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 "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 fail_point_swap_settings(fp, entries); 405 } 406 407 static inline void 408 fail_point_pause(struct fail_point *fp, enum fail_point_return_code *pret, 409 struct mtx *mtx_sleep) 410 { 411 412 if (fp->fp_pre_sleep_fn) 413 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 414 415 msleep_spin(FP_PAUSE_CHANNEL(fp), mtx_sleep, "failpt", 0); 416 417 if (fp->fp_post_sleep_fn) 418 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg); 419 } 420 421 static inline void 422 fail_point_sleep(struct fail_point *fp, int msecs, 423 enum fail_point_return_code *pret) 424 { 425 int timo; 426 427 /* Convert from millisecs to ticks, rounding up */ 428 timo = howmany(msecs * hz, 1000); 429 430 if (timo > 0) { 431 if (!(fp->fp_flags & FAIL_POINT_USE_TIMEOUT_PATH)) { 432 if (fp->fp_pre_sleep_fn) 433 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 434 435 tsleep(FP_SLEEP_CHANNEL(fp), PWAIT, "failpt", timo); 436 437 if (fp->fp_post_sleep_fn) 438 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg); 439 } else { 440 if (fp->fp_pre_sleep_fn) 441 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg); 442 443 timeout(fp->fp_post_sleep_fn, fp->fp_post_sleep_arg, 444 timo); 445 *pret = FAIL_POINT_RC_QUEUED; 446 } 447 } 448 } 449 450 static char *parse_fail_point(struct fail_point_setting *, char *); 451 static char *parse_term(struct fail_point_setting *, char *); 452 static char *parse_number(int *out_units, int *out_decimal, char *); 453 static char *parse_type(struct fail_point_entry *, char *); 454 455 /** 456 * Initialize a fail_point. The name is formed in a printf-like fashion 457 * from "fmt" and subsequent arguments. This function is generally used 458 * for custom failpoints located at odd places in the sysctl tree, and is 459 * not explicitly needed for standard in-line-declared failpoints. 460 * 461 * @ingroup failpoint 462 */ 463 void 464 fail_point_init(struct fail_point *fp, const char *fmt, ...) 465 { 466 va_list ap; 467 char *name; 468 int n; 469 470 fp->fp_setting = NULL; 471 fp->fp_flags = 0; 472 473 /* Figure out the size of the name. */ 474 va_start(ap, fmt); 475 n = vsnprintf(NULL, 0, fmt, ap); 476 va_end(ap); 477 478 /* Allocate the name and fill it in. */ 479 name = fp_malloc(n + 1, M_WAITOK); 480 if (name != NULL) { 481 va_start(ap, fmt); 482 vsnprintf(name, n + 1, fmt, ap); 483 va_end(ap); 484 } 485 fp->fp_name = name; 486 fp->fp_location = ""; 487 fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME; 488 fp->fp_pre_sleep_fn = NULL; 489 fp->fp_pre_sleep_arg = NULL; 490 fp->fp_post_sleep_fn = NULL; 491 fp->fp_post_sleep_arg = NULL; 492 } 493 494 /** 495 * Free the resources held by a fail_point, and wake any paused threads. 496 * Thou shalt not allow threads to hit this fail point after you enter this 497 * function, nor shall you call this multiple times for a given fp. 498 * @ingroup failpoint 499 */ 500 void 501 fail_point_destroy(struct fail_point *fp) 502 { 503 504 fail_point_drain(fp, 0); 505 506 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) { 507 fp_free(__DECONST(void *, fp->fp_name)); 508 fp->fp_name = NULL; 509 } 510 fp->fp_flags = 0; 511 512 sx_xlock(&sx_fp_set); 513 fail_point_garbage_collect(); 514 sx_xunlock(&sx_fp_set); 515 } 516 517 /** 518 * This does the real work of evaluating a fail point. If the fail point tells 519 * us to return a value, this function returns 1 and fills in 'return_value' 520 * (return_value is allowed to be null). If the fail point tells us to panic, 521 * we never return. Otherwise we just return 0 after doing some work, which 522 * means "keep going". 