1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * watchdog_dev.c 4 * 5 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>, 6 * All Rights Reserved. 7 * 8 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>. 9 * 10 * 11 * This source code is part of the generic code that can be used 12 * by all the watchdog timer drivers. 13 * 14 * This part of the generic code takes care of the following 15 * misc device: /dev/watchdog. 16 * 17 * Based on source code of the following authors: 18 * Matt Domsch <Matt_Domsch@dell.com>, 19 * Rob Radez <rob@osinvestor.com>, 20 * Rusty Lynch <rusty@linux.co.intel.com> 21 * Satyam Sharma <satyam@infradead.org> 22 * Randy Dunlap <randy.dunlap@oracle.com> 23 * 24 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. 25 * admit liability nor provide warranty for any of this software. 26 * This material is provided "AS-IS" and at no charge. 27 */ 28 29 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 30 31 #include <linux/cdev.h> /* For character device */ 32 #include <linux/errno.h> /* For the -ENODEV/... values */ 33 #include <linux/fs.h> /* For file operations */ 34 #include <linux/init.h> /* For __init/__exit/... */ 35 #include <linux/hrtimer.h> /* For hrtimers */ 36 #include <linux/kernel.h> /* For printk/panic/... */ 37 #include <linux/kthread.h> /* For kthread_work */ 38 #include <linux/miscdevice.h> /* For handling misc devices */ 39 #include <linux/module.h> /* For module stuff/... */ 40 #include <linux/mutex.h> /* For mutexes */ 41 #include <linux/reboot.h> /* For reboot notifier */ 42 #include <linux/slab.h> /* For memory functions */ 43 #include <linux/types.h> /* For standard types (like size_t) */ 44 #include <linux/watchdog.h> /* For watchdog specific items */ 45 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */ 46 47 #include <uapi/linux/sched/types.h> /* For struct sched_param */ 48 49 #include "watchdog_core.h" 50 #include "watchdog_pretimeout.h" 51 52 /* 53 * struct watchdog_core_data - watchdog core internal data 54 * @dev: The watchdog's internal device 55 * @cdev: The watchdog's Character device. 56 * @wdd: Pointer to watchdog device. 57 * @lock: Lock for watchdog core. 58 * @status: Watchdog core internal status bits. 59 */ 60 struct watchdog_core_data { 61 struct device dev; 62 struct cdev cdev; 63 struct watchdog_device *wdd; 64 struct mutex lock; 65 ktime_t last_keepalive; 66 ktime_t last_hw_keepalive; 67 ktime_t open_deadline; 68 struct hrtimer timer; 69 struct kthread_work work; 70 unsigned long status; /* Internal status bits */ 71 #define _WDOG_DEV_OPEN 0 /* Opened ? */ 72 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */ 73 #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */ 74 }; 75 76 /* the dev_t structure to store the dynamically allocated watchdog devices */ 77 static dev_t watchdog_devt; 78 /* Reference to watchdog device behind /dev/watchdog */ 79 static struct watchdog_core_data *old_wd_data; 80 81 static struct kthread_worker *watchdog_kworker; 82 83 static bool handle_boot_enabled = 84 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED); 85 86 static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT; 87 88 static bool watchdog_past_open_deadline(struct watchdog_core_data *data) 89 { 90 return ktime_after(ktime_get(), data->open_deadline); 91 } 92 93 static void watchdog_set_open_deadline(struct watchdog_core_data *data) 94 { 95 data->open_deadline = open_timeout ? 96 ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX; 97 } 98 99 static inline bool watchdog_need_worker(struct watchdog_device *wdd) 100 { 101 /* All variables in milli-seconds */ 102 unsigned int hm = wdd->max_hw_heartbeat_ms; 103 unsigned int t = wdd->timeout * 1000; 104 105 /* 106 * A worker to generate heartbeat requests is needed if all of the 107 * following conditions are true. 108 * - Userspace activated the watchdog. 109 * - The driver provided a value for the maximum hardware timeout, and 110 * thus is aware that the framework supports generating heartbeat 111 * requests. 112 * - Userspace requests a longer timeout than the hardware can handle. 113 * 114 * Alternatively, if userspace has not opened the watchdog 115 * device, we take care of feeding the watchdog if it is 116 * running. 