1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2009 Isilon Inc http://www.isilon.com/
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27 /**
28 * @file
29 *
30 * fail(9) Facility.
31 *
32 * @ingroup failpoint_private
33 */
34 /**
35 * @defgroup failpoint fail(9) Facility
36 *
37 * Failpoints allow for injecting fake errors into running code on the fly,
38 * without modifying code or recompiling with flags. Failpoints are always
39 * present, and are very efficient when disabled. Failpoints are described
40 * in man fail(9).
41 */
42 /**
43 * @defgroup failpoint_private Private fail(9) Implementation functions
44 *
45 * Private implementations for the actual failpoint code.
46 *
47 * @ingroup failpoint
48 */
49 /**
50 * @addtogroup failpoint_private
51 * @{
52 */
53
54 #include <sys/cdefs.h>
55 #include "opt_stack.h"
56
57 #include <sys/ctype.h>
58 #include <sys/errno.h>
59 #include <sys/fail.h>
60 #include <sys/kernel.h>
61 #include <sys/libkern.h>
62 #include <sys/limits.h>
63 #include <sys/lock.h>
64 #include <sys/malloc.h>
65 #include <sys/mutex.h>
66 #include <sys/proc.h>
67 #include <sys/sbuf.h>
68 #include <sys/sleepqueue.h>
69 #include <sys/sx.h>
70 #include <sys/sysctl.h>
71 #include <sys/types.h>
72
73 #include <machine/atomic.h>
74 #include <machine/stdarg.h>
75
76 #ifdef ILOG_DEFINE_FOR_FILE
77 ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point);
78 #endif
79
80 static MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system");
81 #define fp_free(ptr) free(ptr, M_FAIL_POINT)
82 #define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags))
83 #define fs_free(ptr) fp_free(ptr)
84 #define fs_malloc() fp_malloc(sizeof(struct fail_point_setting), \
85 M_WAITOK | M_ZERO)
86
87 /**
88 * These define the wchans that are used for sleeping, pausing respectively.
89 * They are chosen arbitrarily but need to be distinct to the failpoint and
90 * the sleep/pause distinction.
91 */
92 #define FP_SLEEP_CHANNEL(fp) (void*)(fp)
93 #define FP_PAUSE_CHANNEL(fp) __DEVOLATILE(void*, &fp->fp_setting)
94
95 /**
96 * Don't allow more than this many entries in a fail point set by sysctl.
97 * The 99.99...% case is to have 1 entry. I can't imagine having this many
98 * entries, so it should not limit us. Saves on re-mallocs while holding
99 * a non-sleepable lock.
100 */
101 #define FP_MAX_ENTRY_COUNT 20
102
103 /* Used to drain sbufs to the sysctl output */
104 int fail_sysctl_drain_func(void *, const char *, int);
105
106 /* Head of tailq of struct fail_point_entry */
107 TAILQ_HEAD(fail_point_entry_queue, fail_point_entry);
108
109 /**
110 * fp entries garbage list; outstanding entries are cleaned up in the
111 * garbage collector
112 */
113 STAILQ_HEAD(fail_point_setting_garbage, fail_point_setting);
114 static struct fail_point_setting_garbage fp_setting_garbage =
115 STAILQ_HEAD_INITIALIZER(fp_setting_garbage);
116 static struct mtx mtx_garbage_list;
117 MTX_SYSINIT(mtx_garbage_list, &mtx_garbage_list, "fail point garbage mtx",
118 MTX_SPIN);
119
120 static struct sx sx_fp_set;
121 SX_SYSINIT(sx_fp_set, &sx_fp_set, "fail point set sx");
122
123 /**
124 * Failpoint types.
125 * Don't change these without changing fail_type_strings in fail.c.
126 * @ingroup failpoint_private
127 */
128 enum fail_point_t {
129 FAIL_POINT_OFF, /**< don't fail */
130 FAIL_POINT_PANIC, /**< panic */
131 FAIL_POINT_RETURN, /**< return an errorcode */
132 FAIL_POINT_BREAK, /**< break into the debugger */
133 FAIL_POINT_PRINT, /**< print a message */
134 FAIL_POINT_SLEEP, /**< sleep for some msecs */
135 FAIL_POINT_PAUSE, /**< sleep until failpoint is set to off */
136 FAIL_POINT_YIELD, /**< yield the cpu */
137 FAIL_POINT_DELAY, /**< busy wait the cpu */
138 FAIL_POINT_NUMTYPES,
139 FAIL_POINT_INVALID = -1
140 };
141
142 static struct {
143 const char *name;
144 int nmlen;
145 } fail_type_strings[] = {
146 #define FP_TYPE_NM_LEN(s) { s, sizeof(s) - 1 }
147 [FAIL_POINT_OFF] = FP_TYPE_NM_LEN("off"),
148 [FAIL_POINT_PANIC] = FP_TYPE_NM_LEN("panic"),
149 [FAIL_POINT_RETURN] = FP_TYPE_NM_LEN("return"),
150 [FAIL_POINT_BREAK] = FP_TYPE_NM_LEN("break"),
151 [FAIL_POINT_PRINT] = FP_TYPE_NM_LEN("print"),
152 [FAIL_POINT_SLEEP] = FP_TYPE_NM_LEN("sleep"),
153 [FAIL_POINT_PAUSE] = FP_TYPE_NM_LEN("pause"),
154 [FAIL_POINT_YIELD] = FP_TYPE_NM_LEN("yield"),
155 [FAIL_POINT_DELAY] = FP_TYPE_NM_LEN("delay"),
156 };
157
158 #define FE_COUNT_UNTRACKED (INT_MIN)
159
160 /**
161 * Internal structure tracking a single term of a complete failpoint.
