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/lock.h> 61 #include <sys/malloc.h> 62 #include <sys/mutex.h> 63 #include <sys/proc.h> 64 #include <sys/sbuf.h> 65 66 #include <machine/stdarg.h> 67 68 #ifdef ILOG_DEFINE_FOR_FILE 69 ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point); 70 #endif 71 72 static MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system"); 73 #define fp_free(ptr) free(ptr, M_FAIL_POINT) 74 #define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags)) 75 76 static struct mtx g_fp_mtx; 77 MTX_SYSINIT(g_fp_mtx, &g_fp_mtx, "fail point mtx", MTX_DEF); 78 #define FP_LOCK() mtx_lock(&g_fp_mtx) 79 #define FP_UNLOCK() mtx_unlock(&g_fp_mtx) 80 81 /** 82 * Failpoint types. 83 * Don't change these without changing fail_type_strings in fail.c. 84 * @ingroup failpoint_private 85 */ 86 enum fail_point_t { 87 FAIL_POINT_OFF, /**< don't fail */ 88 FAIL_POINT_PANIC, /**< panic */ 89 FAIL_POINT_RETURN, /**< return an errorcode */ 90 FAIL_POINT_BREAK, /**< break into the debugger */ 91 FAIL_POINT_PRINT, /**< print a message */ 92 FAIL_POINT_SLEEP, /**< sleep for some msecs */ 93 FAIL_POINT_NUMTYPES 94 }; 95 96 static struct { 97 const char *name; 98 int nmlen; 99 } fail_type_strings[] = { 100 #define FP_TYPE_NM_LEN(s) { s, sizeof(s) - 1 } 101 [FAIL_POINT_OFF] = FP_TYPE_NM_LEN("off"), 102 [FAIL_POINT_PANIC] = FP_TYPE_NM_LEN("panic"), 103 [FAIL_POINT_RETURN] = FP_TYPE_NM_LEN("return"), 104 [FAIL_POINT_BREAK] = FP_TYPE_NM_LEN("break"), 105 [FAIL_POINT_PRINT] = FP_TYPE_NM_LEN("print"), 106 [FAIL_POINT_SLEEP] = FP_TYPE_NM_LEN("sleep"), 107 }; 108 109 /** 110 * Internal structure tracking a single term of a complete failpoint. 111 * @ingroup failpoint_private 112 */ 113 struct fail_point_entry { 114 enum fail_point_t fe_type; /**< type of entry */ 115 int fe_arg; /**< argument to type (e.g. return value) */ 116 int fe_prob; /**< likelihood of firing in millionths */ 117 int fe_count; /**< number of times to fire, 0 means always */ 118 pid_t fe_pid; /**< only fail for this process */ 119 TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry in fail point */ 120 }; 121 122 static inline void 123 fail_point_sleep(struct fail_point *fp, struct fail_point_entry *ent, 124 int msecs, enum fail_point_return_code *pret) 125 { 126 /* convert from millisecs to ticks, rounding up */ 127 int timo = ((msecs * hz) + 999) / 1000; 128 129 if (timo > 0) { 130 if (fp->fp_sleep_fn == NULL) { 131 msleep(fp, &g_fp_mtx, PWAIT, "failpt", timo); 132 } else { 133 timeout(fp->fp_sleep_fn, fp->fp_sleep_arg, timo); 134 *pret = FAIL_POINT_RC_QUEUED; 135 } 136 } 137 } 138 139 140 /** 141 * Defines stating the equivalent of probablilty one (100%) 142 */ 143 enum { 144 PROB_MAX = 1000000, /* probability between zero and this number */ 145 PROB_DIGITS = 6, /* number of zero's in above number */ 146 }; 147 148 static char *parse_fail_point(struct fail_point_entries *, char *); 149 static char *parse_term(struct fail_point_entries *, char *); 150 static char *parse_number(int *out_units, int *out_decimal, char *); 151 static char *parse_type(struct fail_point_entry *, char *); 152 static void free_entry(struct fail_point_entries *, struct fail_point_entry *); 153 static void clear_entries(struct fail_point_entries *); 154 155 /** 156 * Initialize a fail_point. The name is formed in a printf-like fashion 157 * from "fmt" and subsequent arguments. This function is generally used 158 * for custom failpoints located at odd places in the sysctl tree, and is 159 * not explicitly needed for standard in-line-declared failpoints. 