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/kref.h> /* For data references */ 38 #include <linux/kthread.h> /* For kthread_work */ 39 #include <linux/miscdevice.h> /* For handling misc devices */ 40 #include <linux/module.h> /* For module stuff/... */ 41 #include <linux/mutex.h> /* For mutexes */ 42 #include <linux/reboot.h> /* For reboot notifier */ 43 #include <linux/slab.h> /* For memory functions */ 44 #include <linux/types.h> /* For standard types (like size_t) */ 45 #include <linux/watchdog.h> /* For watchdog specific items */ 46 #include <linux/uaccess.h> /* For copy_to_user/put_user/... */ 47 48 #include <uapi/linux/sched/types.h> /* For struct sched_param */ 49 50 #include "watchdog_core.h" 51 #include "watchdog_pretimeout.h" 52 53 /* 54 * struct watchdog_core_data - watchdog core internal data 55 * @kref: Reference count. 56 * @cdev: The watchdog's Character device. 57 * @wdd: Pointer to watchdog device. 58 * @lock: Lock for watchdog core. 59 * @status: Watchdog core internal status bits. 60 */ 61 struct watchdog_core_data { 62 struct kref kref; 63 struct cdev cdev; 64 struct watchdog_device *wdd; 65 struct mutex lock; 66 ktime_t last_keepalive; 67 ktime_t last_hw_keepalive; 68 ktime_t open_deadline; 69 struct hrtimer timer; 70 struct kthread_work work; 71 unsigned long status; /* Internal status bits */ 72 #define _WDOG_DEV_OPEN 0 /* Opened ? */ 73 #define _WDOG_ALLOW_RELEASE 1 /* Did we receive the magic char ? */ 74 #define _WDOG_KEEPALIVE 2 /* Did we receive a keepalive ? */ 75 }; 76 77 /* the dev_t structure to store the dynamically allocated watchdog devices */ 78 static dev_t watchdog_devt; 79 /* Reference to watchdog device behind /dev/watchdog */ 80 static struct watchdog_core_data *old_wd_data; 81 82 static struct kthread_worker *watchdog_kworker; 83 84 static bool handle_boot_enabled = 85 IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED); 86 87 static unsigned open_timeout = CONFIG_WATCHDOG_OPEN_TIMEOUT; 88 89 static bool watchdog_past_open_deadline(struct watchdog_core_data *data) 90 { 91 return ktime_after(ktime_get(), data->open_deadline); 92 } 93 94 static void watchdog_set_open_deadline(struct watchdog_core_data *data) 95 { 96 data->open_deadline = open_timeout ? 97 ktime_get() + ktime_set(open_timeout, 0) : KTIME_MAX; 98 } 99 100 static inline bool watchdog_need_worker(struct watchdog_device *wdd) 101 { 102 /* All variables in milli-seconds */ 103 unsigned int hm = wdd->max_hw_heartbeat_ms; 104 unsigned int t = wdd->timeout * 1000; 105 106 /* 107 * A worker to generate heartbeat requests is needed if all of the 108 * following conditions are true. 109 * - Userspace activated the watchdog. 110 * - The driver provided a value for the maximum hardware timeout, and 111 * thus is aware that the framework supports generating heartbeat 112 * requests. 113 * - Userspace requests a longer timeout than the hardware can handle. 114 * 115 * Alternatively, if userspace has not opened the watchdog 116 * device, we take care of feeding the watchdog if it is 117 * running. 118 */ 119 return (hm && watchdog_active(wdd) && t > hm) || 120 (t && !watchdog_active(wdd) && watchdog_hw_running(wdd)); 121 } 122 123 static ktime_t watchdog_next_keepalive(struct watchdog_device *wdd) 124 { 125 struct watchdog_core_data *wd_data = wdd->wd_data; 126 unsigned int timeout_ms = wdd->timeout * 1000; 127 ktime_t keepalive_interval; 128 ktime_t last_heartbeat, latest_heartbeat; 129 ktime_t virt_timeout; 130 unsigned int hw_heartbeat_ms; 131 132 if (watchdog_active(wdd)) 133 virt_timeout = ktime_add(wd_data->last_keepalive, 134 ms_to_ktime(timeout_ms)); 135 else 136 virt_timeout = wd_data->open_deadline; 137 138 hw_heartbeat_ms = min_not_zero(timeout_ms, wdd->max_hw_heartbeat_ms); 139 keepalive_interval = ms_to_ktime(hw_heartbeat_ms / 2); 140 141 /* 142 * To ensure that the watchdog times out wdd->timeout seconds 143 * after the most recent ping from userspace, the last 144 * worker ping has to come in hw_heartbeat_ms before this timeout. 