Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_fail.c
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1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD 3 * 4 * Copyright (c) 2009 Isilon Inc http://www.isilon.com/ 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 /** 28 * @file 29 * 30 * fail(9) Facility. 31 * 32 * @ingroup failpoint_private 33 */ 34 /** 35 * @defgroup failpoint fail(9) Facility 36 * 37 * Failpoints allow for injecting fake errors into running code on the fly, 38 * without modifying code or recompiling with flags. Failpoints are always 39 * present, and are very efficient when disabled. Failpoints are described 40 * in man fail(9). 41 */ 42 /** 43 * @defgroup failpoint_private Private fail(9) Implementation functions 44 * 45 * Private implementations for the actual failpoint code. 46 * 47 * @ingroup failpoint 48 */ 49 /** 50 * @addtogroup failpoint_private 51 * @{ 52 */ 53 54 #include <sys/cdefs.h> 55 __FBSDID("$FreeBSD$"); 56 57 #include "opt_stack.h" 58 59 #include <sys/ctype.h> 60 #include <sys/errno.h> 61 #include <sys/fail.h> 62 #include <sys/kernel.h> 63 #include <sys/libkern.h> 64 #include <sys/limits.h> 65 #include <sys/lock.h> 66 #include <sys/malloc.h> 67 #include <sys/mutex.h> 68 #include <sys/proc.h> 69 #include <sys/sbuf.h> 70 #include <sys/sleepqueue.h> 71 #include <sys/sx.h> 72 #include <sys/sysctl.h> 73 #include <sys/types.h> 74 75 #include <machine/atomic.h> 76 #include <machine/stdarg.h> 77 78 #ifdef ILOG_DEFINE_FOR_FILE 79 ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point); 80 #endif 81 82 static MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system"); 83 #define fp_free(ptr) free(ptr, M_FAIL_POINT) 84 #define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags)) 85 #define fs_free(ptr) fp_free(ptr) 86 #define fs_malloc() fp_malloc(sizeof(struct fail_point_setting), \ 87 M_WAITOK | M_ZERO) 88 89 /** 90 * These define the wchans that are used for sleeping, pausing respectively. 91 * They are chosen arbitrarily but need to be distinct to the failpoint and 92 * the sleep/pause distinction. 93 */ 94 #define FP_SLEEP_CHANNEL(fp) (void*)(fp) 95 #define FP_PAUSE_CHANNEL(fp) __DEVOLATILE(void*, &fp->fp_setting) 96 97 /** 98 * Don't allow more than this many entries in a fail point set by sysctl. 99 * The 99.99...% case is to have 1 entry. I can't imagine having this many 100 * entries, so it should not limit us. Saves on re-mallocs while holding 101 * a non-sleepable lock. 102 */ 103 #define FP_MAX_ENTRY_COUNT 20 104 105 /* Used to drain sbufs to the sysctl output */ 106 int fail_sysctl_drain_func(void *, const char *, int); 107 108 /* Head of tailq of struct fail_point_entry */ 109 TAILQ_HEAD(fail_point_entry_queue, fail_point_entry); 110 111 /** 112 * fp entries garbage list; outstanding entries are cleaned up in the 113 * garbage collector 114 */ 115 STAILQ_HEAD(fail_point_setting_garbage, fail_point_setting); 116 static struct fail_point_setting_garbage fp_setting_garbage = 117 STAILQ_HEAD_INITIALIZER(fp_setting_garbage); 118 static struct mtx mtx_garbage_list; 119 MTX_SYSINIT(mtx_garbage_list, &mtx_garbage_list, "fail point garbage mtx", 120 MTX_SPIN); 121 122 static struct sx sx_fp_set; 123 SX_SYSINIT(sx_fp_set, &sx_fp_set, "fail point set sx"); 124 125 /** 126 * Failpoint types. 127 * Don't change these without changing fail_type_strings in fail.c. 128 * @ingroup failpoint_private 129 */ 130 enum fail_point_t { 131 FAIL_POINT_OFF, /**< don't fail */ 132 FAIL_POINT_PANIC, /**< panic */ 133 FAIL_POINT_RETURN, /**< return an errorcode */ 134 FAIL_POINT_BREAK, /**< break into the debugger */ 135 FAIL_POINT_PRINT, /**< print a message */ 136 FAIL_POINT_SLEEP, /**< sleep for some msecs */ 137 FAIL_POINT_PAUSE, /**< sleep until failpoint is set to off */ 138 FAIL_POINT_YIELD, /**< yield the cpu */ 139 FAIL_POINT_DELAY, /**< busy wait the cpu */ 140 FAIL_POINT_NUMTYPES, 