1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 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 if (fp->fp_callout) 407 callout_drain(fp->fp_callout); 408 fail_point_swap_settings(fp, entries); 409 } 410 411 static inline void 412 fail_point_pause(struct fail_point *fp, enum fail_point_return_code *pret, 413 struct mtx *mtx_sleep) 414 { 415 416 if (fp->fp_pre_sleep_fn) 417 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 418 419 msleep_spin(FP_PAUSE_CHANNEL(fp), mtx_sleep, "failpt", 0); 420 421 if (fp->fp_post_sleep_fn) 422 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg); 423 } 424 425 static inline void 426 fail_point_sleep(struct fail_point *fp, int msecs, 427 enum fail_point_return_code *pret) 428 { 429 int timo; 430 431 /* Convert from millisecs to ticks, rounding up */ 432 timo = howmany((int64_t)msecs * hz, 1000L); 433 434 if (timo > 0) { 435 if (!(fp->fp_flags & FAIL_POINT_USE_TIMEOUT_PATH)) { 436 if (fp->fp_pre_sleep_fn) 437 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 438 439 tsleep(FP_SLEEP_CHANNEL(fp), PWAIT, "failpt", timo); 440 441 if (fp->fp_post_sleep_fn) 442 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg); 443 } else { 444 if (fp->fp_pre_sleep_fn) 445 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 446 447 callout_reset(fp->fp_callout, timo, 448 fp->fp_post_sleep_fn, fp->fp_post_sleep_arg); 449 *pret = FAIL_POINT_RC_QUEUED; 450 } 451 } 452 } 453 454 static char *parse_fail_point(struct fail_point_setting *, char *); 455 static char *parse_term(struct fail_point_setting *, char *); 456 static char *parse_number(int *out_units, int *out_decimal, char *); 457 static char *parse_type(struct fail_point_entry *, char *); 458 459 /** 460 * Initialize a fail_point. The name is formed in a printf-like fashion 461 * from "fmt" and subsequent arguments. This function is generally used 462 * for custom failpoints located at odd places in the sysctl tree, and is 463 * not explicitly needed for standard in-line-declared failpoints. 464 * 465 * @ingroup failpoint 466 */ 467 void 468 fail_point_init(struct fail_point *fp, const char *fmt, ...) 469 { 470 va_list ap; 471 char *name; 472 int n; 473 474 fp->fp_setting = NULL; 475 fp->fp_flags = 0; 476 477 /* Figure out the size of the name. */ 478 va_start(ap, fmt); 479 n = vsnprintf(NULL, 0, fmt, ap); 480 va_end(ap); 481 482 /* Allocate the name and fill it in. */ 483 name = fp_malloc(n + 1, M_WAITOK); 484 if (name != NULL) { 485 va_start(ap, fmt); 486 vsnprintf(name, n + 1, fmt, ap); 487 va_end(ap); 488 } 489 fp->fp_name = name; 490 fp->fp_location = ""; 491 fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME; 492 fp->fp_pre_sleep_fn = NULL; 493 fp->fp_pre_sleep_arg = NULL; 494 fp->fp_post_sleep_fn = NULL; 495 fp->fp_post_sleep_arg = NULL; 496 } 497 498 void 499 fail_point_alloc_callout(struct fail_point *fp) 500 { 501 502 /** 503 * This assumes that calls to fail_point_use_timeout_path() 504 * will not race. 505 */ 506 if (fp->fp_callout != NULL) 507 return; 508 fp->fp_callout = fp_malloc(sizeof(*fp->fp_callout), M_WAITOK); 509 callout_init(fp->fp_callout, CALLOUT_MPSAFE); 510 } 511 512 /** 513 * Free the resources held by a fail_point, and wake any paused threads. 514 * Thou shalt not allow threads to hit this fail point after you enter this 515 * function, nor shall you call this multiple times for a given fp. 516 * @ingroup failpoint 517 */ 518 void 519 fail_point_destroy(struct fail_point *fp) 520 { 521 522 fail_point_drain(fp, 0); 523 524 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) { 525 fp_free(__DECONST(void *, fp->fp_name)); 526 fp->fp_name = NULL; 527 } 528 fp->fp_flags = 0; 529 if (fp->fp_callout) { 530 fp_free(fp->fp_callout); 531 fp->fp_callout = NULL; 532 } 533 534 sx_xlock(&sx_fp_set); 535 fail_point_garbage_collect(); 536 sx_xunlock(&sx_fp_set); 537 } 538 539 /** 540 * This does the real work of evaluating a fail point. If the fail point tells 541 * us to return a value, this function returns 1 and fills in 'return_value' 542 * (return_value is allowed to be null). If the fail point tells us to panic, 543 * we never return. Otherwise we just return 0 after doing some work, which 544 * means "keep going". 