145 */ 146 last_heartbeat = ktime_sub(virt_timeout, ms_to_ktime(hw_heartbeat_ms)); 147 latest_heartbeat = ktime_sub(last_heartbeat, ktime_get()); 148 if (ktime_before(latest_heartbeat, keepalive_interval)) 149 return latest_heartbeat; 150 return keepalive_interval; 151 } 152 153 static inline void watchdog_update_worker(struct watchdog_device *wdd) 154 { 155 struct watchdog_core_data *wd_data = wdd->wd_data; 156 157 if (watchdog_need_worker(wdd)) { 158 ktime_t t = watchdog_next_keepalive(wdd); 159 160 if (t > 0) 161 hrtimer_start(&wd_data->timer, t, HRTIMER_MODE_REL); 162 } else { 163 hrtimer_cancel(&wd_data->timer); 164 } 165 } 166 167 static int __watchdog_ping(struct watchdog_device *wdd) 168 { 169 struct watchdog_core_data *wd_data = wdd->wd_data; 170 ktime_t earliest_keepalive, now; 171 int err; 172 173 earliest_keepalive = ktime_add(wd_data->last_hw_keepalive, 174 ms_to_ktime(wdd->min_hw_heartbeat_ms)); 175 now = ktime_get(); 176 177 if (ktime_after(earliest_keepalive, now)) { 178 hrtimer_start(&wd_data->timer, 179 ktime_sub(earliest_keepalive, now), 180 HRTIMER_MODE_REL); 181 return 0; 182 } 183 184 wd_data->last_hw_keepalive = now; 185 186 if (wdd->ops->ping) 187 err = wdd->ops->ping(wdd); /* ping the watchdog */ 188 else 189 err = wdd->ops->start(wdd); /* restart watchdog */ 190 191 watchdog_update_worker(wdd); 192 193 return err; 194 } 195 196 /* 197 * watchdog_ping: ping the watchdog. 198 * @wdd: the watchdog device to ping 199 * 200 * The caller must hold wd_data->lock. 201 * 202 * If the watchdog has no own ping operation then it needs to be 203 * restarted via the start operation. This wrapper function does 204 * exactly that. 205 * We only ping when the watchdog device is running. 206 */ 207 208 static int watchdog_ping(struct watchdog_device *wdd) 209 { 210 struct watchdog_core_data *wd_data = wdd->wd_data; 211 212 if (!watchdog_active(wdd) && !watchdog_hw_running(wdd)) 213 return 0; 214 215 set_bit(_WDOG_KEEPALIVE, &wd_data->status); 216 217 wd_data->last_keepalive = ktime_get(); 218 return __watchdog_ping(wdd); 219 } 220 221 static bool watchdog_worker_should_ping(struct watchdog_core_data *wd_data) 222 { 223 struct watchdog_device *wdd = wd_data->wdd; 224 225 if (!wdd) 226 return false; 227 228 if (watchdog_active(wdd)) 229 return true; 230 231 return watchdog_hw_running(wdd) && !watchdog_past_open_deadline(wd_data); 232 } 233 234 static void watchdog_ping_work(struct kthread_work *work) 235 { 236 struct watchdog_core_data *wd_data; 237 238 wd_data = container_of(work, struct watchdog_core_data, work); 239 240 mutex_lock(&wd_data->lock); 241 if (watchdog_worker_should_ping(wd_data)) 242 __watchdog_ping(wd_data->wdd); 243 mutex_unlock(&wd_data->lock); 244 } 245 246 static enum hrtimer_restart watchdog_timer_expired(struct hrtimer *timer) 247 { 248 struct watchdog_core_data *wd_data; 249 250 wd_data = container_of(timer, struct watchdog_core_data, timer); 251 252 kthread_queue_work(watchdog_kworker, &wd_data->work); 253 return HRTIMER_NORESTART; 254 } 255 256 /* 257 * watchdog_start: wrapper to start the watchdog. 258 * @wdd: the watchdog device to start 259 * 260 * The caller must hold wd_data->lock. 261 * 262 * Start the watchdog if it is not active and mark it active. 263 * This function returns zero on success or a negative errno code for 264 * failure. 265 */ 266 267 static int watchdog_start(struct watchdog_device *wdd) 268 { 269 struct watchdog_core_data *wd_data = wdd->wd_data; 270 ktime_t started_at; 271 int err; 272 273 if (watchdog_active(wdd)) 274 return 0; 275 276 set_bit(_WDOG_KEEPALIVE, &wd_data->status); 277 278 started_at = ktime_get(); 279 if (watchdog_hw_running(wdd) && wdd->ops->ping) 280 err = wdd->ops->ping(wdd); 281 else 282 err = wdd->ops->start(wdd); 283 if (err == 0) { 284 set_bit(WDOG_ACTIVE, &wdd->status); 285 wd_data->last_keepalive = started_at; 286 watchdog_update_worker(wdd); 287 } 288 289 return err; 290 } 291 292 /* 293 * watchdog_stop: wrapper to stop the watchdog. 294 * @wdd: the watchdog device to stop 295 * 296 * The caller must hold wd_data->lock. 297 * 298 * Stop the watchdog if it is still active and unmark it active. 299 * This function returns zero on success or a negative errno code for 300 * failure. 301 * If the 'nowayout' feature was set, the watchdog cannot be stopped. 