/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* 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 "opt_stack.h"
#include <sys/ctype.h>
#include <sys/errno.h>
#include <sys/fail.h>
#include <sys/kernel.h>
#include <sys/libkern.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sbuf.h>
#include <sys/sleepqueue.h>
#include <sys/sx.h>
#include <sys/sysctl.h>
#include <sys/types.h>
#include <machine/atomic.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))
#define fs_free(ptr) fp_free(ptr)
#define fs_malloc() fp_malloc(sizeof(struct fail_point_setting), \
M_WAITOK | M_ZERO)
/**
* These define the wchans that are used for sleeping, pausing respectively.
* They are chosen arbitrarily but need to be distinct to the failpoint and
* the sleep/pause distinction.
*/
#define FP_SLEEP_CHANNEL(fp) (void*)(fp)
#define FP_PAUSE_CHANNEL(fp) __DEVOLATILE(void*, &fp->fp_setting)
/**
* Don't allow more than this many entries in a fail point set by sysctl.
* The 99.99...% case is to have 1 entry. I can't imagine having this many
* entries, so it should not limit us. Saves on re-mallocs while holding
* a non-sleepable lock.
*/
#define FP_MAX_ENTRY_COUNT 20
/* Used to drain sbufs to the sysctl output */
int fail_sysctl_drain_func(void *, const char *, int);
/* Head of tailq of struct fail_point_entry */
TAILQ_HEAD(fail_point_entry_queue, fail_point_entry);
/**
* fp entries garbage list; outstanding entries are cleaned up in the
* garbage collector
*/
STAILQ_HEAD(fail_point_setting_garbage, fail_point_setting);
static struct fail_point_setting_garbage fp_setting_garbage =
STAILQ_HEAD_INITIALIZER(fp_setting_garbage);
static struct mtx mtx_garbage_list;
MTX_SYSINIT(mtx_garbage_list, &mtx_garbage_list, "fail point garbage mtx",
MTX_SPIN);
static struct sx sx_fp_set;
SX_SYSINIT(sx_fp_set, &sx_fp_set, "fail point set sx");
/**
* 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_PAUSE, /**< sleep until failpoint is set to off */
FAIL_POINT_YIELD, /**< yield the cpu */
FAIL_POINT_DELAY, /**< busy wait the cpu */
FAIL_POINT_NUMTYPES,
FAIL_POINT_INVALID = -1
};
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"),
[FAIL_POINT_PAUSE] = FP_TYPE_NM_LEN("pause"),
[FAIL_POINT_YIELD] = FP_TYPE_NM_LEN("yield"),
[FAIL_POINT_DELAY] = FP_TYPE_NM_LEN("delay"),
};
#define FE_COUNT_UNTRACKED (INT_MIN)
/**
* Internal structure tracking a single term of a complete failpoint.
* @ingroup failpoint_private
*/
struct fail_point_entry {
volatile bool fe_stale;
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 */
int32_t fe_count; /**< number of times to fire, -1 means infinite */
pid_t fe_pid; /**< only fail for this process */
struct fail_point *fe_parent; /**< backpointer to fp */
TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry ptr */
};
struct fail_point_setting {
STAILQ_ENTRY(fail_point_setting) fs_garbage_link;
struct fail_point_entry_queue fp_entry_queue;
struct fail_point * fs_parent;
struct mtx feq_mtx; /* Gives fail_point_pause something to do. */
};
/**
* 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 */
};
/* Get a ref on an fp's fp_setting */
static inline struct fail_point_setting *fail_point_setting_get_ref(
struct fail_point *fp);
/* Release a ref on an fp_setting */
static inline void fail_point_setting_release_ref(struct fail_point *fp);
/* Allocate and initialize a struct fail_point_setting */
static struct fail_point_setting *fail_point_setting_new(struct
fail_point *);
/* Free a struct fail_point_setting */
static void fail_point_setting_destroy(struct fail_point_setting *fp_setting);
/* Allocate and initialize a struct fail_point_entry */
static struct fail_point_entry *fail_point_entry_new(struct
fail_point_setting *);
/* Free a struct fail_point_entry */
static void fail_point_entry_destroy(struct fail_point_entry *fp_entry);
/* Append fp setting to garbage list */
static inline void fail_point_setting_garbage_append(
struct fail_point_setting *fp_setting);
/* Swap fp's setting with fp_setting_new */