162 * @ingroup failpoint_private
163 */
164 struct fail_point_entry {
165 volatile bool fe_stale;
166 enum fail_point_t fe_type; /**< type of entry */
167 int fe_arg; /**< argument to type (e.g. return value) */
168 int fe_prob; /**< likelihood of firing in millionths */
169 int32_t fe_count; /**< number of times to fire, -1 means infinite */
170 pid_t fe_pid; /**< only fail for this process */
171 struct fail_point *fe_parent; /**< backpointer to fp */
172 TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry ptr */
173 };
174
175 struct fail_point_setting {
176 STAILQ_ENTRY(fail_point_setting) fs_garbage_link;
177 struct fail_point_entry_queue fp_entry_queue;
178 struct fail_point * fs_parent;
179 struct mtx feq_mtx; /* Gives fail_point_pause something to do. */
180 };
181
182 /**
183 * Defines stating the equivalent of probablilty one (100%)
184 */
185 enum {
186 PROB_MAX = 1000000, /* probability between zero and this number */
187 PROB_DIGITS = 6 /* number of zero's in above number */
188 };
189
190 /* Get a ref on an fp's fp_setting */
191 static inline struct fail_point_setting *fail_point_setting_get_ref(
192 struct fail_point *fp);
193 /* Release a ref on an fp_setting */
194 static inline void fail_point_setting_release_ref(struct fail_point *fp);
195 /* Allocate and initialize a struct fail_point_setting */
196 static struct fail_point_setting *fail_point_setting_new(struct
197 fail_point *);
198 /* Free a struct fail_point_setting */
199 static void fail_point_setting_destroy(struct fail_point_setting *fp_setting);
200 /* Allocate and initialize a struct fail_point_entry */
201 static struct fail_point_entry *fail_point_entry_new(struct
202 fail_point_setting *);
203 /* Free a struct fail_point_entry */
204 static void fail_point_entry_destroy(struct fail_point_entry *fp_entry);
205 /* Append fp setting to garbage list */
206 static inline void fail_point_setting_garbage_append(
207 struct fail_point_setting *fp_setting);
208 /* Swap fp's setting with fp_setting_new */
209 static inline struct fail_point_setting *
210 fail_point_swap_settings(struct fail_point *fp,
211 struct fail_point_setting *fp_setting_new);
212 /* Free up any zero-ref setting in the garbage queue */
213 static void fail_point_garbage_collect(void);
214 /* If this fail point's setting are empty, then swap it out to NULL. */
215 static inline void fail_point_eval_swap_out(struct fail_point *fp,
216 struct fail_point_setting *fp_setting);
217
218 bool
fail_point_is_off(struct fail_point * fp)219 fail_point_is_off(struct fail_point *fp)
220 {
221 bool return_val;
222 struct fail_point_setting *fp_setting;
223 struct fail_point_entry *ent;
224
225 return_val = true;
226
227 fp_setting = fail_point_setting_get_ref(fp);
228 if (fp_setting != NULL) {
229 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue,
230 fe_entries) {
231 if (!ent->fe_stale) {
232 return_val = false;
233 break;
234 }
235 }
236 }
237 fail_point_setting_release_ref(fp);
238
239 return (return_val);
240 }
241
242 /* Allocate and initialize a struct fail_point_setting */
243 static struct fail_point_setting *
fail_point_setting_new(struct fail_point * fp)244 fail_point_setting_new(struct fail_point *fp)
245 {
246 struct fail_point_setting *fs_new;
247
248 fs_new = fs_malloc();
249 fs_new->fs_parent = fp;
250 TAILQ_INIT(&fs_new->fp_entry_queue);
251 mtx_init(&fs_new->feq_mtx, "fail point entries", NULL, MTX_SPIN);
252
253 fail_point_setting_garbage_append(fs_new);
254
255 return (fs_new);
256 }
257
258 /* Free a struct fail_point_setting */
259 static void
fail_point_setting_destroy(struct fail_point_setting * fp_setting)260 fail_point_setting_destroy(struct fail_point_setting *fp_setting)