302 */ 303 304 static int watchdog_stop(struct watchdog_device *wdd) 305 { 306 int err = 0; 307 308 if (!watchdog_active(wdd)) 309 return 0; 310 311 if (test_bit(WDOG_NO_WAY_OUT, &wdd->status)) { 312 pr_info("watchdog%d: nowayout prevents watchdog being stopped!\n", 313 wdd->id); 314 return -EBUSY; 315 } 316 317 if (wdd->ops->stop) { 318 clear_bit(WDOG_HW_RUNNING, &wdd->status); 319 err = wdd->ops->stop(wdd); 320 } else { 321 set_bit(WDOG_HW_RUNNING, &wdd->status); 322 } 323 324 if (err == 0) { 325 clear_bit(WDOG_ACTIVE, &wdd->status); 326 watchdog_update_worker(wdd); 327 } 328 329 return err; 330 } 331 332 /* 333 * watchdog_get_status: wrapper to get the watchdog status 334 * @wdd: the watchdog device to get the status from 335 * 336 * The caller must hold wd_data->lock. 337 * 338 * Get the watchdog's status flags. 339 */ 340 341 static unsigned int watchdog_get_status(struct watchdog_device *wdd) 342 { 343 struct watchdog_core_data *wd_data = wdd->wd_data; 344 unsigned int status; 345 346 if (wdd->ops->status) 347 status = wdd->ops->status(wdd); 348 else 349 status = wdd->bootstatus & (WDIOF_CARDRESET | 350 WDIOF_OVERHEAT | 351 WDIOF_FANFAULT | 352 WDIOF_EXTERN1 | 353 WDIOF_EXTERN2 | 354 WDIOF_POWERUNDER | 355 WDIOF_POWEROVER); 356 357 if (test_bit(_WDOG_ALLOW_RELEASE, &wd_data->status)) 358 status |= WDIOF_MAGICCLOSE; 359 360 if (test_and_clear_bit(_WDOG_KEEPALIVE, &wd_data->status)) 361 status |= WDIOF_KEEPALIVEPING; 362 363 return status; 364 } 365 366 /* 367 * watchdog_set_timeout: set the watchdog timer timeout 368 * @wdd: the watchdog device to set the timeout for 369 * @timeout: timeout to set in seconds 370 * 371 * The caller must hold wd_data->lock. 372 */ 373 374 static int watchdog_set_timeout(struct watchdog_device *wdd, 375 unsigned int timeout) 376 { 377 int err = 0; 378 379 if (!(wdd->info->options & WDIOF_SETTIMEOUT)) 380 return -EOPNOTSUPP; 381 382 if (watchdog_timeout_invalid(wdd, timeout)) 383 return -EINVAL; 384 385 if (wdd->ops->set_timeout) { 386 err = wdd->ops->set_timeout(wdd, timeout); 387 } else { 388 wdd->timeout = timeout; 389 /* Disable pretimeout if it doesn't fit the new timeout */ 390 if (wdd->pretimeout >= wdd->timeout) 391 wdd->pretimeout = 0; 392 } 393 394 watchdog_update_worker(wdd); 395 396 return err; 397 } 398 399 /* 400 * watchdog_set_pretimeout: set the watchdog timer pretimeout 401 * @wdd: the watchdog device to set the timeout for 402 * @timeout: pretimeout to set in seconds 403 */ 404 405 static int watchdog_set_pretimeout(struct watchdog_device *wdd, 406 unsigned int timeout) 407 { 408 int err = 0; 409 410 if (!(wdd->info->options & WDIOF_PRETIMEOUT)) 411 return -EOPNOTSUPP; 412 413 if (watchdog_pretimeout_invalid(wdd, timeout)) 414 return -EINVAL; 415 416 if (wdd->ops->set_pretimeout) 417 err = wdd->ops->set_pretimeout(wdd, timeout); 418 else 419 wdd->pretimeout = timeout; 420 421 return err; 422 } 423 424 /* 425 * watchdog_get_timeleft: wrapper to get the time left before a reboot 426 * @wdd: the watchdog device to get the remaining time from 427 * @timeleft: the time that's left 428 * 429 * The caller must hold wd_data->lock. 430 * 431 * Get the time before a watchdog will reboot (if not pinged). 432 */ 433 434 static int watchdog_get_timeleft(struct watchdog_device *wdd, 435 unsigned int *timeleft) 436 { 437 *timeleft = 0; 438 439 if (!wdd->ops->get_timeleft) 440 return -EOPNOTSUPP; 441 442 *timeleft = wdd->ops->get_timeleft(wdd); 443 444 return 0; 445 } 446 447 #ifdef CONFIG_WATCHDOG_SYSFS 448 static ssize_t nowayout_show(struct device *dev, struct device_attribute *attr, 449 char *buf) 450 { 451 struct watchdog_device *wdd = dev_get_drvdata(dev); 452 453 return sprintf(buf, "%d\n", !!test_bit(WDOG_NO_WAY_OUT, &wdd->status)); 454 } 455 static DEVICE_ATTR_RO(nowayout); 456 457 static ssize_t status_show(struct device *dev, struct device_attribute *attr, 458 char *buf) 459 { 460 struct watchdog_device *wdd = dev_get_drvdata(dev); 461 struct watchdog_core_data *wd_data = wdd->wd_data; 462 unsigned int status; 463 464 mutex_lock(&wd_data->lock); 465 status = watchdog_get_status(wdd); 466 