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 #include "opt_stack.h" 56 57 #include <sys/ctype.h> 58 #include <sys/errno.h> 59 #include <sys/fail.h> 60 #include <sys/kernel.h> 61 #include <sys/libkern.h> 62 #include <sys/limits.h> 63 #include <sys/lock.h> 64 #include <sys/malloc.h> 65 #include <sys/mutex.h> 66 #include <sys/proc.h> 67 #include <sys/sbuf.h> 68 #include <sys/sleepqueue.h> 69 #include <sys/sx.h> 70 #include <sys/sysctl.h> 71 #include <sys/types.h> 72 73 #include <machine/atomic.h> 74 #include <machine/stdarg.h> 75 76 #ifdef ILOG_DEFINE_FOR_FILE 77 ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point); 78 #endif 79 80 static MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system"); 81 #define fp_free(ptr) free(ptr, M_FAIL_POINT) 82 #define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags)) 83 #define fs_free(ptr) fp_free(ptr) 84 #define fs_malloc() fp_malloc(sizeof(struct fail_point_setting), \ 85 M_WAITOK | M_ZERO) 86 87 /** 88 * These define the wchans that are used for sleeping, pausing respectively. 89 * They are chosen arbitrarily but need to be distinct to the failpoint and 90 * the sleep/pause distinction. 91 */ 92 #define FP_SLEEP_CHANNEL(fp) (void*)(fp) 93 #define FP_PAUSE_CHANNEL(fp) __DEVOLATILE(void*, &fp->fp_setting) 94 95 /** 96 * Don't allow more than this many entries in a fail point set by sysctl. 97 * The 99.99...% case is to have 1 entry. I can't imagine having this many 98 * entries, so it should not limit us. Saves on re-mallocs while holding 99 * a non-sleepable lock. 100 */ 101 #define FP_MAX_ENTRY_COUNT 20 102 103 /* Used to drain sbufs to the sysctl output */ 104 int fail_sysctl_drain_func(void *, const char *, int); 105 106 /* Head of tailq of struct fail_point_entry */ 107 TAILQ_HEAD(fail_point_entry_queue, fail_point_entry); 108 109 /** 110 * fp entries garbage list; outstanding entries are cleaned up in the 111 * garbage collector 112 */ 113 STAILQ_HEAD(fail_point_setting_garbage, fail_point_setting); 114 static struct fail_point_setting_garbage fp_setting_garbage = 115 STAILQ_HEAD_INITIALIZER(fp_setting_garbage); 116 static struct mtx mtx_garbage_list; 117 MTX_SYSINIT(mtx_garbage_list, &mtx_garbage_list, "fail point garbage mtx", 118 MTX_SPIN); 119 120 static struct sx sx_fp_set; 121 SX_SYSINIT(sx_fp_set, &sx_fp_set, "fail point set sx"); 122 123 /** 124 * Failpoint types. 125 * Don't change these without changing fail_type_strings in fail.c. 126 * @ingroup failpoint_private 127 */ 128 enum fail_point_t { 129 FAIL_POINT_OFF, /**< don't fail */ 130 FAIL_POINT_PANIC, /**< panic */ 131 FAIL_POINT_RETURN, /**< return an errorcode */ 132 FAIL_POINT_BREAK, /**< break into the debugger */ 133 FAIL_POINT_PRINT, /**< print a message */ 134 FAIL_POINT_SLEEP, /**< sleep for some msecs */ 135 FAIL_POINT_PAUSE, /**< sleep until failpoint is set to off */ 136 FAIL_POINT_YIELD, /**< yield the cpu */ 137 FAIL_POINT_DELAY, /**< busy wait the cpu */ 138 FAIL_POINT_NUMTYPES, 139 FAIL_POINT_INVALID = -1 140 }; 141 142 static struct { 143 const char *name; 144 int nmlen; 145 } fail_type_strings[] = { 146 #define FP_TYPE_NM_LEN(s) { s, sizeof(s) - 1 } 147 [FAIL_POINT_OFF] = FP_TYPE_NM_LEN("off"), 148 [FAIL_POINT_PANIC] = FP_TYPE_NM_LEN("panic"), 149 [FAIL_POINT_RETURN] = FP_TYPE_NM_LEN("return"), 150 [FAIL_POINT_BREAK] = FP_TYPE_NM_LEN("break"), 151 [FAIL_POINT_PRINT] = FP_TYPE_NM_LEN("print"), 152 [FAIL_POINT_SLEEP] = FP_TYPE_NM_LEN("sleep"), 153 [FAIL_POINT_PAUSE] = FP_TYPE_NM_LEN("pause"), 154 [FAIL_POINT_YIELD] = FP_TYPE_NM_LEN("yield"), 155 [FAIL_POINT_DELAY] = FP_TYPE_NM_LEN("delay"), 156 }; 157 158 #define FE_COUNT_UNTRACKED (INT_MIN) 159 160 /** 161 * Internal structure tracking a single term of a complete failpoint. 