FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_fail.c
1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
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 __FBSDID("$FreeBSD$");
56
57 #include "opt_stack.h"
58
59 #include <sys/ctype.h>
60 #include <sys/errno.h>
61 #include <sys/fail.h>
62 #include <sys/kernel.h>
63 #include <sys/libkern.h>
64 #include <sys/limits.h>
65 #include <sys/lock.h>
66 #include <sys/malloc.h>
67 #include <sys/mutex.h>
68 #include <sys/proc.h>
69 #include <sys/sbuf.h>
70 #include <sys/sleepqueue.h>
71 #include <sys/sx.h>
72 #include <sys/sysctl.h>
73 #include <sys/types.h>
74
75 #include <machine/atomic.h>
76 #include <machine/stdarg.h>
77
78 #ifdef ILOG_DEFINE_FOR_FILE
79 ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point);
80 #endif
81
82 static MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system");
83 #define fp_free(ptr) free(ptr, M_FAIL_POINT)
84 #define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags))
85 #define fs_free(ptr) fp_free(ptr)
86 #define fs_malloc() fp_malloc(sizeof(struct fail_point_setting), \
87 M_WAITOK | M_ZERO)
88
89 /**
90 * These define the wchans that are used for sleeping, pausing respectively.
91 * They are chosen arbitrarily but need to be distinct to the failpoint and
92 * the sleep/pause distinction.
93 */
94 #define FP_SLEEP_CHANNEL(fp) (void*)(fp)
95 #define FP_PAUSE_CHANNEL(fp) __DEVOLATILE(void*, &fp->fp_setting)
96
97 /**
98 * Don't allow more than this many entries in a fail point set by sysctl.
99 * The 99.99...% case is to have 1 entry. I can't imagine having this many
100 * entries, so it should not limit us. Saves on re-mallocs while holding
101 * a non-sleepable lock.
102 */
103 #define FP_MAX_ENTRY_COUNT 20
104
105 /* Used to drain sbufs to the sysctl output */
106 int fail_sysctl_drain_func(void *, const char *, int);
107
108 /* Head of tailq of struct fail_point_entry */
109 TAILQ_HEAD(fail_point_entry_queue, fail_point_entry);
110
111 /**
112 * fp entries garbage list; outstanding entries are cleaned up in the
113 * garbage collector
114 */
115 STAILQ_HEAD(fail_point_setting_garbage, fail_point_setting);
116 static struct fail_point_setting_garbage fp_setting_garbage =
117 STAILQ_HEAD_INITIALIZER(fp_setting_garbage);
118 static struct mtx mtx_garbage_list;
119 MTX_SYSINIT(mtx_garbage_list, &mtx_garbage_list, "fail point garbage mtx",
120 MTX_SPIN);
121
122 static struct sx sx_fp_set;
123 SX_SYSINIT(sx_fp_set, &sx_fp_set, "fail point set sx");
124
125 /**
126 * Failpoint types.
127 * Don't change these without changing fail_type_strings in fail.c.
128 * @ingroup failpoint_private
129 */
130 enum fail_point_t {
131 FAIL_POINT_OFF, /**< don't fail */
132 FAIL_POINT_PANIC, /**< panic */
133 FAIL_POINT_RETURN, /**< return an errorcode */
134 FAIL_POINT_BREAK, /**< break into the debugger */
135 FAIL_POINT_PRINT, /**< print a message */
136 FAIL_POINT_SLEEP, /**< sleep for some msecs */
137 FAIL_POINT_PAUSE, /**< sleep until failpoint is set to off */
138 FAIL_POINT_YIELD, /**< yield the cpu */
139 FAIL_POINT_DELAY, /**< busy wait the cpu */
140 FAIL_POINT_NUMTYPES,
141 FAIL_POINT_INVALID = -1
142 };
143
144 static struct {
145 const char *name;
146 int nmlen;
147 } fail_type_strings[] = {
148 #define FP_TYPE_NM_LEN(s) { s, sizeof(s) - 1 }
149 [FAIL_POINT_OFF] = FP_TYPE_NM_LEN("off"),
150 [FAIL_POINT_PANIC] = FP_TYPE_NM_LEN("panic"),
151 [FAIL_POINT_RETURN] = FP_TYPE_NM_LEN("return"),
152 [FAIL_POINT_BREAK] = FP_TYPE_NM_LEN("break"),
153 [FAIL_POINT_PRINT] = FP_TYPE_NM_LEN("print"),
154 [FAIL_POINT_SLEEP] = FP_TYPE_NM_LEN("sleep"),
155 [FAIL_POINT_PAUSE] = FP_TYPE_NM_LEN("pause"),
156 [FAIL_POINT_YIELD] = FP_TYPE_NM_LEN("yield"),
157 [FAIL_POINT_DELAY] = FP_TYPE_NM_LEN("delay"),
158 };
159
160 #define FE_COUNT_UNTRACKED (INT_MIN)
161
162 /**
163 * Internal structure tracking a single term of a complete failpoint.