141 FAIL_POINT_INVALID = -1 142 }; 143 144 static struct { 145 const char *name; 146 int nmlen; 147 } fail_type_strings[] = { 148 #define FP_TYPE_NM_LEN(s) { s, sizeof(s) - 1 } 149 [FAIL_POINT_OFF] = FP_TYPE_NM_LEN("off"), 150 [FAIL_POINT_PANIC] = FP_TYPE_NM_LEN("panic"), 151 [FAIL_POINT_RETURN] = FP_TYPE_NM_LEN("return"), 152 [FAIL_POINT_BREAK] = FP_TYPE_NM_LEN("break"), 153 [FAIL_POINT_PRINT] = FP_TYPE_NM_LEN("print"), 154 [FAIL_POINT_SLEEP] = FP_TYPE_NM_LEN("sleep"), 155 [FAIL_POINT_PAUSE] = FP_TYPE_NM_LEN("pause"), 156 [FAIL_POINT_YIELD] = FP_TYPE_NM_LEN("yield"), 157 [FAIL_POINT_DELAY] = FP_TYPE_NM_LEN("delay"), 158 }; 159 160 #define FE_COUNT_UNTRACKED (INT_MIN) 161 162 /** 163 * Internal structure tracking a single term of a complete failpoint. 164 * @ingroup failpoint_private 165 */ 166 struct fail_point_entry { 167 volatile bool fe_stale; 168 enum fail_point_t fe_type; /**< type of entry */ 169 int fe_arg; /**< argument to type (e.g. return value) */ 170 int fe_prob; /**< likelihood of firing in millionths */ 171 int32_t fe_count; /**< number of times to fire, -1 means infinite */ 172 pid_t fe_pid; /**< only fail for this process */ 173 struct fail_point *fe_parent; /**< backpointer to fp */ 174 TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry ptr */ 175 }; 176 177 struct fail_point_setting { 178 STAILQ_ENTRY(fail_point_setting) fs_garbage_link; 179 struct fail_point_entry_queue fp_entry_queue; 180 struct fail_point * fs_parent; 181 struct mtx feq_mtx; /* Gives fail_point_pause something to do. */ 182 }; 183 184 /** 185 * Defines stating the equivalent of probablilty one (100%) 186 */ 187 enum { 188 PROB_MAX = 1000000, /* probability between zero and this number */ 189 PROB_DIGITS = 6 /* number of zero's in above number */ 190 }; 191 192 /* Get a ref on an fp's fp_setting */ 193 static inline struct fail_point_setting *fail_point_setting_get_ref( 194 struct fail_point *fp); 195 /* Release a ref on an fp_setting */ 196 static inline void fail_point_setting_release_ref(struct fail_point *fp); 197 /* Allocate and initialize a struct fail_point_setting */ 198 static struct fail_point_setting *fail_point_setting_new(struct 199 fail_point *); 200 /* Free a struct fail_point_setting */ 201 static void fail_point_setting_destroy(struct fail_point_setting *fp_setting); 202 /* Allocate and initialize a struct fail_point_entry */ 203 static struct fail_point_entry *fail_point_entry_new(struct 204 fail_point_setting *); 205 /* Free a struct fail_point_entry */ 206 static void fail_point_entry_destroy(struct fail_point_entry *fp_entry); 207 /* Append fp setting to garbage list */ 208 static inline void fail_point_setting_garbage_append( 209 struct fail_point_setting *fp_setting); 210 /* Swap fp's setting with fp_setting_new */ 211 static inline struct fail_point_setting * 212 fail_point_swap_settings(struct fail_point *fp, 213 struct fail_point_setting *fp_setting_new); 214 /* Free up any zero-ref setting in the garbage queue */ 215 static void fail_point_garbage_collect(void); 216 /* If this fail point's setting are empty, then swap it out to NULL. */ 217 static inline void fail_point_eval_swap_out(struct fail_point *fp, 218 struct fail_point_setting *fp_setting); 219 220 bool 221 fail_point_is_off(struct fail_point *fp) 222 { 223 bool return_val; 224 struct fail_point_setting *fp_setting; 225 struct fail_point_entry *ent; 226 227 return_val = true; 228 229 fp_setting = fail_point_setting_get_ref(fp); 230 if (fp_setting != NULL) { 231 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, 232 fe_entries) { 233 if (!ent->fe_stale) { 234 return_val = false; 235 break; 236 } 237 } 238 } 239 fail_point_setting_release_ref(fp); 240 241 return (return_val); 242 } 243 244 /* Allocate and initialize a struct fail_point_setting */ 245 static struct fail_point_setting * 246 fail_point_setting_new(struct fail_point *fp) 247 { 248 