261 {
262 struct fail_point_entry *ent;
263
264 while (!TAILQ_EMPTY(&fp_setting->fp_entry_queue)) {
265 ent = TAILQ_FIRST(&fp_setting->fp_entry_queue);
266 TAILQ_REMOVE(&fp_setting->fp_entry_queue, ent, fe_entries);
267 fail_point_entry_destroy(ent);
268 }
269
270 fs_free(fp_setting);
271 }
272
273 /* Allocate and initialize a struct fail_point_entry */
274 static struct fail_point_entry *
fail_point_entry_new(struct fail_point_setting * fp_setting)275 fail_point_entry_new(struct fail_point_setting *fp_setting)
276 {
277 struct fail_point_entry *fp_entry;
278
279 fp_entry = fp_malloc(sizeof(struct fail_point_entry),
280 M_WAITOK | M_ZERO);
281 fp_entry->fe_parent = fp_setting->fs_parent;
282 fp_entry->fe_prob = PROB_MAX;
283 fp_entry->fe_pid = NO_PID;
284 fp_entry->fe_count = FE_COUNT_UNTRACKED;
285 TAILQ_INSERT_TAIL(&fp_setting->fp_entry_queue, fp_entry,
286 fe_entries);
287
288 return (fp_entry);
289 }
290
291 /* Free a struct fail_point_entry */
292 static void
fail_point_entry_destroy(struct fail_point_entry * fp_entry)293 fail_point_entry_destroy(struct fail_point_entry *fp_entry)
294 {
295
296 fp_free(fp_entry);
297 }
298
299 /* Get a ref on an fp's fp_setting */
300 static inline struct fail_point_setting *
fail_point_setting_get_ref(struct fail_point * fp)301 fail_point_setting_get_ref(struct fail_point *fp)
302 {
303 struct fail_point_setting *fp_setting;
304
305 /* Invariant: if we have a ref, our pointer to fp_setting is safe */
306 atomic_add_acq_32(&fp->fp_ref_cnt, 1);
307 fp_setting = fp->fp_setting;
308
309 return (fp_setting);
310 }
311
312 /* Release a ref on an fp_setting */
313 static inline void
fail_point_setting_release_ref(struct fail_point * fp)314 fail_point_setting_release_ref(struct fail_point *fp)
315 {
316
317 KASSERT(&fp->fp_ref_cnt > 0, ("Attempting to deref w/no refs"));
318 atomic_subtract_rel_32(&fp->fp_ref_cnt, 1);
319 }
320
321 /* Append fp entries to fp garbage list */
322 static inline void
fail_point_setting_garbage_append(struct fail_point_setting * fp_setting)323 fail_point_setting_garbage_append(struct fail_point_setting *fp_setting)
324 {
325
326 mtx_lock_spin(&mtx_garbage_list);
327 STAILQ_INSERT_TAIL(&fp_setting_garbage, fp_setting,
328 fs_garbage_link);
329 mtx_unlock_spin(&mtx_garbage_list);
330 }
331
332 /* Swap fp's entries with fp_setting_new */
333 static struct fail_point_setting *
fail_point_swap_settings(struct fail_point * fp,struct fail_point_setting * fp_setting_new)334 fail_point_swap_settings(struct fail_point *fp,
335 struct fail_point_setting *fp_setting_new)
336 {
337 struct fail_point_setting *fp_setting_old;
338
339 fp_setting_old = fp->fp_setting;
340 fp->fp_setting = fp_setting_new;
341
342 return (fp_setting_old);
343 }
344
345 static inline void
fail_point_eval_swap_out(struct fail_point * fp,struct fail_point_setting * fp_setting)346 fail_point_eval_swap_out(struct fail_point *fp,
347 struct fail_point_setting *fp_setting)
348 {
349
350 /* We may have already been swapped out and replaced; ignore. */
351 if (fp->fp_setting == fp_setting)
352 fail_point_swap_settings(fp, NULL);
353 }
354
355 /* Free up any zero-ref entries in the garbage queue */
356 static void
fail_point_garbage_collect(void)357 fail_point_garbage_collect(void)
358 {
359 struct fail_point_setting *fs_current, *fs_next;
360 struct fail_point_setting_garbage fp_ents_free_list;
361
362 /**
363 * We will transfer the entries to free to fp_ents_free_list while holding
364 * the spin mutex, then free it after we drop the lock. This avoids
365 * triggering witness due to sleepable mutexes in the memory
366 * allocator.