162 * @ingroup failpoint_private 163 */ 164 struct fail_point_entry { 165 volatile bool fe_stale; 166 enum fail_point_t fe_type; /**< type of entry */ 167 int fe_arg; /**< argument to type (e.g. return value) */ 168 int fe_prob; /**< likelihood of firing in millionths */ 169 int32_t fe_count; /**< number of times to fire, -1 means infinite */ 170 pid_t fe_pid; /**< only fail for this process */ 171 struct fail_point *fe_parent; /**< backpointer to fp */ 172 TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry ptr */ 173 }; 174 175 struct fail_point_setting { 176 STAILQ_ENTRY(fail_point_setting) fs_garbage_link; 177 struct fail_point_entry_queue fp_entry_queue; 178 struct fail_point * fs_parent; 179 struct mtx feq_mtx; /* Gives fail_point_pause something to do. */ 180 }; 181 182 /** 183 * Defines stating the equivalent of probablilty one (100%) 184 */ 185 enum { 186 PROB_MAX = 1000000, /* probability between zero and this number */ 187 PROB_DIGITS = 6 /* number of zero's in above number */ 188 }; 189 190 /* Get a ref on an fp's fp_setting */ 191 static inline struct fail_point_setting *fail_point_setting_get_ref( 192 struct fail_point *fp); 193 /* Release a ref on an fp_setting */ 194 static inline void fail_point_setting_release_ref(struct fail_point *fp); 195 /* Allocate and initialize a struct fail_point_setting */ 196 static struct fail_point_setting *fail_point_setting_new(struct 197 fail_point *); 198 /* Free a struct fail_point_setting */ 199 static void fail_point_setting_destroy(struct fail_point_setting *fp_setting); 200 /* Allocate and initialize a struct fail_point_entry */ 201 static struct fail_point_entry *fail_point_entry_new(struct 202 fail_point_setting *); 203 /* Free a struct fail_point_entry */ 204 static void fail_point_entry_destroy(struct fail_point_entry *fp_entry); 205 /* Append fp setting to garbage list */ 206 static inline void fail_point_setting_garbage_append( 207 struct fail_point_setting *fp_setting); 208 /* Swap fp's setting with fp_setting_new */ 209 static inline struct fail_point_setting * 210 fail_point_swap_settings(struct fail_point *fp, 211 struct fail_point_setting *fp_setting_new); 212 /* Free up any zero-ref setting in the garbage queue */ 213 static void fail_point_garbage_collect(void); 214 /* If this fail point's setting are empty, then swap it out to NULL. */ 215 static inline void fail_point_eval_swap_out(struct fail_point *fp, 216 struct fail_point_setting *fp_setting); 217 218 bool 219 fail_point_is_off(struct fail_point *fp) 220 { 221 bool return_val; 222 struct fail_point_setting *fp_setting; 223 struct fail_point_entry *ent; 224 225 return_val = true; 226 227 fp_setting = fail_point_setting_get_ref(fp); 228 if (fp_setting != NULL) { 229 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, 230 fe_entries) { 231 if (!ent->fe_stale) { 232 return_val = false; 233 break; 234 } 235 } 236 } 237 fail_point_setting_release_ref(fp); 238 239 return (return_val); 240 } 241 242 /* Allocate and initialize a struct fail_point_setting */ 243 static struct fail_point_setting * 244 fail_point_setting_new(struct fail_point *fp) 245 { 246 struct fail_point_setting *fs_new; 247 248 fs_new = fs_malloc(); 249 fs_new->fs_parent = fp; 250 TAILQ_INIT(&fs_new->fp_entry_queue); 251 mtx_init(&fs_new->feq_mtx, "fail point entries", NULL, MTX_SPIN); 252 253 fail_point_setting_garbage_append(fs_new); 254 255 return (fs_new); 