struct fail_point_setting *fs_new; 249 250 fs_new = fs_malloc(); 251 fs_new->fs_parent = fp; 252 TAILQ_INIT(&fs_new->fp_entry_queue); 253 mtx_init(&fs_new->feq_mtx, "fail point entries", NULL, MTX_SPIN); 254 255 fail_point_setting_garbage_append(fs_new); 256 257 return (fs_new); 258 } 259 260 /* Free a struct fail_point_setting */ 261 static void 262 fail_point_setting_destroy(struct fail_point_setting *fp_setting) 263 { 264 struct fail_point_entry *ent; 265 266 while (!TAILQ_EMPTY(&fp_setting->fp_entry_queue)) { 267 ent = TAILQ_FIRST(&fp_setting->fp_entry_queue); 268 TAILQ_REMOVE(&fp_setting->fp_entry_queue, ent, fe_entries); 269 fail_point_entry_destroy(ent); 270 } 271 272 fs_free(fp_setting); 273 } 274 275 /* Allocate and initialize a struct fail_point_entry */ 276 static struct fail_point_entry * 277 fail_point_entry_new(struct fail_point_setting *fp_setting) 278 { 279 struct fail_point_entry *fp_entry; 280 281 fp_entry = fp_malloc(sizeof(struct fail_point_entry), 282 M_WAITOK | M_ZERO); 283 fp_entry->fe_parent = fp_setting->fs_parent; 284 fp_entry->fe_prob = PROB_MAX; 285 fp_entry->fe_pid = NO_PID; 286 fp_entry->fe_count = FE_COUNT_UNTRACKED; 287 TAILQ_INSERT_TAIL(&fp_setting->fp_entry_queue, fp_entry, 288 fe_entries); 289 290 return (fp_entry); 291 } 292 293 /* Free a struct fail_point_entry */ 294 static void 295 fail_point_entry_destroy(struct fail_point_entry *fp_entry) 296 { 297 298 fp_free(fp_entry); 299 } 300 301 /* Get a ref on an fp's fp_setting */ 302 static inline struct fail_point_setting * 303 fail_point_setting_get_ref(struct fail_point *fp) 304 { 305 struct fail_point_setting *fp_setting; 306 307 /* Invariant: if we have a ref, our pointer to fp_setting is safe */ 308 atomic_add_acq_32(&fp->fp_ref_cnt, 1); 309 fp_setting = fp->fp_setting; 310 311 return (fp_setting); 312 } 313 314 /* Release a ref on an fp_setting */ 315 static inline void 316 fail_point_setting_release_ref(struct fail_point *fp) 317 { 318 319 KASSERT(&fp->fp_ref_cnt > 0, ("Attempting to deref w/no refs")); 320 atomic_subtract_rel_32(&fp->fp_ref_cnt, 1); 321 } 322 323 /* Append fp entries to fp garbage list */ 324 static inline void 325 fail_point_setting_garbage_append(struct fail_point_setting *fp_setting) 326 { 327 328 mtx_lock_spin(&mtx_garbage_list); 329 STAILQ_INSERT_TAIL(&fp_setting_garbage, fp_setting, 330 fs_garbage_link); 331 mtx_unlock_spin(&mtx_garbage_list); 332 } 333 334 /* Swap fp's entries with fp_setting_new */ 335 static struct fail_point_setting * 336 fail_point_swap_settings(struct fail_point *fp, 337 struct fail_point_setting *fp_setting_new) 338 { 339 struct fail_point_setting *fp_setting_old; 340 341 fp_setting_old = fp->fp_setting; 342 fp->fp_setting = fp_setting_new; 343 344 return (fp_setting_old); 345 } 346 347 static inline void 348 fail_point_eval_swap_out(struct fail_point *fp, 349 struct fail_point_setting *fp_setting) 350 { 351 352 /* We may have already been swapped out and replaced; ignore. */ 353 if (fp->fp_setting == fp_setting) 354 fail_point_swap_settings(fp, NULL); 355 } 356 357 /* Free up any zero-ref entries in the garbage queue */ 358 static void 359 fail_point_garbage_collect(void) 360 { 361 struct fail_point_setting *fs_current, *fs_next; 362 struct fail_point_setting_garbage fp_ents_free_list; 363 364 /** 365 * We will transfer the entries to free to fp_ents_free_list while holding 366 * the spin mutex, then free it after we drop the lock. This avoids 367 * triggering witness due to sleepable mutexes in the memory 368 * allocator. 