367 */
368 STAILQ_INIT(&fp_ents_free_list);
369
370 mtx_lock_spin(&mtx_garbage_list);
371 STAILQ_FOREACH_SAFE(fs_current, &fp_setting_garbage, fs_garbage_link,
372 fs_next) {
373 if (fs_current->fs_parent->fp_setting != fs_current &&
374 fs_current->fs_parent->fp_ref_cnt == 0) {
375 STAILQ_REMOVE(&fp_setting_garbage, fs_current,
376 fail_point_setting, fs_garbage_link);
377 STAILQ_INSERT_HEAD(&fp_ents_free_list, fs_current,
378 fs_garbage_link);
379 }
380 }
381 mtx_unlock_spin(&mtx_garbage_list);
382
383 STAILQ_FOREACH_SAFE(fs_current, &fp_ents_free_list, fs_garbage_link,
384 fs_next)
385 fail_point_setting_destroy(fs_current);
386 }
387
388 /* Drain out all refs from this fail point */
389 static inline void
fail_point_drain(struct fail_point * fp,int expected_ref)390 fail_point_drain(struct fail_point *fp, int expected_ref)
391 {
392 struct fail_point_setting *entries;
393
394 entries = fail_point_swap_settings(fp, NULL);
395 /**
396 * We have unpaused all threads; so we will wait no longer
397 * than the time taken for the longest remaining sleep, or
398 * the length of time of a long-running code block.
399 */
400 while (fp->fp_ref_cnt > expected_ref) {
401 wakeup(FP_PAUSE_CHANNEL(fp));
402 tsleep(&fp, PWAIT, "fail_point_drain", hz / 100);
403 }
404 if (fp->fp_callout)
405 callout_drain(fp->fp_callout);
406 fail_point_swap_settings(fp, entries);
407 }
408
409 static inline void
fail_point_pause(struct fail_point * fp,enum fail_point_return_code * pret,struct mtx * mtx_sleep)410 fail_point_pause(struct fail_point *fp, enum fail_point_return_code *pret,
411 struct mtx *mtx_sleep)
412 {
413
414 if (fp->fp_pre_sleep_fn)
415 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
416
417 msleep_spin(FP_PAUSE_CHANNEL(fp), mtx_sleep, "failpt", 0);
418
419 if (fp->fp_post_sleep_fn)
420 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg);
421 }
422
423 static inline void
fail_point_sleep(struct fail_point * fp,int msecs,enum fail_point_return_code * pret)424 fail_point_sleep(struct fail_point *fp, int msecs,
425 enum fail_point_return_code *pret)
426 {
427 int timo;
428
429 /* Convert from millisecs to ticks, rounding up */
430 timo = howmany((int64_t)msecs * hz, 1000L);
431
432 if (timo > 0) {
433 if (!(fp->fp_flags & FAIL_POINT_USE_TIMEOUT_PATH)) {
434 if (fp->fp_pre_sleep_fn)
435 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
436
437 tsleep(FP_SLEEP_CHANNEL(fp), PWAIT, "failpt", timo);
438
439 if (fp->fp_post_sleep_fn)
440 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg);
441 } else {
442 if (fp->fp_pre_sleep_fn)
443 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
444
445 callout_reset(fp->fp_callout, timo,
446 fp->fp_post_sleep_fn, fp->fp_post_sleep_arg);
447 *pret = FAIL_POINT_RC_QUEUED;
448 }
449 }
450 }
451
452 static char *parse_fail_point(struct fail_point_setting *, char *);
453 static char *parse_term(struct fail_point_setting *, char *);
454 static char *parse_number(int *out_units, int *out_decimal, char *);
455 static char *parse_type(struct fail_point_entry *, char *);
456
457 /**
458 * Initialize a fail_point. The name is formed in a printf-like fashion
459 * from "fmt" and subsequent arguments. This function is generally used
460 * for custom failpoints located at odd places in the sysctl tree, and is
461 * not explicitly needed for standard in-line-declared failpoints.
462 *
463 * @ingroup failpoint
464 */
465 void
fail_point_init(struct fail_point * fp,const char * fmt,...)466 fail_point_init(struct fail_point *fp, const char *fmt, ...)
467 {
468 va_list ap;
469 char *name;
470 int n;
471
472 fp->fp_setting = NULL;
473 fp->fp_flags = 0;
474
475 /* Figure out the size of the name. */
476 va_start(ap, fmt);
477 n = vsnprintf(NULL, 0, fmt, ap);
478 va_end(ap);
479
480 /* Allocate the name and fill it in. */
481 name = fp_malloc(n + 1, M_WAITOK);
482 if (name != NULL) {
483 va_start(ap, fmt);
484 vsnprintf(name, n + 1, fmt, ap);
485 va_end(ap);
486 }
487 fp->fp_name = name;
488 fp->fp_location = "";
489 fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME;
490 fp->fp_pre_sleep_fn = NULL;
491 fp->fp_pre_sleep_arg = NULL;
492 fp->fp_post_sleep_fn = NULL;
493 fp->fp_post_sleep_arg = NULL;
494 }
495
496 void
fail_point_alloc_callout(struct fail_point * fp)497 fail_point_alloc_callout(struct fail_point *fp)
498 {
499
500 /**
501 * This assumes that calls to fail_point_use_timeout_path()
502 * will not race.
503 */
504 if (fp->fp_callout != NULL)
505 return;
506 fp->fp_callout = fp_malloc(sizeof(*fp->fp_callout), M_WAITOK);
507 callout_init(fp->fp_callout, CALLOUT_MPSAFE);
508 }
509
510 /**
511 * Free the resources held by a fail_point, and wake any paused threads.