static inline struct fail_point_setting *
fail_point_swap_settings(struct fail_point *fp,
struct fail_point_setting *fp_setting_new);
/* Free up any zero-ref setting in the garbage queue */
static void fail_point_garbage_collect(void);
/* If this fail point's setting are empty, then swap it out to NULL. */
static inline void fail_point_eval_swap_out(struct fail_point *fp,
struct fail_point_setting *fp_setting);
bool
fail_point_is_off(struct fail_point *fp)
{
bool return_val;
struct fail_point_setting *fp_setting;
struct fail_point_entry *ent;
return_val = true;
fp_setting = fail_point_setting_get_ref(fp);
if (fp_setting != NULL) {
TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue,
fe_entries) {
if (!ent->fe_stale) {
return_val = false;
break;
}
}
}
fail_point_setting_release_ref(fp);
return (return_val);
}
/* Allocate and initialize a struct fail_point_setting */
static struct fail_point_setting *
fail_point_setting_new(struct fail_point *fp)
{
struct fail_point_setting *fs_new;
fs_new = fs_malloc();
fs_new->fs_parent = fp;
TAILQ_INIT(&fs_new->fp_entry_queue);
mtx_init(&fs_new->feq_mtx, "fail point entries", NULL, MTX_SPIN);
fail_point_setting_garbage_append(fs_new);
return (fs_new);
}
/* Free a struct fail_point_setting */
static void
fail_point_setting_destroy(struct fail_point_setting *fp_setting)
{
struct fail_point_entry *ent;
while (!TAILQ_EMPTY(&fp_setting->fp_entry_queue)) {
ent = TAILQ_FIRST(&fp_setting->fp_entry_queue);
TAILQ_REMOVE(&fp_setting->fp_entry_queue, ent, fe_entries);
fail_point_entry_destroy(ent);
}
fs_free(fp_setting);
}
/* Allocate and initialize a struct fail_point_entry */
static struct fail_point_entry *
fail_point_entry_new(struct fail_point_setting *fp_setting)
{
struct fail_point_entry *fp_entry;
fp_entry = fp_malloc(sizeof(struct fail_point_entry),
M_WAITOK | M_ZERO);
fp_entry->fe_parent = fp_setting->fs_parent;
fp_entry->fe_prob = PROB_MAX;
fp_entry->fe_pid = NO_PID;
fp_entry->fe_count = FE_COUNT_UNTRACKED;
TAILQ_INSERT_TAIL(&fp_setting->fp_entry_queue, fp_entry,
fe_entries);
return (fp_entry);
}
/* Free a struct fail_point_entry */
static void
fail_point_entry_destroy(struct fail_point_entry *fp_entry)
{
fp_free(fp_entry);
}
/* Get a ref on an fp's fp_setting */
static inline struct fail_point_setting *
fail_point_setting_get_ref(struct fail_point *fp)
{
struct fail_point_setting *fp_setting;
/* Invariant: if we have a ref, our pointer to fp_setting is safe */
atomic_add_acq_32(&fp->fp_ref_cnt, 1);
fp_setting = fp->fp_setting;
return (fp_setting);
}
/* Release a ref on an fp_setting */
static inline void
fail_point_setting_release_ref(struct fail_point *fp)
{
KASSERT(&fp->fp_ref_cnt > 0, ("Attempting to deref w/no refs"));
atomic_subtract_rel_32(&fp->fp_ref_cnt, 1);
}
/* Append fp entries to fp garbage list */
static inline void
fail_point_setting_garbage_append(struct fail_point_setting *fp_setting)
{
mtx_lock_spin(&mtx_garbage_list);
STAILQ_INSERT_TAIL(&fp_setting_garbage, fp_setting,
fs_garbage_link);
mtx_unlock_spin(&mtx_garbage_list);
}
/* Swap fp's entries with fp_setting_new */
static struct fail_point_setting *
fail_point_swap_settings(struct fail_point *fp,
struct fail_point_setting *fp_setting_new)
{
struct fail_point_setting *fp_setting_old;
fp_setting_old = fp->fp_setting;
fp->fp_setting = fp_setting_new;
return (fp_setting_old);
}
static inline void
fail_point_eval_swap_out(struct fail_point *fp,
struct fail_point_setting *fp_setting)
{
/* We may have already been swapped out and replaced; ignore. */
if (fp->fp_setting == fp_setting)
fail_point_swap_settings(fp, NULL);
}
/* Free up any zero-ref entries in the garbage queue */
static void
fail_point_garbage_collect(void)
{
struct fail_point_setting *fs_current, *fs_next;
struct fail_point_setting_garbage fp_ents_free_list;
/**
* We will transfer the entries to free to fp_ents_free_list while holding
* the spin mutex, then free it after we drop the lock. This avoids
* triggering witness due to sleepable mutexes in the memory
* allocator.