117 */ 118 return (hm && watchdog_active(wdd) && t > hm) || 119 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd)); 120 } 121 122 static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd) 123 { 124 struct watchdog_core_data *wd_data = wdd->wd_data; 125 unsigned int timeout_ms = wdd->timeout * 1000; 126 ktime_t keepalive_interval; 127 ktime_t last_heartbeat, latest_heartbeat; 128 ktime_t virt_timeout; 129 unsigned int hw_heartbeat_ms; 130 131 if (watchdog_active(wdd)) 132 virt_timeout = ktime_add(wd_data->last_keepalive, 133 ms_to_ktime(timeout_ms)); 134 else 135 virt_timeout = wd_data->open_deadline; 136 137 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms); 138 keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2); 139 140 /* 141 * To ensure that the watchdog times out wdd->timeout seconds 142 * after the most recent ping from userspace, the last 143 * worker ping has to come in hw_heartbeat_ms before this timeout. 144 */ 145 last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms)); 146 latest_heartbeat = ktime_sub(last_heartbeat, ktime_get()); 147 if (ktime_before(latest_heartbeat, keepalive_interval)) 148 return latest_heartbeat; 149 return keepalive_interval; 150 } 151 152 static inline void watchdog_update_worker(struct watchdog_device *wdd) 153 { 154 struct watchdog_core_data *wd_data = wdd->wd_data; 155 156 if (watchdog_need_worker(wdd)) { 157 ktime_t t = watchdog_next_keepalive(wdd); 158 159 if (t > 0) 160 hrtimer_start(&wd_data->timer, t, HRTIMER_MODE_REL); 161 } else { 162 hrtimer_cancel(&wd_data->timer); 163 } 164 } 165 166 static int __watchdog_ping(struct watchdog_device *wdd) 167 { 168 struct watchdog_core_data *wd_data = wdd->wd_data; 169 ktime_t earliest_keepalive, now; 170 int err; 171 172 earliest_keepalive = ktime_add(wd_data->last_hw_keepalive, 173 ms_to_ktime(wdd->min_hw_heartbeat_ms)); 174 now = ktime_get(); 175 176 if (ktime_after(earliest_keepalive, now)) { 177 hrtimer_start(&wd_data->timer, 178 ktime_sub(earliest_keepalive, now), 179 HRTIMER_MODE_REL); 180 return 0; 181 } 182 183 wd_data->last_hw_keepalive = now; 184 185 if (wdd->ops->ping) 186 err = wdd->ops->ping(wdd); /* ping the watchdog */ 187 else 188 err = wdd->ops->start(wdd); /* restart watchdog */ 189 190 watchdog_update_worker(wdd); 191 192 return err; 193 } 194 195 /* 196 * watchdog_ping: ping the watchdog. 197 * @wdd: the watchdog device to ping 198 * 199 * The caller must hold wd_data->lock. 200 * 201 * If the watchdog has no own ping operation then it needs to be 202 * restarted via the start operation. This wrapper function does 203 * exactly that. 204 * We only ping when the watchdog device is running. 205 */ 206 207 static int watchdog_ping(struct watchdog_device *wdd) 208 { 209 struct watchdog_core_data *wd_data = wdd->wd_data; 210 211 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd)) 212 return 0; 213 214 set_bit(_WDOG_KEEPALIVE, &wd_data->status); 215 216 wd_data->last_keepalive = ktime_get(); 217 return __watchdog_ping(wdd); 218 } 219 220 static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data) 221 { 222 struct watchdog_device *wdd = wd_data->wdd; 223 224 if (!wdd) 225 return false; 226 227 if (watchdog_active(wdd)) 228 return true; 229 230 return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data); 231 } 232 233 static void watchdog_ping_work(struct kthread_work *work) 234 { 235 struct watchdog_core_data *wd_data; 236 237 wd_data = container_of(work, struct watchdog_core_data, work); 238 239 mutex_lock(&wd_data->lock); 240 if (watchdog_worker_should_ping(wd_data)) 241 __watchdog_ping(wd_data->wdd); 242 mutex_unlock(&wd_data->lock); 243 } 244 245 static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer) 246 { 247 struct watchdog_core_data *wd_data; 248 249 wd_data = container_of(timer, struct watchdog_core_data, timer); 250 251 kthread_queue_work(watchdog_kworker, &wd_data->work); 252 return HRTIMER_NORESTART; 253 } 254 255 /* 256 * watchdog_start: wrapper to start the watchdog. 257 * @wdd: the watchdog device to start 258 * 259 * The caller must hold wd_data->lock. 260 * 261 * Start the watchdog if it is not active and mark it active. 262 * This function returns zero on success or a negative errno code for 263 * failure. 