1 /* 2 * watchdog_dev.c 3 * 4 * (c) Copyright 2008-2011 Alan Cox <alan@lxorguk.ukuu.org.uk>, 5 * All Rights Reserved. 6 * 7 * (c) Copyright 2008-2011 Wim Van Sebroeck <wim@iguana.be>. 8 * 9 * 10 * This source code is part of the generic code that can be used 11 * by all the watchdog timer drivers. 12 * 13 * This part of the generic code takes care of the following 14 * misc device: /dev/watchdog. 15 * 16 * Based on source code of the following authors: 17 * Matt Domsch <Matt_Domsch@dell.com>, 18 * Rob Radez <rob@osinvestor.com>, 19 * Rusty Lynch <rusty@linux.co.intel.com> 20 * Satyam Sharma <satyam@infradead.org> 21 * 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. 27 * 28 * Neither Alan Cox, CymruNet Ltd., Wim Van Sebroeck nor Iguana vzw. 29 * admit liability nor provide warranty for any of this software. 30 * This material is provided "AS-IS" and at no charge. 31 */ 32 33 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 34 35 #include <linux/cdev.h> /* For character device */ 36 #include <linux/errno.h> /* For the -ENODEV/... values */ 37 #include <linux/fs.h> /* For file operations */ 38 #include <linux/init.h> /* For __init/__exit/... */ 39 #include <linux/hrtimer.h> /* For hrtimers */ 40 #include <linux/kernel.h> /* For printk/panic/... */ 41 #include <linux/kref.h> /* For data references */ 42 #include <linux/kthread.h> /* For kthread_work */ 43 #include <linux/miscdevice.h> /* For handling misc devices */ 44 #include <linux/module.h> /* For module stuff/... */ 45 #include <linux/mutex.h> /* For mutexes */ 46 #include <linux/reboot.h> /* For reboot notifier */ 47 #include <linux/slab.h> /* For memory functions */ 48 #include <linux/types.h> /* For standard types (like size_t) */ 49 #include <linux/watchdog.h> /* For watchdog specific items */ 50 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */ 51 52 #include <uapi/linux/sched/types.h> /* For struct sched_param */ 53 54 #include "watchdog_core.h" 55 #include "watchdog_pretimeout.h" 56 57 /* 58 * struct watchdog_core_data - watchdog core internal data 59 * @kref: Reference count. 60 * @cdev: The watchdog's Character device. 61 * @wdd: Pointer to watchdog device. 62 * @lock: Lock for watchdog core. 63 * @status: Watchdog core internal status bits. 64 */ 65 struct watchdog_core_data { 66 struct kref kref; 67 struct cdev cdev; 68 struct watchdog_device *wdd; 69 struct mutex lock; 70 ktime_t last_keepalive; 71 ktime_t last_hw_keepalive; 72 ktime_t open_deadline; 73 struct hrtimer timer; 74 struct kthread_work work; 75 unsigned long status; /* Internal status bits */ 76 #define _WDOG_DEV_OPEN 0 /* Opened ? */ 77 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */ 78 #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */ 79 }; 80 81 /* the dev_t structure to store the dynamically allocated watchdog devices */ 82 static dev_t watchdog_devt; 83 /* Reference to watchdog device behind /dev/watchdog */ 84 static struct watchdog_core_data *old_wd_data; 85 86 static struct kthread_worker *watchdog_kworker; 87 88 static bool handle_boot_enabled = 89 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED); 90 91 static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT; 92 93 static bool watchdog_past_open_deadline(struct watchdog_core_data *data) 94 { 95 return ktime_after(ktime_get(), data->open_deadline); 96 } 97 98 static void watchdog_set_open_deadline(struct watchdog_core_data *data) 99 { 100 data->open_deadline = open_timeout ? 101 ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX; 102 } 103 104 static inline bool watchdog_need_worker(struct watchdog_device *wdd) 105 { 106 /* All variables in milli-seconds */ 107 unsigned int hm = wdd->max_hw_heartbeat_ms; 108 unsigned int t = wdd->timeout * 1000; 109 110 /* 111 * A worker to generate heartbeat requests is needed if all of the 112 * following conditions are true. 113 * - Userspace activated the watchdog. 114 * - The driver provided a value for the maximum hardware timeout, and 115 * thus is aware that the framework supports generating heartbeat 116 * requests. 117 * - Userspace requests a longer timeout than the hardware can handle. 118 * 119 * Alternatively, if userspace has not opened the watchdog 120 * device, we take care of feeding the watchdog if it is 121 * running. 