164 * @ingroup failpoint_private
165 */
166 struct fail_point_entry {
167 volatile bool fe_stale;
168 enum fail_point_t fe_type; /**< type of entry */
169 int fe_arg; /**< argument to type (e.g. return value) */
170 int fe_prob; /**< likelihood of firing in millionths */
171 int32_t fe_count; /**< number of times to fire, -1 means infinite */
172 pid_t fe_pid; /**< only fail for this process */
173 struct fail_point *fe_parent; /**< backpointer to fp */
174 TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry ptr */
175 };
176
177 struct fail_point_setting {
178 STAILQ_ENTRY(fail_point_setting) fs_garbage_link;
179 struct fail_point_entry_queue fp_entry_queue;
180 struct fail_point * fs_parent;
181 struct mtx feq_mtx; /* Gives fail_point_pause something to do. */
182 };
183
184 /**
185 * Defines stating the equivalent of probablilty one (100%)
186 */
187 enum {
188 PROB_MAX = 1000000, /* probability between zero and this number */
189 PROB_DIGITS = 6 /* number of zero's in above number */
190 };
191
192 /* Get a ref on an fp's fp_setting */
193 static inline struct fail_point_setting *fail_point_setting_get_ref(
194 struct fail_point *fp);
195 /* Release a ref on an fp_setting */
196 static inline void fail_point_setting_release_ref(struct fail_point *fp);
197 /* Allocate and initialize a struct fail_point_setting */
198 static struct fail_point_setting *fail_point_setting_new(struct
199 fail_point *);
200 /* Free a struct fail_point_setting */
201 static void fail_point_setting_destroy(struct fail_point_setting *fp_setting);
202 /* Allocate and initialize a struct fail_point_entry */
203 static struct fail_point_entry *fail_point_entry_new(struct
204 fail_point_setting *);
205 /* Free a struct fail_point_entry */
206 static void fail_point_entry_destroy(struct fail_point_entry *fp_entry);
207 /* Append fp setting to garbage list */
208 static inline void fail_point_setting_garbage_append(
209 struct fail_point_setting *fp_setting);
210 /* Swap fp's setting with fp_setting_new */
211 static inline struct fail_point_setting *
212 fail_point_swap_settings(struct fail_point *fp,
213 struct fail_point_setting *fp_setting_new);
214 /* Free up any zero-ref setting in the garbage queue */
215 static void fail_point_garbage_collect(void);
216 /* If this fail point's setting are empty, then swap it out to NULL. */
217 static inline void fail_point_eval_swap_out(struct fail_point *fp,
218 struct fail_point_setting *fp_setting);
219
220 bool
221 fail_point_is_off(struct fail_point *fp)
222 {
223 bool return_val;
224 struct fail_point_setting *fp_setting;
225 struct fail_point_entry *ent;
226
227 return_val = true;
228
229 fp_setting = fail_point_setting_get_ref(fp);
230 if (fp_setting != NULL) {
231 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue,
232 fe_entries) {
233 if (!ent->fe_stale) {
234 return_val = false;
235 break;
236 }
237 }
238 }
239 fail_point_setting_release_ref(fp);
240
241 return (return_val);
242 }
243
244 /* Allocate and initialize a struct fail_point_setting */
245 static struct fail_point_setting *
246 fail_point_setting_new(struct fail_point *fp)
247 {
248 struct fail_point_setting *fs_new;
249
250 fs_new = fs_malloc();
251 fs_new->fs_parent = fp;
252 TAILQ_INIT(&fs_new->fp_entry_queue);
253 mtx_init(&fs_new->feq_mtx, "fail point entries", NULL, MTX_SPIN);