264 */ 265 266 static int watchdog_start(struct watchdog_device *wdd) 267 { 268 struct watchdog_core_data *wd_data = wdd->wd_data; 269 ktime_t started_at; 270 int err; 271 272 if (watchdog_active(wdd)) 273 return 0; 274 275 set_bit(_WDOG_KEEPALIVE, &wd_data->status); 276 277 started_at = ktime_get(); 278 if (watchdog_hw_running(wdd) && wdd->ops->ping) 279 err = wdd->ops->ping(wdd); 280 else 281 err = wdd->ops->start(wdd); 282 if (err == 0) { 283 set_bit(WDOG_ACTIVE, &wdd->status); 284 wd_data->last_keepalive = started_at; 285 watchdog_update_worker(wdd); 286 } 287 288 return err; 289 } 290 291 /* 292 * watchdog_stop: wrapper to stop the watchdog. 293 * @wdd: the watchdog device to stop 294 * 295 * The caller must hold wd_data->lock. 296 * 297 * Stop the watchdog if it is still active and unmark it active. 298 * This function returns zero on success or a negative errno code for 299 * failure. 300 * If the 'nowayout' feature was set, the watchdog cannot be stopped. 301 */ 302 303 static int watchdog_stop(struct watchdog_device *wdd) 304 { 305 int err = 0; 306 307 if (!watchdog_active(wdd)) 308 return 0; 309 310 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) { 311 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n", 312 wdd->id); 313 return -EBUSY; 314 } 315 316 if (wdd->ops->stop) { 317 clear_bit(WDOG_HW_RUNNING, &wdd->status); 318 err = wdd->ops->stop(wdd); 319 } else { 320 set_bit(WDOG_HW_RUNNING, &wdd->status); 321 } 322 323 if (err == 0) { 324 clear_bit(WDOG_ACTIVE, &wdd->status); 325 watchdog_update_worker(wdd); 326 } 327 328 return err; 329 } 330 331 /* 332 * watchdog_get_status: wrapper to get the watchdog status 333 * @wdd: the watchdog device to get the status from 334 * 335 * The caller must hold wd_data->lock. 336 * 337 * Get the watchdog's status flags. 338 */ 339 340 static unsigned int watchdog_get_status(struct watchdog_device *wdd) 341 { 342 struct watchdog_core_data *wd_data = wdd->wd_data; 343 unsigned int status; 344 345 if (wdd->ops->status) 346 status = wdd->ops->status(wdd); 347 else 348 status = wdd->bootstatus & (WDIOF_CARDRESET | 349 WDIOF_OVERHEAT | 350 WDIOF_FANFAULT | 351 WDIOF_EXTERN1 | 352 WDIOF_EXTERN2 | 353 WDIOF_POWERUNDER | 354 WDIOF_POWEROVER); 355 356 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status)) 357 status |= WDIOF_MAGICCLOSE; 358 359 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status)) 360 status |= WDIOF_KEEPALIVEPING; 361 362 return status; 363 } 364 365 /* 366 * watchdog_set_timeout: set the watchdog timer timeout 367 * @wdd: the watchdog device to set the timeout for 368 * @timeout: timeout to set in seconds 369 * 370 * The caller must hold wd_data->lock. 371 */ 372 373 static int watchdog_set_timeout(struct watchdog_device *wdd, 374 unsigned int timeout) 375 { 376 int err = 0; 377 378 if (!(wdd->info->options & WDIOF_SETTIMEOUT)) 379 return -EOPNOTSUPP; 380 381 if (watchdog_timeout_invalid(wdd, timeout)) 382 return -EINVAL; 383 384 if (wdd->ops->set_timeout) { 385 err = wdd->ops->set_timeout(wdd, timeout); 386 } else { 387 wdd->timeout = timeout; 388 /* Disable pretimeout if it doesn't fit the new timeout */ 389 if (wdd->pretimeout >= wdd->timeout) 390 wdd->pretimeout = 0; 391 } 392 393 watchdog_update_worker(wdd); 394 395 return err; 396 } 397 398 /* 399 * watchdog_set_pretimeout: set the watchdog timer pretimeout 400 * @wdd: the watchdog device to set the timeout for 401 * @timeout: pretimeout to set in seconds 402 */ 403 404 static int watchdog_set_pretimeout(struct watchdog_device *wdd, 405 unsigned int timeout) 406 { 407 int err = 0; 408 409 if (!(wdd->info->options & WDIOF_PRETIMEOUT)) 410 return -EOPNOTSUPP; 411 412 if (watchdog_pretimeout_invalid(wdd, timeout)) 413 return -EINVAL; 414 415 if (wdd->ops->set_pretimeout) 416 err = wdd->ops->set_pretimeout(wdd, timeout); 417 else 418 wdd->pretimeout = timeout; 419 420 return err; 421 } 422 423 /* 424 * watchdog_get_timeleft: wrapper to get the time left before a reboot 425 * @wdd: the watchdog device to get the remaining time from 426 * @timeleft: the time that's left 427 * 428 * The caller must hold wd_data->lock. 429 * 430 * Get the time before a watchdog will reboot (if not pinged). 