160 * 161 * @ingroup failpoint 162 */ 163 void 164 fail_point_init(struct fail_point *fp, const char *fmt, ...) 165 { 166 va_list ap; 167 char *name; 168 int n; 169 170 TAILQ_INIT(&fp->fp_entries); 171 fp->fp_flags = 0; 172 173 /* Figure out the size of the name. */ 174 va_start(ap, fmt); 175 n = vsnprintf(NULL, 0, fmt, ap); 176 va_end(ap); 177 178 /* Allocate the name and fill it in. */ 179 name = fp_malloc(n + 1, M_WAITOK); 180 if (name != NULL) { 181 va_start(ap, fmt); 182 vsnprintf(name, n + 1, fmt, ap); 183 va_end(ap); 184 } 185 fp->fp_name = name; 186 fp->fp_location = ""; 187 fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME; 188 fp->fp_sleep_fn = NULL; 189 fp->fp_sleep_arg = NULL; 190 } 191 192 /** 193 * Free the resources held by a fail_point. 194 * 195 * @ingroup failpoint 196 */ 197 void 198 fail_point_destroy(struct fail_point *fp) 199 { 200 201 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) { 202 fp_free(__DECONST(void *, fp->fp_name)); 203 fp->fp_name = NULL; 204 } 205 fp->fp_flags = 0; 206 clear_entries(&fp->fp_entries); 207 } 208 209 /** 210 * This does the real work of evaluating a fail point. If the fail point tells 211 * us to return a value, this function returns 1 and fills in 'return_value' 212 * (return_value is allowed to be null). If the fail point tells us to panic, 213 * we never return. Otherwise we just return 0 after doing some work, which 214 * means "keep going". 215 */ 216 enum fail_point_return_code 217 fail_point_eval_nontrivial(struct fail_point *fp, int *return_value) 218 { 219 enum fail_point_return_code ret = FAIL_POINT_RC_CONTINUE; 220 struct fail_point_entry *ent, *next; 221 int msecs; 222 223 FP_LOCK(); 224 225 TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, next) { 226 int cont = 0; /* don't continue by default */ 227 228 if (ent->fe_prob < PROB_MAX && 229 ent->fe_prob < random() % PROB_MAX) 230 continue; 231 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid) 232 continue; 233 234 switch (ent->fe_type) { 235 case FAIL_POINT_PANIC: 236 panic("fail point %s panicking", fp->fp_name); 237 /* NOTREACHED */ 238 239 case FAIL_POINT_RETURN: 240 if (return_value != NULL) 241 *return_value = ent->fe_arg; 242 ret = FAIL_POINT_RC_RETURN; 243 break; 244 245 case FAIL_POINT_BREAK: 246 printf("fail point %s breaking to debugger\n", 247 fp->fp_name); 248 breakpoint(); 249 break; 250 251 case FAIL_POINT_PRINT: 252 printf("fail point %s executing\n", fp->fp_name); 253 cont = ent->fe_arg; 254 break; 255 256 case FAIL_POINT_SLEEP: 257 /* 258 * Free the entry now if necessary, since 259 * we're about to drop the mutex and sleep. 260 */ 261 msecs = ent->fe_arg; 262 if (ent->fe_count > 0 && --ent->fe_count == 0) { 263 free_entry(&fp->fp_entries, ent); 264 ent = NULL; 265 } 266 267 if (msecs) 268 fail_point_sleep(fp, ent, msecs, &ret); 269 break; 270 271 default: 272 break; 273 } 274 275 if (ent != NULL && ent->fe_count > 0 && --ent->fe_count == 0) 276 free_entry(&fp->fp_entries, ent); 277 if (cont == 0) 278 break; 279 } 280 281 /* Get rid of "off"s at the end. */ 282 while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) && 283 ent->fe_type == FAIL_POINT_OFF) 284 free_entry(&fp->fp_entries, ent); 285 286 FP_UNLOCK(); 287 288 return (ret); 289 } 290 291 /** 292 * Translate internal fail_point structure into human-readable text. 293 */ 294 static void 295 fail_point_get(struct fail_point *fp, struct sbuf *sb) 296 { 297 struct fail_point_entry *ent; 298 299 FP_LOCK(); 300 301 TAILQ_FOREACH(ent, &fp->fp_entries, fe_entries) { 302 if (ent->fe_prob < PROB_MAX) { 303 int decimal = ent->fe_prob % (PROB_MAX / 100); 304 int units = ent->fe_prob / (PROB_MAX / 100); 305 sbuf_printf(sb, "%d", units); 306 if (decimal) { 307 int digits = PROB_DIGITS - 2; 308 while (!