545 */ 546 enum fail_point_return_code 547 fail_point_eval_nontrivial(struct fail_point *fp, int *return_value) 548 { 549 bool execute = false; 550 struct fail_point_entry *ent; 551 struct fail_point_setting *fp_setting; 552 enum fail_point_return_code ret; 553 int cont; 554 int count; 555 int msecs; 556 int usecs; 557 558 ret = FAIL_POINT_RC_CONTINUE; 559 cont = 0; /* don't continue by default */ 560 561 fp_setting = fail_point_setting_get_ref(fp); 562 if (fp_setting == NULL) 563 goto abort; 564 565 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 566 if (ent->fe_stale) 567 continue; 568 569 if (ent->fe_prob < PROB_MAX && 570 ent->fe_prob < random() % PROB_MAX) 571 continue; 572 573 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid) 574 continue; 575 576 if (ent->fe_count != FE_COUNT_UNTRACKED) { 577 count = ent->fe_count; 578 while (count > 0) { 579 if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) { 580 count--; 581 execute = true; 582 break; 583 } 584 count = ent->fe_count; 585 } 586 if (execute == false) 587 /* We lost the race; consider the entry stale and bail now */ 588 continue; 589 if (count == 0) 590 ent->fe_stale = true; 591 } 592 593 switch (ent->fe_type) { 594 case FAIL_POINT_PANIC: 595 panic("fail point %s panicking", fp->fp_name); 596 /* NOTREACHED */ 597 598 case FAIL_POINT_RETURN: 599 if (return_value != NULL) 600 *return_value = ent->fe_arg; 601 ret = FAIL_POINT_RC_RETURN; 602 break; 603 604 case FAIL_POINT_BREAK: 605 printf("fail point %s breaking to debugger\n", 606 fp->fp_name); 607 breakpoint(); 608 break; 609 610 case FAIL_POINT_PRINT: 611 printf("fail point %s executing\n", fp->fp_name); 612 cont = ent->fe_arg; 613 break; 614 615 case FAIL_POINT_SLEEP: 616 msecs = ent->fe_arg; 617 if (msecs) 618 fail_point_sleep(fp, msecs, &ret); 619 break; 620 621 case FAIL_POINT_PAUSE: 622 /** 623 * Pausing is inherently strange with multiple 624 * entries given our design. That is because some 625 * entries could be unreachable, for instance in cases like: 626 * pause->return. We can never reach the return entry. 627 * The sysctl layer actually truncates all entries after 628 * a pause for this reason. 629 */ 630 mtx_lock_spin(&fp_setting->feq_mtx); 631 fail_point_pause(fp, &ret, &fp_setting->feq_mtx); 632 mtx_unlock_spin(&fp_setting->feq_mtx); 633 break; 634 635 case FAIL_POINT_YIELD: 636 kern_yield(PRI_UNCHANGED); 637 break; 638 639 case FAIL_POINT_DELAY: 640 usecs = ent->fe_arg; 641 DELAY(usecs); 642 break; 643 644 default: 645 break; 646 } 647 648 if (cont == 0) 649 break; 650 } 651 652 if (fail_point_is_off(fp)) 653 fail_point_eval_swap_out(fp, fp_setting); 654 655 abort: 656 fail_point_setting_release_ref(fp); 657 658 return (ret); 659 } 660 661 /** 662 * Translate internal fail_point structure into human-readable text. 663 */ 664 static void 665 fail_point_get(struct fail_point *fp, struct sbuf *sb, 666 bool verbose) 667 { 668 struct fail_point_entry *ent; 669 struct fail_point_setting *fp_setting; 670 struct fail_point_entry *fp_entry_cpy; 671 int cnt_sleeping; 672 int idx; 673 int printed_entry_count; 674 675 cnt_sleeping = 0; 676 idx = 0; 677 printed_entry_count = 0; 678 679 fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) * 680 (FP_MAX_ENTRY_COUNT + 1), M_WAITOK); 681 682 fp_setting = fail_point_setting_get_ref(fp); 683 684 if (fp_setting != NULL) { 685 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 686 if (ent->fe_stale) 687 continue; 688 689 KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT, 