431 */ 432 433 static int watchdog_get_timeleft(struct watchdog_device *wdd, 434 unsigned int *timeleft) 435 { 436 *timeleft = 0; 437 438 if (!wdd->ops->get_timeleft) 439 return -EOPNOTSUPP; 440 441 *timeleft = wdd->ops->get_timeleft(wdd); 442 443 return 0; 444 } 445 446 #ifdef CONFIG_WATCHDOG_SYSFS 447 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr, 448 char *buf) 449 { 450 struct watchdog_device *wdd = dev_get_drvdata(dev); 451 452 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status)); 453 } 454 static DEVICE_ATTR_RO(nowayout); 455 456 static ssize_t status_show(struct device *dev, struct device_attribute *attr, 457 char *buf) 458 { 459 struct watchdog_device *wdd = dev_get_drvdata(dev); 460 struct watchdog_core_data *wd_data = wdd->wd_data; 461 unsigned int status; 462 463 mutex_lock(&wd_data->lock); 464 status = watchdog_get_status(wdd); 465 mutex_unlock(&wd_data->lock); 466 467 return sprintf(buf, "0x%x\n", status); 468 } 469 static DEVICE_ATTR_RO(status); 470 471 static ssize_t bootstatus_show(struct device *dev, 472 struct device_attribute *attr, char *buf) 473 { 474 struct watchdog_device *wdd = dev_get_drvdata(dev); 475 476 return sprintf(buf, "%u\n", wdd->bootstatus); 477 } 478 static DEVICE_ATTR_RO(bootstatus); 479 480 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr, 481 char *buf) 482 { 483 struct watchdog_device *wdd = dev_get_drvdata(dev); 484 struct watchdog_core_data *wd_data = wdd->wd_data; 485 ssize_t status; 486 unsigned int val; 487 488 mutex_lock(&wd_data->lock); 489 status = watchdog_get_timeleft(wdd, &val); 490 mutex_unlock(&wd_data->lock); 491 if (!status) 492 status = sprintf(buf, "%u\n", val); 493 494 return status; 495 } 496 static DEVICE_ATTR_RO(timeleft); 497 498 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, 499 char *buf) 500 { 501 struct watchdog_device *wdd = dev_get_drvdata(dev); 502 503 return sprintf(buf, "%u\n", wdd->timeout); 504 } 505 static DEVICE_ATTR_RO(timeout); 506 507 static ssize_t pretimeout_show(struct device *dev, 508 struct device_attribute *attr, char *buf) 509 { 510 struct watchdog_device *wdd = dev_get_drvdata(dev); 511 512 return sprintf(buf, "%u\n", wdd->pretimeout); 513 } 514 static DEVICE_ATTR_RO(pretimeout); 515 516 static ssize_t identity_show(struct device *dev, struct device_attribute *attr, 517 char *buf) 518 { 519 struct watchdog_device *wdd = dev_get_drvdata(dev); 520 521 return sprintf(buf, "%s\n", wdd->info->identity); 522 } 523 static DEVICE_ATTR_RO(identity); 524 525 static ssize_t state_show(struct device *dev, struct device_attribute *attr, 526 char *buf) 527 { 528 struct watchdog_device *wdd = dev_get_drvdata(dev); 529 530 if (watchdog_active(wdd)) 531 return sprintf(buf, "active\n"); 532 533 return sprintf(buf, "inactive\n"); 534 } 535 static DEVICE_ATTR_RO(state); 536 537 static ssize_t pretimeout_available_governors_show(struct device *dev, 538 struct device_attribute *attr, char *buf) 539 { 540 return watchdog_pretimeout_available_governors_get(buf); 541 } 542 static DEVICE_ATTR_RO(pretimeout_available_governors); 543 544 static ssize_t pretimeout_governor_show(struct device *dev, 545 struct device_attribute *attr, 546 char *buf) 547 { 548 struct watchdog_device *wdd = dev_get_drvdata(dev); 549 550 return watchdog_pretimeout_governor_get(wdd, buf); 551 } 552 553 static ssize_t pretimeout_governor_store(struct device *dev, 554 struct device_attribute *attr, 555 const char *buf, size_t count) 556 { 557 struct watchdog_device *wdd = dev_get_drvdata(dev); 558 int ret = watchdog_pretimeout_governor_set(wdd, buf); 559 560 if (!ret) 561 ret = count; 562 563 return ret; 564 } 565 static DEVICE_ATTR_RW(pretimeout_governor); 566 567 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr, 568 int n) 569 { 570 struct device *dev = container_of(kobj, struct device, kobj); 571 struct watchdog_device *wdd = dev_get_drvdata(dev); 572 umode_t mode = attr->mode; 573 574 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft) 575 mode = 0; 576 else if (attr == &dev_attr_pretimeout.attr && 577 !(wdd->info->options & WDIOF_PRETIMEOUT)) 578 mode = 0; 579 else if ((attr == &dev_attr_pretimeout_governor.attr || 580 attr == &dev_attr_pretimeout_available_governors.attr) && 581 (!