523 */ 524 enum fail_point_return_code 525 fail_point_eval_nontrivial(struct fail_point *fp, int *return_value) 526 { 527 bool execute = false; 528 struct fail_point_entry *ent; 529 struct fail_point_setting *fp_setting; 530 enum fail_point_return_code ret; 531 int cont; 532 int count; 533 int msecs; 534 int usecs; 535 536 ret = FAIL_POINT_RC_CONTINUE; 537 cont = 0; /* don't continue by default */ 538 539 fp_setting = fail_point_setting_get_ref(fp); 540 if (fp_setting == NULL) 541 goto abort; 542 543 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 544 545 if (ent->fe_stale) 546 continue; 547 548 if (ent->fe_prob < PROB_MAX && 549 ent->fe_prob < random() % PROB_MAX) 550 continue; 551 552 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid) 553 continue; 554 555 if (ent->fe_count != FE_COUNT_UNTRACKED) { 556 count = ent->fe_count; 557 while (count > 0) { 558 if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) { 559 count--; 560 execute = true; 561 break; 562 } 563 count = ent->fe_count; 564 } 565 if (execute == false) 566 /* We lost the race; consider the entry stale and bail now */ 567 continue; 568 if (count == 0) 569 ent->fe_stale = true; 570 } 571 572 switch (ent->fe_type) { 573 case FAIL_POINT_PANIC: 574 panic("fail point %s panicking", fp->fp_name); 575 /* NOTREACHED */ 576 577 case FAIL_POINT_RETURN: 578 if (return_value != NULL) 579 *return_value = ent->fe_arg; 580 ret = FAIL_POINT_RC_RETURN; 581 break; 582 583 case FAIL_POINT_BREAK: 584 printf("fail point %s breaking to debugger\n", 585 fp->fp_name); 586 breakpoint(); 587 break; 588 589 case FAIL_POINT_PRINT: 590 printf("fail point %s executing\n", fp->fp_name); 591 cont = ent->fe_arg; 592 break; 593 594 case FAIL_POINT_SLEEP: 595 msecs = ent->fe_arg; 596 if (msecs) 597 fail_point_sleep(fp, msecs, &ret); 598 break; 599 600 case FAIL_POINT_PAUSE: 601 /** 602 * Pausing is inherently strange with multiple 603 * entries given our design. That is because some 604 * entries could be unreachable, for instance in cases like: 605 * pause->return. We can never reach the return entry. 606 * The sysctl layer actually truncates all entries after 607 * a pause for this reason. 608 */ 609 mtx_lock_spin(&fp_setting->feq_mtx); 610 fail_point_pause(fp, &ret, &fp_setting->feq_mtx); 611 mtx_unlock_spin(&fp_setting->feq_mtx); 612 break; 613 614 case FAIL_POINT_YIELD: 615 kern_yield(-1); 616 break; 617 618 case FAIL_POINT_DELAY: 619 usecs = ent->fe_arg; 620 DELAY(usecs); 621 break; 622 623 default: 624 break; 625 } 626 627 if (cont == 0) 628 break; 629 } 630 631 if (fail_point_is_off(fp)) 632 fail_point_eval_swap_out(fp, fp_setting); 633 634 abort: 635 fail_point_setting_release_ref(fp); 636 637 return (ret); 638 } 639 640 /** 641 * Translate internal fail_point structure into human-readable text. 642 */ 643 static void 644 fail_point_get(struct fail_point *fp, struct sbuf *sb, 645 bool verbose) 646 { 647 struct fail_point_entry *ent; 648 struct fail_point_setting *fp_setting; 649 struct fail_point_entry *fp_entry_cpy; 650 int cnt_sleeping; 651 int idx; 652 int printed_entry_count; 653 654 cnt_sleeping = 0; 655 idx = 0; 656 printed_entry_count = 0; 657 658 fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) * 659 (FP_MAX_ENTRY_COUNT + 1), M_WAITOK); 660 661 fp_setting = fail_point_setting_get_ref(fp); 662 663 if (fp_setting != NULL) { 664 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) { 665 if (ent->fe_stale) 666 continue; 667 668 KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT, 669 ("FP entry list larger than allowed")); 670 671 fp_entry_cpy[printed_entry_count] = *ent; 672 ++printed_entry_count; 673 } 674 } 675 fail_point_setting_release_ref(fp); 676 677 /* This is our equivalent of a NULL terminator */ 678 fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID; 679 680 while (idx < printed_entry_count) { 681 ent = &fp_entry_cpy[idx]; 682 ++idx; 683 if (ent->fe_prob < PROB_MAX) { 684 int decimal = ent->fe_prob % (PROB_MAX / 100); 685 int units = ent->fe_prob / (PROB_MAX / 100); 686 sbuf_printf(sb, "%d", units); 687 if (decimal) { 688 int digits = PROB_DIGITS - 2; 689 while (!