(decimal % 10)) { 309 digits--; 310 decimal /= 10; 311 } 312 sbuf_printf(sb, ".%0*d", digits, decimal); 313 } 314 sbuf_printf(sb, "%%"); 315 } 316 if (ent->fe_count > 0) 317 sbuf_printf(sb, "%d*", ent->fe_count); 318 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name); 319 if (ent->fe_arg) 320 sbuf_printf(sb, "(%d)", ent->fe_arg); 321 if (ent->fe_pid != NO_PID) 322 sbuf_printf(sb, "[pid %d]", ent->fe_pid); 323 if (TAILQ_NEXT(ent, fe_entries)) 324 sbuf_printf(sb, "->"); 325 } 326 if (TAILQ_EMPTY(&fp->fp_entries)) 327 sbuf_printf(sb, "off"); 328 329 FP_UNLOCK(); 330 } 331 332 /** 333 * Set an internal fail_point structure from a human-readable failpoint string 334 * in a lock-safe manner. 335 */ 336 static int 337 fail_point_set(struct fail_point *fp, char *buf) 338 { 339 int error = 0; 340 struct fail_point_entry *ent, *ent_next; 341 struct fail_point_entries new_entries; 342 343 /* Parse new entries. */ 344 TAILQ_INIT(&new_entries); 345 if (!parse_fail_point(&new_entries, buf)) { 346 clear_entries(&new_entries); 347 error = EINVAL; 348 goto end; 349 } 350 351 FP_LOCK(); 352 353 /* Move new entries in. */ 354 TAILQ_SWAP(&fp->fp_entries, &new_entries, fail_point_entry, fe_entries); 355 clear_entries(&new_entries); 356 357 /* Get rid of useless zero probability entries. */ 358 TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, ent_next) { 359 if (ent->fe_prob == 0) 360 free_entry(&fp->fp_entries, ent); 361 } 362 363 /* Get rid of "off"s at the end. */ 364 while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) && 365 ent->fe_type == FAIL_POINT_OFF) 366 free_entry(&fp->fp_entries, ent); 367 368 FP_UNLOCK(); 369 370 end: 371 #ifdef IWARNING 372 if (error) 373 IWARNING("Failed to set %s %s to %s", 374 fp->fp_name, fp->fp_location, buf); 375 else 376 INOTICE("Set %s %s to %s", 377 fp->fp_name, fp->fp_location, buf); 378 #endif /* IWARNING */ 379 380 return (error); 381 } 382 383 #define MAX_FAIL_POINT_BUF 1023 384 385 /** 386 * Handle kernel failpoint set/get. 387 */ 388 int 389 fail_point_sysctl(SYSCTL_HANDLER_ARGS) 390 { 391 struct fail_point *fp = arg1; 392 char *buf = NULL; 393 struct sbuf sb; 394 int error; 395 396 /* Retrieving */ 397 sbuf_new_for_sysctl(&sb, NULL, 128, req); 398 fail_point_get(fp, &sb); 399 sbuf_trim(&sb); 400 error = sbuf_finish(&sb); 401 sbuf_delete(&sb); 402 403 /* Setting */ 404 if (!error && req->newptr) { 405 if (req->newlen > MAX_FAIL_POINT_BUF) { 406 error = EINVAL; 407 goto out; 408 } 409 410 buf = fp_malloc(req->newlen + 1, M_WAITOK); 411 412 error = SYSCTL_IN(req, buf, req->newlen); 413 if (error) 414 goto out; 415 buf[req->newlen] = '\0'; 416 417 error = fail_point_set(fp, buf); 418 } 419 420 out: 421 fp_free(buf); 422 return (error); 423 } 424 425 /** 426 * Internal helper function to translate a human-readable failpoint string 427 * into a internally-parsable fail_point structure. 428 */ 429 static char * 430 parse_fail_point(struct fail_point_entries *ents, char *p) 431 { 432 /* <fail_point> :: 433 * <term> ( "->" <term> )* 434 */ 435 p = parse_term(ents, p); 436 if (p == NULL) 437 return (NULL); 438 while (*p != '\0') { 439 if (p[0] != '-' || p[1] != '>') 440 return (NULL); 441 p = parse_term(ents, p + 2); 442 if (p == NULL) 443 return (NULL); 444 } 445 return (p); 446 } 447 448 /** 449 * Internal helper function to parse an individual term from a failpoint. 