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 77ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point); 78#endif 79 80static 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 */ 104int fail_sysctl_drain_func(void *, const char *, int); 105 106/* Head of tailq of struct fail_point_entry */ 107TAILQ_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 */ 113STAILQ_HEAD(fail_point_setting_garbage, fail_point_setting); 114static struct fail_point_setting_garbage fp_setting_garbage = 115 STAILQ_HEAD_INITIALIZER(fp_setting_garbage); 116static struct mtx mtx_garbage_list; 117MTX_SYSINIT(mtx_garbage_list, &mtx_garbage_list, "fail point garbage mtx", 118 MTX_SPIN); 119 120static struct sx sx_fp_set; 121SX_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 */ 128enum 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 142static 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 */ 164struct 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 175struct 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 */ 185enum { 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 */ 191static inline struct fail_point_setting *fail_point_setting_get_ref( 192 struct fail_point *fp); 193/* Release a ref on an fp_setting */ 194static inline void fail_point_setting_release_ref(struct fail_point *fp); 195/* Allocate and initialize a struct fail_point_setting */ 196static struct fail_point_setting *fail_point_setting_new(struct 197 fail_point *); 198/* Free a struct fail_point_setting */ 199static void fail_point_setting_destroy(struct fail_point_setting *fp_setting); 200/* Allocate and initialize a struct fail_point_entry */ 201static struct fail_point_entry *fail_point_entry_new(struct 202 fail_point_setting *); 203/* Free a struct fail_point_entry */ 204static void fail_point_entry_destroy(struct fail_point_entry *fp_entry); 205/* Append fp setting to garbage list */ 206static inline void fail_point_setting_garbage_append( 207 struct fail_point_setting *fp_setting); 208/* Swap fp's setting with fp_setting_new */ 209static 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 */ 213static void fail_point_garbage_collect(void); 214/* If this fail point's setting are empty, then swap it out to NULL. */ 215static inline void fail_point_eval_swap_out(struct fail_point *fp, 216 struct fail_point_setting *fp_setting); 217 218bool 219fail_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 */ 243static struct fail_point_setting * 244fail_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 */ 259static void 260fail_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 */ 274static struct fail_point_entry * 275fail_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 */ 292static void 293fail_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 */ 300static inline struct fail_point_setting * 301fail_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 */ 313static inline void 314fail_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 */ 322static inline void 323fail_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 */ 333static struct fail_point_setting * 334fail_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 345static inline void 346fail_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 */ 356static void 357fail_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 */ 389static inline void 390fail_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 409static inline void 410fail_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 423static inline void 424fail_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 452static char *parse_fail_point(struct fail_point_setting *, char *); 453static char *parse_term(struct fail_point_setting *, char *); 454static char *parse_number(int *out_units, int *out_decimal, char *); 455static 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 */ 465void 466fail_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 496void 497fail_point_alloc_callout(struct fail_point *fp) 498{ 499 500 /** 501 * This assumes that calls to fail_point_use_timeout_path() 502 * will not race. 503 */ 504 if (fp->fp_callout != NULL) 505 return; 506 fp->fp_callout = fp_malloc(sizeof(*fp->fp_callout), M_WAITOK); 507 callout_init(fp->fp_callout, CALLOUT_MPSAFE); 508} 509 510/** 511 * Free the resources held by a fail_point, and wake any paused threads. 