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/*-
* 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: release/9.1.0/sys/kern/kern_fail.c 223876 2011-07-08 20:41:12Z mdf $");
#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
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");