256 } 257 258 /* Free a struct fail_point_setting */ 259 static void 260 fail_point_setting_destroy(struct fail_point_setting *fp_setting) 261 { 262 struct fail_point_entry *ent; 263 264 while (!TAILQ_EMPTY(&fp_setting->fp_entry_queue)) { 265 ent = TAILQ_FIRST(&fp_setting->fp_entry_queue); 266 TAILQ_REMOVE(&fp_setting->fp_entry_queue, ent, fe_entries); 267 fail_point_entry_destroy(ent); 268 } 269 270 fs_free(fp_setting); 271 } 272 273 /* Allocate and initialize a struct fail_point_entry */ 274 static struct fail_point_entry * 275 fail_point_entry_new(struct fail_point_setting *fp_setting) 276 { 277 struct fail_point_entry *fp_entry; 278 279 fp_entry = fp_malloc(sizeof(struct fail_point_entry), 280 M_WAITOK | M_ZERO); 281 fp_entry->fe_parent = fp_setting->fs_parent; 282 fp_entry->fe_prob = PROB_MAX; 283 fp_entry->fe_pid = NO_PID; 284 fp_entry->fe_count = FE_COUNT_UNTRACKED; 285 TAILQ_INSERT_TAIL(&fp_setting->fp_entry_queue, fp_entry, 286 fe_entries); 287 288 return (fp_entry); 289 } 290 291 /* Free a struct fail_point_entry */ 292 static void 293 fail_point_entry_destroy(struct fail_point_entry *fp_entry) 294 { 295 296 fp_free(fp_entry); 297 } 298 299 /* Get a ref on an fp's fp_setting */ 300 static inline struct fail_point_setting * 301 fail_point_setting_get_ref(struct fail_point *fp) 302 { 303 struct fail_point_setting *fp_setting; 304 305 /* Invariant: if we have a ref, our pointer to fp_setting is safe */ 306 atomic_add_acq_32(&fp->fp_ref_cnt, 1); 307 fp_setting = fp->fp_setting; 308 309 return (fp_setting); 310 } 311 312 /* Release a ref on an fp_setting */ 313 static inline void 314 fail_point_setting_release_ref(struct fail_point *fp) 315 { 316 317 KASSERT(&fp->fp_ref_cnt > 0, ("Attempting to deref w/no refs")); 318 atomic_subtract_rel_32(&fp->fp_ref_cnt, 1); 319 } 320 321 /* Append fp entries to fp garbage list */ 322 static inline void 323 fail_point_setting_garbage_append(struct fail_point_setting *fp_setting) 324 { 325 326 mtx_lock_spin(&mtx_garbage_list); 327 STAILQ_INSERT_TAIL(&fp_setting_garbage, fp_setting, 328 fs_garbage_link); 329 mtx_unlock_spin(&mtx_garbage_list); 330 } 331 332 /* Swap fp's entries with fp_setting_new */ 333 static struct fail_point_setting * 334 fail_point_swap_settings(struct fail_point *fp, 335 struct fail_point_setting *fp_setting_new) 336 { 337 struct fail_point_setting *fp_setting_old; 338 339 fp_setting_old = fp->fp_setting; 340 fp->fp_setting = fp_setting_new; 341 342 return (fp_setting_old); 343 } 344 345 static inline void 346 fail_point_eval_swap_out(struct fail_point *fp, 347 struct fail_point_setting *fp_setting) 348 { 349 350 /* We may have already been swapped out and replaced; ignore. */ 351 if (fp->fp_setting == fp_setting) 352 fail_point_swap_settings(fp, NULL); 353 } 354 355 /* Free up any zero-ref entries in the garbage queue */ 356 static void 357 fail_point_garbage_collect(void) 358 { 359 struct fail_point_setting *fs_current, *fs_next; 360 struct fail_point_setting_garbage fp_ents_free_list; 361 362 /** 363 * We will transfer the entries to free to fp_ents_free_list while holding 364 * the spin mutex, then free it after we drop the lock. This avoids 365 * triggering witness due to sleepable mutexes in the memory 366 * allocator. 