*/
STAILQ_INIT(&fp_ents_free_list);
mtx_lock_spin(&mtx_garbage_list);
STAILQ_FOREACH_SAFE(fs_current, &fp_setting_garbage, fs_garbage_link,
fs_next) {
if (fs_current->fs_parent->fp_setting != fs_current &&
fs_current->fs_parent->fp_ref_cnt == 0) {
STAILQ_REMOVE(&fp_setting_garbage, fs_current,
fail_point_setting, fs_garbage_link);
STAILQ_INSERT_HEAD(&fp_ents_free_list, fs_current,
fs_garbage_link);
}
}
mtx_unlock_spin(&mtx_garbage_list);
STAILQ_FOREACH_SAFE(fs_current, &fp_ents_free_list, fs_garbage_link,
fs_next)
fail_point_setting_destroy(fs_current);
}
/* Drain out all refs from this fail point */
static inline void
fail_point_drain(struct fail_point *fp, int expected_ref)
{
struct fail_point_setting *entries;
entries = fail_point_swap_settings(fp, NULL);
/**
* We have unpaused all threads; so we will wait no longer
* than the time taken for the longest remaining sleep, or
* the length of time of a long-running code block.
*/
while (fp->fp_ref_cnt > expected_ref) {
wakeup(FP_PAUSE_CHANNEL(fp));
tsleep(&fp, PWAIT, "fail_point_drain", hz / 100);
}
if (fp->fp_callout)
callout_drain(fp->fp_callout);
fail_point_swap_settings(fp, entries);
}
static inline void
fail_point_pause(struct fail_point *fp, enum fail_point_return_code *pret,
struct mtx *mtx_sleep)
{
if (fp->fp_pre_sleep_fn)
fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
msleep_spin(FP_PAUSE_CHANNEL(fp), mtx_sleep, "failpt", 0);
if (fp->fp_post_sleep_fn)
fp->fp_post_sleep_fn(fp->fp_post_sleep_arg);
}
static inline void
fail_point_sleep(struct fail_point *fp, int msecs,
enum fail_point_return_code *pret)
{
int timo;
/* Convert from millisecs to ticks, rounding up */
timo = howmany((int64_t)msecs * hz, 1000L);
if (timo > 0) {
if (!(fp->fp_flags & FAIL_POINT_USE_TIMEOUT_PATH)) {
if (fp->fp_pre_sleep_fn)
fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
tsleep(FP_SLEEP_CHANNEL(fp), PWAIT, "failpt", timo);
if (fp->fp_post_sleep_fn)
fp->fp_post_sleep_fn(fp->fp_post_sleep_arg);
} else {
if (fp->fp_pre_sleep_fn)
fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
callout_reset(fp->fp_callout, timo,
fp->fp_post_sleep_fn, fp->fp_post_sleep_arg);
*pret = FAIL_POINT_RC_QUEUED;
}
}
}
static char *parse_fail_point(struct fail_point_setting *, char *);
static char *parse_term(struct fail_point_setting *, char *);
static char *parse_number(int *out_units, int *out_decimal, char *);
static char *parse_type(struct fail_point_entry *, char *);
/**
* 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;
fp->fp_setting = NULL;
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_pre_sleep_fn = NULL;
fp->fp_pre_sleep_arg = NULL;
fp->fp_post_sleep_fn = NULL;
fp->fp_post_sleep_arg = NULL;
}
void
fail_point_alloc_callout(struct fail_point *fp)
{
/**
* This assumes that calls to fail_point_use_timeout_path()
* will not race.
*/
if (fp->fp_callout != NULL)
return;
fp->fp_callout = fp_malloc(sizeof(*fp->fp_callout), M_WAITOK);
callout_init(fp->fp_callout, CALLOUT_MPSAFE);
}
/**
* Free the resources held by a fail_point, and wake any paused threads.
* Thou shalt not allow threads to hit this fail point after you enter this
* function, nor shall you call this multiple times for a given fp.