690 ("FP entry list larger than allowed")); 691 692 fp_entry_cpy[printed_entry_count] = *ent; 693 ++printed_entry_count; 694 } 695 } 696 fail_point_setting_release_ref(fp); 697 698 /* This is our equivalent of a NULL terminator */ 699 fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID; 700 701 while (idx < printed_entry_count) { 702 ent = &fp_entry_cpy[idx]; 703 ++idx; 704 if (ent->fe_prob < PROB_MAX) { 705 int decimal = ent->fe_prob % (PROB_MAX / 100); 706 int units = ent->fe_prob / (PROB_MAX / 100); 707 sbuf_printf(sb, "%d", units); 708 if (decimal) { 709 int digits = PROB_DIGITS - 2; 710 while (!(decimal % 10)) { 711 digits--; 712 decimal /= 10; 713 } 714 sbuf_printf(sb, ".%0*d", digits, decimal); 715 } 716 sbuf_printf(sb, "%%"); 717 } 718 if (ent->fe_count >= 0) 719 sbuf_printf(sb, "%d*", ent->fe_count); 720 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name); 721 if (ent->fe_arg) 722 sbuf_printf(sb, "(%d)", ent->fe_arg); 723 if (ent->fe_pid != NO_PID) 724 sbuf_printf(sb, "[pid %d]", ent->fe_pid); 725 if (TAILQ_NEXT(ent, fe_entries)) 726 sbuf_printf(sb, "->"); 727 } 728 if (!printed_entry_count) 729 sbuf_printf(sb, "off"); 730 731 fp_free(fp_entry_cpy); 732 if (verbose) { 733 #ifdef STACK 734 /* Print number of sleeping threads. queue=0 is the argument 735 * used by msleep when sending our threads to sleep. */ 736 sbuf_printf(sb, "\nsleeping_thread_stacks = {\n"); 737 sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0, 738 &cnt_sleeping); 739 740 sbuf_printf(sb, "},\n"); 741 #endif 742 sbuf_printf(sb, "sleeping_thread_count = %d,\n", 743 cnt_sleeping); 744 745 #ifdef STACK 746 sbuf_printf(sb, "paused_thread_stacks = {\n"); 747 sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0, 748 &cnt_sleeping); 749 750 sbuf_printf(sb, "},\n"); 751 #endif 752 sbuf_printf(sb, "paused_thread_count = %d\n", 753 cnt_sleeping); 754 } 755 } 756 757 /** 758 * Set an internal fail_point structure from a human-readable failpoint string 759 * in a lock-safe manner. 760 */ 761 static int 762 fail_point_set(struct fail_point *fp, char *buf) 763 { 764 struct fail_point_entry *ent, *ent_next; 765 struct fail_point_setting *entries; 766 bool should_wake_paused; 767 bool should_truncate; 768 int error; 769 770 error = 0; 771 should_wake_paused = false; 772 should_truncate = false; 773 774 /* Parse new entries. */ 775 /** 776 * ref protects our new malloc'd stuff from being garbage collected 777 * before we link it. 778 */ 779 fail_point_setting_get_ref(fp); 780 entries = fail_point_setting_new(fp); 781 if (parse_fail_point(entries, buf) == NULL) { 782 STAILQ_REMOVE(&fp_setting_garbage, entries, 783 fail_point_setting, fs_garbage_link); 784 fail_point_setting_destroy(entries); 785 error = EINVAL; 786 goto end; 787 } 788 789 /** 790 * Transfer the entries we are going to keep to a new list. 791 * Get rid of useless zero probability entries, and entries with hit 792 * count 0. 793 * If 'off' is present, and it has no hit count set, then all entries 794 * after it are discarded since they are unreachable. 795 */ 796 TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) { 797 if (ent->fe_prob == 0 || ent->fe_count == 0) { 798 printf("Discarding entry which cannot execute %s\n", 799 fail_type_strings[ent->fe_type].name); 800 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 801 fe_entries); 802 fp_free(ent); 803 continue; 804 } else if (should_truncate) { 805 printf("Discarding unreachable entry %s\n", 806 fail_type_strings[ent->fe_type].name); 807 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 808 fe_entries); 809 fp_free(ent); 810 continue; 811 } 812 813 if (ent->fe_type == FAIL_POINT_OFF) { 814 should_wake_paused = true; 815 if (ent->fe_count == FE_COUNT_UNTRACKED) { 816 should_truncate = true; 817 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 818 fe_entries); 819 fp_free(ent); 820 } 821 } else if (ent->fe_type == FAIL_POINT_PAUSE) { 822 should_truncate = true; 823 } else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags & 824 FAIL_POINT_NONSLEEPABLE)) { 825 /** 826 * If this fail point is annotated as being in a 827 * non-sleepable ctx, convert sleep to delay and 828 * convert the msec argument to usecs. 