122 */ 123 return (hm && watchdog_active(wdd) && t > hm) || 124 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd)); 125 } 126 127 static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd) 128 { 129 struct watchdog_core_data *wd_data = wdd->wd_data; 130 unsigned int timeout_ms = wdd->timeout * 1000; 131 ktime_t keepalive_interval; 132 ktime_t last_heartbeat, latest_heartbeat; 133 ktime_t virt_timeout; 134 unsigned int hw_heartbeat_ms; 135 136 if (watchdog_active(wdd)) 137 virt_timeout = ktime_add(wd_data->last_keepalive, 138 ms_to_ktime(timeout_ms)); 139 else 140 virt_timeout = wd_data->open_deadline; 141 142 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms); 143 keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2); 144 145 /* 146 * To ensure that the watchdog times out wdd->timeout seconds 147 * after the most recent ping from userspace, the last 148 * worker ping has to come in hw_heartbeat_ms before this timeout. 149 */ 150 last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms)); 151 latest_heartbeat = ktime_sub(last_heartbeat, ktime_get()); 152 if (ktime_before(latest_heartbeat, keepalive_interval)) 153 return latest_heartbeat; 154 return keepalive_interval; 155 } 156 157 static inline void watchdog_update_worker(struct watchdog_device *wdd) 158 { 159 struct watchdog_core_data *wd_data = wdd->wd_data; 160 161 if (watchdog_need_worker(wdd)) { 162 ktime_t t = watchdog_next_keepalive(wdd); 163 164 if (t > 0) 165 hrtimer_start(&wd_data->timer, t, HRTIMER_MODE_REL); 166 } else { 167 hrtimer_cancel(&wd_data->timer); 168 } 169 } 170 171 static int __watchdog_ping(struct watchdog_device *wdd) 172 { 173 struct watchdog_core_data *wd_data = wdd->wd_data; 174 ktime_t earliest_keepalive, now; 175 int err; 176 177 earliest_keepalive = ktime_add(wd_data->last_hw_keepalive, 178 ms_to_ktime(wdd->min_hw_heartbeat_ms)); 179 now = ktime_get(); 180 181 if (ktime_after(earliest_keepalive, now)) { 182 hrtimer_start(&wd_data->timer, 183 ktime_sub(earliest_keepalive, now), 184 HRTIMER_MODE_REL); 185 return 0; 186 } 187 188 wd_data->last_hw_keepalive = now; 189 190 if (wdd->ops->ping) 191 err = wdd->ops->ping(wdd); /* ping the watchdog */ 192 else 193 err = wdd->ops->start(wdd); /* restart watchdog */ 194 195 watchdog_update_worker(wdd); 196 197 return err; 198 } 199 200 /* 201 * watchdog_ping: ping the watchdog. 202 * @wdd: the watchdog device to ping 203 * 204 * The caller must hold wd_data->lock. 205 * 206 * If the watchdog has no own ping operation then it needs to be 207 * restarted via the start operation. This wrapper function does 208 * exactly that. 209 * We only ping when the watchdog device is running. 210 */ 211 212 static int watchdog_ping(struct watchdog_device *wdd) 213 { 214 struct watchdog_core_data *wd_data = wdd->wd_data; 215 216 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd)) 217 return 0; 218 219 set_bit(_WDOG_KEEPALIVE, &wd_data->status); 220 221 wd_data->last_keepalive = ktime_get(); 222 return __watchdog_ping(wdd); 223 } 224 225 static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data) 226 { 227 struct watchdog_device *wdd = wd_data->wdd; 228 229 if (!wdd) 230 return false; 231 232 if (watchdog_active(wdd)) 233 return true; 234 235 return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data); 236 } 237 238 static void watchdog_ping_work(struct kthread_work *work) 239 { 240 struct watchdog_core_data *wd_data; 241 242 wd_data = container_of(work, struct watchdog_core_data, work); 243 244 mutex_lock(&wd_data->lock); 245 if (watchdog_worker_should_ping(wd_data)) 246 __watchdog_ping(wd_data->wdd); 247 mutex_unlock(&wd_data->lock); 248 } 249 250 static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer) 251 { 252 struct watchdog_core_data *wd_data; 253 254 wd_data = container_of(timer, struct watchdog_core_data, timer); 255 256 kthread_queue_work(watchdog_kworker, &wd_data->work); 257 return HRTIMER_NORESTART; 258 } 259 260 /* 261 * watchdog_start: wrapper to start the watchdog. 262 * @wdd: the watchdog device to start 263 * 264 * The caller must hold wd_data->lock. 265 * 266 * Start the watchdog if it is not active and mark it active. 