367 */ 368 STAILQ_INIT(&fp_ents_free_list); 369 370 mtx_lock_spin(&mtx_garbage_list); 371 STAILQ_FOREACH_SAFE(fs_current, &fp_setting_garbage, fs_garbage_link, 372 fs_next) { 373 if (fs_current->fs_parent->fp_setting != fs_current && 374 fs_current->fs_parent->fp_ref_cnt == 0) { 375 STAILQ_REMOVE(&fp_setting_garbage, fs_current, 376 fail_point_setting, fs_garbage_link); 377 STAILQ_INSERT_HEAD(&fp_ents_free_list, fs_current, 378 fs_garbage_link); 379 } 380 } 381 mtx_unlock_spin(&mtx_garbage_list); 382 383 STAILQ_FOREACH_SAFE(fs_current, &fp_ents_free_list, fs_garbage_link, 384 fs_next) 385 fail_point_setting_destroy(fs_current); 386 } 387 388 /* Drain out all refs from this fail point */ 389 static inline void 390 fail_point_drain(struct fail_point *fp, int expected_ref) 391 { 392 struct fail_point_setting *entries; 393 394 entries = fail_point_swap_settings(fp, NULL); 395 /** 396 * We have unpaused all threads; so we will wait no longer 397 * than the time taken for the longest remaining sleep, or 398 * the length of time of a long-running code block. 399 */ 400 while (fp->fp_ref_cnt > expected_ref) { 401 wakeup(FP_PAUSE_CHANNEL(fp)); 402 tsleep(&fp, PWAIT, "fail_point_drain", hz / 100); 403 } 404 if (fp->fp_callout) 405 callout_drain(fp->fp_callout); 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 callout_reset(fp->fp_callout, timo, 446 fp->fp_post_sleep_fn, fp->fp_post_sleep_arg); 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 va_start(ap, fmt); 483 vsnprintf(name, n + 1, fmt, ap); 484 va_end(ap); 485 486 fp->fp_name = name; 487 fp->fp_location = ""; 488 fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME; 489 fp->fp_pre_sleep_fn = NULL; 490 fp->fp_pre_sleep_arg = NULL; 491 fp->fp_post_sleep_fn = NULL; 492 fp->fp_post_sleep_arg = NULL; 493 } 494 495 void 496 fail_point_alloc_callout(struct fail_point *fp) 497 { 498 499 /** 500 * This assumes that calls to fail_point_use_timeout_path() 501 * will not race. 502 */ 503 if (fp->fp_callout != NULL) 504 return; 505 fp->fp_callout = fp_malloc(sizeof(*fp->fp_callout), M_WAITOK); 506 callout_init(fp->fp_callout, CALLOUT_MPSAFE); 507 } 508 509 /** 510 * Free the resources held by a fail_point, and wake any paused threads. 511 * Thou shalt not allow threads to hit this fail point after you enter this 512 * function, nor shall you call this multiple times for a given fp. 513 * @ingroup failpoint 514 */ 515 void 516 fail_point_destroy(struct fail_point *fp) 517 { 518 519 fail_point_drain(fp, 0); 520 521 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) { 522 fp_free(__DECONST(void *, fp->fp_name)); 523 fp->fp_name = NULL; 524 } 525 fp->fp_flags = 0; 526 if (fp->fp_callout) { 527 fp_free(fp->fp_callout); 528 fp->fp_callout = NULL; 529 } 530 531 sx_xlock(&sx_fp_set); 532 fail_point_garbage_collect(); 533 sx_xunlock(&sx_fp_set); 534 } 535 536 /** 537 * This does the real work of evaluating a fail point. If the fail point tells 538 * us to return a value, this function returns 1 and fills in 'return_value' 539 * (return_value is allowed to be null). If the fail point tells us to panic, 540 * we never return. Otherwise we just return 0 after doing some work, which 541 * means "keep going". 542 */ 543 enum fail_point_return_code 544 fail_point_eval_nontrivial(struct fail_point *fp, int *return_value) 545 { 546 bool execute = false; 547 struct fail_point_entry *ent; 548 struct fail_point_setting *fp_setting; 549 enum fail_point_return_code ret; 550 int cont; 551 int count; 552 int msecs; 553 int usecs; 554 555 ret = FAIL_POINT_RC_CONTINUE; 556 cont = 0; /* don't continue by default */ 557 558 fp_setting = fail_point_setting_get_ref(fp); 559 if (fp_setting == NULL) 560 goto abort; 561 562 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 563 if (ent->fe_stale) 564 continue; 565 566 if (ent->fe_prob < PROB_MAX && 567 ent->fe_prob < random() % PROB_MAX) 568 continue; 569 570 