829 */ 830 printf("Sleep call request on fail point in " 831 "non-sleepable context; using delay instead " 832 "of sleep\n"); 833 ent->fe_type = FAIL_POINT_DELAY; 834 ent->fe_arg *= 1000; 835 } 836 } 837 838 if (TAILQ_EMPTY(&entries->fp_entry_queue)) { 839 entries = fail_point_swap_settings(fp, NULL); 840 if (entries != NULL) 841 wakeup(FP_PAUSE_CHANNEL(fp)); 842 } else { 843 if (should_wake_paused) 844 wakeup(FP_PAUSE_CHANNEL(fp)); 845 fail_point_swap_settings(fp, entries); 846 } 847 848 end: 849 #ifdef IWARNING 850 if (error) 851 IWARNING("Failed to set %s %s to %s", 852 fp->fp_name, fp->fp_location, buf); 853 else 854 INOTICE("Set %s %s to %s", 855 fp->fp_name, fp->fp_location, buf); 856 #endif /* IWARNING */ 857 858 fail_point_setting_release_ref(fp); 859 return (error); 860 } 861 862 #define MAX_FAIL_POINT_BUF 1023 863 864 /** 865 * Handle kernel failpoint set/get. 866 */ 867 int 868 fail_point_sysctl(SYSCTL_HANDLER_ARGS) 869 { 870 struct fail_point *fp; 871 char *buf; 872 struct sbuf sb, *sb_check; 873 int error; 874 875 buf = NULL; 876 error = 0; 877 fp = arg1; 878 879 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 880 if (sb_check != &sb) 881 return (ENOMEM); 882 883 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 884 885 /* Setting */ 886 /** 887 * Lock protects any new entries from being garbage collected before we 888 * can link them to the fail point. 889 */ 890 sx_xlock(&sx_fp_set); 891 if (req->newptr) { 892 if (req->newlen > MAX_FAIL_POINT_BUF) { 893 error = EINVAL; 894 goto out; 895 } 896 897 buf = fp_malloc(req->newlen + 1, M_WAITOK); 898 899 error = SYSCTL_IN(req, buf, req->newlen); 900 if (error) 901 goto out; 902 buf[req->newlen] = '\0'; 903 904 error = fail_point_set(fp, buf); 905 } 906 907 fail_point_garbage_collect(); 908 sx_xunlock(&sx_fp_set); 909 910 /* Retrieving. */ 911 fail_point_get(fp, &sb, false); 912 913 out: 914 sbuf_finish(&sb); 915 sbuf_delete(&sb); 916 917 if (buf) 918 fp_free(buf); 919 920 return (error); 921 } 922 923 int 924 fail_point_sysctl_status(SYSCTL_HANDLER_ARGS) 925 { 926 struct fail_point *fp; 927 struct sbuf sb, *sb_check; 928 929 fp = arg1; 930 931 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 932 if (sb_check != &sb) 933 return (ENOMEM); 934 935 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 936 937 /* Retrieving. */ 938 fail_point_get(fp, &sb, true); 939 940 sbuf_finish(&sb); 941 sbuf_delete(&sb); 942 943 /** 944 * Lock protects any new entries from being garbage collected before we 945 * can link them to the fail point. 946 */ 947 sx_xlock(&sx_fp_set); 948 fail_point_garbage_collect(); 949 sx_xunlock(&sx_fp_set); 950 951 return (0); 952 } 953 954 int 955 fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len) 956 { 957 struct sysctl_req *sa; 958 int error; 959 960 sa = sysctl_args; 961 962 error = SYSCTL_OUT(sa, buf, len); 963 964 if (error == ENOMEM) 965 return (-1); 966 else 967 return (len); 968 } 969 970 /** 971 * Internal helper function to translate a human-readable failpoint string 972 * into a internally-parsable fail_point structure. 973 */ 974 static char * 975 parse_fail_point(struct fail_point_setting *ents, char *p) 976 { 977 /* <fail_point> :: 978 * <term> ( "->" <term> )* 979 */ 980 uint8_t term_count; 981 982 term_count = 1; 983 984 p = parse_term(ents, p); 985 if (p == NULL) 986 return (NULL); 987 988 while (*p != '\0') { 989 term_count++; 990 if (p[0] != '-' || p[1] != '>' || 991 (p = parse_term(ents, p+2)) == NULL || 992 term_count > FP_MAX_ENTRY_COUNT) 993 return (NULL); 994 } 995 return (p); 996 } 997 998 /** 999 * Internal helper function to parse an individual term from a failpoint. 