(wdd->info->options & WDIOF_PRETIMEOUT) || 582 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV))) 583 mode = 0; 584 585 return mode; 586 } 587 static struct attribute *wdt_attrs[] = { 588 &dev_attr_state.attr, 589 &dev_attr_identity.attr, 590 &dev_attr_timeout.attr, 591 &dev_attr_pretimeout.attr, 592 &dev_attr_timeleft.attr, 593 &dev_attr_bootstatus.attr, 594 &dev_attr_status.attr, 595 &dev_attr_nowayout.attr, 596 &dev_attr_pretimeout_governor.attr, 597 &dev_attr_pretimeout_available_governors.attr, 598 NULL, 599 }; 600 601 static const struct attribute_group wdt_group = { 602 .attrs = wdt_attrs, 603 .is_visible = wdt_is_visible, 604 }; 605 __ATTRIBUTE_GROUPS(wdt); 606 #else 607 #define wdt_groups NULL 608 #endif 609 610 /* 611 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined 612 * @wdd: the watchdog device to do the ioctl on 613 * @cmd: watchdog command 614 * @arg: argument pointer 615 * 616 * The caller must hold wd_data->lock. 617 */ 618 619 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd, 620 unsigned long arg) 621 { 622 if (!wdd->ops->ioctl) 623 return -ENOIOCTLCMD; 624 625 return wdd->ops->ioctl(wdd, cmd, arg); 626 } 627 628 /* 629 * watchdog_write: writes to the watchdog. 630 * @file: file from VFS 631 * @data: user address of data 632 * @len: length of data 633 * @ppos: pointer to the file offset 634 * 635 * A write to a watchdog device is defined as a keepalive ping. 636 * Writing the magic 'V' sequence allows the next close to turn 637 * off the watchdog (if 'nowayout' is not set). 638 */ 639 640 static ssize_t watchdog_write(struct file *file, const char __user *data, 641 size_t len, loff_t *ppos) 642 { 643 struct watchdog_core_data *wd_data = file->private_data; 644 struct watchdog_device *wdd; 645 int err; 646 size_t i; 647 char c; 648 649 if (len == 0) 650 return 0; 651 652 /* 653 * Note: just in case someone wrote the magic character 654 * five months ago... 655 */ 656 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 657 658 /* scan to see whether or not we got the magic character */ 659 for (i = 0; i != len; i++) { 660 if (get_user(c, data + i)) 661 return -EFAULT; 662 if (c == 'V') 663 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 664 } 665 666 /* someone wrote to us, so we send the watchdog a keepalive ping */ 667 668 err = -ENODEV; 669 mutex_lock(&wd_data->lock); 670 wdd = wd_data->wdd; 671 if (wdd) 672 err = watchdog_ping(wdd); 673 mutex_unlock(&wd_data->lock); 674 675 if (err < 0) 676 return err; 677 678 return len; 679 } 680 681 /* 682 * watchdog_ioctl: handle the different ioctl's for the watchdog device. 683 * @file: file handle to the device 684 * @cmd: watchdog command 685 * @arg: argument pointer 686 * 687 * The watchdog API defines a common set of functions for all watchdogs 688 * according to their available features. 689 */ 690 691 static long watchdog_ioctl(struct file *file, unsigned int cmd, 692 unsigned long arg) 693 { 694 struct watchdog_core_data *wd_data = file->private_data; 695 void __user *argp = (void __user *)arg; 696 struct watchdog_device *wdd; 697 int __user *p = argp; 698 unsigned int val; 699 int err; 700 701 mutex_lock(&wd_data->lock); 702 703 wdd = wd_data->wdd; 704 if (!wdd) { 705 err = -ENODEV; 706 goto out_ioctl; 707 } 708 709 err = watchdog_ioctl_op(wdd, cmd, arg); 710 if (err != -ENOIOCTLCMD) 711 goto out_ioctl; 712 713 switch (cmd) { 714 case WDIOC_GETSUPPORT: 715 err = copy_to_user(argp, wdd->info, 716 sizeof(struct watchdog_info)) ? -EFAULT : 0; 717 break; 718 case WDIOC_GETSTATUS: 719 val = watchdog_get_status(wdd); 720 err = put_user(val, p); 721 break; 722 case WDIOC_GETBOOTSTATUS: 723 err = put_user(wdd->bootstatus, p); 724 break; 725 case WDIOC_SETOPTIONS: 726 if (get_user(val, p)) { 727 err = -EFAULT; 728 break; 729 } 730 if (val & WDIOS_DISABLECARD) { 731 err = watchdog_stop(wdd); 732 if (err < 0) 733 break; 734 } 735 if (val & WDIOS_ENABLECARD) 736 err = watchdog_start(wdd); 737 break; 738 case WDIOC_KEEPALIVE: 739 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) { 740 err = -EOPNOTSUPP; 741 break; 742 } 743 err = watchdog_ping(wdd); 744 break; 745 case WDIOC_SETTIMEOUT: 746 if (get_user(val, p)) { 747 err = -EFAULT; 748 break; 749 } 750 err = watchdog_set_timeout(wdd, val); 