512 * Thou shalt not allow threads to hit this fail point after you enter this
513 * function, nor shall you call this multiple times for a given fp.
514 * @ingroup failpoint
515 */
516 void
fail_point_destroy(struct fail_point * fp)517 fail_point_destroy(struct fail_point *fp)
518 {
519
520 fail_point_drain(fp, 0);
521
522 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) {
523 fp_free(__DECONST(void *, fp->fp_name));
524 fp->fp_name = NULL;
525 }
526 fp->fp_flags = 0;
527 if (fp->fp_callout) {
528 fp_free(fp->fp_callout);
529 fp->fp_callout = NULL;
530 }
531
532 sx_xlock(&sx_fp_set);
533 fail_point_garbage_collect();
534 sx_xunlock(&sx_fp_set);
535 }
536
537 /**
538 * This does the real work of evaluating a fail point. If the fail point tells
539 * us to return a value, this function returns 1 and fills in 'return_value'
540 * (return_value is allowed to be null). If the fail point tells us to panic,
541 * we never return. Otherwise we just return 0 after doing some work, which
542 * means "keep going".
543 */
544 enum fail_point_return_code
fail_point_eval_nontrivial(struct fail_point * fp,int * return_value)545 fail_point_eval_nontrivial(struct fail_point *fp, int *return_value)
546 {
547 bool execute = false;
548 struct fail_point_entry *ent;
549 struct fail_point_setting *fp_setting;
550 enum fail_point_return_code ret;
551 int cont;
552 int count;
553 int msecs;
554 int usecs;
555
556 ret = FAIL_POINT_RC_CONTINUE;
557 cont = 0; /* don't continue by default */
558
559 fp_setting = fail_point_setting_get_ref(fp);
560 if (fp_setting == NULL)
561 goto abort;
562
563 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) {
564 if (ent->fe_stale)
565 continue;
566
567 if (ent->fe_prob < PROB_MAX &&
568 ent->fe_prob < random() % PROB_MAX)
569 continue;
570
571 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid)
572 continue;
573
574 if (ent->fe_count != FE_COUNT_UNTRACKED) {
575 count = ent->fe_count;
576 while (count > 0) {
577 if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) {
578 count--;
579 execute = true;
580 break;
581 }
582 count = ent->fe_count;
583 }
584 if (execute == false)
585 /* We lost the race; consider the entry stale and bail now */
586 continue;
587 if (count == 0)
588 ent->fe_stale = true;
589 }
590
591 switch (ent->fe_type) {
592 case FAIL_POINT_PANIC:
593 panic("fail point %s panicking", fp->fp_name);
594 /* NOTREACHED */
595
596 case FAIL_POINT_RETURN:
597 if (return_value != NULL)
598 *return_value = ent->fe_arg;
599 ret = FAIL_POINT_RC_RETURN;
600 break;
601
602 case FAIL_POINT_BREAK:
603 printf("fail point %s breaking to debugger\n",
604 fp->fp_name);
605 breakpoint();
606 break;
607
608 case FAIL_POINT_PRINT:
609 printf("fail point %s executing\n", fp->fp_name);
610 cont = ent->fe_arg;
611 break;
612
613 case FAIL_POINT_SLEEP:
614 msecs = ent->fe_arg;
615 if (msecs)
616 fail_point_sleep(fp, msecs, &ret);
617 break;
618
619 case FAIL_POINT_PAUSE:
620 /**
621 * Pausing is inherently strange with multiple
622 * entries given our design. That is because some
623 * entries could be unreachable, for instance in cases like:
624 * pause->return. We can never reach the return entry.
625 * The sysctl layer actually truncates all entries after
626 * a pause for this reason.
627 */
628 mtx_lock_spin(&fp_setting->feq_mtx);
629 fail_point_pause(fp, &ret, &fp_setting->feq_mtx);
630 mtx_unlock_spin(&fp_setting->feq_mtx);
631 break;
632
633 case FAIL_POINT_YIELD:
634 kern_yield(PRI_UNCHANGED);
635 break;
636
637 case FAIL_POINT_DELAY:
638 usecs = ent->fe_arg;
639 DELAY(usecs);
640 break;
641
642 default:
643 break;
644 }
645
646 if (cont == 0)
647 break;
648 }
649
650 if (fail_point_is_off(fp))
651 fail_point_eval_swap_out(fp, fp_setting);
652
653 abort:
654 fail_point_setting_release_ref(fp);
655
656 return (ret);
657 }
658
659 /**
660 * Translate internal fail_point structure into human-readable text.