267 * This function returns zero on success or a negative errno code for 268 * failure. 269 */ 270 271 static int watchdog_start(struct watchdog_device *wdd) 272 { 273 struct watchdog_core_data *wd_data = wdd->wd_data; 274 ktime_t started_at; 275 int err; 276 277 if (watchdog_active(wdd)) 278 return 0; 279 280 set_bit(_WDOG_KEEPALIVE, &wd_data->status); 281 282 started_at = ktime_get(); 283 if (watchdog_hw_running(wdd) && wdd->ops->ping) 284 err = wdd->ops->ping(wdd); 285 else 286 err = wdd->ops->start(wdd); 287 if (err == 0) { 288 set_bit(WDOG_ACTIVE, &wdd->status); 289 wd_data->last_keepalive = started_at; 290 watchdog_update_worker(wdd); 291 } 292 293 return err; 294 } 295 296 /* 297 * watchdog_stop: wrapper to stop the watchdog. 298 * @wdd: the watchdog device to stop 299 * 300 * The caller must hold wd_data->lock. 301 * 302 * Stop the watchdog if it is still active and unmark it active. 303 * This function returns zero on success or a negative errno code for 304 * failure. 305 * If the 'nowayout' feature was set, the watchdog cannot be stopped. 306 */ 307 308 static int watchdog_stop(struct watchdog_device *wdd) 309 { 310 int err = 0; 311 312 if (!watchdog_active(wdd)) 313 return 0; 314 315 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) { 316 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n", 317 wdd->id); 318 return -EBUSY; 319 } 320 321 if (wdd->ops->stop) { 322 clear_bit(WDOG_HW_RUNNING, &wdd->status); 323 err = wdd->ops->stop(wdd); 324 } else { 325 set_bit(WDOG_HW_RUNNING, &wdd->status); 326 } 327 328 if (err == 0) { 329 clear_bit(WDOG_ACTIVE, &wdd->status); 330 watchdog_update_worker(wdd); 331 } 332 333 return err; 334 } 335 336 /* 337 * watchdog_get_status: wrapper to get the watchdog status 338 * @wdd: the watchdog device to get the status from 339 * 340 * The caller must hold wd_data->lock. 341 * 342 * Get the watchdog's status flags. 343 */ 344 345 static unsigned int watchdog_get_status(struct watchdog_device *wdd) 346 { 347 struct watchdog_core_data *wd_data = wdd->wd_data; 348 unsigned int status; 349 350 if (wdd->ops->status) 351 status = wdd->ops->status(wdd); 352 else 353 status = wdd->bootstatus & (WDIOF_CARDRESET | 354 WDIOF_OVERHEAT | 355 WDIOF_FANFAULT | 356 WDIOF_EXTERN1 | 357 WDIOF_EXTERN2 | 358 WDIOF_POWERUNDER | 359 WDIOF_POWEROVER); 360 361 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status)) 362 status |= WDIOF_MAGICCLOSE; 363 364 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status)) 365 status |= WDIOF_KEEPALIVEPING; 366 367 return status; 368 } 369 370 /* 371 * watchdog_set_timeout: set the watchdog timer timeout 372 * @wdd: the watchdog device to set the timeout for 373 * @timeout: timeout to set in seconds 374 * 375 * The caller must hold wd_data->lock. 376 */ 377 378 static int watchdog_set_timeout(struct watchdog_device *wdd, 379 unsigned int timeout) 380 { 381 int err = 0; 382 383 if (!(wdd->info->options & WDIOF_SETTIMEOUT)) 384 return -EOPNOTSUPP; 385 386 if (watchdog_timeout_invalid(wdd, timeout)) 387 return -EINVAL; 388 389 if (wdd->ops->set_timeout) { 390 err = wdd->ops->set_timeout(wdd, timeout); 391 } else { 392 wdd->timeout = timeout; 393 /* Disable pretimeout if it doesn't fit the new timeout */ 394 if (wdd->pretimeout >= wdd->timeout) 395 wdd->pretimeout = 0; 396 } 397 398 watchdog_update_worker(wdd); 399 400 return err; 401 } 402 403 /* 404 * watchdog_set_pretimeout: set the watchdog timer pretimeout 405 * @wdd: the watchdog device to set the timeout for 406 * @timeout: pretimeout to set in seconds 407 */ 408 409 static int watchdog_set_pretimeout(struct watchdog_device *wdd, 410 unsigned int timeout) 411 { 412 int err = 0; 413 414 if (!(wdd->info->options & WDIOF_PRETIMEOUT)) 415 return -EOPNOTSUPP; 416 417 if (watchdog_pretimeout_invalid(wdd, timeout)) 418 return -EINVAL; 419 420 if (wdd->ops->set_pretimeout) 421 err = wdd->ops->set_pretimeout(wdd, timeout); 422 else 423 wdd->pretimeout = timeout; 424 425 return err; 426 } 427 428 /* 429 * watchdog_get_timeleft: wrapper to get the time left before a reboot 430 * @wdd: the watchdog device to get the remaining time from 431 * @timeleft: the time that's left 432 * 433 * The caller must hold wd_data->lock. 434 * 435 * Get the time before a watchdog will reboot (if not pinged). 