751 if (err < 0) 752 break; 753 /* If the watchdog is active then we send a keepalive ping 754 * to make sure that the watchdog keep's running (and if 755 * possible that it takes the new timeout) */ 756 err = watchdog_ping(wdd); 757 if (err < 0) 758 break; 759 /* fall through */ 760 case WDIOC_GETTIMEOUT: 761 /* timeout == 0 means that we don't know the timeout */ 762 if (wdd->timeout == 0) { 763 err = -EOPNOTSUPP; 764 break; 765 } 766 err = put_user(wdd->timeout, p); 767 break; 768 case WDIOC_GETTIMELEFT: 769 err = watchdog_get_timeleft(wdd, &val); 770 if (err < 0) 771 break; 772 err = put_user(val, p); 773 break; 774 case WDIOC_SETPRETIMEOUT: 775 if (get_user(val, p)) { 776 err = -EFAULT; 777 break; 778 } 779 err = watchdog_set_pretimeout(wdd, val); 780 break; 781 case WDIOC_GETPRETIMEOUT: 782 err = put_user(wdd->pretimeout, p); 783 break; 784 default: 785 err = -ENOTTY; 786 break; 787 } 788 789 out_ioctl: 790 mutex_unlock(&wd_data->lock); 791 return err; 792 } 793 794 /* 795 * watchdog_open: open the /dev/watchdog* devices. 796 * @inode: inode of device 797 * @file: file handle to device 798 * 799 * When the /dev/watchdog* device gets opened, we start the watchdog. 800 * Watch out: the /dev/watchdog device is single open, so we make sure 801 * it can only be opened once. 802 */ 803 804 static int watchdog_open(struct inode *inode, struct file *file) 805 { 806 struct watchdog_core_data *wd_data; 807 struct watchdog_device *wdd; 808 bool hw_running; 809 int err; 810 811 /* Get the corresponding watchdog device */ 812 if (imajor(inode) == MISC_MAJOR) 813 wd_data = old_wd_data; 814 else 815 wd_data = container_of(inode->i_cdev, struct watchdog_core_data, 816 cdev); 817 818 /* the watchdog is single open! */ 819 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status)) 820 return -EBUSY; 821 822 wdd = wd_data->wdd; 823 824 /* 825 * If the /dev/watchdog device is open, we don't want the module 826 * to be unloaded. 827 */ 828 hw_running = watchdog_hw_running(wdd); 829 if (!hw_running && !try_module_get(wdd->ops->owner)) { 830 err = -EBUSY; 831 goto out_clear; 832 } 833 834 err = watchdog_start(wdd); 835 if (err < 0) 836 goto out_mod; 837 838 file->private_data = wd_data; 839 840 if (!hw_running) 841 get_device(&wd_data->dev); 842 843 /* 844 * open_timeout only applies for the first open from 845 * userspace. Set open_deadline to infinity so that the kernel 846 * will take care of an always-running hardware watchdog in 847 * case the device gets magic-closed or WDIOS_DISABLECARD is 848 * applied. 849 */ 850 wd_data->open_deadline = KTIME_MAX; 851 852 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ 853 return stream_open(inode, file); 854 855 out_mod: 856 module_put(wd_data->wdd->ops->owner); 857 out_clear: 858 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 859 return err; 860 } 861 862 static void watchdog_core_data_release(struct device *dev) 863 { 864 struct watchdog_core_data *wd_data; 865 866 wd_data = container_of(dev, struct watchdog_core_data, dev); 867 868 kfree(wd_data); 869 } 870 871 /* 872 * watchdog_release: release the watchdog device. 873 * @inode: inode of device 874 * @file: file handle to device 875 * 876 * This is the code for when /dev/watchdog gets closed. We will only 877 * stop the watchdog when we have received the magic char (and nowayout 878 * was not set), else the watchdog will keep running. 879 */ 880 881 static int watchdog_release(struct inode *inode, struct file *file) 882 { 883 struct watchdog_core_data *wd_data = file->private_data; 884 struct watchdog_device *wdd; 885 int err = -EBUSY; 886 bool running; 887 888 mutex_lock(&wd_data->lock); 889 890 wdd = wd_data->wdd; 891 if (!wdd) 892 goto done; 893 894 /* 895 * We only stop the watchdog if we received the magic character 896 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then 897 * watchdog_stop will fail. 898 */ 899 if (!test_bit(WDOG_ACTIVE, &wdd->status)) 900 err = 0; 901 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) || 902 !