661 */
662 static void
fail_point_get(struct fail_point * fp,struct sbuf * sb,bool verbose)663 fail_point_get(struct fail_point *fp, struct sbuf *sb,
664 bool verbose)
665 {
666 struct fail_point_entry *ent;
667 struct fail_point_setting *fp_setting;
668 struct fail_point_entry *fp_entry_cpy;
669 int cnt_sleeping;
670 int idx;
671 int printed_entry_count;
672
673 cnt_sleeping = 0;
674 idx = 0;
675 printed_entry_count = 0;
676
677 fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) *
678 (FP_MAX_ENTRY_COUNT + 1), M_WAITOK);
679
680 fp_setting = fail_point_setting_get_ref(fp);
681
682 if (fp_setting != NULL) {
683 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) {
684 if (ent->fe_stale)
685 continue;
686
687 KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT,
688 ("FP entry list larger than allowed"));
689
690 fp_entry_cpy[printed_entry_count] = *ent;
691 ++printed_entry_count;
692 }
693 }
694 fail_point_setting_release_ref(fp);
695
696 /* This is our equivalent of a NULL terminator */
697 fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID;
698
699 while (idx < printed_entry_count) {
700 ent = &fp_entry_cpy[idx];
701 ++idx;
702 if (ent->fe_prob < PROB_MAX) {
703 int decimal = ent->fe_prob % (PROB_MAX / 100);
704 int units = ent->fe_prob / (PROB_MAX / 100);
705 sbuf_printf(sb, "%d", units);
706 if (decimal) {
707 int digits = PROB_DIGITS - 2;
708 while (!(decimal % 10)) {
709 digits--;
710 decimal /= 10;
711 }
712 sbuf_printf(sb, ".%0*d", digits, decimal);
713 }
714 sbuf_printf(sb, "%%");
715 }
716 if (ent->fe_count >= 0)
717 sbuf_printf(sb, "%d*", ent->fe_count);
718 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name);
719 if (ent->fe_arg)
720 sbuf_printf(sb, "(%d)", ent->fe_arg);
721 if (ent->fe_pid != NO_PID)
722 sbuf_printf(sb, "[pid %d]", ent->fe_pid);
723 if (TAILQ_NEXT(ent, fe_entries))
724 sbuf_cat(sb, "->");
725 }
726 if (!printed_entry_count)
727 sbuf_cat(sb, "off");
728
729 fp_free(fp_entry_cpy);
730 if (verbose) {
731 #ifdef STACK
732 /* Print number of sleeping threads. queue=0 is the argument
733 * used by msleep when sending our threads to sleep. */
734 sbuf_cat(sb, "\nsleeping_thread_stacks = {\n");
735 sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0,
736 &cnt_sleeping);
737
738 sbuf_cat(sb, "},\n");
739 #endif
740 sbuf_printf(sb, "sleeping_thread_count = %d,\n",
741 cnt_sleeping);
742
743 #ifdef STACK
744 sbuf_cat(sb, "paused_thread_stacks = {\n");
745 sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0,
746 &cnt_sleeping);
747
748 sbuf_cat(sb, "},\n");
749 #endif
750 sbuf_printf(sb, "paused_thread_count = %d\n",
751 cnt_sleeping);
752 }
753 }
754
755 /**
756 * Set an internal fail_point structure from a human-readable failpoint string
757 * in a lock-safe manner.
758 */
759 static int
fail_point_set(struct fail_point * fp,char * buf)760 fail_point_set(struct fail_point *fp, char *buf)
761 {
762 struct fail_point_entry *ent, *ent_next;
763 struct fail_point_setting *entries;
764 bool should_wake_paused;
765 bool should_truncate;
766 int error;
767
768 error = 0;
769 should_wake_paused = false;
770 should_truncate = false;
771
772 /* Parse new entries. */
773 /**
774 * ref protects our new malloc'd stuff from being garbage collected
775 * before we link it.
776 */
777 fail_point_setting_get_ref(fp);
778 entries = fail_point_setting_new(fp);
779 if (parse_fail_point(entries, buf) == NULL) {
780 STAILQ_REMOVE(&fp_setting_garbage, entries,
781 fail_point_setting, fs_garbage_link);
782 fail_point_setting_destroy(entries);
783 error = EINVAL;
784 goto end;
785 }
786
787 /**
788 * Transfer the entries we are going to keep to a new list.
789 * Get rid of useless zero probability entries, and entries with hit
790 * count 0.
791 * If 'off' is present, and it has no hit count set, then all entries
792 * after it are discarded since they are unreachable.
793 */
794 TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) {
795 if (ent->fe_prob == 0 || ent->fe_count == 0) {
796 printf("Discarding entry which cannot execute %s\n",
797 fail_type_strings[ent->fe_type].name);
798 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
799 fe_entries);
800 fp_free(ent);
801 continue;
802 } else if (should_truncate) {
803 printf("Discarding unreachable entry %s\n",
804 fail_type_strings[ent->fe_type].name);
805 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
806 fe_entries);
807 fp_free(ent);
808 continue;
809 }
810
811 if (ent->fe_type == FAIL_POINT_OFF) {
812 should_wake_paused = true;
813 if (ent->fe_count == FE_COUNT_UNTRACKED) {
814 should_truncate = true;
815 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
816 fe_entries);
817 fp_free(ent);
818 }
819 } else if (ent->fe_type == FAIL_POINT_PAUSE) {
820 should_truncate = true;
821 } else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags &
822 FAIL_POINT_NONSLEEPABLE)) {
823 /**
824 * If this fail point is annotated as being in a
825 * non-sleepable ctx, convert sleep to delay and
826 * convert the msec argument to usecs.