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid) 571 continue; 572 573 if (ent->fe_count != FE_COUNT_UNTRACKED) { 574 count = ent->fe_count; 575 while (count > 0) { 576 if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) { 577 count--; 578 execute = true; 579 break; 580 } 581 count = ent->fe_count; 582 } 583 if (execute == false) 584 /* We lost the race; consider the entry stale and bail now */ 585 continue; 586 if (count == 0) 587 ent->fe_stale = true; 588 } 589 590 switch (ent->fe_type) { 591 case FAIL_POINT_PANIC: 592 panic("fail point %s panicking", fp->fp_name); 593 /* NOTREACHED */ 594 595 case FAIL_POINT_RETURN: 596 if (return_value != NULL) 597 *return_value = ent->fe_arg; 598 ret = FAIL_POINT_RC_RETURN; 599 break; 600 601 case FAIL_POINT_BREAK: 602 printf("fail point %s breaking to debugger\n", 603 fp->fp_name); 604 breakpoint(); 605 break; 606 607 case FAIL_POINT_PRINT: 608 printf("fail point %s executing\n", fp->fp_name); 609 cont = ent->fe_arg; 610 break; 611 612 case FAIL_POINT_SLEEP: 613 msecs = ent->fe_arg; 614 if (msecs) 615 fail_point_sleep(fp, msecs, &ret); 616 break; 617 618 case FAIL_POINT_PAUSE: 619 /** 620 * Pausing is inherently strange with multiple 621 * entries given our design. That is because some 622 * entries could be unreachable, for instance in cases like: 623 * pause->return. We can never reach the return entry. 624 * The sysctl layer actually truncates all entries after 625 * a pause for this reason. 626 */ 627 mtx_lock_spin(&fp_setting->feq_mtx); 628 fail_point_pause(fp, &ret, &fp_setting->feq_mtx); 629 mtx_unlock_spin(&fp_setting->feq_mtx); 630 break; 631 632 case FAIL_POINT_YIELD: 633 kern_yield(PRI_UNCHANGED); 634 break; 635 636 case FAIL_POINT_DELAY: 637 usecs = ent->fe_arg; 638 DELAY(usecs); 639 break; 640 641 default: 642 break; 643 } 644 645 if (cont == 0) 646 break; 647 } 648 649 if (fail_point_is_off(fp)) 650 fail_point_eval_swap_out(fp, fp_setting); 651 652 abort: 653 fail_point_setting_release_ref(fp); 654 655 return (ret); 656 } 657 658 /** 659 * Translate internal fail_point structure into human-readable text. 660 */ 661 static void 662 fail_point_get(struct fail_point *fp, struct sbuf *sb, 663 bool verbose) 664 { 665 struct fail_point_entry *ent; 666 struct fail_point_setting *fp_setting; 667 struct fail_point_entry *fp_entry_cpy; 668 int cnt_sleeping; 669 int idx; 670 int printed_entry_count; 671 672 cnt_sleeping = 0; 673 idx = 0; 674 printed_entry_count = 0; 675 676 fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) * 677 (FP_MAX_ENTRY_COUNT + 1), M_WAITOK); 678 679 fp_setting = fail_point_setting_get_ref(fp); 680 681 if (fp_setting != NULL) { 682 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 683 if (ent->fe_stale) 684 continue; 685 686 KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT, 687 ("FP entry list larger than allowed")); 688 689 fp_entry_cpy[printed_entry_count] = *ent; 690 ++printed_entry_count; 691 } 692 } 693 fail_point_setting_release_ref(fp); 694 695 /* This is our equivalent of a NULL terminator */ 696 fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID; 697 698 while (idx < printed_entry_count) { 699 ent = &fp_entry_cpy[idx]; 700 ++idx; 701 if (ent->fe_prob < PROB_MAX) { 702 int decimal = ent->fe_prob % (PROB_MAX / 100); 703 int units = ent->fe_prob / (PROB_MAX / 100); 704 sbuf_printf(sb, "%d", units); 705 if (decimal) { 706 int digits = PROB_DIGITS - 2; 707 while (!(decimal % 10)) { 708 digits--; 709 decimal /= 10; 710 } 711 sbuf_printf(sb, ".