512 * Thou shalt not allow threads to hit this fail point after you enter this 513 * function, nor shall you call this multiple times for a given fp. 514 * @ingroup failpoint 515 */ 516void 517fail_point_destroy(struct fail_point *fp) 518{ 519 520 fail_point_drain(fp, 0); 521 522 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) { 523 fp_free(__DECONST(void *, fp->fp_name)); 524 fp->fp_name = NULL; 525 } 526 fp->fp_flags = 0; 527 if (fp->fp_callout) { 528 fp_free(fp->fp_callout); 529 fp->fp_callout = NULL; 530 } 531 532 sx_xlock(&sx_fp_set); 533 fail_point_garbage_collect(); 534 sx_xunlock(&sx_fp_set); 535} 536 537/** 538 * This does the real work of evaluating a fail point. If the fail point tells 539 * us to return a value, this function returns 1 and fills in 'return_value' 540 * (return_value is allowed to be null). If the fail point tells us to panic, 541 * we never return. Otherwise we just return 0 after doing some work, which 542 * means "keep going". 543 */ 544enum fail_point_return_code 545fail_point_eval_nontrivial(struct fail_point *fp, int *return_value) 546{ 547 bool execute = false; 548 struct fail_point_entry *ent; 549 struct fail_point_setting *fp_setting; 550 enum fail_point_return_code ret; 551 int cont; 552 int count; 553 int msecs; 554 int usecs; 555 556 ret = FAIL_POINT_RC_CONTINUE; 557 cont = 0; /* don't continue by default */ 558 559 fp_setting = fail_point_setting_get_ref(fp); 560 if (fp_setting == NULL) 561 goto abort; 562 563 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 564 if (ent->fe_stale) 565 continue; 566 567 if (ent->fe_prob < PROB_MAX && 568 ent->fe_prob < random() % PROB_MAX) 569 continue; 570 571 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid) 572 continue; 573 574 if (ent->fe_count != FE_COUNT_UNTRACKED) { 575 count = ent->fe_count; 576 while (count > 0) { 577 if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) { 578 count--; 579 execute = true; 580 break; 581 } 582 count = ent->fe_count; 583 } 584 if (execute == false) 585 /* We lost the race; consider the entry stale and bail now */ 586 continue; 587 if (count == 0) 588 ent->fe_stale = true; 589 } 590 591 switch (ent->fe_type) { 592 case FAIL_POINT_PANIC: 593 panic("fail point %s panicking", fp->fp_name); 594 /* NOTREACHED */ 595 596 case FAIL_POINT_RETURN: 597 if (return_value != NULL) 598 *return_value = ent->fe_arg; 599 ret = FAIL_POINT_RC_RETURN; 600 break; 601 602 case FAIL_POINT_BREAK: 603 printf("fail point %s breaking to debugger\n", 604 fp->fp_name); 605 breakpoint(); 606 break; 607 608 case FAIL_POINT_PRINT: 609 printf("fail point %s executing\n", fp->fp_name); 610 cont = ent->fe_arg; 611 break; 612 613 case FAIL_POINT_SLEEP: 614 msecs = ent->fe_arg; 615 if (msecs) 616 fail_point_sleep(fp, msecs, &ret); 617 break; 618 619 case FAIL_POINT_PAUSE: 620 /** 621 * Pausing is inherently strange with multiple 622 * entries given our design. That is because some 623 * entries could be unreachable, for instance in cases like: 624 * pause->return. We can never reach the return entry. 625 * The sysctl layer actually truncates all entries after 626 * a pause for this reason. 627 */ 628 mtx_lock_spin(&fp_setting->feq_mtx); 629 fail_point_pause(fp, &ret, &fp_setting->feq_mtx); 630 mtx_unlock_spin(&fp_setting->feq_mtx); 631 break; 632 633 case FAIL_POINT_YIELD: 634 kern_yield(PRI_UNCHANGED); 635 break; 636 637 case FAIL_POINT_DELAY: 638 usecs = ent->fe_arg; 639 DELAY(usecs); 640 break; 641 642 default: 643 break; 644 } 645 646 if (cont == 0) 647 break; 648 } 649 650 if (fail_point_is_off(fp)) 651 fail_point_eval_swap_out(fp, fp_setting); 652 653abort: 654 fail_point_setting_release_ref(fp); 655 656 return (ret); 657} 658 659/** 660 * Translate internal fail_point structure into