450 */ 451 static char * 452 parse_term(struct fail_point_entries *ents, char *p) 453 { 454 struct fail_point_entry *ent; 455 456 ent = fp_malloc(sizeof *ent, M_WAITOK | M_ZERO); 457 ent->fe_prob = PROB_MAX; 458 ent->fe_pid = NO_PID; 459 TAILQ_INSERT_TAIL(ents, ent, fe_entries); 460 461 /* 462 * <term> :: 463 * ( (<float> "%") | (<integer> "*" ) )* 464 * <type> 465 * [ "(" <integer> ")" ] 466 * [ "[pid " <integer> "]" ] 467 */ 468 469 /* ( (<float> "%") | (<integer> "*" ) )* */ 470 while (isdigit(*p) || *p == '.') { 471 int units, decimal; 472 473 p = parse_number(&units, &decimal, p); 474 if (p == NULL) 475 return (NULL); 476 477 if (*p == '%') { 478 if (units > 100) /* prevent overflow early */ 479 units = 100; 480 ent->fe_prob = units * (PROB_MAX / 100) + decimal; 481 if (ent->fe_prob > PROB_MAX) 482 ent->fe_prob = PROB_MAX; 483 } else if (*p == '*') { 484 if (!units || decimal) 485 return (NULL); 486 ent->fe_count = units; 487 } else 488 return (NULL); 489 p++; 490 } 491 492 /* <type> */ 493 p = parse_type(ent, p); 494 if (p == NULL) 495 return (NULL); 496 if (*p == '\0') 497 return (p); 498 499 /* [ "(" <integer> ")" ] */ 500 if (*p != '(') 501 return p; 502 p++; 503 if (!isdigit(*p) && *p != '-') 504 return (NULL); 505 ent->fe_arg = strtol(p, &p, 0); 506 if (*p++ != ')') 507 return (NULL); 508 509 /* [ "[pid " <integer> "]" ] */ 510 #define PID_STRING "[pid " 511 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0) 512 return (p); 513 p += sizeof(PID_STRING) - 1; 514 if (!isdigit(*p)) 515 return (NULL); 516 ent->fe_pid = strtol(p, &p, 0); 517 if (*p++ != ']') 518 return (NULL); 519 520 return (p); 521 } 522 523 /** 524 * Internal helper function to parse a numeric for a failpoint term. 525 */ 526 static char * 527 parse_number(int *out_units, int *out_decimal, char *p) 528 { 529 char *old_p; 530 531 /* 532 * <number> :: 533 * <integer> [ "." <integer> ] | 534 * "." <integer> 535 */ 536 537 /* whole part */ 538 old_p = p; 539 *out_units = strtol(p, &p, 10); 540 if (p == old_p && *p != '.') 541 return (NULL); 542 543 /* fractional part */ 544 *out_decimal = 0; 545 if (*p == '.') { 546 int digits = 0; 547 p++; 548 while (isdigit(*p)) { 549 int digit = *p - '0'; 550 if (digits < PROB_DIGITS - 2) 551 *out_decimal = *out_decimal * 10 + digit; 552 else if (digits == PROB_DIGITS - 2 && digit >= 5) 553 (*out_decimal)++; 554 digits++; 555 p++; 556 } 557 if (!digits) /* need at least one digit after '.' */ 558 return (NULL); 559 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */ 560 *out_decimal *= 10; 561 } 562 563 return (p); /* success */ 564 } 565 566 /** 567 * Internal helper function to parse an individual type for a failpoint term. 568 */ 569 static char * 570 parse_type(struct fail_point_entry *ent, char *beg) 571 { 572 enum fail_point_t type; 573 int len; 574 575 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) { 576 len = fail_type_strings[type].nmlen; 577 if (strncmp(fail_type_strings[type].name, beg, len) == 0) { 578 ent->fe_type = type; 579 return (beg + len); 580 } 581 } 582 return (NULL); 583 } 584 585 /** 586 * Internal helper function to free an individual failpoint term. 587 */ 588 static void 589 free_entry(struct fail_point_entries *ents, struct fail_point_entry *ent) 590 { 591 TAILQ_REMOVE(ents, ent, fe_entries); 592 fp_free(ent); 593 } 594 595 /** 596 * Internal helper function to clear out all failpoint terms for a single 597 * failpoint. 598 */ 599 static void 600 clear_entries(struct fail_point_entries *ents) 601 { 602 struct fail_point_entry *ent, *ent_next; 603 604 TAILQ_FOREACH_SAFE(ent, ents, fe_entries, ent_next) 605 fp_free(ent); 606 TAILQ_INIT(ents); 607 } 608 609 /* The fail point sysctl tree. */ 610 SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW, 0, "fail points"); 611