(wdd->info->options & WDIOF_MAGICCLOSE)) 903 err = watchdog_stop(wdd); 904 905 /* If the watchdog was not stopped, send a keepalive ping */ 906 if (err < 0) { 907 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id); 908 watchdog_ping(wdd); 909 } 910 911 watchdog_update_worker(wdd); 912 913 /* make sure that /dev/watchdog can be re-opened */ 914 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 915 916 done: 917 running = wdd && watchdog_hw_running(wdd); 918 mutex_unlock(&wd_data->lock); 919 /* 920 * Allow the owner module to be unloaded again unless the watchdog 921 * is still running. If the watchdog is still running, it can not 922 * be stopped, and its driver must not be unloaded. 923 */ 924 if (!running) { 925 module_put(wd_data->cdev.owner); 926 put_device(&wd_data->dev); 927 } 928 return 0; 929 } 930 931 static const struct file_operations watchdog_fops = { 932 .owner = THIS_MODULE, 933 .write = watchdog_write, 934 .unlocked_ioctl = watchdog_ioctl, 935 .open = watchdog_open, 936 .release = watchdog_release, 937 }; 938 939 static struct miscdevice watchdog_miscdev = { 940 .minor = WATCHDOG_MINOR, 941 .name = "watchdog", 942 .fops = &watchdog_fops, 943 }; 944 945 static struct class watchdog_class = { 946 .name = "watchdog", 947 .owner = THIS_MODULE, 948 .dev_groups = wdt_groups, 949 }; 950 951 /* 952 * watchdog_cdev_register: register watchdog character device 953 * @wdd: watchdog device 954 * 955 * Register a watchdog character device including handling the legacy 956 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 957 * thus we set it up like that. 958 */ 959 960 static int watchdog_cdev_register(struct watchdog_device *wdd) 961 { 962 struct watchdog_core_data *wd_data; 963 int err; 964 965 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL); 966 if (!wd_data) 967 return -ENOMEM; 968 mutex_init(&wd_data->lock); 969 970 wd_data->wdd = wdd; 971 wdd->wd_data = wd_data; 972 973 if (IS_ERR_OR_NULL(watchdog_kworker)) 974 return -ENODEV; 975 976 kthread_init_work(&wd_data->work, watchdog_ping_work); 977 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 978 wd_data->timer.function = watchdog_timer_expired; 979 980 if (wdd->id == 0) { 981 old_wd_data = wd_data; 982 watchdog_miscdev.parent = wdd->parent; 983 err = misc_register(&watchdog_miscdev); 984 if (err != 0) { 985 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", 986 wdd->info->identity, WATCHDOG_MINOR, err); 987 if (err == -EBUSY) 988 pr_err("%s: a legacy watchdog module is probably present.\n", 989 wdd->info->identity); 990 old_wd_data = NULL; 991 kfree(wd_data); 992 return err; 993 } 994 } 995 996 device_initialize(&wd_data->dev); 997 wd_data->dev.devt = MKDEV(MAJOR(watchdog_devt), wdd->id); 998 wd_data->dev.class = &watchdog_class; 999 wd_data->dev.parent = wdd->parent; 1000 wd_data->dev.groups = wdd->groups; 1001 wd_data->dev.release = watchdog_core_data_release; 1002 dev_set_drvdata(&wd_data->dev, wdd); 1003 dev_set_name(&wd_data->dev, "watchdog%d", wdd->id); 1004 1005 /* Fill in the data structures */ 1006 cdev_init(&wd_data->cdev, &watchdog_fops); 1007 1008 /* Add the device */ 1009 err = cdev_device_add(&wd_data->cdev, &wd_data->dev); 1010 if (err) { 1011 pr_err("watchdog%d unable to add device %d:%d\n", 1012 wdd->id, MAJOR(watchdog_devt), wdd->id); 1013 if (wdd->id == 0) { 1014 misc_deregister(&watchdog_miscdev); 1015 old_wd_data = NULL; 1016 put_device(&wd_data->dev); 1017 } 1018 return err; 1019 } 1020 1021 wd_data->cdev.owner = wdd->ops->owner; 1022 1023 /* Record time of most recent heartbeat as 'just before now'. */ 1024 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1); 1025 watchdog_set_open_deadline(wd_data); 1026 1027 /* 1028 * If the watchdog is running, prevent its driver from being unloaded, 1029 * and schedule an immediate ping. 1030 */ 1031 if (watchdog_hw_running(wdd)) { 1032 __module_get(wdd->ops->owner); 1033 get_device(&wd_data->dev); 1034 if (handle_boot_enabled) 1035 hrtimer_start(&wd_data->timer, 0, HRTIMER_MODE_REL); 1036 else 1037 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n", 1038 wdd->id); 1039 } 1040 1041 return 0; 1042 } 1043 1044 /* 1045 * watchdog_cdev_unregister: unregister watchdog character device 1046 * @watchdog: watchdog device 1047 * 1048 * Unregister watchdog character device and if needed the legacy 1049 * /dev/watchdog device. 