human-readable text. 661 */ 662static void 663fail_point_get(struct fail_point *fp, struct sbuf *sb, 664 bool verbose) 665{ 666 struct fail_point_entry *ent; 667 struct fail_point_setting *fp_setting; 668 struct fail_point_entry *fp_entry_cpy; 669 int cnt_sleeping; 670 int idx; 671 int printed_entry_count; 672 673 cnt_sleeping = 0; 674 idx = 0; 675 printed_entry_count = 0; 676 677 fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) * 678 (FP_MAX_ENTRY_COUNT + 1), M_WAITOK); 679 680 fp_setting = fail_point_setting_get_ref(fp); 681 682 if (fp_setting != NULL) { 683 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 684 if (ent->fe_stale) 685 continue; 686 687 KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT, 688 ("FP entry list larger than allowed")); 689 690 fp_entry_cpy[printed_entry_count] = *ent; 691 ++printed_entry_count; 692 } 693 } 694 fail_point_setting_release_ref(fp); 695 696 /* This is our equivalent of a NULL terminator */ 697 fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID; 698 699 while (idx < printed_entry_count) { 700 ent = &fp_entry_cpy[idx]; 701 ++idx; 702 if (ent->fe_prob < PROB_MAX) { 703 int decimal = ent->fe_prob % (PROB_MAX / 100); 704 int units = ent->fe_prob / (PROB_MAX / 100); 705 sbuf_printf(sb, "%d", units); 706 if (decimal) { 707 int digits = PROB_DIGITS - 2; 708 while (!(decimal % 10)) { 709 digits--; 710 decimal /= 10; 711 } 712 sbuf_printf(sb, ".%0*d", digits, decimal); 713 } 714 sbuf_printf(sb, "%%"); 715 } 716 if (ent->fe_count >= 0) 717 sbuf_printf(sb, "%d*", ent->fe_count); 718 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name); 719 if (ent->fe_arg) 720 sbuf_printf(sb, "(%d)", ent->fe_arg); 721 if (ent->fe_pid != NO_PID) 722 sbuf_printf(sb, "[pid %d]", ent->fe_pid); 723 if (TAILQ_NEXT(ent, fe_entries)) 724 sbuf_cat(sb, "->"); 725 } 726 if (!printed_entry_count) 727 sbuf_cat(sb, "off"); 728 729 fp_free(fp_entry_cpy); 730 if (verbose) { 731#ifdef STACK 732 /* Print number of sleeping threads. queue=0 is the argument 733 * used by msleep when sending our threads to sleep. */ 734 sbuf_cat(sb, "\nsleeping_thread_stacks = {\n"); 735 sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0, 736 &cnt_sleeping); 737 738 sbuf_cat(sb, "},\n"); 739#endif 740 sbuf_printf(sb, "sleeping_thread_count = %d,\n", 741 cnt_sleeping); 742 743#ifdef STACK 744 sbuf_cat(sb, "paused_thread_stacks = {\n"); 745 sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0, 746 &cnt_sleeping); 747 748 sbuf_cat(sb, "},\n"); 749#endif 750 sbuf_printf(sb, "paused_thread_count = %d\n", 751 cnt_sleeping); 752 } 753} 754 755/** 756 * Set an internal fail_point structure from a human-readable failpoint string 757 * in a lock-safe manner. 758 */ 759static int 760fail_point_set(struct fail_point *fp, char *buf) 761{ 762 struct fail_point_entry *ent, *ent_next; 763 struct fail_point_setting *entries; 764 bool should_wake_paused; 765 bool should_truncate; 766 int error; 767 768 error = 0; 769 should_wake_paused = false; 770 should_truncate = false; 771 772 /* Parse new entries. */ 773 /** 774 * ref protects our new malloc'd stuff from being garbage collected 775 * before we link it. 776 */ 777 fail_point_setting_get_ref(fp); 778 entries = fail_point_setting_new(fp); 779 if (parse_fail_point(entries, buf) == NULL) { 780 STAILQ_REMOVE(&fp_setting_garbage, entries, 781 fail_point_setting, fs_garbage_link); 782 fail_point_setting_destroy(entries); 783 error = EINVAL; 784 goto end; 785 } 786 787 /** 788 * Transfer the entries we are going to keep to a new list. 789 * Get rid of useless zero probability entries, and entries with hit 790 * count 0. 791 * If 'off' is present, and it has no hit count set, then all entries 792 * after it are discarded since they are unreachable. 