827 */
828 printf("Sleep call request on fail point in "
829 "non-sleepable context; using delay instead "
830 "of sleep\n");
831 ent->fe_type = FAIL_POINT_DELAY;
832 ent->fe_arg *= 1000;
833 }
834 }
835
836 if (TAILQ_EMPTY(&entries->fp_entry_queue)) {
837 entries = fail_point_swap_settings(fp, NULL);
838 if (entries != NULL)
839 wakeup(FP_PAUSE_CHANNEL(fp));
840 } else {
841 if (should_wake_paused)
842 wakeup(FP_PAUSE_CHANNEL(fp));
843 fail_point_swap_settings(fp, entries);
844 }
845
846 end:
847 #ifdef IWARNING
848 if (error)
849 IWARNING("Failed to set %s %s to %s",
850 fp->fp_name, fp->fp_location, buf);
851 else
852 INOTICE("Set %s %s to %s",
853 fp->fp_name, fp->fp_location, buf);
854 #endif /* IWARNING */
855
856 fail_point_setting_release_ref(fp);
857 return (error);
858 }
859
860 #define MAX_FAIL_POINT_BUF 1023
861
862 /**
863 * Handle kernel failpoint set/get.
864 */
865 int
fail_point_sysctl(SYSCTL_HANDLER_ARGS)866 fail_point_sysctl(SYSCTL_HANDLER_ARGS)
867 {
868 struct fail_point *fp;
869 char *buf;
870 struct sbuf sb, *sb_check;
871 int error;
872
873 buf = NULL;
874 error = 0;
875 fp = arg1;
876
877 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND);
878 if (sb_check != &sb)
879 return (ENOMEM);
880
881 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req);
882
883 /* Setting */
884 /**
885 * Lock protects any new entries from being garbage collected before we
886 * can link them to the fail point.
887 */
888 sx_xlock(&sx_fp_set);
889 if (req->newptr) {
890 if (req->newlen > MAX_FAIL_POINT_BUF) {
891 error = EINVAL;
892 goto out;
893 }
894
895 buf = fp_malloc(req->newlen + 1, M_WAITOK);
896
897 error = SYSCTL_IN(req, buf, req->newlen);
898 if (error)
899 goto out;
900 buf[req->newlen] = '\0';
901
902 error = fail_point_set(fp, buf);
903 }
904
905 fail_point_garbage_collect();
906 sx_xunlock(&sx_fp_set);
907
908 /* Retrieving. */
909 fail_point_get(fp, &sb, false);
910
911 out:
912 sbuf_finish(&sb);
913 sbuf_delete(&sb);
914
915 if (buf)
916 fp_free(buf);
917
918 return (error);
919 }
920
921 int
fail_point_sysctl_status(SYSCTL_HANDLER_ARGS)922 fail_point_sysctl_status(SYSCTL_HANDLER_ARGS)
923 {
924 struct fail_point *fp;
925 struct sbuf sb, *sb_check;
926
927 fp = arg1;
928
929 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND);
930 if (sb_check != &sb)
931 return (ENOMEM);
932
933 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req);
934
935 /* Retrieving. */
936 fail_point_get(fp, &sb, true);
937
938 sbuf_finish(&sb);
939 sbuf_delete(&sb);
940
941 /**
942 * Lock protects any new entries from being garbage collected before we
943 * can link them to the fail point.
944 */
945 sx_xlock(&sx_fp_set);
946 fail_point_garbage_collect();
947 sx_xunlock(&sx_fp_set);
948
949 return (0);
950 }
951
952 int
fail_sysctl_drain_func(void * sysctl_args,const char * buf,int len)953 fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len)
954 {
955 struct sysctl_req *sa;
956 int error;
957
958 sa = sysctl_args;
959
960 error = SYSCTL_OUT(sa, buf, len);
961
962 if (error == ENOMEM)
963 return (-1);
964 else
965 return (len);
966 }
967
968 /**
969 * Internal helper function to translate a human-readable failpoint string
970 * into a internally-parsable fail_point structure.
971 */
972 static char *
parse_fail_point(struct fail_point_setting * ents,char * p)973 parse_fail_point(struct fail_point_setting *ents, char *p)
974 {
975 /* <fail_point> ::
976 * <term> ( "->" <term> )*
977 */
978 uint8_t term_count;
979
980 term_count = 1;
981
982 p = parse_term(ents, p);
983 if (p == NULL)
984 return (NULL);
985
986 while (*p != '\0') {
987 term_count++;
988 if (p[0] != '-' || p[1] != '>' ||
989 (p = parse_term(ents, p+2)) == NULL ||
990 term_count > FP_MAX_ENTRY_COUNT)
991 return (NULL);
992 }
993 return (p);
994 }
995
996 /**
997 * Internal helper function to parse an individual term from a failpoint.
