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