793 */ 794 TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) { 795 if (ent->fe_prob == 0 || ent->fe_count == 0) { 796 printf("Discarding entry which cannot execute %s\n", 797 fail_type_strings[ent->fe_type].name); 798 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 799 fe_entries); 800 fp_free(ent); 801 continue; 802 } else if (should_truncate) { 803 printf("Discarding unreachable entry %s\n", 804 fail_type_strings[ent->fe_type].name); 805 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 806 fe_entries); 807 fp_free(ent); 808 continue; 809 } 810 811 if (ent->fe_type == FAIL_POINT_OFF) { 812 should_wake_paused = true; 813 if (ent->fe_count == FE_COUNT_UNTRACKED) { 814 should_truncate = true; 815 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 816 fe_entries); 817 fp_free(ent); 818 } 819 } else if (ent->fe_type == FAIL_POINT_PAUSE) { 820 should_truncate = true; 821 } else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags & 822 FAIL_POINT_NONSLEEPABLE)) { 823 /** 824 * If this fail point is annotated as being in a 825 * non-sleepable ctx, convert sleep to delay and 826 * convert the msec argument to usecs. 827 */ 828 printf("Sleep call request on fail point in " 829 "non-sleepable context; using delay instead " 830 "of sleep\n"); 831 ent->fe_type = FAIL_POINT_DELAY; 832 ent->fe_arg *= 1000; 833 } 834 } 835 836 if (TAILQ_EMPTY(&entries->fp_entry_queue)) { 837 entries = fail_point_swap_settings(fp, NULL); 838 if (entries != NULL) 839 wakeup(FP_PAUSE_CHANNEL(fp)); 840 } else { 841 if (should_wake_paused) 842 wakeup(FP_PAUSE_CHANNEL(fp)); 843 fail_point_swap_settings(fp, entries); 844 } 845 846end: 847#ifdef IWARNING 848 if (error) 849 IWARNING("Failed to set %s %s to %s", 850 fp->fp_name, fp->fp_location, buf); 851 else 852 INOTICE("Set %s %s to %s", 853 fp->fp_name, fp->fp_location, buf); 854#endif /* IWARNING */ 855 856 fail_point_setting_release_ref(fp); 857 return (error); 858} 859 860#define MAX_FAIL_POINT_BUF 1023 861 862/** 863 * Handle kernel failpoint set/get. 864 */ 865int 866fail_point_sysctl(SYSCTL_HANDLER_ARGS) 867{ 868 struct fail_point *fp; 869 char *buf; 870 struct sbuf sb, *sb_check; 871 int error; 872 873 buf = NULL; 874 error = 0; 875 fp = arg1; 876 877 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 878 if (sb_check != &sb) 879 return (ENOMEM); 880 881 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 882 883 /* Setting */ 884 /** 885 * Lock protects any new entries from being garbage collected before we 886 * can link them to the fail point. 887 */ 888 sx_xlock(&sx_fp_set); 889 if (req->newptr) { 890 if (req->newlen > MAX_FAIL_POINT_BUF) { 891 error = EINVAL; 892 goto out; 893 } 894 895 buf = fp_malloc(req->newlen + 1, M_WAITOK); 896 897 error = SYSCTL_IN(req, buf, req->newlen); 898 if (error) 899 goto out; 900 buf[req->newlen] = '\0'; 901 902 error = fail_point_set(fp, buf); 903 } 904 905 fail_point_garbage_collect(); 906 sx_xunlock(&sx_fp_set); 907 908 /* Retrieving. */ 909 fail_point_get(fp, &sb, false); 910 911out: 912 sbuf_finish(&sb); 913 sbuf_delete(&sb); 914 915 if (buf) 916 fp_free(buf); 917 918 return (error); 919} 920 921int 922fail_point_sysctl_status(SYSCTL_HANDLER_ARGS) 923{ 924 struct fail_point *fp; 925 struct sbuf sb, *sb_check; 926 927 fp = arg1; 928 929 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 930 if (sb_check != &sb) 931 return (ENOMEM); 932 933 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 934 935 /* Retrieving. */ 936 fail_point_get(fp, &sb, true); 937 938 sbuf_finish(&sb); 939 sbuf_delete(&sb); 940 941 /** 942 * Lock protects any new entries from being garbage collected before we 943 * can link them to the fail point. 944 */ 945 sx_xlock(&sx_fp_set); 946 fail_point_garbage_collect(); 947 sx_xunlock(&sx_fp_set); 948 949 return (0); 950} 951 952int 953fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len) 954{ 955 struct sysctl_req *sa; 956 int error; 957 958 sa = sysctl_args; 959 960 error = SYSCTL_OUT(sa, buf, len); 961 962 if (error == ENOMEM) 963 return (-1); 964 else 965 return (len); 966} 967 968/** 969 * Internal helper function to translate a human-readable failpoint string 970 * into a internally-parsable fail_point structure. 