diff options
Diffstat (limited to 'sys/kern/kern_fail.c')
| -rw-r--r-- | sys/kern/kern_fail.c | 611 |
1 files changed, 611 insertions, 0 deletions
diff --git a/sys/kern/kern_fail.c b/sys/kern/kern_fail.c new file mode 100644 index 0000000..85d81e8 --- /dev/null +++ b/sys/kern/kern_fail.c @@ -0,0 +1,611 @@ +/*- + * 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 <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include <sys/ctype.h> +#include <sys/errno.h> +#include <sys/fail.h> +#include <sys/kernel.h> +#include <sys/libkern.h> +#include <sys/lock.h> +#include <sys/malloc.h> +#include <sys/mutex.h> +#include <sys/proc.h> +#include <sys/sbuf.h> + +#include <machine/stdarg.h> + +#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) +{ + /* <fail_point> :: + * <term> ( "->" <term> )* + */ + 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); + + /* + * <term> :: + * ( (<float> "%") | (<integer> "*" ) )* + * <type> + * [ "(" <integer> ")" ] + * [ "[pid " <integer> "]" ] + */ + + /* ( (<float> "%") | (<integer> "*" ) )* */ + 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++; + } + + /* <type> */ + p = parse_type(ent, p); + if (p == NULL) + return (NULL); + if (*p == '\0') + return (p); + + /* [ "(" <integer> ")" ] */ + if (*p != '(') + return p; + p++; + if (!isdigit(*p) && *p != '-') + return (NULL); + ent->fe_arg = strtol(p, &p, 0); + if (*p++ != ')') + return (NULL); + + /* [ "[pid " <integer> "]" ] */ +#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; + + /* + * <number> :: + * <integer> [ "." <integer> ] | + * "." <integer> + */ + + /* 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"); |