436 */ 437 438 static int watchdog_get_timeleft(struct watchdog_device *wdd, 439 unsigned int *timeleft) 440 { 441 *timeleft = 0; 442 443 if (!wdd->ops->get_timeleft) 444 return -EOPNOTSUPP; 445 446 *timeleft = wdd->ops->get_timeleft(wdd); 447 448 return 0; 449 } 450 451 #ifdef CONFIG_WATCHDOG_SYSFS 452 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr, 453 char *buf) 454 { 455 struct watchdog_device *wdd = dev_get_drvdata(dev); 456 457 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status)); 458 } 459 static DEVICE_ATTR_RO(nowayout); 460 461 static ssize_t status_show(struct device *dev, struct device_attribute *attr, 462 char *buf) 463 { 464 struct watchdog_device *wdd = dev_get_drvdata(dev); 465 struct watchdog_core_data *wd_data = wdd->wd_data; 466 unsigned int status; 467 468 mutex_lock(&wd_data->lock); 469 status = watchdog_get_status(wdd); 470 mutex_unlock(&wd_data->lock); 471 472 return sprintf(buf, "0x%x\n", status); 473 } 474 static DEVICE_ATTR_RO(status); 475 476 static ssize_t bootstatus_show(struct device *dev, 477 struct device_attribute *attr, char *buf) 478 { 479 struct watchdog_device *wdd = dev_get_drvdata(dev); 480 481 return sprintf(buf, "%u\n", wdd->bootstatus); 482 } 483 static DEVICE_ATTR_RO(bootstatus); 484 485 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr, 486 char *buf) 487 { 488 struct watchdog_device *wdd = dev_get_drvdata(dev); 489 struct watchdog_core_data *wd_data = wdd->wd_data; 490 ssize_t status; 491 unsigned int val; 492 493 mutex_lock(&wd_data->lock); 494 status = watchdog_get_timeleft(wdd, &val); 495 mutex_unlock(&wd_data->lock); 496 if (!status) 497 status = sprintf(buf, "%u\n", val); 498 499 return status; 500 } 501 static DEVICE_ATTR_RO(timeleft); 502 503 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, 504 char *buf) 505 { 506 struct watchdog_device *wdd = dev_get_drvdata(dev); 507 508 return sprintf(buf, "%u\n", wdd->timeout); 509 } 510 static DEVICE_ATTR_RO(timeout); 511 512 static ssize_t pretimeout_show(struct device *dev, 513 struct device_attribute *attr, char *buf) 514 { 515 struct watchdog_device *wdd = dev_get_drvdata(dev); 516 517 return sprintf(buf, "%u\n", wdd->pretimeout); 518 } 519 static DEVICE_ATTR_RO(pretimeout); 520 521 static ssize_t identity_show(struct device *dev, struct device_attribute *attr, 522 char *buf) 523 { 524 struct watchdog_device *wdd = dev_get_drvdata(dev); 525 526 return sprintf(buf, "%s\n", wdd->info->identity); 527 } 528 static DEVICE_ATTR_RO(identity); 529 530 static ssize_t state_show(struct device *dev, struct device_attribute *attr, 531 char *buf) 532 { 533 struct watchdog_device *wdd = dev_get_drvdata(dev); 534 535 if (watchdog_active(wdd)) 536 return sprintf(buf, "active\n"); 537 538 return sprintf(buf, "inactive\n"); 539 } 540 static DEVICE_ATTR_RO(state); 541 542 static ssize_t pretimeout_available_governors_show(struct device *dev, 543 struct device_attribute *attr, char *buf) 544 { 545 return watchdog_pretimeout_available_governors_get(buf); 546 } 547 static DEVICE_ATTR_RO(pretimeout_available_governors); 548 549 static ssize_t pretimeout_governor_show(struct device *dev, 550 struct device_attribute *attr, 551 char *buf) 552 { 553 struct watchdog_device *wdd = dev_get_drvdata(dev); 554 555 return watchdog_pretimeout_governor_get(wdd, buf); 556 } 557 558 static ssize_t pretimeout_governor_store(struct device *dev, 559 struct device_attribute *attr, 560 const char *buf, size_t count) 561 { 562 struct watchdog_device *wdd = dev_get_drvdata(dev); 563 int ret = watchdog_pretimeout_governor_set(wdd, buf); 564 565 if (!ret) 566 ret = count; 567 568 return ret; 569 } 570 static DEVICE_ATTR_RW(pretimeout_governor); 571 572 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr, 573 int n) 574 { 575 struct device *dev = container_of(kobj, struct device, kobj); 576 struct watchdog_device *wdd = dev_get_drvdata(dev); 577 umode_t mode = attr->mode; 578 579 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft) 580 mode = 0; 581 else if (attr == &dev_attr_pretimeout.attr && 582 !(wdd->info->options & WDIOF_PRETIMEOUT)) 583 mode = 0; 584 else if ((attr == &dev_attr_pretimeout_governor.attr || 585 attr == &dev_attr_pretimeout_available_governors.attr) && 586 (!