369 */ 370 STAILQ_INIT(&fp_ents_free_list); 371 372 mtx_lock_spin(&mtx_garbage_list); 373 STAILQ_FOREACH_SAFE(fs_current, &fp_setting_garbage, fs_garbage_link, 374 fs_next) { 375 if (fs_current->fs_parent->fp_setting != fs_current && 376 fs_current->fs_parent->fp_ref_cnt == 0) { 377 STAILQ_REMOVE(&fp_setting_garbage, fs_current, 378 fail_point_setting, fs_garbage_link); 379 STAILQ_INSERT_HEAD(&fp_ents_free_list, fs_current, 380 fs_garbage_link); 381 } 382 } 383 mtx_unlock_spin(&mtx_garbage_list); 384 385 STAILQ_FOREACH_SAFE(fs_current, &fp_ents_free_list, fs_garbage_link, 386 fs_next) 387 fail_point_setting_destroy(fs_current); 388 } 389 390 /* Drain out all refs from this fail point */ 391 static inline void 392 fail_point_drain(struct fail_point *fp, int expected_ref) 393 { 394 struct fail_point_setting *entries; 395 396 entries = fail_point_swap_settings(fp, NULL); 397 /** 398 * We have unpaused all threads; so we will wait no longer 399 * than the time taken for the longest remaining sleep, or 400 * the length of time of a long-running code block. 401 */ 402 while (fp->fp_ref_cnt > expected_ref) { 403 wakeup(FP_PAUSE_CHANNEL(fp)); 404 tsleep(&fp, PWAIT, "fail_point_drain", hz / 100); 405 } 406 fail_point_swap_settings(fp, entries); 407 } 408 409 static inline void 410 fail_point_pause(struct fail_point *fp, enum fail_point_return_code *pret, 411 struct mtx *mtx_sleep) 412 { 413 414 if (fp->fp_pre_sleep_fn) 415 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 416 417 msleep_spin(FP_PAUSE_CHANNEL(fp), mtx_sleep, "failpt", 0); 418 419 if (fp->fp_post_sleep_fn) 420 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg); 421 } 422 423 static inline void 424 fail_point_sleep(struct fail_point *fp, int msecs, 425 enum fail_point_return_code *pret) 426 { 427 int timo; 428 429 /* Convert from millisecs to ticks, rounding up */ 430 timo = howmany((int64_t)msecs * hz, 1000L); 431 432 if (timo > 0) { 433 if (!(fp->fp_flags & FAIL_POINT_USE_TIMEOUT_PATH)) { 434 if (fp->fp_pre_sleep_fn) 435 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 436 437 tsleep(FP_SLEEP_CHANNEL(fp), PWAIT, "failpt", timo); 438 439 if (fp->fp_post_sleep_fn) 440 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg); 441 } else { 442 if (fp->fp_pre_sleep_fn) 443 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 444 445 timeout(fp->fp_post_sleep_fn, fp->fp_post_sleep_arg, 446 timo); 447 *pret = FAIL_POINT_RC_QUEUED; 448 } 449 } 450 } 451 452 static char *parse_fail_point(struct fail_point_setting *, char *); 453 static char *parse_term(struct fail_point_setting *, char *); 454 static char *parse_number(int *out_units, int *out_decimal, char *); 455 static char *parse_type(struct fail_point_entry *, char *); 456 457 /** 458 * Initialize a fail_point. The name is formed in a printf-like fashion 459 * from "fmt" and subsequent arguments. This function is generally used 460 * for custom failpoints located at odd places in the sysctl tree, and is 461 * not explicitly needed for standard in-line-declared failpoints. 462 * 463 * @ingroup failpoint 464 */ 465 void 466 fail_point_init(struct fail_point *fp, const char *fmt, ...) 467 { 468 va_list ap; 469 char *name; 470 int n; 471 472 fp->fp_setting = NULL; 473 fp->fp_flags = 0; 474 475 /* Figure out the size of the name. */ 476 va_start(ap, fmt); 477 n = vsnprintf(NULL, 0, fmt, ap); 478 va_end(ap); 479 480 /* Allocate the name and fill it in. */ 481 name = fp_malloc(n + 1, M_WAITOK); 482 if (name != NULL) { 483 va_start(ap, fmt); 484 vsnprintf(name, n + 1, fmt, ap); 485 va_end(ap); 486 } 487 fp->fp_name = name; 488 fp->fp_location = ""; 489 fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME; 490 fp->fp_pre_sleep_fn = NULL; 491 fp->fp_pre_sleep_arg = NULL; 492 fp->fp_post_sleep_fn = NULL; 493 fp->fp_post_sleep_arg = NULL; 494 } 495 496 /** 497 * Free the resources held by a fail_point, and wake any paused threads. 