254
255 fail_point_setting_garbage_append(fs_new);
256
257 return (fs_new);
258 }
259
260 /* Free a struct fail_point_setting */
261 static void
262 fail_point_setting_destroy(struct fail_point_setting *fp_setting)
263 {
264 struct fail_point_entry *ent;
265
266 while (!TAILQ_EMPTY(&fp_setting->fp_entry_queue)) {
267 ent = TAILQ_FIRST(&fp_setting->fp_entry_queue);
268 TAILQ_REMOVE(&fp_setting->fp_entry_queue, ent, fe_entries);
269 fail_point_entry_destroy(ent);
270 }
271
272 fs_free(fp_setting);
273 }
274
275 /* Allocate and initialize a struct fail_point_entry */
276 static struct fail_point_entry *
277 fail_point_entry_new(struct fail_point_setting *fp_setting)
278 {
279 struct fail_point_entry *fp_entry;
280
281 fp_entry = fp_malloc(sizeof(struct fail_point_entry),
282 M_WAITOK | M_ZERO);
283 fp_entry->fe_parent = fp_setting->fs_parent;
284 fp_entry->fe_prob = PROB_MAX;
285 fp_entry->fe_pid = NO_PID;
286 fp_entry->fe_count = FE_COUNT_UNTRACKED;
287 TAILQ_INSERT_TAIL(&fp_setting->fp_entry_queue, fp_entry,
288 fe_entries);
289
290 return (fp_entry);
291 }
292
293 /* Free a struct fail_point_entry */
294 static void
295 fail_point_entry_destroy(struct fail_point_entry *fp_entry)
296 {
297
298 fp_free(fp_entry);
299 }
300
301 /* Get a ref on an fp's fp_setting */
302 static inline struct fail_point_setting *
303 fail_point_setting_get_ref(struct fail_point *fp)
304 {
305 struct fail_point_setting *fp_setting;
306
307 /* Invariant: if we have a ref, our pointer to fp_setting is safe */
308 atomic_add_acq_32(&fp->fp_ref_cnt, 1);
309 fp_setting = fp->fp_setting;
310
311 return (fp_setting);
312 }
313
314 /* Release a ref on an fp_setting */
315 static inline void
316 fail_point_setting_release_ref(struct fail_point *fp)
317 {
318
319 KASSERT(&fp->fp_ref_cnt > 0, ("Attempting to deref w/no refs"));
320 atomic_subtract_rel_32(&fp->fp_ref_cnt, 1);
321 }
322
323 /* Append fp entries to fp garbage list */
324 static inline void
325 fail_point_setting_garbage_append(struct fail_point_setting *fp_setting)
326 {
327
328 mtx_lock_spin(&mtx_garbage_list);
329 STAILQ_INSERT_TAIL(&fp_setting_garbage, fp_setting,
330 fs_garbage_link);
331 mtx_unlock_spin(&mtx_garbage_list);
332 }
333
334 /* Swap fp's entries with fp_setting_new */
335 static struct fail_point_setting *
336 fail_point_swap_settings(struct fail_point *fp,
337 struct fail_point_setting *fp_setting_new)
338 {
339 struct fail_point_setting *fp_setting_old;
340
341 fp_setting_old = fp->fp_setting;
342 fp->fp_setting = fp_setting_new;
343
344 return (fp_setting_old);
345 }
346
347 static inline void
348 fail_point_eval_swap_out(struct fail_point *fp,
349 struct fail_point_setting *fp_setting)
350 {
351
352 /* We may have already been swapped out and replaced; ignore. */
353 if (fp->fp_setting == fp_setting)
354 fail_point_swap_settings(fp, NULL);
355 }
356
357 /* Free up any zero-ref entries in the garbage queue */
358 static void
359 fail_point_garbage_collect(void)
360 {
361 struct fail_point_setting *fs_current, *fs_next;
362 struct fail_point_setting_garbage fp_ents_free_list;
363
364 /**
365 * We will transfer the entries to free to fp_ents_free_list while holding
366 * the spin mutex, then free it after we drop the lock. This avoids
367 * triggering witness due to sleepable mutexes in the memory
368 * allocator.
