_deadline);
88
+}
89
+
90
+static void watchdog_set_open_deadline(struct watchdog_core_data *data)
91
+{
92
+	data->open_deadline = open_timeout ?
93
+		ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX;
94
+}
8795 
8896 static inline bool watchdog_need_worker(struct watchdog_device *wdd)
8997 {
....@@ -117,13 +125,14 @@
117125 	ktime_t virt_timeout;
118126 	unsigned int hw_heartbeat_ms;
119127 
120
-	virt_timeout = ktime_add(wd_data->last_keepalive,
121
-				 ms_to_ktime(timeout_ms));
128
+	if (watchdog_active(wdd))
129
+		virt_timeout = ktime_add(wd_data->last_keepalive,
130
+					 ms_to_ktime(timeout_ms));
131
+	else
132
+		virt_timeout = wd_data->open_deadline;
133
+
122134 	hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms);
123135 	keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2);
124
-
125
-	if (!watchdog_active(wdd))
126
-		return keepalive_interval;
127136 
128137 	/*
129138 	 * To ensure that the watchdog times out wdd->timeout seconds
....@@ -145,7 +154,8 @@
145154 		ktime_t t = watchdog_next_keepalive(wdd);
146155 
147156 		if (t > 0)
148
-			hrtimer_start(&wd_data->timer, t, HRTIMER_MODE_REL);
157
+			hrtimer_start(&wd_data->timer, t,
158
+				      HRTIMER_MODE_REL_HARD);
149159 	} else {
150160 		hrtimer_cancel(&wd_data->timer);
151161 	}
....@@ -164,7 +174,7 @@
164174 	if (ktime_after(earliest_keepalive, now)) {
165175 		hrtimer_start(&wd_data->timer,
166176 			      ktime_sub(earliest_keepalive, now),
167
-			      HRTIMER_MODE_REL);
177
+			      HRTIMER_MODE_REL_HARD);
168178 		return 0;
169179 	}
170180 
....@@ -209,7 +219,13 @@
209219 {
210220 	struct watchdog_device *wdd = wd_data->wdd;
211221 
212
-	return wdd && (watchdog_active(wdd) || watchdog_hw_running(wdd));
222
+	if (!wdd)
223
+		return false;
224
+
225
+	if (watchdog_active(wdd))
226
+		return true;
227
+
228
+	return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data);
213229 }
214230 
215231 static void watchdog_ping_work(struct kthread_work *work)
....@@ -257,15 +273,18 @@
257273 	set_bit(_WDOG_KEEPALIVE, &wd_data->status);
258274 
259275 	started_at = ktime_get();
260
-	if (watchdog_hw_running(wdd) && wdd->ops->ping)
261
-		err = wdd->ops->ping(wdd);
262
-	else
276
+	if (watchdog_hw_running(wdd) && wdd->ops->ping) {
277
+		err = __watchdog_ping(wdd);
278
+		if (err == 0)
279
+			set_bit(WDOG_ACTIVE, &wdd->status);
280
+	} else {
263281 		err = wdd->ops->start(wdd);
264
-	if (err == 0) {
265
-		set_bit(WDOG_ACTIVE, &wdd->status);
266
-		wd_data->last_keepalive = started_at;
267
-		wd_data->last_hw_keepalive = started_at;
268
-		watchdog_update_worker(wdd);
282
+		if (err == 0) {
283
+			set_bit(WDOG_ACTIVE, &wdd->status);
284
+			wd_data->last_keepalive = started_at;
285
+			wd_data->last_hw_keepalive = started_at;
286
+			watchdog_update_worker(wdd);
287
+		}
269288 	}
270289 
271290 	return err;
....@@ -434,7 +453,26 @@
434453 
435454 	return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status));
436455 }
437
-static DEVICE_ATTR_RO(nowayout);
456
+
457
+static ssize_t nowayout_store(struct device *dev, struct device_attribute *attr,
458
+				const char *buf, size_t len)
459
+{
460
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
461
+	unsigned int value;
462
+	int ret;
463
+
464
+	ret = kstrtouint(buf, 0, &value);
465
+	if (ret)
466
+		return ret;
467
+	if (value > 1)
468
+		return -EINVAL;
469
+	/* nowayout cannot be disabled once set */
470
+	if (test_bit(WDOG_NO_WAY_OUT, &wdd->status) && !value)
471
+		return -EPERM;
472
+	watchdog_set_nowayout(wdd, value);
473
+	return len;
474
+}
475
+static DEVICE_ATTR_RW(nowayout);
438476 
439477 static ssize_t status_show(struct device *dev, struct device_attribute *attr,
440478 				char *buf)
....@@ -550,7 +588,7 @@
550588 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr,
551589 				int n)
552590 {
553
-	struct device *dev = container_of(kobj, struct device, kobj);
591
+	struct device *dev = kobj_to_dev(kobj);
554592 	struct watchdog_device *wdd = dev_get_drvdata(dev);
555593 	umode_t mode = attr->mode;
556594 
....@@ -739,7 +777,7 @@
739777 		err = watchdog_ping(wdd);
740778 		if (err < 0)
741779 			break;
742
-		/* fall through */
780
+		fallthrough;
743781 	case WDIOC_GETTIMEOUT:
744782 		/* timeout == 0 means that we don't know the timeout */
745783 		if (wdd->timeout == 0) {
....@@ -823,8 +861,17 @@
823861 	if (!hw_running)
824862 		get_device(&wd_data->dev);
825863 
864
+	/*
865
+	 * open_timeout only applies for the first open from
866
+	 * userspace. Set open_deadline to infinity so that the kernel
867
+	 * will take care of an always-running hardware watchdog in
868
+	 * case the device gets magic-closed or WDIOS_DISABLECARD is
869
+	 * applied.