(decimal % 10)) { 690 digits--; 691 decimal /= 10; 692 } 693 sbuf_printf(sb, ".%0*d", digits, decimal); 694 } 695 sbuf_printf(sb, "%%"); 696 } 697 if (ent->fe_count >= 0) 698 sbuf_printf(sb, "%d*", ent->fe_count); 699 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name); 700 if (ent->fe_arg) 701 sbuf_printf(sb, "(%d)", ent->fe_arg); 702 if (ent->fe_pid != NO_PID) 703 sbuf_printf(sb, "[pid %d]", ent->fe_pid); 704 if (TAILQ_NEXT(ent, fe_entries)) 705 sbuf_printf(sb, "->"); 706 } 707 if (!printed_entry_count) 708 sbuf_printf(sb, "off"); 709 710 fp_free(fp_entry_cpy); 711 if (verbose) { 712 #ifdef STACK 713 /* Print number of sleeping threads. queue=0 is the argument 714 * used by msleep when sending our threads to sleep. */ 715 sbuf_printf(sb, "\nsleeping_thread_stacks = {\n"); 716 sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0, 717 &cnt_sleeping); 718 719 sbuf_printf(sb, "},\n"); 720 #endif 721 sbuf_printf(sb, "sleeping_thread_count = %d,\n", 722 cnt_sleeping); 723 724 #ifdef STACK 725 sbuf_printf(sb, "paused_thread_stacks = {\n"); 726 sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0, 727 &cnt_sleeping); 728 729 sbuf_printf(sb, "},\n"); 730 #endif 731 sbuf_printf(sb, "paused_thread_count = %d\n", 732 cnt_sleeping); 733 } 734 } 735 736 /** 737 * Set an internal fail_point structure from a human-readable failpoint string 738 * in a lock-safe manner. 739 */ 740 static int 741 fail_point_set(struct fail_point *fp, char *buf) 742 { 743 struct fail_point_entry *ent, *ent_next; 744 struct fail_point_setting *entries; 745 bool should_wake_paused; 746 bool should_truncate; 747 int error; 748 749 error = 0; 750 should_wake_paused = false; 751 should_truncate = false; 752 753 /* Parse new entries. */ 754 /** 755 * ref protects our new malloc'd stuff from being garbage collected 756 * before we link it. 757 */ 758 fail_point_setting_get_ref(fp); 759 entries = fail_point_setting_new(fp); 760 if (parse_fail_point(entries, buf) == NULL) { 761 STAILQ_REMOVE(&fp_setting_garbage, entries, 762 fail_point_setting, fs_garbage_link); 763 fail_point_setting_destroy(entries); 764 error = EINVAL; 765 goto end; 766 } 767 768 /** 769 * Transfer the entries we are going to keep to a new list. 770 * Get rid of useless zero probability entries, and entries with hit 771 * count 0. 772 * If 'off' is present, and it has no hit count set, then all entries 773 * after it are discarded since they are unreachable. 774 */ 775 TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) { 776 if (ent->fe_prob == 0 || ent->fe_count == 0) { 777 printf("Discarding entry which cannot execute %s\n", 778 fail_type_strings[ent->fe_type].name); 779 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 780 fe_entries); 781 fp_free(ent); 782 continue; 783 } else if (should_truncate) { 784 printf("Discarding unreachable entry %s\n", 785 fail_type_strings[ent->fe_type].name); 786 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 787 fe_entries); 788 fp_free(ent); 789 continue; 790 } 791 792 if (ent->fe_type == FAIL_POINT_OFF) { 793 should_wake_paused = true; 794 if (ent->fe_count == FE_COUNT_UNTRACKED) { 795 should_truncate = true; 796 TAILQ_REMOVE(&entries->fp_entry_queue, ent, 797 fe_entries); 798 fp_free(ent); 799 } 800 } else if (ent->fe_type == FAIL_POINT_PAUSE) { 801 should_truncate = true; 802 } else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags & 803 FAIL_POINT_NONSLEEPABLE)) { 804 /** 805 * If this fail point is annotated as being in a 806 * non-sleepable ctx, convert sleep to delay and 807 * convert the msec argument to usecs. 