mutex_unlock(&wd_data->lock); 467 468 return sprintf(buf, "0x%x\n", status); 469 } 470 static DEVICE_ATTR_RO(status); 471 472 static ssize_t bootstatus_show(struct device *dev, 473 struct device_attribute *attr, char *buf) 474 { 475 struct watchdog_device *wdd = dev_get_drvdata(dev); 476 477 return sprintf(buf, "%u\n", wdd->bootstatus); 478 } 479 static DEVICE_ATTR_RO(bootstatus); 480 481 static ssize_t timeleft_show(struct device *dev, struct device_attribute *attr, 482 char *buf) 483 { 484 struct watchdog_device *wdd = dev_get_drvdata(dev); 485 struct watchdog_core_data *wd_data = wdd->wd_data; 486 ssize_t status; 487 unsigned int val; 488 489 mutex_lock(&wd_data->lock); 490 status = watchdog_get_timeleft(wdd, &val); 491 mutex_unlock(&wd_data->lock); 492 if (!status) 493 status = sprintf(buf, "%u\n", val); 494 495 return status; 496 } 497 static DEVICE_ATTR_RO(timeleft); 498 499 static ssize_t timeout_show(struct device *dev, struct device_attribute *attr, 500 char *buf) 501 { 502 struct watchdog_device *wdd = dev_get_drvdata(dev); 503 504 return sprintf(buf, "%u\n", wdd->timeout); 505 } 506 static DEVICE_ATTR_RO(timeout); 507 508 static ssize_t pretimeout_show(struct device *dev, 509 struct device_attribute *attr, char *buf) 510 { 511 struct watchdog_device *wdd = dev_get_drvdata(dev); 512 513 return sprintf(buf, "%u\n", wdd->pretimeout); 514 } 515 static DEVICE_ATTR_RO(pretimeout); 516 517 static ssize_t identity_show(struct device *dev, struct device_attribute *attr, 518 char *buf) 519 { 520 struct watchdog_device *wdd = dev_get_drvdata(dev); 521 522 return sprintf(buf, "%s\n", wdd->info->identity); 523 } 524 static DEVICE_ATTR_RO(identity); 525 526 static ssize_t state_show(struct device *dev, struct device_attribute *attr, 527 char *buf) 528 { 529 struct watchdog_device *wdd = dev_get_drvdata(dev); 530 531 if (watchdog_active(wdd)) 532 return sprintf(buf, "active\n"); 533 534 return sprintf(buf, "inactive\n"); 535 } 536 static DEVICE_ATTR_RO(state); 537 538 static ssize_t pretimeout_available_governors_show(struct device *dev, 539 struct device_attribute *attr, char *buf) 540 { 541 return watchdog_pretimeout_available_governors_get(buf); 542 } 543 static DEVICE_ATTR_RO(pretimeout_available_governors); 544 545 static ssize_t pretimeout_governor_show(struct device *dev, 546 struct device_attribute *attr, 547 char *buf) 548 { 549 struct watchdog_device *wdd = dev_get_drvdata(dev); 550 551 return watchdog_pretimeout_governor_get(wdd, buf); 552 } 553 554 static ssize_t pretimeout_governor_store(struct device *dev, 555 struct device_attribute *attr, 556 const char *buf, size_t count) 557 { 558 struct watchdog_device *wdd = dev_get_drvdata(dev); 559 int ret = watchdog_pretimeout_governor_set(wdd, buf); 560 561 if (!ret) 562 ret = count; 563 564 return ret; 565 } 566 static DEVICE_ATTR_RW(pretimeout_governor); 567 568 static umode_t wdt_is_visible(struct kobject *kobj, struct attribute *attr, 569 int n) 570 { 571 struct device *dev = container_of(kobj, struct device, kobj); 572 struct watchdog_device *wdd = dev_get_drvdata(dev); 573 umode_t mode = attr->mode; 574 575 if (attr == &dev_attr_timeleft.attr && !wdd->ops->get_timeleft) 576 mode = 0; 577 else if (attr == &dev_attr_pretimeout.attr && 578 !(wdd->info->options & WDIOF_PRETIMEOUT)) 579 mode = 0; 580 else if ((attr == &dev_attr_pretimeout_governor.attr || 581 attr == &dev_attr_pretimeout_available_governors.attr) && 582 (!(wdd->info->options & WDIOF_PRETIMEOUT) || 583 !IS_ENABLED(CONFIG_WATCHDOG_PRETIMEOUT_GOV))) 584 mode = 0; 585 586 return mode; 587 } 588 static struct attribute *wdt_attrs[] = { 589 &dev_attr_state.attr, 590 &dev_attr_identity.attr, 591 &dev_attr_timeout.attr, 592 &dev_attr_pretimeout.attr, 593 &dev_attr_timeleft.attr, 594 &dev_attr_bootstatus.attr, 595 &dev_attr_status.attr, 596 &dev_attr_nowayout.attr, 597 &dev_attr_pretimeout_governor.attr, 598 &dev_attr_pretimeout_available_governors.attr, 599 NULL, 600 }; 601 602 static const struct attribute_group wdt_group = { 603 .attrs = wdt_attrs, 604 .is_visible = wdt_is_visible, 605 }; 606 __ATTRIBUTE_GROUPS(wdt); 607 #else 608 #define wdt_groups NULL 609 #endif 610 611 /* 612 * watchdog_ioctl_op: call the watchdog drivers ioctl op if defined 613 * @wdd: the watchdog device to do the ioctl on 614 * @cmd: watchdog command 615 * @arg: argument pointer 616 * 617 * The caller must hold wd_data->lock. 618 */ 619 620 static int watchdog_ioctl_op(struct watchdog_device *wdd, unsigned int cmd, 621 unsigned long arg) 622 { 623 if (!wdd->ops->ioctl) 624 return -ENOIOCTLCMD; 625 626 return wdd->ops->ioctl(wdd, cmd, arg); 627 } 628 629 /* 630 * watchdog_write: writes to the watchdog. 