1000 */ 1001 static char * 1002 parse_term(struct fail_point_setting *ents, char *p) 1003 { 1004 struct fail_point_entry *ent; 1005 1006 ent = fail_point_entry_new(ents); 1007 1008 /* 1009 * <term> :: 1010 * ( (<float> "%") | (<integer> "*" ) )* 1011 * <type> 1012 * [ "(" <integer> ")" ] 1013 * [ "[pid " <integer> "]" ] 1014 */ 1015 1016 /* ( (<float> "%") | (<integer> "*" ) )* */ 1017 while (isdigit(*p) || *p == '.') { 1018 int units, decimal; 1019 1020 p = parse_number(&units, &decimal, p); 1021 if (p == NULL) 1022 return (NULL); 1023 1024 if (*p == '%') { 1025 if (units > 100) /* prevent overflow early */ 1026 units = 100; 1027 ent->fe_prob = units * (PROB_MAX / 100) + decimal; 1028 if (ent->fe_prob > PROB_MAX) 1029 ent->fe_prob = PROB_MAX; 1030 } else if (*p == '*') { 1031 if (!units || units < 0 || decimal) 1032 return (NULL); 1033 ent->fe_count = units; 1034 } else 1035 return (NULL); 1036 p++; 1037 } 1038 1039 /* <type> */ 1040 p = parse_type(ent, p); 1041 if (p == NULL) 1042 return (NULL); 1043 if (*p == '\0') 1044 return (p); 1045 1046 /* [ "(" <integer> ")" ] */ 1047 if (*p != '(') 1048 return (p); 1049 p++; 1050 if (!isdigit(*p) && *p != '-') 1051 return (NULL); 1052 ent->fe_arg = strtol(p, &p, 0); 1053 if (*p++ != ')') 1054 return (NULL); 1055 1056 /* [ "[pid " <integer> "]" ] */ 1057 #define PID_STRING "[pid " 1058 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0) 1059 return (p); 1060 p += sizeof(PID_STRING) - 1; 1061 if (!isdigit(*p)) 1062 return (NULL); 1063 ent->fe_pid = strtol(p, &p, 0); 1064 if (*p++ != ']') 1065 return (NULL); 1066 1067 return (p); 1068 } 1069 1070 /** 1071 * Internal helper function to parse a numeric for a failpoint term. 1072 */ 1073 static char * 1074 parse_number(int *out_units, int *out_decimal, char *p) 1075 { 1076 char *old_p; 1077 1078 /** 1079 * <number> :: 1080 * <integer> [ "." <integer> ] | 1081 * "." <integer> 1082 */ 1083 1084 /* whole part */ 1085 old_p = p; 1086 *out_units = strtol(p, &p, 10); 1087 if (p == old_p && *p != '.') 1088 return (NULL); 1089 1090 /* fractional part */ 1091 *out_decimal = 0; 1092 if (*p == '.') { 1093 int digits = 0; 1094 p++; 1095 while (isdigit(*p)) { 1096 int digit = *p - '0'; 1097 if (digits < PROB_DIGITS - 2) 1098 *out_decimal = *out_decimal * 10 + digit; 1099 else if (digits == PROB_DIGITS - 2 && digit >= 5) 1100 (*out_decimal)++; 1101 digits++; 1102 p++; 1103 } 1104 if (!digits) /* need at least one digit after '.' */ 1105 return (NULL); 1106 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */ 1107 *out_decimal *= 10; 1108 } 1109 1110 return (p); /* success */ 1111 } 1112 1113 /** 1114 * Internal helper function to parse an individual type for a failpoint term. 1115 */ 1116 static char * 1117 parse_type(struct fail_point_entry *ent, char *beg) 1118 { 1119 enum fail_point_t type; 1120 int len; 1121 1122 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) { 1123 len = fail_type_strings[type].nmlen; 1124 if (strncmp(fail_type_strings[type].name, beg, len) == 0) { 1125 ent->fe_type = type; 1126 return (beg + len); 1127 } 1128 } 1129 return (NULL); 1130 } 1131 1132 /* The fail point sysctl tree. */ 1133 SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 1134 "fail points"); 1135 1136 /* Debugging/testing stuff for fail point */ 1137 static int 1138 sysctl_test_fail_point(SYSCTL_HANDLER_ARGS) 1139 { 1140 1141 KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point); 1142 return (0); 1143 } 1144 SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point, 1145 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT, NULL, 0, 1146 sysctl_test_fail_point, "A", 1147 "Trigger test fail points"); 1148