(wdd->info->options & WDIOF_PRETIMEOUT) || 587 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV))) 588 mode = 0; 589 590 return mode; 591 } 592 static struct attribute *wdt_attrs[] = { 593 &dev_attr_state.attr, 594 &dev_attr_identity.attr, 595 &dev_attr_timeout.attr, 596 &dev_attr_pretimeout.attr, 597 &dev_attr_timeleft.attr, 598 &dev_attr_bootstatus.attr, 599 &dev_attr_status.attr, 600 &dev_attr_nowayout.attr, 601 &dev_attr_pretimeout_governor.attr, 602 &dev_attr_pretimeout_available_governors.attr, 603 NULL, 604 }; 605 606 static const struct attribute_group wdt_group = { 607 .attrs = wdt_attrs, 608 .is_visible = wdt_is_visible, 609 }; 610 __ATTRIBUTE_GROUPS(wdt); 611 #else 612 #define wdt_groups NULL 613 #endif 614 615 /* 616 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined 617 * @wdd: the watchdog device to do the ioctl on 618 * @cmd: watchdog command 619 * @arg: argument pointer 620 * 621 * The caller must hold wd_data->lock. 622 */ 623 624 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd, 625 unsigned long arg) 626 { 627 if (!wdd->ops->ioctl) 628 return -ENOIOCTLCMD; 629 630 return wdd->ops->ioctl(wdd, cmd, arg); 631 } 632 633 /* 634 * watchdog_write: writes to the watchdog. 635 * @file: file from VFS 636 * @data: user address of data 637 * @len: length of data 638 * @ppos: pointer to the file offset 639 * 640 * A write to a watchdog device is defined as a keepalive ping. 641 * Writing the magic 'V' sequence allows the next close to turn 642 * off the watchdog (if 'nowayout' is not set). 643 */ 644 645 static ssize_t watchdog_write(struct file *file, const char __user *data, 646 size_t len, loff_t *ppos) 647 { 648 struct watchdog_core_data *wd_data = file->private_data; 649 struct watchdog_device *wdd; 650 int err; 651 size_t i; 652 char c; 653 654 if (len == 0) 655 return 0; 656 657 /* 658 * Note: just in case someone wrote the magic character 659 * five months ago... 660 */ 661 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 662 663 /* scan to see whether or not we got the magic character */ 664 for (i = 0; i != len; i++) { 665 if (get_user(c, data + i)) 666 return -EFAULT; 667 if (c == 'V') 668 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 669 } 670 671 /* someone wrote to us, so we send the watchdog a keepalive ping */ 672 673 err = -ENODEV; 674 mutex_lock(&wd_data->lock); 675 wdd = wd_data->wdd; 676 if (wdd) 677 err = watchdog_ping(wdd); 678 mutex_unlock(&wd_data->lock); 679 680 if (err < 0) 681 return err; 682 683 return len; 684 } 685 686 /* 687 * watchdog_ioctl: handle the different ioctl's for the watchdog device. 688 * @file: file handle to the device 689 * @cmd: watchdog command 690 * @arg: argument pointer 691 * 692 * The watchdog API defines a common set of functions for all watchdogs 693 * according to their available features. 694 */ 695 696 static long watchdog_ioctl(struct file *file, unsigned int cmd, 697 unsigned long arg) 698 { 699 struct watchdog_core_data *wd_data = file->private_data; 700 void __user *argp = (void __user *)arg; 701 struct watchdog_device *wdd; 702 int __user *p = argp; 703 unsigned int val; 704 int err; 705 706 mutex_lock(&wd_data->lock); 707 708 wdd = wd_data->wdd; 709 if (!wdd) { 710 err = -ENODEV; 711 goto out_ioctl; 712 } 713 714 err = watchdog_ioctl_op(wdd, cmd, arg); 715 if (err != -ENOIOCTLCMD) 716 goto out_ioctl; 717 718 switch (cmd) { 719 case WDIOC_GETSUPPORT: 720 err = copy_to_user(argp, wdd->info, 721 sizeof(struct watchdog_info)) ? -EFAULT : 0; 722 break; 723 case WDIOC_GETSTATUS: 724 val = watchdog_get_status(wdd); 725 err = put_user(val, p); 726 break; 727 case WDIOC_GETBOOTSTATUS: 728 err = put_user(wdd->bootstatus, p); 729 break; 730 case WDIOC_SETOPTIONS: 731 if (get_user(val, p)) { 732 err = -EFAULT; 733 break; 734 } 735 if (val & WDIOS_DISABLECARD) { 736 err = watchdog_stop(wdd); 737 if (err < 0) 738 break; 739 } 740 if (val & WDIOS_ENABLECARD) 741 err = watchdog_start(wdd); 742 break; 743 case WDIOC_KEEPALIVE: 744 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) { 745 err = -EOPNOTSUPP; 746 break; 747 } 748 err = watchdog_ping(wdd); 749 break; 750 case