631 * @file: file from VFS 632 * @data: user address of data 633 * @len: length of data 634 * @ppos: pointer to the file offset 635 * 636 * A write to a watchdog device is defined as a keepalive ping. 637 * Writing the magic 'V' sequence allows the next close to turn 638 * off the watchdog (if 'nowayout' is not set). 639 */ 640 641 static ssize_t watchdog_write(struct file *file, const char __user *data, 642 size_t len, loff_t *ppos) 643 { 644 struct watchdog_core_data *wd_data = file->private_data; 645 struct watchdog_device *wdd; 646 int err; 647 size_t i; 648 char c; 649 650 if (len == 0) 651 return 0; 652 653 /* 654 * Note: just in case someone wrote the magic character 655 * five months ago... 656 */ 657 clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 658 659 /* scan to see whether or not we got the magic character */ 660 for (i = 0; i != len; i++) { 661 if (get_user(c, data + i)) 662 return -EFAULT; 663 if (c == 'V') 664 set_bit(_WDOG_ALLOW_RELEASE, &wd_data->status); 665 } 666 667 /* someone wrote to us, so we send the watchdog a keepalive ping */ 668 669 err = -ENODEV; 670 mutex_lock(&wd_data->lock); 671 wdd = wd_data->wdd; 672 if (wdd) 673 err = watchdog_ping(wdd); 674 mutex_unlock(&wd_data->lock); 675 676 if (err < 0) 677 return err; 678 679 return len; 680 } 681 682 /* 683 * watchdog_ioctl: handle the different ioctl's for the watchdog device. 684 * @file: file handle to the device 685 * @cmd: watchdog command 686 * @arg: argument pointer 687 * 688 * The watchdog API defines a common set of functions for all watchdogs 689 * according to their available features. 690 */ 691 692 static long watchdog_ioctl(struct file *file, unsigned int cmd, 693 unsigned long arg) 694 { 695 struct watchdog_core_data *wd_data = file->private_data; 696 void __user *argp = (void __user *)arg; 697 struct watchdog_device *wdd; 698 int __user *p = argp; 699 unsigned int val; 700 int err; 701 702 mutex_lock(&wd_data->lock); 703 704 wdd = wd_data->wdd; 705 if (!wdd) { 706 err = -ENODEV; 707 goto out_ioctl; 708 } 709 710 err = watchdog_ioctl_op(wdd, cmd, arg); 711 if (err != -ENOIOCTLCMD) 712 goto out_ioctl; 713 714 switch (cmd) { 715 case WDIOC_GETSUPPORT: 716 err = copy_to_user(argp, wdd->info, 717 sizeof(struct watchdog_info)) ? -EFAULT : 0; 718 break; 719 case WDIOC_GETSTATUS: 720 val = watchdog_get_status(wdd); 721 err = put_user(val, p); 722 break; 723 case WDIOC_GETBOOTSTATUS: 724 err = put_user(wdd->bootstatus, p); 725 break; 726 case WDIOC_SETOPTIONS: 727 if (get_user(val, p)) { 728 err = -EFAULT; 729 break; 730 } 731 if (val & WDIOS_DISABLECARD) { 732 err = watchdog_stop(wdd); 733 if (err < 0) 734 break; 735 } 736 if (val & WDIOS_ENABLECARD) 737 err = watchdog_start(wdd); 738 break; 739 case WDIOC_KEEPALIVE: 740 if (!(wdd->info->options & WDIOF_KEEPALIVEPING)) { 741 err = -EOPNOTSUPP; 742 break; 743 } 744 err = watchdog_ping(wdd); 745 break; 746 case WDIOC_SETTIMEOUT: 747 if (get_user(val, p)) { 748 err = -EFAULT; 749 break; 750 } 751 err = watchdog_set_timeout(wdd, val); 752 if (err < 0) 753 break; 754 /* If the watchdog is active then we send a keepalive ping 755 * to make sure that the watchdog keep's running (and if 756 * possible that it takes the new timeout) */ 757 err = watchdog_ping(wdd); 758 if (err < 0) 759 break; 760 /* fall through */ 761 case WDIOC_GETTIMEOUT: 762 /* timeout == 0 means that we don't know the timeout */ 763 if (wdd->timeout == 0) { 764 err = -EOPNOTSUPP; 765 break; 766 } 767 err = put_user(wdd->timeout, p); 768 break; 769 case WDIOC_GETTIMELEFT: 770 err = watchdog_get_timeleft(wdd, &val); 771 if (err < 0) 772 break; 773 err = put_user(val, p); 774 break; 775 case WDIOC_SETPRETIMEOUT: 776 if (get_user(val, p)) { 777 err = -EFAULT; 778 break; 779 } 780 err = watchdog_set_pretimeout(wdd, val); 781 break; 782 case WDIOC_GETPRETIMEOUT: 783 err = put_user(wdd->pretimeout, p); 784 break; 785 default: 786 err = -ENOTTY; 787 break; 788 } 789 790 out_ioctl: 791 mutex_unlock(&wd_data->lock); 792 return err; 793 } 794 795 /* 796 * watchdog_open: open the /dev/watchdog* devices. 