870
+	 */
871
+	wd_data->open_deadline = KTIME_MAX;
872
+
826873 	/* dev/watchdog is a virtual (and thus non-seekable) filesystem */
827
-	return nonseekable_open(inode, file);
874
+	return stream_open(inode, file);
828875 
829876 out_mod:
830877 	module_put(wd_data->wdd->ops->owner);
....@@ -870,7 +917,7 @@
870917 	 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then
871918 	 * watchdog_stop will fail.
872919 	 */
873
-	if (!test_bit(WDOG_ACTIVE, &wdd->status))
920
+	if (!watchdog_active(wdd))
874921 		err = 0;
875922 	else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) ||
876923 		 !(wdd->info->options & WDIOF_MAGICCLOSE))
....@@ -906,6 +953,7 @@
906953 	.owner		= THIS_MODULE,
907954 	.write		= watchdog_write,
908955 	.unlocked_ioctl	= watchdog_ioctl,
956
+	.compat_ioctl	= compat_ptr_ioctl,
909957 	.open		= watchdog_open,
910958 	.release	= watchdog_release,
911959 };
....@@ -959,7 +1007,7 @@
9591007 	dev_set_name(&wd_data->dev, "watchdog%d", wdd->id);
9601008 
9611009 	kthread_init_work(&wd_data->work, watchdog_ping_work);
962
-	hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
1010
+	hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
9631011 	wd_data->timer.function = watchdog_timer_expired;
9641012 
9651013 	if (wdd->id == 0) {
....@@ -998,6 +1046,7 @@
9981046 
9991047 	/* Record time of most recent heartbeat as 'just before now'. */
10001048 	wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1);
1049
+	watchdog_set_open_deadline(wd_data);
10011050 
10021051 	/*
10031052 	 * If the watchdog is running, prevent its driver from being unloaded,
....@@ -1007,7 +1056,8 @@
10071056 		__module_get(wdd->ops->owner);
10081057 		get_device(&wd_data->dev);
10091058 		if (handle_boot_enabled)
1010
-			hrtimer_start(&wd_data->timer, 0, HRTIMER_MODE_REL);
1059
+			hrtimer_start(&wd_data->timer, 0,
1060
+				      HRTIMER_MODE_REL_HARD);
10111061 		else
10121062 			pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n",
10131063 				wdd->id);
....@@ -1089,6 +1139,39 @@
10891139 }
10901140 
10911141 /*
1142
+ *	watchdog_set_last_hw_keepalive: set last HW keepalive time for watchdog
1143
+ *	@wdd: watchdog device
1144
+ *	@last_ping_ms: time since last HW heartbeat
1145
+ *
1146
+ *	Adjusts the last known HW keepalive time for a watchdog timer.
1147
+ *	This is needed if the watchdog is already running when the probe
1148
+ *	function is called, and it can't be pinged immediately. This
1149
+ *	function must be called immediately after watchdog registration,
1150
+ *	and min_hw_heartbeat_ms must be set for this to be useful.
1151
+ */
1152
+int watchdog_set_last_hw_keepalive(struct watchdog_device *wdd,
1153
+				   unsigned int last_ping_ms)
1154
+{
1155
+	struct watchdog_core_data *wd_data;
1156
+	ktime_t now;
1157
+
1158
+	if (!wdd)
1159
+		return -EINVAL;
1160
+
1161
+	wd_data = wdd->wd_data;
1162
+
1163
+	now = ktime_get();
1164
+
1165
+	wd_data->last_hw_keepalive = ktime_sub(now, ms_to_ktime(last_ping_ms));
1166
+
1167
+	if (watchdog_hw_running(wdd) && handle_boot_enabled)
1168
+		return __watchdog_ping(wdd);
1169
+
1170
+	return 0;
1171
+}
1172
+EXPORT_SYMBOL_GPL(watchdog_set_last_hw_keepalive);
1173
+
1174
+/*
10921175  *	watchdog_dev_init: init dev part of watchdog core
10931176  *
10941177  *	Allocate a range of chardev nodes to use for watchdog devices
....@@ -1097,14 +1180,13 @@
10971180 int __init watchdog_dev_init(void)
10981181 {
10991182 	int err;
1100
-	struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,};
11011183 
11021184 	watchdog_kworker = kthread_create_worker(0, "watchdogd");
11031185 	if (IS_ERR(watchdog_kworker)) {
11041186 		pr_err("Failed to create watchdog kworker\n");
11051187 		return PTR_ERR(watchdog_kworker);
11061188 	}
1107
-	sched_setscheduler(watchdog_kworker->task, SCHED_FIFO, &param);
1189
+	sched_set_fifo(watchdog_kworker->task);
11081190 
11091191 	err = class_register(&watchdog_class);
11101192 	if (err < 0) {
....@@ -1144,3 +1226,8 @@
11441226 MODULE_PARM_DESC(handle_boot_enabled,
11451227 	"Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default="
11461228 	__MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")");
1229
+
1230
+module_param(open_timeout, uint, 0644);
1231
+MODULE_PARM_DESC(open_timeout,
1232
+	"Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default="
1233
+	__MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")");