498 * Thou shalt not allow threads to hit this fail point after you enter this 499 * function, nor shall you call this multiple times for a given fp. 500 * @ingroup failpoint 501 */ 502 void 503 fail_point_destroy(struct fail_point *fp) 504 { 505 506 fail_point_drain(fp, 0); 507 508 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) { 509 fp_free(__DECONST(void *, fp->fp_name)); 510 fp->fp_name = NULL; 511 } 512 fp->fp_flags = 0; 513 514 sx_xlock(&sx_fp_set); 515 fail_point_garbage_collect(); 516 sx_xunlock(&sx_fp_set); 517 } 518 519 /** 520 * This does the real work of evaluating a fail point. If the fail point tells 521 * us to return a value, this function returns 1 and fills in 'return_value' 522 * (return_value is allowed to be null). If the fail point tells us to panic, 523 * we never return. Otherwise we just return 0 after doing some work, which 524 * means "keep going". 525 */ 526 enum fail_point_return_code 527 fail_point_eval_nontrivial(struct fail_point *fp, int *return_value) 528 { 529 bool execute = false; 530 struct fail_point_entry *ent; 531 struct fail_point_setting *fp_setting; 532 enum fail_point_return_code ret; 533 int cont; 534 int count; 535 int msecs; 536 int usecs; 537 538 ret = FAIL_POINT_RC_CONTINUE; 539 cont = 0; /* don't continue by default */ 540 541 fp_setting = fail_point_setting_get_ref(fp); 542 if (fp_setting == NULL) 543 goto abort; 544 545 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 546 547 if (ent->fe_stale) 548 continue; 549 550 if (ent->fe_prob < PROB_MAX && 551 ent->fe_prob < random() % PROB_MAX) 552 continue; 553 554 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid) 555 continue; 556 557 if (ent->fe_count != FE_COUNT_UNTRACKED) { 558 count = ent->fe_count; 559 while (count > 0) { 560 if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) { 561 count--; 562 execute = true; 563 break; 564 } 565 count = ent->fe_count; 566 } 567 if (execute == false) 568 /* We lost the race; consider the entry stale and bail now */ 569 continue; 570 if (count == 0) 571 ent->fe_stale = true; 572 } 573 574 switch (ent->fe_type) { 575 case FAIL_POINT_PANIC: 576 panic("fail point %s panicking", fp->fp_name); 577 /* NOTREACHED */ 578 579 case FAIL_POINT_RETURN: 580 if (return_value != NULL) 581 *return_value = ent->fe_arg; 582 ret = FAIL_POINT_RC_RETURN; 583 break; 584 585 case FAIL_POINT_BREAK: 586 printf("fail point %s breaking to debugger\n", 587 fp->fp_name); 588 breakpoint(); 589 break; 590 591 case FAIL_POINT_PRINT: 592 printf("fail point %s executing\n", fp->fp_name); 593 cont = ent->fe_arg; 594 break; 595 596 case FAIL_POINT_SLEEP: 597 msecs = ent->fe_arg; 598 if (msecs) 599 fail_point_sleep(fp, msecs, &ret); 600 break; 601 602 case FAIL_POINT_PAUSE: 603 /** 604 * Pausing is inherently strange with multiple 605 * entries given our design. That is because some 606 * entries could be unreachable, for instance in cases like: 607 * pause->return. We can never reach the return entry. 608 * The sysctl layer actually truncates all entries after 609 * a pause for this reason. 610 */ 611 mtx_lock_spin(&fp_setting->feq_mtx); 612 fail_point_pause(fp, &ret, &fp_setting->feq_mtx); 613 mtx_unlock_spin(&fp_setting->feq_mtx); 614 break; 615 616 case FAIL_POINT_YIELD: 617 kern_yield(PRI_UNCHANGED); 618 break; 619 620 case FAIL_POINT_DELAY: 621 usecs = ent->fe_arg; 622 DELAY(usecs); 623 break; 624 625 default: 626 break; 627 } 628 629 if (cont == 0) 630 break; 631 } 632 633 if (fail_point_is_off(fp)) 634 fail_point_eval_swap_out(fp, fp_setting); 635 636 abort: 637 fail_point_setting_release_ref(fp); 638 639 return (ret); 640 } 641 642 /** 643 * Translate internal fail_point structure into human-readable text. 644 */ 645 static void 646 fail_point_get(struct fail_point *fp, struct sbuf *sb, 647 bool verbose) 648 { 649 struct fail_point_entry *ent; 650 struct fail_point_setting *fp_setting; 651 struct fail_point_entry *fp_entry_cpy; 652 int cnt_sleeping; 653 int idx; 654 int printed_entry_count; 655 656 cnt_sleeping = 0; 657 idx = 0; 658 printed_entry_count = 0; 659 660 fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) * 661 (FP_MAX_ENTRY_COUNT + 1), M_WAITOK); 662 663 fp_setting = fail_point_setting_get_ref(fp); 664 665 if (fp_setting != NULL) { 666 