%0*d", digits, decimal); 712 } 713 sbuf_printf(sb, "%%"); 714 } 715 if (ent->fe_count >= 0) 716 sbuf_printf(sb, "%d*", ent->fe_count); 717 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name); 718 if (ent->fe_arg) 719 sbuf_printf(sb, "(%d)", ent->fe_arg); 720 if (ent->fe_pid != NO_PID) 721 sbuf_printf(sb, "[pid %d]", ent->fe_pid); 722 if (TAILQ_NEXT(ent, fe_entries)) 723 sbuf_cat(sb, "->"); 724 } 725 if (!printed_entry_count) 726 sbuf_cat(sb, "off"); 727 728 fp_free(fp_entry_cpy); 729 if (verbose) { 730 #ifdef STACK 731 /* Print number of sleeping threads. queue=0 is the argument 732 * used by msleep when sending our threads to sleep. */ 733 sbuf_cat(sb, "\nsleeping_thread_stacks = {\n"); 734 sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0, 735 &cnt_sleeping); 736 737 sbuf_cat(sb, "},\n"); 738 #endif 739 sbuf_printf(sb, "sleeping_thread_count = %d,\n", 740 cnt_sleeping); 741 742 #ifdef STACK 743 sbuf_cat(sb, "paused_thread_stacks = {\n"); 744 sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0, 745 &cnt_sleeping); 746 747 sbuf_cat(sb, "},\n"); 748 #endif 749 sbuf_printf(sb, "paused_thread_count = %d\n", 750 cnt_sleeping); 751 } 752 } 753 754 /** 755 * Set an internal fail_point structure from a human-readable failpoint string 756 * in a lock-safe manner. 757 */ 758 static int 759 fail_point_set(struct fail_point *fp, char *buf) 760 { 761 struct fail_point_entry *ent, *ent_next; 762 struct fail_point_setting *entries; 763 bool should_wake_paused; 764 bool should_truncate; 765 int error; 766 767 error = 0; 768 should_wake_paused = false; 769 should_truncate = false; 770 771 /* Parse new entries. */ 772 /** 773 * ref protects our new malloc'd stuff from being garbage collected 774 * before we link it. 775 */ 776 fail_point_setting_get_ref(fp); 777 entries = fail_point_setting_new(fp); 778 if (parse_fail_point(entries, buf) == NULL) { 779 STAILQ_REMOVE(&fp_setting_garbage, entries, 780 fail_point_setting, fs_garbage_link); 781 fail_point_setting_destroy(entries); 782 error = EINVAL; 783 goto end; 784 } 785 786 /** 787 * Transfer the entries we are going to keep to a new list. 788 * Get rid of useless zero probability entries, and entries with hit 789 * count 0. 790 * If 'off' is present, and it has no hit count set, then all entries 791 * after it are discarded since they are unreachable. 792 */ 793 TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) { 794 if (ent->fe_prob == 0 || ent->fe_count == 0) { 795 printf("Discarding entry which cannot execute %s\n", 796 fail_type_strings[ent->fe_type].name); 797 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 798 fe_entries); 799 fp_free(ent); 800 continue; 801 } else if (should_truncate) { 802 printf("Discarding unreachable entry %s\n", 803 fail_type_strings[ent->fe_type].name); 804 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 805 fe_entries); 806 fp_free(ent); 807 continue; 808 } 809 810 if (ent->fe_type == FAIL_POINT_OFF) { 811 should_wake_paused = true; 812 if (ent->fe_count == FE_COUNT_UNTRACKED) { 813 should_truncate = true; 814 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 815 fe_entries); 816 fp_free(ent); 817 } 818 } else if (ent->fe_type == FAIL_POINT_PAUSE) { 819 should_truncate = true; 820 } else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags & 821 FAIL_POINT_NONSLEEPABLE)) { 822 /** 823 * If this fail point is annotated as being in a 824 * non-sleepable ctx, convert sleep to delay and 825 * convert the msec argument to usecs. 