WDIOC_SETTIMEOUT: 751 if (get_user(val, p)) { 752 err = -EFAULT; 753 break; 754 } 755 err = watchdog_set_timeout(wdd, val); 756 if (err < 0) 757 break; 758 /* If the watchdog is active then we send a keepalive ping 759 * to make sure that the watchdog keep's running (and if 760 * possible that it takes the new timeout) */ 761 err = watchdog_ping(wdd); 762 if (err < 0) 763 break; 764 /* fall through */ 765 case WDIOC_GETTIMEOUT: 766 /* timeout == 0 means that we don't know the timeout */ 767 if (wdd->timeout == 0) { 768 err = -EOPNOTSUPP; 769 break; 770 } 771 err = put_user(wdd->timeout, p); 772 break; 773 case WDIOC_GETTIMELEFT: 774 err = watchdog_get_timeleft(wdd, &val); 775 if (err < 0) 776 break; 777 err = put_user(val, p); 778 break; 779 case WDIOC_SETPRETIMEOUT: 780 if (get_user(val, p)) { 781 err = -EFAULT; 782 break; 783 } 784 err = watchdog_set_pretimeout(wdd, val); 785 break; 786 case WDIOC_GETPRETIMEOUT: 787 err = put_user(wdd->pretimeout, p); 788 break; 789 default: 790 err = -ENOTTY; 791 break; 792 } 793 794 out_ioctl: 795 mutex_unlock(&wd_data->lock); 796 return err; 797 } 798 799 /* 800 * watchdog_open: open the /dev/watchdog* devices. 801 * @inode: inode of device 802 * @file: file handle to device 803 * 804 * When the /dev/watchdog* device gets opened, we start the watchdog. 805 * Watch out: the /dev/watchdog device is single open, so we make sure 806 * it can only be opened once. 807 */ 808 809 static int watchdog_open(struct inode *inode, struct file *file) 810 { 811 struct watchdog_core_data *wd_data; 812 struct watchdog_device *wdd; 813 bool hw_running; 814 int err; 815 816 /* Get the corresponding watchdog device */ 817 if (imajor(inode) == MISC_MAJOR) 818 wd_data = old_wd_data; 819 else 820 wd_data = container_of(inode->i_cdev, struct watchdog_core_data, 821 cdev); 822 823 /* the watchdog is single open! */ 824 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status)) 825 return -EBUSY; 826 827 wdd = wd_data->wdd; 828 829 /* 830 * If the /dev/watchdog device is open, we don't want the module 831 * to be unloaded. 832 */ 833 hw_running = watchdog_hw_running(wdd); 834 if (!hw_running && !try_module_get(wdd->ops->owner)) { 835 err = -EBUSY; 836 goto out_clear; 837 } 838 839 err = watchdog_start(wdd); 840 if (err < 0) 841 goto out_mod; 842 843 file->private_data = wd_data; 844 845 if (!hw_running) 846 kref_get(&wd_data->kref); 847 848 /* 849 * open_timeout only applies for the first open from 850 * userspace. Set open_deadline to infinity so that the kernel 851 * will take care of an always-running hardware watchdog in 852 * case the device gets magic-closed or WDIOS_DISABLECARD is 853 * applied. 854 */ 855 wd_data->open_deadline = KTIME_MAX; 856 857 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ 858 return stream_open(inode, file); 859 860 out_mod: 861 module_put(wd_data->wdd->ops->owner); 862 out_clear: 863 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 864 return err; 865 } 866 867 static void watchdog_core_data_release(struct kref *kref) 868 { 869 struct watchdog_core_data *wd_data; 870 871 wd_data = container_of(kref, struct watchdog_core_data, kref); 872 873 kfree(wd_data); 874 } 875 876 /* 877 * watchdog_release: release the watchdog device. 878 * @inode: inode of device 879 * @file: file handle to device 880 * 881 * This is the code for when /dev/watchdog gets closed. We will only 882 * stop the watchdog when we have received the magic char (and nowayout 883 * was not set), else the watchdog will keep running. 884 */ 885 886 static int watchdog_release(struct inode *inode, struct file *file) 887 { 888 struct watchdog_core_data *wd_data = file->private_data; 889 struct watchdog_device *wdd; 890 int err = -EBUSY; 891 bool running; 892 893 mutex_lock(&wd_data->lock); 894 895 wdd = wd_data->wdd; 896 if (!wdd) 897 goto done; 898 899 /* 900 * We only stop the watchdog if we received the magic character 901 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then 902 * watchdog_stop will fail. 903 */ 904 if (!test_bit(WDOG_ACTIVE, &wdd->status)) 905 err = 0; 906 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) || 907 !