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 667 if (ent->fe_stale) 668 continue; 669 670 KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT, 671 ("FP entry list larger than allowed")); 672 673 fp_entry_cpy[printed_entry_count] = *ent; 674 ++printed_entry_count; 675 } 676 } 677 fail_point_setting_release_ref(fp); 678 679 /* This is our equivalent of a NULL terminator */ 680 fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID; 681 682 while (idx < printed_entry_count) { 683 ent = &fp_entry_cpy[idx]; 684 ++idx; 685 if (ent->fe_prob < PROB_MAX) { 686 int decimal = ent->fe_prob % (PROB_MAX / 100); 687 int units = ent->fe_prob / (PROB_MAX / 100); 688 sbuf_printf(sb, "%d", units); 689 if (decimal) { 690 int digits = PROB_DIGITS - 2; 691 while (!(decimal % 10)) { 692 digits--; 693 decimal /= 10; 694 } 695 sbuf_printf(sb, ".%0*d", digits, decimal); 696 } 697 sbuf_printf(sb, "%%"); 698 } 699 if (ent->fe_count >= 0) 700 sbuf_printf(sb, "%d*", ent->fe_count); 701 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name); 702 if (ent->fe_arg) 703 sbuf_printf(sb, "(%d)", ent->fe_arg); 704 if (ent->fe_pid != NO_PID) 705 sbuf_printf(sb, "[pid %d]", ent->fe_pid); 706 if (TAILQ_NEXT(ent, fe_entries)) 707 sbuf_printf(sb, "->"); 708 } 709 if (!printed_entry_count) 710 sbuf_printf(sb, "off"); 711 712 fp_free(fp_entry_cpy); 713 if (verbose) { 714 #ifdef STACK 715 /* Print number of sleeping threads. queue=0 is the argument 716 * used by msleep when sending our threads to sleep. */ 717 sbuf_printf(sb, "\nsleeping_thread_stacks = {\n"); 718 sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0, 719 &cnt_sleeping); 720 721 sbuf_printf(sb, "},\n"); 722 #endif 723 sbuf_printf(sb, "sleeping_thread_count = %d,\n", 724 cnt_sleeping); 725 726 #ifdef STACK 727 sbuf_printf(sb, "paused_thread_stacks = {\n"); 728 sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0, 729 &cnt_sleeping); 730 731 sbuf_printf(sb, "},\n"); 732 #endif 733 sbuf_printf(sb, "paused_thread_count = %d\n", 734 cnt_sleeping); 735 } 736 } 737 738 /** 739 * Set an internal fail_point structure from a human-readable failpoint string 740 * in a lock-safe manner. 741 */ 742 static int 743 fail_point_set(struct fail_point *fp, char *buf) 744 { 745 struct fail_point_entry *ent, *ent_next; 746 struct fail_point_setting *entries; 747 bool should_wake_paused; 748 bool should_truncate; 749 int error; 750 751 error = 0; 752 should_wake_paused = false; 753 should_truncate = false; 754 755 /* Parse new entries. */ 756 /** 757 * ref protects our new malloc'd stuff from being garbage collected 758 * before we link it. 759 */ 760 fail_point_setting_get_ref(fp); 761 entries = fail_point_setting_new(fp); 762 if (parse_fail_point(entries, buf) == NULL) { 763 STAILQ_REMOVE(&fp_setting_garbage, entries, 764 fail_point_setting, fs_garbage_link); 765 fail_point_setting_destroy(entries); 766 error = EINVAL; 767 goto end; 768 } 769 770 /** 771 * Transfer the entries we are going to keep to a new list. 772 * Get rid of useless zero probability entries, and entries with hit 773 * count 0. 774 * If 'off' is present, and it has no hit count set, then all entries 775 * after it are discarded since they are unreachable. 776 */ 777 TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) { 778 if (ent->fe_prob == 0 || ent->fe_count == 0) { 779 printf("Discarding entry which cannot execute %s\n", 780 fail_type_strings[ent->fe_type].name); 781 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 782 fe_entries); 783 fp_free(ent); 784 continue; 785 } else if (should_truncate) { 786 printf("Discarding unreachable entry %s\n", 787 fail_type_strings[ent->fe_type].name); 788 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 789 fe_entries); 790 fp_free(ent); 791 continue; 792 } 793 794 if (ent->fe_type == FAIL_POINT_OFF) { 795 should_wake_paused = true; 796 if (ent->fe_count == FE_COUNT_UNTRACKED) { 797 should_truncate = true; 798 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 799 fe_entries); 800 fp_free(ent); 801 } 802 } else if (ent->fe_type == FAIL_POINT_PAUSE) { 803 should_truncate = true; 804 } else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags & 805 FAIL_POINT_NONSLEEPABLE)) { 806 /** 807 * If this fail point is annotated as being in a 808 * non-sleepable ctx, convert sleep to delay and 809 * convert the msec argument to usecs. 