826 */ 827 printf("Sleep call request on fail point in " 828 "non-sleepable context; using delay instead " 829 "of sleep\n"); 830 ent->fe_type = FAIL_POINT_DELAY; 831 ent->fe_arg *= 1000; 832 } 833 } 834 835 if (TAILQ_EMPTY(&entries->fp_entry_queue)) { 836 entries = fail_point_swap_settings(fp, NULL); 837 if (entries != NULL) 838 wakeup(FP_PAUSE_CHANNEL(fp)); 839 } else { 840 if (should_wake_paused) 841 wakeup(FP_PAUSE_CHANNEL(fp)); 842 fail_point_swap_settings(fp, entries); 843 } 844 845 end: 846 #ifdef IWARNING 847 if (error) 848 IWARNING("Failed to set %s %s to %s", 849 fp->fp_name, fp->fp_location, buf); 850 else 851 INOTICE("Set %s %s to %s", 852 fp->fp_name, fp->fp_location, buf); 853 #endif /* IWARNING */ 854 855 fail_point_setting_release_ref(fp); 856 return (error); 857 } 858 859 #define MAX_FAIL_POINT_BUF 1023 860 861 /** 862 * Handle kernel failpoint set/get. 863 */ 864 int 865 fail_point_sysctl(SYSCTL_HANDLER_ARGS) 866 { 867 struct fail_point *fp; 868 char *buf; 869 struct sbuf sb, *sb_check; 870 int error; 871 872 buf = NULL; 873 error = 0; 874 fp = arg1; 875 876 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 877 if (sb_check != &sb) 878 return (ENOMEM); 879 880 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 881 882 /* Setting */ 883 /** 884 * Lock protects any new entries from being garbage collected before we 885 * can link them to the fail point. 886 */ 887 sx_xlock(&sx_fp_set); 888 if (req->newptr) { 889 if (req->newlen > MAX_FAIL_POINT_BUF) { 890 error = EINVAL; 891 goto out; 892 } 893 894 buf = fp_malloc(req->newlen + 1, M_WAITOK); 895 896 error = SYSCTL_IN(req, buf, req->newlen); 897 if (error) 898 goto out; 899 buf[req->newlen] = '\0'; 900 901 error = fail_point_set(fp, buf); 902 } 903 904 fail_point_garbage_collect(); 905 sx_xunlock(&sx_fp_set); 906 907 /* Retrieving. */ 908 fail_point_get(fp, &sb, false); 909 910 out: 911 sbuf_finish(&sb); 912 sbuf_delete(&sb); 913 914 if (buf) 915 fp_free(buf); 916 917 return (error); 918 } 919 920 int 921 fail_point_sysctl_status(SYSCTL_HANDLER_ARGS) 922 { 923 struct fail_point *fp; 924 struct sbuf sb, *sb_check; 925 926 fp = arg1; 927 928 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 929 if (sb_check != &sb) 930 return (ENOMEM); 931 932 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 933 934 /* Retrieving. */ 935 fail_point_get(fp, &sb, true); 936 937 sbuf_finish(&sb); 938 sbuf_delete(&sb); 939 940 /** 941 * Lock protects any new entries from being garbage collected before we 942 * can link them to the fail point. 943 */ 944 sx_xlock(&sx_fp_set); 945 fail_point_garbage_collect(); 946 sx_xunlock(&sx_fp_set); 947 948 return (0); 949 } 950 951 int 952 fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len) 953 { 954 struct sysctl_req *sa; 955 int error; 956 957 sa = sysctl_args; 958 959 error = SYSCTL_OUT(sa, buf, len); 960 961 if (error == ENOMEM) 962 return (-1); 963 else 964 return (len); 965 } 966 967 /** 968 * Internal helper function to translate a human-readable failpoint string 969 * into a internally-parsable fail_point structure. 970 */ 971 static char * 972 parse_fail_point(struct fail_point_setting *ents, char *p) 973 { 974 /* <fail_point> :: 975 * <term> ( "->" <term> )* 976 */ 977 uint8_t term_count; 978 979 term_count = 1; 980 981 p = parse_term(ents, p); 982 if (p == NULL) 983 return (NULL); 984 985 while (*p != '\0') { 986 term_count++; 987 if (p[0] != '-' || p[1] != '>' || 988 (p = parse_term(ents, p+2)) == NULL || 989 term_count > FP_MAX_ENTRY_COUNT) 990 return (NULL); 991 } 992 return (p); 993 } 994 995 /** 996 * Internal helper function to parse an individual term from a failpoint. 