* @ingroup failpoint
*/
void
fail_point_destroy(struct fail_point *fp)
{
fail_point_drain(fp, 0);
if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) {
fp_free(__DECONST(void *, fp->fp_name));
fp->fp_name = NULL;
}
fp->fp_flags = 0;
if (fp->fp_callout) {
fp_free(fp->fp_callout);
fp->fp_callout = NULL;
}
sx_xlock(&sx_fp_set);
fail_point_garbage_collect();
sx_xunlock(&sx_fp_set);
}
/**
* 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)
{
bool execute = false;
struct fail_point_entry *ent;
struct fail_point_setting *fp_setting;
enum fail_point_return_code ret;
int cont;
int count;
int msecs;
int usecs;
ret = FAIL_POINT_RC_CONTINUE;
cont = 0; /* don't continue by default */
fp_setting = fail_point_setting_get_ref(fp);
if (fp_setting == NULL)
goto abort;
TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) {
if (ent->fe_stale)
continue;
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;
if (ent->fe_count != FE_COUNT_UNTRACKED) {
count = ent->fe_count;
while (count > 0) {
if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) {
count--;
execute = true;
break;
}
count = ent->fe_count;
}
if (execute == false)
/* We lost the race; consider the entry stale and bail now */
continue;
if (count == 0)
ent->fe_stale = true;
}
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:
msecs = ent->fe_arg;
if (msecs)
fail_point_sleep(fp, msecs, &ret);
break;
case FAIL_POINT_PAUSE:
/**
* Pausing is inherently strange with multiple
* entries given our design. That is because some
* entries could be unreachable, for instance in cases like:
* pause->return. We can never reach the return entry.
* The sysctl layer actually truncates all entries after
* a pause for this reason.
*/
mtx_lock_spin(&fp_setting->feq_mtx);
fail_point_pause(fp, &ret, &fp_setting->feq_mtx);
mtx_unlock_spin(&fp_setting->feq_mtx);
break;
case FAIL_POINT_YIELD:
kern_yield(PRI_UNCHANGED);
break;
case FAIL_POINT_DELAY:
usecs = ent->fe_arg;
DELAY(usecs);
break;
default:
break;
}
if (cont == 0)
break;
}
if (fail_point_is_off(fp))
fail_point_eval_swap_out(fp, fp_setting);
abort:
fail_point_setting_release_ref(fp);
return (ret);
}
/**
* Translate internal fail_point structure into human-readable text.
*/
static void
fail_point_get(struct fail_point *fp, struct sbuf *sb,
bool verbose)
{
struct fail_point_entry *ent;
struct fail_point_setting *fp_setting;
struct fail_point_entry *fp_entry_cpy;
int cnt_sleeping;
int idx;
int printed_entry_count;
cnt_sleeping = 0;
idx = 0;
printed_entry_count = 0;
fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) *
(FP_MAX_ENTRY_COUNT + 1), M_WAITOK);
fp_setting = fail_point_setting_get_ref(fp);
if (fp_setting != NULL) {
TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) {
if (ent->fe_stale)
continue;
KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT,
("FP entry list larger than allowed"));
fp_entry_cpy[printed_entry_count] = *ent;
++printed_entry_count;
}
}
fail_point_setting_release_ref(fp);
/* This is our equivalent of a NULL terminator */
fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID;
while (idx < printed_entry_count) {
ent = &fp_entry_cpy[idx];
++idx;
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 (!printed_entry_count)
sbuf_printf(sb, "off");
fp_free(fp_entry_cpy);
if (verbose) {
#ifdef STACK
/* Print number of sleeping threads. queue=0 is the argument
* used by msleep when sending our threads to sleep. */
sbuf_printf(sb, "\nsleeping_thread_stacks = {\n");
sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0,
&cnt_sleeping);
sbuf_printf(sb, "},\n");
#endif
sbuf_printf(sb, "sleeping_thread_count = %d,\n",
cnt_sleeping);
#ifdef STACK
sbuf_printf(sb, "paused_thread_stacks = {\n");
sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0,
&cnt_sleeping);
sbuf_printf(sb, "},\n");
#endif
sbuf_printf(sb, "paused_thread_count = %d\n",
cnt_sleeping);
}
}
/**
* 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)
{
struct fail_point_entry *ent, *ent_next;
struct fail_point_setting *entries;
bool should_wake_paused;
bool should_truncate;
int error;
error = 0;
should_wake_paused = false;
should_truncate = false;
/* Parse new entries. */
/**
* ref protects our new malloc'd stuff from being garbage collected
* before we link it.
*/
fail_point_setting_get_ref(fp);
entries = fail_point_setting_new(fp);
if (parse_fail_point(entries, buf) == NULL) {
STAILQ_REMOVE(&fp_setting_garbage, entries,
fail_point_setting, fs_garbage_link);
fail_point_setting_destroy(entries);
error = EINVAL;
goto end;
}
/**
* Transfer the entries we are going to keep to a new list.
* Get rid of useless zero probability entries, and entries with hit
* count 0.
* If 'off' is present, and it has no hit count set, then all entries
* after it are discarded since they are unreachable.