797 * @inode: inode of device 798 * @file: file handle to device 799 * 800 * When the /dev/watchdog* device gets opened, we start the watchdog. 801 * Watch out: the /dev/watchdog device is single open, so we make sure 802 * it can only be opened once. 803 */ 804 805 static int watchdog_open(struct inode *inode, struct file *file) 806 { 807 struct watchdog_core_data *wd_data; 808 struct watchdog_device *wdd; 809 bool hw_running; 810 int err; 811 812 /* Get the corresponding watchdog device */ 813 if (imajor(inode) == MISC_MAJOR) 814 wd_data = old_wd_data; 815 else 816 wd_data = container_of(inode->i_cdev, struct watchdog_core_data, 817 cdev); 818 819 /* the watchdog is single open! */ 820 if (test_and_set_bit(_WDOG_DEV_OPEN, &wd_data->status)) 821 return -EBUSY; 822 823 wdd = wd_data->wdd; 824 825 /* 826 * If the /dev/watchdog device is open, we don't want the module 827 * to be unloaded. 828 */ 829 hw_running = watchdog_hw_running(wdd); 830 if (!hw_running && !try_module_get(wdd->ops->owner)) { 831 err = -EBUSY; 832 goto out_clear; 833 } 834 835 err = watchdog_start(wdd); 836 if (err < 0) 837 goto out_mod; 838 839 file->private_data = wd_data; 840 841 if (!hw_running) 842 kref_get(&wd_data->kref); 843 844 /* 845 * open_timeout only applies for the first open from 846 * userspace. Set open_deadline to infinity so that the kernel 847 * will take care of an always-running hardware watchdog in 848 * case the device gets magic-closed or WDIOS_DISABLECARD is 849 * applied. 850 */ 851 wd_data->open_deadline = KTIME_MAX; 852 853 /* dev/watchdog is a virtual (and thus non-seekable) filesystem */ 854 return stream_open(inode, file); 855 856 out_mod: 857 module_put(wd_data->wdd->ops->owner); 858 out_clear: 859 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 860 return err; 861 } 862 863 static void watchdog_core_data_release(struct kref *kref) 864 { 865 struct watchdog_core_data *wd_data; 866 867 wd_data = container_of(kref, struct watchdog_core_data, kref); 868 869 kfree(wd_data); 870 } 871 872 /* 873 * watchdog_release: release the watchdog device. 874 * @inode: inode of device 875 * @file: file handle to device 876 * 877 * This is the code for when /dev/watchdog gets closed. We will only 878 * stop the watchdog when we have received the magic char (and nowayout 879 * was not set), else the watchdog will keep running. 880 */ 881 882 static int watchdog_release(struct inode *inode, struct file *file) 883 { 884 struct watchdog_core_data *wd_data = file->private_data; 885 struct watchdog_device *wdd; 886 int err = -EBUSY; 887 bool running; 888 889 mutex_lock(&wd_data->lock); 890 891 wdd = wd_data->wdd; 892 if (!wdd) 893 goto done; 894 895 /* 896 * We only stop the watchdog if we received the magic character 897 * or if WDIOF_MAGICCLOSE is not set. If nowayout was set then 898 * watchdog_stop will fail. 899 */ 900 if (!test_bit(WDOG_ACTIVE, &wdd->status)) 901 err = 0; 902 else if (test_and_clear_bit(_WDOG_ALLOW_RELEASE, &wd_data->status) || 903 !(wdd->info->options & WDIOF_MAGICCLOSE)) 904 err = watchdog_stop(wdd); 905 906 /* If the watchdog was not stopped, send a keepalive ping */ 907 if (err < 0) { 908 pr_crit("watchdog%d: watchdog did not stop!\n", wdd->id); 909 watchdog_ping(wdd); 910 } 911 912 watchdog_update_worker(wdd); 913 914 /* make sure that /dev/watchdog can be re-opened */ 915 clear_bit(_WDOG_DEV_OPEN, &wd_data->status); 916 917 done: 918 running = wdd && watchdog_hw_running(wdd); 919 mutex_unlock(&wd_data->lock); 920 /* 921 * Allow the owner module to be unloaded again unless the watchdog 922 * is still running. If the watchdog is still running, it can not 923 * be stopped, and its driver must not be unloaded. 