997 */ 998 static char * 999 parse_term(struct fail_point_setting *ents, char *p) 1000 { 1001 struct fail_point_entry *ent; 1002 1003 ent = fail_point_entry_new(ents); 1004 1005 /* 1006 * <term> :: 1007 * ( (<float> "%") | (<integer> "*" ) )* 1008 * <type> 1009 * [ "(" <integer> ")" ] 1010 * [ "[pid " <integer> "]" ] 1011 */ 1012 1013 /* ( (<float> "%") | (<integer> "*" ) )* */ 1014 while (isdigit(*p) || *p == '.') { 1015 int units, decimal; 1016 1017 p = parse_number(&units, &decimal, p); 1018 if (p == NULL) 1019 return (NULL); 1020 1021 if (*p == '%') { 1022 if (units > 100) /* prevent overflow early */ 1023 units = 100; 1024 ent->fe_prob = units * (PROB_MAX / 100) + decimal; 1025 if (ent->fe_prob > PROB_MAX) 1026 ent->fe_prob = PROB_MAX; 1027 } else if (*p == '*') { 1028 if (!units || units < 0 || decimal) 1029 return (NULL); 1030 ent->fe_count = units; 1031 } else 1032 return (NULL); 1033 p++; 1034 } 1035 1036 /* <type> */ 1037 p = parse_type(ent, p); 1038 if (p == NULL) 1039 return (NULL); 1040 if (*p == '\0') 1041 return (p); 1042 1043 /* [ "(" <integer> ")" ] */ 1044 if (*p != '(') 1045 return (p); 1046 p++; 1047 if (!isdigit(*p) && *p != '-') 1048 return (NULL); 1049 ent->fe_arg = strtol(p, &p, 0); 1050 if (*p++ != ')') 1051 return (NULL); 1052 1053 /* [ "[pid " <integer> "]" ] */ 1054 #define PID_STRING "[pid " 1055 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0) 1056 return (p); 1057 p += sizeof(PID_STRING) - 1; 1058 if (!isdigit(*p)) 1059 return (NULL); 1060 ent->fe_pid = strtol(p, &p, 0); 1061 if (*p++ != ']') 1062 return (NULL); 1063 1064 return (p); 1065 } 1066 1067 /** 1068 * Internal helper function to parse a numeric for a failpoint term. 1069 */ 1070 static char * 1071 parse_number(int *out_units, int *out_decimal, char *p) 1072 { 1073 char *old_p; 1074 1075 /** 1076 * <number> :: 1077 * <integer> [ "." <integer> ] | 1078 * "." <integer> 1079 */ 1080 1081 /* whole part */ 1082 old_p = p; 1083 *out_units = strtol(p, &p, 10); 1084 if (p == old_p && *p != '.') 1085 return (NULL); 1086 1087 /* fractional part */ 1088 *out_decimal = 0; 1089 if (*p == '.') { 1090 int digits = 0; 1091 p++; 1092 while (isdigit(*p)) { 1093 int digit = *p - '0'; 1094 if (digits < PROB_DIGITS - 2) 1095 *out_decimal = *out_decimal * 10 + digit; 1096 else if (digits == PROB_DIGITS - 2 && digit >= 5) 1097 (*out_decimal)++; 1098 digits++; 1099 p++; 1100 } 1101 if (!digits) /* need at least one digit after '.' */ 1102 return (NULL); 1103 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */ 1104 *out_decimal *= 10; 1105 } 1106 1107 return (p); /* success */ 1108 } 1109 1110 /** 1111 * Internal helper function to parse an individual type for a failpoint term. 1112 */ 1113 static char * 1114 parse_type(struct fail_point_entry *ent, char *beg) 1115 { 1116 enum fail_point_t type; 1117 int len; 1118 1119 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) { 1120 len = fail_type_strings[type].nmlen; 1121 if (strncmp(fail_type_strings[type].name, beg, len) == 0) { 1122 ent->fe_type = type; 1123 return (beg + len); 1124 } 1125 } 1126 return (NULL); 1127 } 1128 1129 /* The fail point sysctl tree. */ 1130 SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 1131 "fail points"); 1132 1133 /* Debugging/testing stuff for fail point */ 1134 static int 1135 sysctl_test_fail_point(SYSCTL_HANDLER_ARGS) 1136 { 1137 1138 KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point); 1139 return (0); 1140 } 1141 SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point, 1142 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT, NULL, 0, 1143 sysctl_test_fail_point, "A", 1144 "Trigger test fail points"); 1145