808 */ 809 printf("Sleep call request on fail point in " 810 "non-sleepable context; using delay instead " 811 "of sleep\n"); 812 ent->fe_type = FAIL_POINT_DELAY; 813 ent->fe_arg *= 1000; 814 } 815 } 816 817 if (TAILQ_EMPTY(&entries->fp_entry_queue)) { 818 entries = fail_point_swap_settings(fp, NULL); 819 if (entries != NULL) 820 wakeup(FP_PAUSE_CHANNEL(fp)); 821 } else { 822 if (should_wake_paused) 823 wakeup(FP_PAUSE_CHANNEL(fp)); 824 fail_point_swap_settings(fp, entries); 825 } 826 827 end: 828 #ifdef IWARNING 829 if (error) 830 IWARNING("Failed to set %s %s to %s", 831 fp->fp_name, fp->fp_location, buf); 832 else 833 INOTICE("Set %s %s to %s", 834 fp->fp_name, fp->fp_location, buf); 835 #endif /* IWARNING */ 836 837 fail_point_setting_release_ref(fp); 838 return (error); 839 } 840 841 #define MAX_FAIL_POINT_BUF 1023 842 843 /** 844 * Handle kernel failpoint set/get. 845 */ 846 int 847 fail_point_sysctl(SYSCTL_HANDLER_ARGS) 848 { 849 struct fail_point *fp; 850 char *buf; 851 struct sbuf sb, *sb_check; 852 int error; 853 854 buf = NULL; 855 error = 0; 856 fp = arg1; 857 858 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 859 if (sb_check != &sb) 860 return (ENOMEM); 861 862 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 863 864 /* Setting */ 865 /** 866 * Lock protects any new entries from being garbage collected before we 867 * can link them to the fail point. 868 */ 869 sx_xlock(&sx_fp_set); 870 if (req->newptr) { 871 if (req->newlen > MAX_FAIL_POINT_BUF) { 872 error = EINVAL; 873 goto out; 874 } 875 876 buf = fp_malloc(req->newlen + 1, M_WAITOK); 877 878 error = SYSCTL_IN(req, buf, req->newlen); 879 if (error) 880 goto out; 881 buf[req->newlen] = '\0'; 882 883 error = fail_point_set(fp, buf); 884 } 885 886 fail_point_garbage_collect(); 887 sx_xunlock(&sx_fp_set); 888 889 /* Retrieving. */ 890 fail_point_get(fp, &sb, false); 891 892 out: 893 sbuf_finish(&sb); 894 sbuf_delete(&sb); 895 896 if (buf) 897 fp_free(buf); 898 899 return (error); 900 } 901 902 int 903 fail_point_sysctl_status(SYSCTL_HANDLER_ARGS) 904 { 905 struct fail_point *fp; 906 struct sbuf sb, *sb_check; 907 908 fp = arg1; 909 910 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND); 911 if (sb_check != &sb) 912 return (ENOMEM); 913 914 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req); 915 916 /* Retrieving. */ 917 fail_point_get(fp, &sb, true); 918 919 sbuf_finish(&sb); 920 sbuf_delete(&sb); 921 922 /** 923 * Lock protects any new entries from being garbage collected before we 924 * can link them to the fail point. 925 */ 926 sx_xlock(&sx_fp_set); 927 fail_point_garbage_collect(); 928 sx_xunlock(&sx_fp_set); 929 930 return (0); 931 } 932 933 int 934 fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len) 935 { 936 struct sysctl_req *sa; 937 int error; 938 939 sa = sysctl_args; 940 941 error = SYSCTL_OUT(sa, buf, len); 942 943 if (error == ENOMEM) 944 return (-1); 945 else 946 return (len); 947 } 948 949 /** 950 * Internal helper function to translate a human-readable failpoint string 951 * into a internally-parsable fail_point structure. 952 */ 953 static char * 954 parse_fail_point(struct fail_point_setting *ents, char *p) 955 { 956 /* <fail_point> :: 957 * <term> ( "->" <term> )* 958 */ 959 uint8_t term_count; 960 961 term_count = 1; 962 963 p = parse_term(ents, p); 964 if (p == NULL) 965 return (NULL); 966 967 while (*p != '\0') { 968 term_count++; 969 if (p[0] != '-' || p[1] != '>' || 970 (p = parse_term(ents, p+2)) == NULL || 971 term_count > FP_MAX_ENTRY_COUNT) 972 return (NULL); 973 } 974 return (p); 975 } 976 977 /** 978 * Internal helper function to parse an individual term from a failpoint. 