(wdd->info->options & WDIOF_MAGICCLOSE)) 908 err = watchdog_stop(wdd); 909 910 /* If the watchdog was not stopped, send a keepalive ping */ 911 if (err < 0) { 912 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id); 913 watchdog_ping(wdd); 914 } 915 916 watchdog_update_worker(wdd); 917 918 /* make sure that /dev/watchdog can be re-opened */ 919 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 920 921 done: 922 running = wdd && watchdog_hw_running(wdd); 923 mutex_unlock(&wd_data->lock); 924 /* 925 * Allow the owner module to be unloaded again unless the watchdog 926 * is still running. If the watchdog is still running, it can not 927 * be stopped, and its driver must not be unloaded. 928 */ 929 if (!running) { 930 module_put(wd_data->cdev.owner); 931 kref_put(&wd_data->kref, watchdog_core_data_release); 932 } 933 return 0; 934 } 935 936 static const struct file_operations watchdog_fops = { 937 .owner = THIS_MODULE, 938 .write = watchdog_write, 939 .unlocked_ioctl = watchdog_ioctl, 940 .open = watchdog_open, 941 .release = watchdog_release, 942 }; 943 944 static struct miscdevice watchdog_miscdev = { 945 .minor = WATCHDOG_MINOR, 946 .name = "watchdog", 947 .fops = &watchdog_fops, 948 }; 949 950 /* 951 * watchdog_cdev_register: register watchdog character device 952 * @wdd: watchdog device 953 * @devno: character device number 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, dev_t devno) 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 kref_init(&wd_data->kref); 969 mutex_init(&wd_data->lock); 970 971 wd_data->wdd = wdd; 972 wdd->wd_data = wd_data; 973 974 if (IS_ERR_OR_NULL(watchdog_kworker)) 975 return -ENODEV; 976 977 kthread_init_work(&wd_data->work, watchdog_ping_work); 978 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 979 wd_data->timer.function = watchdog_timer_expired; 980 981 if (wdd->id == 0) { 982 old_wd_data = wd_data; 983 watchdog_miscdev.parent = wdd->parent; 984 err = misc_register(&watchdog_miscdev); 985 if (err != 0) { 986 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", 987 wdd->info->identity, WATCHDOG_MINOR, err); 988 if (err == -EBUSY) 989 pr_err("%s: a legacy watchdog module is probably present.\n", 990 wdd->info->identity); 991 old_wd_data = NULL; 992 kfree(wd_data); 993 return err; 994 } 995 } 996 997 /* Fill in the data structures */ 998 cdev_init(&wd_data->cdev, &watchdog_fops); 999 wd_data->cdev.owner = wdd->ops->owner; 1000 1001 /* Add the device */ 1002 err = cdev_add(&wd_data->cdev, devno, 1); 1003 if (err) { 1004 pr_err("watchdog%d unable to add device %d:%d\n", 1005 wdd->id, MAJOR(watchdog_devt), wdd->id); 1006 if (wdd->id == 0) { 1007 misc_deregister(&watchdog_miscdev); 1008 old_wd_data = NULL; 1009 kref_put(&wd_data->kref, watchdog_core_data_release); 1010 } 1011 return err; 1012 } 1013 1014 /* Record time of most recent heartbeat as 'just before now'. */ 1015 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1); 1016 watchdog_set_open_deadline(wd_data); 1017 1018 /* 1019 * If the watchdog is running, prevent its driver from being unloaded, 1020 * and schedule an immediate ping. 1021 */ 1022 if (watchdog_hw_running(wdd)) { 1023 __module_get(wdd->ops->owner); 1024 kref_get(&wd_data->kref); 1025 if (handle_boot_enabled) 1026 hrtimer_start(&wd_data->timer, 0, HRTIMER_MODE_REL); 1027 else 1028 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n", 1029 wdd->id); 1030 } 1031 1032 return 0; 1033 } 1034 1035 /* 1036 * watchdog_cdev_unregister: unregister watchdog character device 1037 * @watchdog: watchdog device 1038 * 1039 * Unregister watchdog character device and if needed the legacy 1040 * /dev/watchdog device. 1041 */ 1042 1043 static void watchdog_cdev_unregister(struct watchdog_device *wdd) 1044 { 1045 struct watchdog_core_data *wd_data = wdd->wd_data; 1046 1047 cdev_del(&wd_data->cdev); 1048 if (wdd->id == 0) { 1049 misc_deregister(&watchdog_miscdev); 1050 old_wd_data = NULL; 1051 } 1052 1053 if (watchdog_active(wdd) && 1054 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) { 1055 watchdog_stop(wdd); 1056 } 1057 1058 mutex_lock(&wd_data->lock); 1059 wd_data->wdd = NULL; 1060 wdd->wd_data = NULL; 1061 mutex_unlock(&wd_data->lock); 1062 1063 hrtimer_cancel(&wd_data->timer); 1064 kthread_cancel_work_sync(&wd_data->work); 1065 1066 