810 */ 811 printf("Sleep call request on fail point in " 812 "non-sleepable context; using delay instead " 813 "of sleep\n"); 814 ent->fe_type = FAIL_POINT_DELAY; 815 ent->fe_arg *= 1000; 816 } 817 } 818 819 if (TAILQ_EMPTY(&entries->fp_entry_queue)) { 820 entries = fail_point_swap_settings(fp, NULL); 821 if (entries != NULL) 822 wakeup(FP_PAUSE_CHANNEL(fp)); 823 } else { 824 if (should_wake_paused) 825 wakeup(FP_PAUSE_CHANNEL(fp)); 826 fail_point_swap_settings(fp, entries); 827 } 828 829 end: 830 #ifdef IWARNING 831 if (error) 832 IWARNING("Failed to set %s %s to %s", 833 fp->fp_name, fp->fp_location, buf); 834 else 835 INOTICE("Set %s %s to %s", 836 fp->fp_name, fp->fp_location, buf); 837 #endif /* IWARNING */ 838 839 fail_point_setting_release_ref(fp); 840 return (error); 841 } 842 843 #define MAX_FAIL_POINT_BUF 1023 844 845 /** 846 * Handle kernel failpoint set/get. 847 */ 848 int 849 fail_point_sysctl(SYSCTL_HANDLER_ARGS) 850 { 851 struct fail_point *fp; 852 char *buf; 853 struct sbuf sb, *sb_check; 854 int error; 855 856 buf = NULL; 857 error = 0; 858 fp = arg1; 859 860 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 861 if (sb_check != &sb) 862 return (ENOMEM); 863 864 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 865 866 /* Setting */ 867 /** 868 * Lock protects any new entries from being garbage collected before we 869 * can link them to the fail point. 870 */ 871 sx_xlock(&sx_fp_set); 872 if (req->newptr) { 873 if (req->newlen > MAX_FAIL_POINT_BUF) { 874 error = EINVAL; 875 goto out; 876 } 877 878 buf = fp_malloc(req->newlen + 1, M_WAITOK); 879 880 error = SYSCTL_IN(req, buf, req->newlen); 881 if (error) 882 goto out; 883 buf[req->newlen] = '\0'; 884 885 error = fail_point_set(fp, buf); 886 } 887 888 fail_point_garbage_collect(); 889 sx_xunlock(&sx_fp_set); 890 891 /* Retrieving. */ 892 fail_point_get(fp, &sb, false); 893 894 out: 895 sbuf_finish(&sb); 896 sbuf_delete(&sb); 897 898 if (buf) 899 fp_free(buf); 900 901 return (error); 902 } 903 904 int 905 fail_point_sysctl_status(SYSCTL_HANDLER_ARGS) 906 { 907 struct fail_point *fp; 908 struct sbuf sb, *sb_check; 909 910 fp = arg1; 911 912 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 913 if (sb_check != &sb) 914 return (ENOMEM); 915 916 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 917 918 /* Retrieving. */ 919 fail_point_get(fp, &sb, true); 920 921 sbuf_finish(&sb); 922 sbuf_delete(&sb); 923 924 /** 925 * Lock protects any new entries from being garbage collected before we 926 * can link them to the fail point. 927 */ 928 sx_xlock(&sx_fp_set); 929 fail_point_garbage_collect(); 930 sx_xunlock(&sx_fp_set); 931 932 return (0); 933 } 934 935 int 936 fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len) 937 { 938 struct sysctl_req *sa; 939 int error; 940 941 sa = sysctl_args; 942 943 error = SYSCTL_OUT(sa, buf, len); 944 945 if (error == ENOMEM) 946 return (-1); 947 else 948 return (len); 949 } 950 951 /** 952 * Internal helper function to translate a human-readable failpoint string 953 * into a internally-parsable fail_point structure. 954 */ 955 static char * 956 parse_fail_point(struct fail_point_setting *ents, char *p) 957 { 958 /* <fail_point> :: 959 * <term> ( "->" <term> )* 960 */ 961 uint8_t term_count; 962 963 term_count = 1; 964 965 p = parse_term(ents, p); 966 if (p == NULL) 967 return (NULL); 968 969 while (*p != '\0') { 970 term_count++; 971 if (p[0] != '-' || p[1] != '>' || 972 (p = parse_term(ents, p+2)) == NULL || 973 term_count > FP_MAX_ENTRY_COUNT) 974 return (NULL); 975 } 976 return (p); 977 } 978 979 /** 980 * Internal helper function to parse an individual term from a failpoint. 