*/
TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) {
if (ent->fe_prob == 0 || ent->fe_count == 0) {
printf("Discarding entry which cannot execute %s\n",
fail_type_strings[ent->fe_type].name);
TAILQ_REMOVE(&entries->fp_entry_queue, ent,
fe_entries);
fp_free(ent);
continue;
} else if (should_truncate) {
printf("Discarding unreachable entry %s\n",
fail_type_strings[ent->fe_type].name);
TAILQ_REMOVE(&entries->fp_entry_queue, ent,
fe_entries);
fp_free(ent);
continue;
}
if (ent->fe_type == FAIL_POINT_OFF) {
should_wake_paused = true;
if (ent->fe_count == FE_COUNT_UNTRACKED) {
should_truncate = true;
TAILQ_REMOVE(&entries->fp_entry_queue, ent,
fe_entries);
fp_free(ent);
}
} else if (ent->fe_type == FAIL_POINT_PAUSE) {
should_truncate = true;
} else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags &
FAIL_POINT_NONSLEEPABLE)) {
/**
* If this fail point is annotated as being in a
* non-sleepable ctx, convert sleep to delay and
* convert the msec argument to usecs.
*/
printf("Sleep call request on fail point in "
"non-sleepable context; using delay instead "
"of sleep\n");
ent->fe_type = FAIL_POINT_DELAY;
ent->fe_arg *= 1000;
}
}
if (TAILQ_EMPTY(&entries->fp_entry_queue)) {
entries = fail_point_swap_settings(fp, NULL);
if (entries != NULL)
wakeup(FP_PAUSE_CHANNEL(fp));
} else {
if (should_wake_paused)
wakeup(FP_PAUSE_CHANNEL(fp));
fail_point_swap_settings(fp, entries);
}
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 */
fail_point_setting_release_ref(fp);
return (error);
}
#define MAX_FAIL_POINT_BUF 1023
/**
* Handle kernel failpoint set/get.
*/
int
fail_point_sysctl(SYSCTL_HANDLER_ARGS)
{
struct fail_point *fp;
char *buf;
struct sbuf sb, *sb_check;
int error;
buf = NULL;
error = 0;
fp = arg1;
sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND);
if (sb_check != &sb)
return (ENOMEM);
sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req);
/* Setting */
/**
* Lock protects any new entries from being garbage collected before we
* can link them to the fail point.
*/
sx_xlock(&sx_fp_set);
if (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);
}
fail_point_garbage_collect();
sx_xunlock(&sx_fp_set);
/* Retrieving. */
fail_point_get(fp, &sb, false);
out:
sbuf_finish(&sb);
sbuf_delete(&sb);
if (buf)
fp_free(buf);
return (error);
}
int
fail_point_sysctl_status(SYSCTL_HANDLER_ARGS)
{
struct fail_point *fp;
struct sbuf sb, *sb_check;
fp = arg1;
sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND);
if (sb_check != &sb)
return (ENOMEM);
sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req);
/* Retrieving. */
fail_point_get(fp, &sb, true);
sbuf_finish(&sb);
sbuf_delete(&sb);
/**
* Lock protects any new entries from being garbage collected before we
* can link them to the fail point.
*/
sx_xlock(&sx_fp_set);
fail_point_garbage_collect();
sx_xunlock(&sx_fp_set);
return (0);
}
int
fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len)
{
struct sysctl_req *sa;
int error;
sa = sysctl_args;
error = SYSCTL_OUT(sa, buf, len);
if (error == ENOMEM)
return (-1);
else
return (len);
}
/**
* 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_setting *ents, char *p)
{
/* <fail_point> ::
* <term> ( "->" <term> )*
*/
uint8_t term_count;
term_count = 1;
p = parse_term(ents, p);
if (p == NULL)
return (NULL);
while (*p != '\0') {
term_count++;
if (p[0] != '-' || p[1] != '>' ||
(p = parse_term(ents, p+2)) == NULL ||
term_count > FP_MAX_ENTRY_COUNT)
return (NULL);
}
return (p);
}
/**
* Internal helper function to parse an individual term from a failpoint.
*/
static char *
parse_term(struct fail_point_setting *ents, char *p)
{
struct fail_point_entry *ent;
ent = fail_point_entry_new(ents);
/*
* <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 || units < 0 || 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);
}
/* The fail point sysctl tree. */
SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
"fail points");
/* Debugging/testing stuff for fail point */
static int
sysctl_test_fail_point(SYSCTL_HANDLER_ARGS)
{
KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point);
return (0);
}
SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point,
CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT, NULL, 0,
sysctl_test_fail_point, "A",
"Trigger test fail points");