kref_put(&wd_data->kref, watchdog_core_data_release); 1067 } 1068 1069 static struct class watchdog_class = { 1070 .name = "watchdog", 1071 .owner = THIS_MODULE, 1072 .dev_groups = wdt_groups, 1073 }; 1074 1075 static int watchdog_reboot_notifier(struct notifier_block *nb, 1076 unsigned long code, void *data) 1077 { 1078 struct watchdog_device *wdd; 1079 1080 wdd = container_of(nb, struct watchdog_device, reboot_nb); 1081 if (code == SYS_DOWN || code == SYS_HALT) { 1082 if (watchdog_active(wdd)) { 1083 int ret; 1084 1085 ret = wdd->ops->stop(wdd); 1086 if (ret) 1087 return NOTIFY_BAD; 1088 } 1089 } 1090 1091 return NOTIFY_DONE; 1092 } 1093 1094 /* 1095 * watchdog_dev_register: register a watchdog device 1096 * @wdd: watchdog device 1097 * 1098 * Register a watchdog device including handling the legacy 1099 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 1100 * thus we set it up like that. 1101 */ 1102 1103 int watchdog_dev_register(struct watchdog_device *wdd) 1104 { 1105 struct device *dev; 1106 dev_t devno; 1107 int ret; 1108 1109 devno = MKDEV(MAJOR(watchdog_devt), wdd->id); 1110 1111 ret = watchdog_cdev_register(wdd, devno); 1112 if (ret) 1113 return ret; 1114 1115 dev = device_create_with_groups(&watchdog_class, wdd->parent, 1116 devno, wdd, wdd->groups, 1117 "watchdog%d", wdd->id); 1118 if (IS_ERR(dev)) { 1119 watchdog_cdev_unregister(wdd); 1120 return PTR_ERR(dev); 1121 } 1122 1123 ret = watchdog_register_pretimeout(wdd); 1124 if (ret) { 1125 device_destroy(&watchdog_class, devno); 1126 watchdog_cdev_unregister(wdd); 1127 return ret; 1128 } 1129 1130 if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { 1131 wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; 1132 1133 ret = devm_register_reboot_notifier(dev, &wdd->reboot_nb); 1134 if (ret) { 1135 pr_err("watchdog%d: Cannot register reboot notifier (%d)\n", 1136 wdd->id, ret); 1137 watchdog_dev_unregister(wdd); 1138 } 1139 } 1140 1141 return ret; 1142 } 1143 1144 /* 1145 * watchdog_dev_unregister: unregister a watchdog device 1146 * @watchdog: watchdog device 1147 * 1148 * Unregister watchdog device and if needed the legacy 1149 * /dev/watchdog device. 1150 */ 1151 1152 void watchdog_dev_unregister(struct watchdog_device *wdd) 1153 { 1154 watchdog_unregister_pretimeout(wdd); 1155 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev); 1156 watchdog_cdev_unregister(wdd); 1157 } 1158 1159 /* 1160 * watchdog_dev_init: init dev part of watchdog core 1161 * 1162 * Allocate a range of chardev nodes to use for watchdog devices 1163 */ 1164 1165 int __init watchdog_dev_init(void) 1166 { 1167 int err; 1168 struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,}; 1169 1170 watchdog_kworker = kthread_create_worker(0, "watchdogd"); 1171 if (IS_ERR(watchdog_kworker)) { 1172 pr_err("Failed to create watchdog kworker\n"); 1173 return PTR_ERR(watchdog_kworker); 1174 } 1175 sched_setscheduler(watchdog_kworker->task, SCHED_FIFO, ¶m); 1176 1177 err = class_register(&watchdog_class); 1178 if (err < 0) { 1179 pr_err("couldn't register class\n"); 1180 goto err_register; 1181 } 1182 1183 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog"); 1184 if (err < 0) { 1185 pr_err("watchdog: unable to allocate char dev region\n"); 1186 goto err_alloc; 1187 } 1188 1189 return 0; 1190 1191 err_alloc: 1192 class_unregister(&watchdog_class); 1193 err_register: 1194 kthread_destroy_worker(watchdog_kworker); 1195 return err; 1196 } 1197 1198 /* 1199 * watchdog_dev_exit: exit dev part of watchdog core 1200 * 1201 * Release the range of chardev nodes used for watchdog devices 1202 */ 1203 1204 void __exit watchdog_dev_exit(void) 1205 { 1206 unregister_chrdev_region(watchdog_devt, MAX_DOGS); 1207 class_unregister(&watchdog_class); 1208 kthread_destroy_worker(watchdog_kworker); 1209 } 1210 1211 module_param(handle_boot_enabled, bool, 0444); 1212 MODULE_PARM_DESC(handle_boot_enabled, 1213 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default=" 1214 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")"); 1215 1216 module_param(open_timeout, uint, 0644); 1217 MODULE_PARM_DESC(open_timeout, 1218 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default=" 1219 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")"); 1220