/*- * Copyright (c) 2009 Isilon Inc http://www.isilon.com/ * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /** * @file * * fail(9) Facility. * * @ingroup failpoint_private */ /** * @defgroup failpoint fail(9) Facility * * Failpoints allow for injecting fake errors into running code on the fly, * without modifying code or recompiling with flags. Failpoints are always * present, and are very efficient when disabled. Failpoints are described * in man fail(9). */ /** * @defgroup failpoint_private Private fail(9) Implementation functions * * Private implementations for the actual failpoint code. * * @ingroup failpoint */ /** * @addtogroup failpoint_private * @{ */ #include __FBSDID("$FreeBSD$"); #include #include #include #include #include #include #include #include #include #include #include #ifdef ILOG_DEFINE_FOR_FILE ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point); #endif static MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system"); #define fp_free(ptr) free(ptr, M_FAIL_POINT) #define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags)) static struct mtx g_fp_mtx; MTX_SYSINIT(g_fp_mtx, &g_fp_mtx, "fail point mtx", MTX_DEF); #define FP_LOCK() mtx_lock(&g_fp_mtx) #define FP_UNLOCK() mtx_unlock(&g_fp_mtx) /** * Failpoint types. * Don't change these without changing fail_type_strings in fail.c. * @ingroup failpoint_private */ enum fail_point_t { FAIL_POINT_OFF, /**< don't fail */ FAIL_POINT_PANIC, /**< panic */ FAIL_POINT_RETURN, /**< return an errorcode */ FAIL_POINT_BREAK, /**< break into the debugger */ FAIL_POINT_PRINT, /**< print a message */ FAIL_POINT_SLEEP, /**< sleep for some msecs */ FAIL_POINT_NUMTYPES }; static struct { const char *name; int nmlen; } fail_type_strings[] = { #define FP_TYPE_NM_LEN(s) { s, sizeof(s) - 1 } [FAIL_POINT_OFF] = FP_TYPE_NM_LEN("off"), [FAIL_POINT_PANIC] = FP_TYPE_NM_LEN("panic"), [FAIL_POINT_RETURN] = FP_TYPE_NM_LEN("return"), [FAIL_POINT_BREAK] = FP_TYPE_NM_LEN("break"), [FAIL_POINT_PRINT] = FP_TYPE_NM_LEN("print"), [FAIL_POINT_SLEEP] = FP_TYPE_NM_LEN("sleep"), }; /** * Internal structure tracking a single term of a complete failpoint. * @ingroup failpoint_private */ struct fail_point_entry { enum fail_point_t fe_type; /**< type of entry */ int fe_arg; /**< argument to type (e.g. return value) */ int fe_prob; /**< likelihood of firing in millionths */ int fe_count; /**< number of times to fire, 0 means always */ pid_t fe_pid; /**< only fail for this process */ TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry in fail point */ }; static inline void fail_point_sleep(struct fail_point *fp, struct fail_point_entry *ent, int msecs, enum fail_point_return_code *pret) { /* convert from millisecs to ticks, rounding up */ int timo = ((msecs * hz) + 999) / 1000; if (timo > 0) { if (fp->fp_sleep_fn == NULL) { msleep(fp, &g_fp_mtx, PWAIT, "failpt", timo); } else { timeout(fp->fp_sleep_fn, fp->fp_sleep_arg, timo); *pret = FAIL_POINT_RC_QUEUED; } } } /** * Defines stating the equivalent of probablilty one (100%) */ enum { PROB_MAX = 1000000, /* probability between zero and this number */ PROB_DIGITS = 6, /* number of zero's in above number */ }; static char *parse_fail_point(struct fail_point_entries *, char *); static char *parse_term(struct fail_point_entries *, char *); static char *parse_number(int *out_units, int *out_decimal, char *); static char *parse_type(struct fail_point_entry *, char *); static void free_entry(struct fail_point_entries *, struct fail_point_entry *); static void clear_entries(struct fail_point_entries *); /** * Initialize a fail_point. The name is formed in a printf-like fashion * from "fmt" and subsequent arguments. This function is generally used * for custom failpoints located at odd places in the sysctl tree, and is * not explicitly needed for standard in-line-declared failpoints. * * @ingroup failpoint */ void fail_point_init(struct fail_point *fp, const char *fmt, ...) { va_list ap; char *name; int n; TAILQ_INIT(&fp->fp_entries); fp->fp_flags = 0; /* Figure out the size of the name. */ va_start(ap, fmt); n = vsnprintf(NULL, 0, fmt, ap); va_end(ap); /* Allocate the name and fill it in. */ name = fp_malloc(n + 1, M_WAITOK); if (name != NULL) { va_start(ap, fmt); vsnprintf(name, n + 1, fmt, ap); va_end(ap); } fp->fp_name = name; fp->fp_location = ""; fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME; fp->fp_sleep_fn = NULL; fp->fp_sleep_arg = NULL; } /** * Free the resources held by a fail_point. * * @ingroup failpoint */ void fail_point_destroy(struct fail_point *fp) { if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) { fp_free(__DECONST(void *, fp->fp_name)); fp->fp_name = NULL; } fp->fp_flags = 0; clear_entries(&fp->fp_entries); } /** * This does the real work of evaluating a fail point. If the fail point tells * us to return a value, this function returns 1 and fills in 'return_value' * (return_value is allowed to be null). If the fail point tells us to panic, * we never return. Otherwise we just return 0 after doing some work, which * means "keep going". */ enum fail_point_return_code fail_point_eval_nontrivial(struct fail_point *fp, int *return_value) { enum fail_point_return_code ret = FAIL_POINT_RC_CONTINUE; struct fail_point_entry *ent, *next; int msecs; FP_LOCK(); TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, next) { int cont = 0; /* don't continue by default */ if (ent->fe_prob < PROB_MAX && ent->fe_prob < random() % PROB_MAX) continue; if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid) continue; switch (ent->fe_type) { case FAIL_POINT_PANIC: panic("fail point %s panicking", fp->fp_name); /* NOTREACHED */ case FAIL_POINT_RETURN: if (return_value != NULL) *return_value = ent->fe_arg; ret = FAIL_POINT_RC_RETURN; break; case FAIL_POINT_BREAK: printf("fail point %s breaking to debugger\n", fp->fp_name); breakpoint(); break; case FAIL_POINT_PRINT: printf("fail point %s executing\n", fp->fp_name); cont = ent->fe_arg; break; case FAIL_POINT_SLEEP: /* * Free the entry now if necessary, since * we're about to drop the mutex and sleep. */ msecs = ent->fe_arg; if (ent->fe_count > 0 && --ent->fe_count == 0) { free_entry(&fp->fp_entries, ent); ent = NULL; } if (msecs) fail_point_sleep(fp, ent, msecs, &ret); break; default: break; } if (ent != NULL && ent->fe_count > 0 && --ent->fe_count == 0) free_entry(&fp->fp_entries, ent); if (cont == 0) break; } /* Get rid of "off"s at the end. */ while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) && ent->fe_type == FAIL_POINT_OFF) free_entry(&fp->fp_entries, ent); FP_UNLOCK(); return (ret); } /** * Translate internal fail_point structure into human-readable text. */ static void fail_point_get(struct fail_point *fp, struct sbuf *sb) { struct fail_point_entry *ent; FP_LOCK(); TAILQ_FOREACH(ent, &fp->fp_entries, fe_entries) { if (ent->fe_prob < PROB_MAX) { int decimal = ent->fe_prob % (PROB_MAX / 100); int units = ent->fe_prob / (PROB_MAX / 100); sbuf_printf(sb, "%d", units); if (decimal) { int digits = PROB_DIGITS - 2; while (!(decimal % 10)) { digits--; decimal /= 10; } sbuf_printf(sb, ".%0*d", digits, decimal); } sbuf_printf(sb, "%%"); } if (ent->fe_count > 0) sbuf_printf(sb, "%d*", ent->fe_count); sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name); if (ent->fe_arg) sbuf_printf(sb, "(%d)", ent->fe_arg); if (ent->fe_pid != NO_PID) sbuf_printf(sb, "[pid %d]", ent->fe_pid); if (TAILQ_NEXT(ent, fe_entries)) sbuf_printf(sb, "->"); } if (TAILQ_EMPTY(&fp->fp_entries)) sbuf_printf(sb, "off"); FP_UNLOCK(); } /** * Set an internal fail_point structure from a human-readable failpoint string * in a lock-safe manner. */ static int fail_point_set(struct fail_point *fp, char *buf) { int error = 0; struct fail_point_entry *ent, *ent_next; struct fail_point_entries new_entries; /* Parse new entries. */ TAILQ_INIT(&new_entries); if (!parse_fail_point(&new_entries, buf)) { clear_entries(&new_entries); error = EINVAL; goto end; } FP_LOCK(); /* Move new entries in. */ TAILQ_SWAP(&fp->fp_entries, &new_entries, fail_point_entry, fe_entries); clear_entries(&new_entries); /* Get rid of useless zero probability entries. */ TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, ent_next) { if (ent->fe_prob == 0) free_entry(&fp->fp_entries, ent); } /* Get rid of "off"s at the end. */ while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) && ent->fe_type == FAIL_POINT_OFF) free_entry(&fp->fp_entries, ent); FP_UNLOCK(); end: #ifdef IWARNING if (error) IWARNING("Failed to set %s %s to %s", fp->fp_name, fp->fp_location, buf); else INOTICE("Set %s %s to %s", fp->fp_name, fp->fp_location, buf); #endif /* IWARNING */ return (error); } #define MAX_FAIL_POINT_BUF 1023 /** * Handle kernel failpoint set/get. */ int fail_point_sysctl(SYSCTL_HANDLER_ARGS) { struct fail_point *fp = arg1; char *buf = NULL; struct sbuf sb; int error; /* Retrieving */ sbuf_new(&sb, NULL, 128, SBUF_AUTOEXTEND); fail_point_get(fp, &sb); sbuf_trim(&sb); sbuf_finish(&sb); error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb)); sbuf_delete(&sb); /* Setting */ if (!error && req->newptr) { if (req->newlen > MAX_FAIL_POINT_BUF) { error = EINVAL; goto out; } buf = fp_malloc(req->newlen + 1, M_WAITOK); error = SYSCTL_IN(req, buf, req->newlen); if (error) goto out; buf[req->newlen] = '\0'; error = fail_point_set(fp, buf); } out: fp_free(buf); return (error); } /** * Internal helper function to translate a human-readable failpoint string * into a internally-parsable fail_point structure. */ static char * parse_fail_point(struct fail_point_entries *ents, char *p) { /* :: * ( "->" )* */ p = parse_term(ents, p); if (p == NULL) return (NULL); while (*p != '\0') { if (p[0] != '-' || p[1] != '>') return (NULL); p = parse_term(ents, p + 2); if (p == NULL) return (NULL); } return (p); } /** * Internal helper function to parse an individual term from a failpoint. */ static char * parse_term(struct fail_point_entries *ents, char *p) { struct fail_point_entry *ent; ent = fp_malloc(sizeof *ent, M_WAITOK | M_ZERO); ent->fe_prob = PROB_MAX; ent->fe_pid = NO_PID; TAILQ_INSERT_TAIL(ents, ent, fe_entries); /* * :: * ( ( "%") | ( "*" ) )* * * [ "(" ")" ] * [ "[pid " "]" ] */ /* ( ( "%") | ( "*" ) )* */ while (isdigit(*p) || *p == '.') { int units, decimal; p = parse_number(&units, &decimal, p); if (p == NULL) return (NULL); if (*p == '%') { if (units > 100) /* prevent overflow early */ units = 100; ent->fe_prob = units * (PROB_MAX / 100) + decimal; if (ent->fe_prob > PROB_MAX) ent->fe_prob = PROB_MAX; } else if (*p == '*') { if (!units || decimal) return (NULL); ent->fe_count = units; } else return (NULL); p++; } /* */ p = parse_type(ent, p); if (p == NULL) return (NULL); if (*p == '\0') return (p); /* [ "(" ")" ] */ if (*p != '(') return p; p++; if (!isdigit(*p) && *p != '-') return (NULL); ent->fe_arg = strtol(p, &p, 0); if (*p++ != ')') return (NULL); /* [ "[pid " "]" ] */ #define PID_STRING "[pid " if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0) return (p); p += sizeof(PID_STRING) - 1; if (!isdigit(*p)) return (NULL); ent->fe_pid = strtol(p, &p, 0); if (*p++ != ']') return (NULL); return (p); } /** * Internal helper function to parse a numeric for a failpoint term. */ static char * parse_number(int *out_units, int *out_decimal, char *p) { char *old_p; /* * :: * [ "." ] | * "." */ /* whole part */ old_p = p; *out_units = strtol(p, &p, 10); if (p == old_p && *p != '.') return (NULL); /* fractional part */ *out_decimal = 0; if (*p == '.') { int digits = 0; p++; while (isdigit(*p)) { int digit = *p - '0'; if (digits < PROB_DIGITS - 2) *out_decimal = *out_decimal * 10 + digit; else if (digits == PROB_DIGITS - 2 && digit >= 5) (*out_decimal)++; digits++; p++; } if (!digits) /* need at least one digit after '.' */ return (NULL); while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */ *out_decimal *= 10; } return (p); /* success */ } /** * Internal helper function to parse an individual type for a failpoint term. */ static char * parse_type(struct fail_point_entry *ent, char *beg) { enum fail_point_t type; int len; for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) { len = fail_type_strings[type].nmlen; if (strncmp(fail_type_strings[type].name, beg, len) == 0) { ent->fe_type = type; return (beg + len); } } return (NULL); } /** * Internal helper function to free an individual failpoint term. */ static void free_entry(struct fail_point_entries *ents, struct fail_point_entry *ent) { TAILQ_REMOVE(ents, ent, fe_entries); fp_free(ent); } /** * Internal helper function to clear out all failpoint terms for a single * failpoint. */ static void clear_entries(struct fail_point_entries *ents) { struct fail_point_entry *ent, *ent_next; TAILQ_FOREACH_SAFE(ent, ents, fe_entries, ent_next) fp_free(ent); TAILQ_INIT(ents); } /* The fail point sysctl tree. */ SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW, 0, "fail points");