924 */ 925 if (!running) { 926 module_put(wd_data->cdev.owner); 927 kref_put(&wd_data->kref, watchdog_core_data_release); 928 } 929 return 0; 930 } 931 932 static const struct file_operations watchdog_fops = { 933 .owner = THIS_MODULE, 934 .write = watchdog_write, 935 .unlocked_ioctl = watchdog_ioctl, 936 .compat_ioctl = compat_ptr_ioctl, 937 .open = watchdog_open, 938 .release = watchdog_release, 939 }; 940 941 static struct miscdevice watchdog_miscdev = { 942 .minor = WATCHDOG_MINOR, 943 .name = "watchdog", 944 .fops = &watchdog_fops, 945 }; 946 947 /* 948 * watchdog_cdev_register: register watchdog character device 949 * @wdd: watchdog device 950 * @devno: character device number 951 * 952 * Register a watchdog character device including handling the legacy 953 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 954 * thus we set it up like that. 955 */ 956 957 static int watchdog_cdev_register(struct watchdog_device *wdd, dev_t devno) 958 { 959 struct watchdog_core_data *wd_data; 960 int err; 961 962 wd_data = kzalloc(sizeof(struct watchdog_core_data), GFP_KERNEL); 963 if (!wd_data) 964 return -ENOMEM; 965 kref_init(&wd_data->kref); 966 mutex_init(&wd_data->lock); 967 968 wd_data->wdd = wdd; 969 wdd->wd_data = wd_data; 970 971 if (IS_ERR_OR_NULL(watchdog_kworker)) 972 return -ENODEV; 973 974 kthread_init_work(&wd_data->work, watchdog_ping_work); 975 hrtimer_init(&wd_data->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); 976 wd_data->timer.function = watchdog_timer_expired; 977 978 if (wdd->id == 0) { 979 old_wd_data = wd_data; 980 watchdog_miscdev.parent = wdd->parent; 981 err = misc_register(&watchdog_miscdev); 982 if (err != 0) { 983 pr_err("%s: cannot register miscdev on minor=%d (err=%d).\n", 984 wdd->info->identity, WATCHDOG_MINOR, err); 985 if (err == -EBUSY) 986 pr_err("%s: a legacy watchdog module is probably present.\n", 987 wdd->info->identity); 988 old_wd_data = NULL; 989 kfree(wd_data); 990 return err; 991 } 992 } 993 994 /* Fill in the data structures */ 995 cdev_init(&wd_data->cdev, &watchdog_fops); 996 wd_data->cdev.owner = wdd->ops->owner; 997 998 /* Add the device */ 999 err = cdev_add(&wd_data->cdev, devno, 1); 1000 if (err) { 1001 pr_err("watchdog%d unable to add device %d:%d\n", 1002 wdd->id, MAJOR(watchdog_devt), wdd->id); 1003 if (wdd->id == 0) { 1004 misc_deregister(&watchdog_miscdev); 1005 old_wd_data = NULL; 1006 kref_put(&wd_data->kref, watchdog_core_data_release); 1007 } 1008 return err; 1009 } 1010 1011 /* Record time of most recent heartbeat as 'just before now'. */ 1012 wd_data->last_hw_keepalive = ktime_sub(ktime_get(), 1); 1013 watchdog_set_open_deadline(wd_data); 1014 1015 /* 1016 * If the watchdog is running, prevent its driver from being unloaded, 1017 * and schedule an immediate ping. 1018 */ 1019 if (watchdog_hw_running(wdd)) { 1020 __module_get(wdd->ops->owner); 1021 kref_get(&wd_data->kref); 1022 if (handle_boot_enabled) 1023 hrtimer_start(&wd_data->timer, 0, HRTIMER_MODE_REL); 1024 else 1025 pr_info("watchdog%d running and kernel based pre-userspace handler disabled\n", 1026 wdd->id); 1027 } 1028 1029 return 0; 1030 } 1031 1032 /* 1033 * watchdog_cdev_unregister: unregister watchdog character device 1034 * @watchdog: watchdog device 1035 * 1036 * Unregister watchdog character device and if needed the legacy 1037 * /dev/watchdog device. 1038 */ 1039 1040 static void watchdog_cdev_unregister(struct watchdog_device *wdd) 1041 { 1042 struct watchdog_core_data *wd_data = wdd->wd_data; 1043 1044 cdev_del(&wd_data->cdev); 1045 if (wdd->id == 0) { 1046 misc_deregister(&watchdog_miscdev); 1047 old_wd_data = NULL; 1048 } 1049 1050 if (watchdog_active(wdd) && 1051 test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) { 1052 watchdog_stop(wdd); 1053 } 1054 1055 mutex_lock(&wd_data->lock); 1056 wd_data->wdd = NULL; 1057 wdd->wd_data = NULL; 1058 mutex_unlock(&wd_data->lock); 1059 1060 hrtimer_cancel(&wd_data->timer); 1061 kthread_cancel_work_sync(&wd_data->work); 1062 1063 kref_put(&wd_data->kref, watchdog_core_data_release); 1064 } 1065 1066 static struct class watchdog_class = { 1067 .name = "watchdog", 1068 .owner = THIS_MODULE, 1069 .dev_groups = wdt_groups, 