998 */
999 static char *
parse_term(struct fail_point_setting * ents,char * p)1000 parse_term(struct fail_point_setting *ents, char *p)
1001 {
1002 struct fail_point_entry *ent;
1003
1004 ent = fail_point_entry_new(ents);
1005
1006 /*
1007 * <term> ::
1008 * ( (<float> "%") | (<integer> "*" ) )*
1009 * <type>
1010 * [ "(" <integer> ")" ]
1011 * [ "[pid " <integer> "]" ]
1012 */
1013
1014 /* ( (<float> "%") | (<integer> "*" ) )* */
1015 while (isdigit(*p) || *p == '.') {
1016 int units, decimal;
1017
1018 p = parse_number(&units, &decimal, p);
1019 if (p == NULL)
1020 return (NULL);
1021
1022 if (*p == '%') {
1023 if (units > 100) /* prevent overflow early */
1024 units = 100;
1025 ent->fe_prob = units * (PROB_MAX / 100) + decimal;
1026 if (ent->fe_prob > PROB_MAX)
1027 ent->fe_prob = PROB_MAX;
1028 } else if (*p == '*') {
1029 if (!units || units < 0 || decimal)
1030 return (NULL);
1031 ent->fe_count = units;
1032 } else
1033 return (NULL);
1034 p++;
1035 }
1036
1037 /* <type> */
1038 p = parse_type(ent, p);
1039 if (p == NULL)
1040 return (NULL);
1041 if (*p == '\0')
1042 return (p);
1043
1044 /* [ "(" <integer> ")" ] */
1045 if (*p != '(')
1046 return (p);
1047 p++;
1048 if (!isdigit(*p) && *p != '-')
1049 return (NULL);
1050 ent->fe_arg = strtol(p, &p, 0);
1051 if (*p++ != ')')
1052 return (NULL);
1053
1054 /* [ "[pid " <integer> "]" ] */
1055 #define PID_STRING "[pid "
1056 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0)
1057 return (p);
1058 p += sizeof(PID_STRING) - 1;
1059 if (!isdigit(*p))
1060 return (NULL);
1061 ent->fe_pid = strtol(p, &p, 0);
1062 if (*p++ != ']')
1063 return (NULL);
1064
1065 return (p);
1066 }
1067
1068 /**
1069 * Internal helper function to parse a numeric for a failpoint term.
1070 */
1071 static char *
parse_number(int * out_units,int * out_decimal,char * p)1072 parse_number(int *out_units, int *out_decimal, char *p)
1073 {
1074 char *old_p;
1075
1076 /**
1077 * <number> ::
1078 * <integer> [ "." <integer> ] |
1079 * "." <integer>
1080 */
1081
1082 /* whole part */
1083 old_p = p;
1084 *out_units = strtol(p, &p, 10);
1085 if (p == old_p && *p != '.')
1086 return (NULL);
1087
1088 /* fractional part */
1089 *out_decimal = 0;
1090 if (*p == '.') {
1091 int digits = 0;
1092 p++;
1093 while (isdigit(*p)) {
1094 int digit = *p - '0';
1095 if (digits < PROB_DIGITS - 2)
1096 *out_decimal = *out_decimal * 10 + digit;
1097 else if (digits == PROB_DIGITS - 2 && digit >= 5)
1098 (*out_decimal)++;
1099 digits++;
1100 p++;
1101 }
1102 if (!digits) /* need at least one digit after '.' */
1103 return (NULL);
1104 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */
1105 *out_decimal *= 10;
1106 }
1107
1108 return (p); /* success */
1109 }
1110
1111 /**
1112 * Internal helper function to parse an individual type for a failpoint term.
1113 */
1114 static char *
parse_type(struct fail_point_entry * ent,char * beg)1115 parse_type(struct fail_point_entry *ent, char *beg)
1116 {
1117 enum fail_point_t type;
1118 int len;
1119
1120 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) {
1121 len = fail_type_strings[type].nmlen;
1122 if (strncmp(fail_type_strings[type].name, beg, len) == 0) {
1123 ent->fe_type = type;
1124 return (beg + len);
1125 }
1126 }
1127 return (NULL);
1128 }
1129
1130 /* The fail point sysctl tree. */
1131 SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
1132 "fail points");
1133
1134 /* Debugging/testing stuff for fail point */
1135 static int
sysctl_test_fail_point(SYSCTL_HANDLER_ARGS)1136 sysctl_test_fail_point(SYSCTL_HANDLER_ARGS)
1137 {
1138
1139 KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point);
1140 return (0);
1141 }
1142 SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point,
1143 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT, NULL, 0,
1144 sysctl_test_fail_point, "A",
1145 "Trigger test fail points");
1146