979 */ 980 static char * 981 parse_term(struct fail_point_setting *ents, char *p) 982 { 983 struct fail_point_entry *ent; 984 985 ent = fail_point_entry_new(ents); 986 987 /* 988 * <term> :: 989 * ( (<float> "%") | (<integer> "*" ) )* 990 * <type> 991 * [ "(" <integer> ")" ] 992 * [ "[pid " <integer> "]" ] 993 */ 994 995 /* ( (<float> "%") | (<integer> "*" ) )* */ 996 while (isdigit(*p) || *p == '.') { 997 int units, decimal; 998 999 p = parse_number(&units, &decimal, p); 1000 if (p == NULL) 1001 return (NULL); 1002 1003 if (*p == '%') { 1004 if (units > 100) /* prevent overflow early */ 1005 units = 100; 1006 ent->fe_prob = units * (PROB_MAX / 100) + decimal; 1007 if (ent->fe_prob > PROB_MAX) 1008 ent->fe_prob = PROB_MAX; 1009 } else if (*p == '*') { 1010 if (!units || units < 0 || decimal) 1011 return (NULL); 1012 ent->fe_count = units; 1013 } else 1014 return (NULL); 1015 p++; 1016 } 1017 1018 /* <type> */ 1019 p = parse_type(ent, p); 1020 if (p == NULL) 1021 return (NULL); 1022 if (*p == '\0') 1023 return (p); 1024 1025 /* [ "(" <integer> ")" ] */ 1026 if (*p != '(') 1027 return (p); 1028 p++; 1029 if (!isdigit(*p) && *p != '-') 1030 return (NULL); 1031 ent->fe_arg = strtol(p, &p, 0); 1032 if (*p++ != ')') 1033 return (NULL); 1034 1035 /* [ "[pid " <integer> "]" ] */ 1036 #define PID_STRING "[pid " 1037 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0) 1038 return (p); 1039 p += sizeof(PID_STRING) - 1; 1040 if (!isdigit(*p)) 1041 return (NULL); 1042 ent->fe_pid = strtol(p, &p, 0); 1043 if (*p++ != ']') 1044 return (NULL); 1045 1046 return (p); 1047 } 1048 1049 /** 1050 * Internal helper function to parse a numeric for a failpoint term. 1051 */ 1052 static char * 1053 parse_number(int *out_units, int *out_decimal, char *p) 1054 { 1055 char *old_p; 1056 1057 /** 1058 * <number> :: 1059 * <integer> [ "." <integer> ] | 1060 * "." <integer> 1061 */ 1062 1063 /* whole part */ 1064 old_p = p; 1065 *out_units = strtol(p, &p, 10); 1066 if (p == old_p && *p != '.') 1067 return (NULL); 1068 1069 /* fractional part */ 1070 *out_decimal = 0; 1071 if (*p == '.') { 1072 int digits = 0; 1073 p++; 1074 while (isdigit(*p)) { 1075 int digit = *p - '0'; 1076 if (digits < PROB_DIGITS - 2) 1077 *out_decimal = *out_decimal * 10 + digit; 1078 else if (digits == PROB_DIGITS - 2 && digit >= 5) 1079 (*out_decimal)++; 1080 digits++; 1081 p++; 1082 } 1083 if (!digits) /* need at least one digit after '.' */ 1084 return (NULL); 1085 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */ 1086 *out_decimal *= 10; 1087 } 1088 1089 return (p); /* success */ 1090 } 1091 1092 /** 1093 * Internal helper function to parse an individual type for a failpoint term. 1094 */ 1095 static char * 1096 parse_type(struct fail_point_entry *ent, char *beg) 1097 { 1098 enum fail_point_t type; 1099 int len; 1100 1101 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) { 1102 len = fail_type_strings[type].nmlen; 1103 if (strncmp(fail_type_strings[type].name, beg, len) == 0) { 1104 ent->fe_type = type; 1105 return (beg + len); 1106 } 1107 } 1108 return (NULL); 1109 } 1110 1111 /* The fail point sysctl tree. */ 1112 SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW, 0, "fail points"); 1113 1114 /* Debugging/testing stuff for fail point */ 1115 static int 1116 sysctl_test_fail_point(SYSCTL_HANDLER_ARGS) 1117 { 1118 1119 KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point); 1120 return (0); 1121 } 1122 SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point, 1123 CTLTYPE_STRING | CTLFLAG_RD, NULL, 0, sysctl_test_fail_point, "A", 1124 "Trigger test fail points"); 1125