981 */ 982 static char * 983 parse_term(struct fail_point_setting *ents, char *p) 984 { 985 struct fail_point_entry *ent; 986 987 ent = fail_point_entry_new(ents); 988 989 /* 990 * <term> :: 991 * ( (<float> "%") | (<integer> "*" ) )* 992 * <type> 993 * [ "(" <integer> ")" ] 994 * [ "[pid " <integer> "]" ] 995 */ 996 997 /* ( (<float> "%") | (<integer> "*" ) )* */ 998 while (isdigit(*p) || *p == '.') { 999 int units, decimal; 1000 1001 p = parse_number(&units, &decimal, p); 1002 if (p == NULL) 1003 return (NULL); 1004 1005 if (*p == '%') { 1006 if (units > 100) /* prevent overflow early */ 1007 units = 100; 1008 ent->fe_prob = units * (PROB_MAX / 100) + decimal; 1009 if (ent->fe_prob > PROB_MAX) 1010 ent->fe_prob = PROB_MAX; 1011 } else if (*p == '*') { 1012 if (!units || units < 0 || decimal) 1013 return (NULL); 1014 ent->fe_count = units; 1015 } else 1016 return (NULL); 1017 p++; 1018 } 1019 1020 /* <type> */ 1021 p = parse_type(ent, p); 1022 if (p == NULL) 1023 return (NULL); 1024 if (*p == '\0') 1025 return (p); 1026 1027 /* [ "(" <integer> ")" ] */ 1028 if (*p != '(') 1029 return (p); 1030 p++; 1031 if (!isdigit(*p) && *p != '-') 1032 return (NULL); 1033 ent->fe_arg = strtol(p, &p, 0); 1034 if (*p++ != ')') 1035 return (NULL); 1036 1037 /* [ "[pid " <integer> "]" ] */ 1038 #define PID_STRING "[pid " 1039 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0) 1040 return (p); 1041 p += sizeof(PID_STRING) - 1; 1042 if (!isdigit(*p)) 1043 return (NULL); 1044 ent->fe_pid = strtol(p, &p, 0); 1045 if (*p++ != ']') 1046 return (NULL); 1047 1048 return (p); 1049 } 1050 1051 /** 1052 * Internal helper function to parse a numeric for a failpoint term. 1053 */ 1054 static char * 1055 parse_number(int *out_units, int *out_decimal, char *p) 1056 { 1057 char *old_p; 1058 1059 /** 1060 * <number> :: 1061 * <integer> [ "." <integer> ] | 1062 * "." <integer> 1063 */ 1064 1065 /* whole part */ 1066 old_p = p; 1067 *out_units = strtol(p, &p, 10); 1068 if (p == old_p && *p != '.') 1069 return (NULL); 1070 1071 /* fractional part */ 1072 *out_decimal = 0; 1073 if (*p == '.') { 1074 int digits = 0; 1075 p++; 1076 while (isdigit(*p)) { 1077 int digit = *p - ''; 1078 if (digits < PROB_DIGITS - 2) 1079 *out_decimal = *out_decimal * 10 + digit; 1080 else if (digits == PROB_DIGITS - 2 && digit >= 5) 1081 (*out_decimal)++; 1082 digits++; 1083 p++; 1084 } 1085 if (!digits) /* need at least one digit after '.' */ 1086 return (NULL); 1087 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */ 1088 *out_decimal *= 10; 1089 } 1090 1091 return (p); /* success */ 1092 } 1093 1094 /** 1095 * Internal helper function to parse an individual type for a failpoint term. 1096 */ 1097 static char * 1098 parse_type(struct fail_point_entry *ent, char *beg) 1099 { 1100 enum fail_point_t type; 1101 int len; 1102 1103 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) { 1104 len = fail_type_strings[type].nmlen; 1105 if (strncmp(fail_type_strings[type].name, beg, len) == 0) { 1106 ent->fe_type = type; 1107 return (beg + len); 1108 } 1109 } 1110 return (NULL); 1111 } 1112 1113 /* The fail point sysctl tree. */ 1114 SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW, 0, "fail points"); 1115 1116 /* Debugging/testing stuff for fail point */ 1117 static int 1118 sysctl_test_fail_point(SYSCTL_HANDLER_ARGS) 1119 { 1120 1121 KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point); 1122 return (0); 1123 } 1124 SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point, 1125 CTLTYPE_STRING | CTLFLAG_RD, NULL, 0, sysctl_test_fail_point, "A", 1126 "Trigger test fail points");
Cache object: e7c7f9983e1a2ae92d18777dfaeb643a
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