1070 }; 1071 1072 static int watchdog_reboot_notifier(struct notifier_block *nb, 1073 unsigned long code, void *data) 1074 { 1075 struct watchdog_device *wdd; 1076 1077 wdd = container_of(nb, struct watchdog_device, reboot_nb); 1078 if (code == SYS_DOWN || code == SYS_HALT) { 1079 if (watchdog_active(wdd)) { 1080 int ret; 1081 1082 ret = wdd->ops->stop(wdd); 1083 if (ret) 1084 return NOTIFY_BAD; 1085 } 1086 } 1087 1088 return NOTIFY_DONE; 1089 } 1090 1091 /* 1092 * watchdog_dev_register: register a watchdog device 1093 * @wdd: watchdog device 1094 * 1095 * Register a watchdog device including handling the legacy 1096 * /dev/watchdog node. /dev/watchdog is actually a miscdevice and 1097 * thus we set it up like that. 1098 */ 1099 1100 int watchdog_dev_register(struct watchdog_device *wdd) 1101 { 1102 struct device *dev; 1103 dev_t devno; 1104 int ret; 1105 1106 devno = MKDEV(MAJOR(watchdog_devt), wdd->id); 1107 1108 ret = watchdog_cdev_register(wdd, devno); 1109 if (ret) 1110 return ret; 1111 1112 dev = device_create_with_groups(&watchdog_class, wdd->parent, 1113 devno, wdd, wdd->groups, 1114 "watchdog%d", wdd->id); 1115 if (IS_ERR(dev)) { 1116 watchdog_cdev_unregister(wdd); 1117 return PTR_ERR(dev); 1118 } 1119 1120 ret = watchdog_register_pretimeout(wdd); 1121 if (ret) { 1122 device_destroy(&watchdog_class, devno); 1123 watchdog_cdev_unregister(wdd); 1124 return ret; 1125 } 1126 1127 if (test_bit(WDOG_STOP_ON_REBOOT, &wdd->status)) { 1128 wdd->reboot_nb.notifier_call = watchdog_reboot_notifier; 1129 1130 ret = devm_register_reboot_notifier(dev, &wdd->reboot_nb); 1131 if (ret) { 1132 pr_err("watchdog%d: Cannot register reboot notifier (%d)\n", 1133 wdd->id, ret); 1134 watchdog_dev_unregister(wdd); 1135 } 1136 } 1137 1138 return ret; 1139 } 1140 1141 /* 1142 * watchdog_dev_unregister: unregister a watchdog device 1143 * @watchdog: watchdog device 1144 * 1145 * Unregister watchdog device and if needed the legacy 1146 * /dev/watchdog device. 1147 */ 1148 1149 void watchdog_dev_unregister(struct watchdog_device *wdd) 1150 { 1151 watchdog_unregister_pretimeout(wdd); 1152 device_destroy(&watchdog_class, wdd->wd_data->cdev.dev); 1153 watchdog_cdev_unregister(wdd); 1154 } 1155 1156 /* 1157 * watchdog_dev_init: init dev part of watchdog core 1158 * 1159 * Allocate a range of chardev nodes to use for watchdog devices 1160 */ 1161 1162 int __init watchdog_dev_init(void) 1163 { 1164 int err; 1165 struct sched_param param = {.sched_priority = MAX_RT_PRIO - 1,}; 1166 1167 watchdog_kworker = kthread_create_worker(0, "watchdogd"); 1168 if (IS_ERR(watchdog_kworker)) { 1169 pr_err("Failed to create watchdog kworker\n"); 1170 return PTR_ERR(watchdog_kworker); 1171 } 1172 sched_setscheduler(watchdog_kworker->task, SCHED_FIFO, ¶m); 1173 1174 err = class_register(&watchdog_class); 1175 if (err < 0) { 1176 pr_err("couldn't register class\n"); 1177 goto err_register; 1178 } 1179 1180 err = alloc_chrdev_region(&watchdog_devt, 0, MAX_DOGS, "watchdog"); 1181 if (err < 0) { 1182 pr_err("watchdog: unable to allocate char dev region\n"); 1183 goto err_alloc; 1184 } 1185 1186 return 0; 1187 1188 err_alloc: 1189 class_unregister(&watchdog_class); 1190 err_register: 1191 kthread_destroy_worker(watchdog_kworker); 1192 return err; 1193 } 1194 1195 /* 1196 * watchdog_dev_exit: exit dev part of watchdog core 1197 * 1198 * Release the range of chardev nodes used for watchdog devices 1199 */ 1200 1201 void __exit watchdog_dev_exit(void) 1202 { 1203 unregister_chrdev_region(watchdog_devt, MAX_DOGS); 1204 class_unregister(&watchdog_class); 1205 kthread_destroy_worker(watchdog_kworker); 1206 } 1207 1208 module_param(handle_boot_enabled, bool, 0444); 1209 MODULE_PARM_DESC(handle_boot_enabled, 1210 "Watchdog core auto-updates boot enabled watchdogs before userspace takes over (default=" 1211 __MODULE_STRING(IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED)) ")"); 1212 1213 module_param(open_timeout, uint, 0644); 1214 MODULE_PARM_DESC(open_timeout, 1215 "Maximum time (in seconds, 0 means infinity) for userspace to take over a running watchdog (default=" 1216 __MODULE_STRING(CONFIG_WATCHDOG_OPEN_TIMEOUT) ")"); 1217