1050 */ 1051 1052 static void watchdog_cdev_unregister(struct watchdog_device *wdd) 1053 { 1054 struct watchdog_core_data *wd_data = wdd->wd_data; 1055 1056 cdev_device_del(&wd_data->cdev, &wd_data->dev); 1057 if (wdd->id == 0) { 1058 misc_deregister(&watchdog_miscdev); 1059 old_wd_data = NULL; 1060 } 1061 1062 if (watchdog_active(wdd) && 1063 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) { 1064 watchdog_stop(wdd); 1065 } 1066 1067 mutex_lock(&wd_data->lock); 1068 wd_data->wdd = NULL; 1069 wdd->wd_data = NULL; 1070 mutex_unlock(&wd_data->lock); 1071 1072 hrtimer_cancel(&wd_data->timer); 1073 kthread_cancel_work_sync(&wd_data->work); 1074 1075 put_device(&wd_data->dev); 1076 } 1077 1078 static int watchdog_reboot_notifier(struct notifier_block *nb, 1079 unsigned long code, void *data) 1080 { 1081 struct watchdog_device *wdd; 1082 1083 wdd = container_of(nb, struct watchdog_device, reboot_nb); 1084 if (code == SYS_DOWN || code == SYS_HALT) { 1085 if (watchdog_active(wdd)) { 1086 int ret; 1087 1088 ret = wdd->ops->stop(wdd); 1089 if (ret) 1090 return NOTIFY_BAD; 1091 } 1092 } 1093 1094 return NOTIFY_DONE; 1095 } 1096 1097 /* 1098 * watchdog_dev_register: register a watchdog device 1099 * @wdd: watchdog device 1100 * 1101 * Register a watchdog device including handling the legacy 1102 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 1103 * thus we set it up like that. 1104 */ 1105 1106 int watchdog_dev_register(struct watchdog_device *wdd) 1107 { 1108 int ret; 1109 1110 ret = watchdog_cdev_register(wdd); 1111 if (ret) 1112 return ret; 1113 1114 ret = watchdog_register_pretimeout(wdd); 1115 if (ret) { 1116 watchdog_cdev_unregister(wdd); 1117 return ret; 1118 } 1119 1120 if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { 1121 wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; 1122 1123 ret = devm_register_reboot_notifier(&wdd->wd_data->dev, 1124 &wdd->reboot_nb); 1125 if (ret) { 1126 pr_err("watchdog%d: Cannot register reboot notifier (%d)\n", 1127 wdd->id, ret); 1128 watchdog_dev_unregister(wdd); 1129 } 1130 } 1131 1132 return ret; 1133 } 1134 1135 /* 1136 * watchdog_dev_unregister: unregister a watchdog device 1137 * @watchdog: watchdog device 1138 * 1139 * Unregister watchdog device and if needed the legacy 1140 * /dev/watchdog device. 1141 */ 1142 1143 void watchdog_dev_unregister(struct watchdog_device *wdd) 1144 { 1145 watchdog_unregister_pretimeout(wdd); 1146 watchdog_cdev_unregister(wdd); 1147 } 1148 1149 /* 1150 * watchdog_dev_init: init dev part of watchdog core 1151 * 1152 * Allocate a range of chardev nodes to use for watchdog devices 1153 */ 1154 1155 int __init watchdog_dev_init(void) 1156 { 1157 int err; 1158 struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,}; 1159 1160 watchdog_kworker = kthread_create_worker(0, "watchdogd"); 1161 if (IS_ERR(watchdog_kworker)) { 1162 pr_err("Failed to create watchdog kworker\n"); 1163 return PTR_ERR(watchdog_kworker); 1164 } 1165 sched_setscheduler(watchdog_kworker->task, SCHED_FIFO, ¶m); 1166 1167 err = class_register(&watchdog_class); 1168 if (err < 0) { 1169 pr_err("couldn't register class\n"); 1170 goto err_register; 1171 } 1172 1173 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog"); 1174 if (err < 0) { 1175 pr_err("watchdog: unable to allocate char dev region\n"); 1176 goto err_alloc; 1177 } 1178 1179 return 0; 1180 1181 err_alloc: 1182 class_unregister(&watchdog_class); 1183 err_register: 1184 kthread_destroy_worker(watchdog_kworker); 1185 return err; 1186 } 1187 1188 /* 1189 * watchdog_dev_exit: exit dev part of watchdog core 1190 * 1191 * Release the range of chardev nodes used for watchdog devices 1192 */ 1193 1194 void __exit watchdog_dev_exit(void) 1195 { 1196 unregister_chrdev_region(watchdog_devt, MAX_DOGS); 1197 class_unregister(&watchdog_class); 1198 kthread_destroy_worker(watchdog_kworker); 1199 } 1200 1201 module_param(handle_boot_enabled, bool, 0444); 1202 MODULE_PARM_DESC(handle_boot_enabled, 1203 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default=" 1204 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")"); 1205 1206 module_param(open_timeout, uint, 0644); 1207 MODULE_PARM_DESC(open_timeout, 1208 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default=" 1209 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")"); 1210