971 */ 972static char * 973parse_fail_point(struct fail_point_setting *ents, char *p) 974{ 975 /* <fail_point> :: 976 * <term> ( "->" <term> )* 977 */ 978 uint8_t term_count; 979 980 term_count = 1; 981 982 p = parse_term(ents, p); 983 if (p == NULL) 984 return (NULL); 985 986 while (*p != '\0') { 987 term_count++; 988 if (p[0] != '-' || p[1] != '>' || 989 (p = parse_term(ents, p+2)) == NULL || 990 term_count > FP_MAX_ENTRY_COUNT) 991 return (NULL); 992 } 993 return (p); 994} 995 996/** 997 * Internal helper function to parse an individual term from a failpoint. 998 */ 999static char * 1000parse_term(struct fail_point_setting *ents, char *p) 1001{ 1002 struct fail_point_entry *ent; 1003 1004 ent = fail_point_entry_new(ents); 1005 1006 /* 1007 * <term> :: 1008 * ( (<float> "%") | (<integer> "*" ) )* 1009 * <type> 1010 * [ "(" <integer> ")" ] 1011 * [ "[pid " <integer> "]" ] 1012 */ 1013 1014 /* ( (<float> "%") | (<integer> "*" ) )* */ 1015 while (isdigit(*p) || *p == '.') { 1016 int units, decimal; 1017 1018 p = parse_number(&units, &decimal, p); 1019 if (p == NULL) 1020 return (NULL); 1021 1022 if (*p == '%') { 1023 if (units > 100) /* prevent overflow early */ 1024 units = 100; 1025 ent->fe_prob = units * (PROB_MAX / 100) + decimal; 1026 if (ent->fe_prob > PROB_MAX) 1027 ent->fe_prob = PROB_MAX; 1028 } else if (*p == '*') { 1029 if (!units || units < 0 || decimal) 1030 return (NULL); 1031 ent->fe_count = units; 1032 } else 1033 return (NULL); 1034 p++; 1035 } 1036 1037 /* <type> */ 1038 p = parse_type(ent, p); 1039 if (p == NULL) 1040 return (NULL); 1041 if (*p == '\0') 1042 return (p); 1043 1044 /* [ "(" <integer> ")" ] */ 1045 if (*p != '(') 1046 return (p); 1047 p++; 1048 if (!isdigit(*p) && *p != '-') 1049 return (NULL); 1050 ent->fe_arg = strtol(p, &p, 0); 1051 if (*p++ != ')') 1052 return (NULL); 1053 1054 /* [ "[pid " <integer> "]" ] */ 1055#define PID_STRING "[pid " 1056 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0) 1057 return (p); 1058 p += sizeof(PID_STRING) - 1; 1059 if (!isdigit(*p)) 1060 return (NULL); 1061 ent->fe_pid = strtol(p, &p, 0); 1062 if (*p++ != ']') 1063 return (NULL); 1064 1065 return (p); 1066} 1067 1068/** 1069 * Internal helper function to parse a numeric for a failpoint term. 1070 */ 1071static char * 1072parse_number(int *out_units, int *out_decimal, char *p) 1073{ 1074 char *old_p; 1075 1076 /** 1077 * <number> :: 1078 * <integer> [ "." <integer> ] | 1079 * "." <integer> 1080 */ 1081 1082 /* whole part */ 1083 old_p = p; 1084 *out_units = strtol(p, &p, 10); 1085 if (p == old_p && *p != '.') 1086 return (NULL); 1087 1088 /* fractional part */ 1089 *out_decimal = 0; 1090 if (*p == '.') { 1091 int digits = 0; 1092 p++; 1093 while (isdigit(*p)) { 1094 int digit = *p - '0'; 1095 if (digits < PROB_DIGITS - 2) 1096 *out_decimal = *out_decimal * 10 + digit; 1097 else if (digits == PROB_DIGITS - 2 && digit >= 5) 1098 (*out_decimal)++; 1099 digits++; 1100 p++; 1101 } 1102 if (!digits) /* need at least one digit after '.' */ 1103 return (NULL); 1104 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */ 1105 *out_decimal *= 10; 1106 } 1107 1108 return (p); /* success */ 1109} 1110 1111/** 1112 * Internal helper function to parse an individual type for a failpoint term. 1113 */ 1114static char * 1115parse_type(struct fail_point_entry *ent, char *beg) 1116{ 1117 enum fail_point_t type; 1118 int len; 1119 1120 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) { 1121 len = fail_type_strings[type].nmlen; 1122 if (strncmp(fail_type_strings[type].name, beg, len) == 0) { 1123 ent->fe_type = type; 1124 return (beg + len); 1125 } 1126 } 1127 return (NULL); 1128} 1129 1130/* The fail point sysctl tree. */ 1131SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW | CTLFLAG_MPSAFE, 0, 1132 "fail points"); 1133 1134/* Debugging/testing stuff for fail point */ 1135static int 1136sysctl_test_fail_point(SYSCTL_HANDLER_ARGS) 1137{ 1138 1139 KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point); 1140 return (0); 1141} 1142SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point, 1143 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT, NULL, 0, 1144 sysctl_test_fail_point, "A", 1145 "Trigger test fail points"); 1146