369 */
370 STAILQ_INIT(&fp_ents_free_list);
371
372 mtx_lock_spin(&mtx_garbage_list);
373 STAILQ_FOREACH_SAFE(fs_current, &fp_setting_garbage, fs_garbage_link,
374 fs_next) {
375 if (fs_current->fs_parent->fp_setting != fs_current &&
376 fs_current->fs_parent->fp_ref_cnt == 0) {
377 STAILQ_REMOVE(&fp_setting_garbage, fs_current,
378 fail_point_setting, fs_garbage_link);
379 STAILQ_INSERT_HEAD(&fp_ents_free_list, fs_current,
380 fs_garbage_link);
381 }
382 }
383 mtx_unlock_spin(&mtx_garbage_list);
384
385 STAILQ_FOREACH_SAFE(fs_current, &fp_ents_free_list, fs_garbage_link,
386 fs_next)
387 fail_point_setting_destroy(fs_current);
388 }
389
390 /* Drain out all refs from this fail point */
391 static inline void
392 fail_point_drain(struct fail_point *fp, int expected_ref)
393 {
394 struct fail_point_setting *entries;
395
396 entries = fail_point_swap_settings(fp, NULL);
397 /**
398 * We have unpaused all threads; so we will wait no longer
399 * than the time taken for the longest remaining sleep, or
400 * the length of time of a long-running code block.
401 */
402 while (fp->fp_ref_cnt > expected_ref) {
403 wakeup(FP_PAUSE_CHANNEL(fp));
404 tsleep(&fp, PWAIT, "fail_point_drain", hz / 100);
405 }
406 if (fp->fp_callout)
407 callout_drain(fp->fp_callout);
408 fail_point_swap_settings(fp, entries);
409 }
410
411 static inline void
412 fail_point_pause(struct fail_point *fp, enum fail_point_return_code *pret,
413 struct mtx *mtx_sleep)
414 {
415
416 if (fp->fp_pre_sleep_fn)
417 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
418
419 msleep_spin(FP_PAUSE_CHANNEL(fp), mtx_sleep, "failpt", 0);
420
421 if (fp->fp_post_sleep_fn)
422 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg);
423 }
424
425 static inline void
426 fail_point_sleep(struct fail_point *fp, int msecs,
427 enum fail_point_return_code *pret)
428 {
429 int timo;
430
431 /* Convert from millisecs to ticks, rounding up */
432 timo = howmany((int64_t)msecs * hz, 1000L);
433
434 if (timo > 0) {
435 if (!(fp->fp_flags & FAIL_POINT_USE_TIMEOUT_PATH)) {
436 if (fp->fp_pre_sleep_fn)
437 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
438
439 tsleep(FP_SLEEP_CHANNEL(fp), PWAIT, "failpt", timo);
440
441 if (fp->fp_post_sleep_fn)
442 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg);
443 } else {
444 if (fp->fp_pre_sleep_fn)
445 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
446
447 callout_reset(fp->fp_callout, timo,
448 fp->fp_post_sleep_fn, fp->fp_post_sleep_arg);
449 *pret = FAIL_POINT_RC_QUEUED;
450 }
451 }
452 }
453
454 static char *parse_fail_point(struct fail_point_setting *, char *);
455 static char *parse_term(struct fail_point_setting *, char *);
456 static char *parse_number(int *out_units, int *out_decimal, char *);
457 static char *parse_type(struct fail_point_entry *, char *);
458
459 /**
460 * Initialize a fail_point. The name is formed in a printf-like fashion
461 * from "fmt" and subsequent arguments. This function is generally used
462 * for custom failpoints located at odd places in the sysctl tree, and is
463 * not explicitly needed for standard in-line-declared failpoints.
464 *
465 * @ingroup failpoint
466 */
467 void
468 fail_point_init(struct fail_point *fp, const char *fmt, ...)
469 {
470 va_list ap;
471 char *name;
472 int n;
473
474 fp->fp_setting = NULL;
475 fp->fp_flags = 0;
476
477 /* Figure out the size of the name. */
478 va_start(ap, fmt);
479 n = vsnprintf(NULL, 0, fmt, ap);
480 va_end(ap);
481
482 /* Allocate the name and fill it in. */
483 name = fp_malloc(n + 1, M_WAITOK);
484 if (name != NULL) {
485 va_start(ap, fmt);
486 vsnprintf(name, n + 1, fmt, ap);
487 va_end(ap);
488 }
489 fp->fp_name = name;
490 fp->fp_location = "";
491 fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME;
492 fp->fp_pre_sleep_fn = NULL;
493 fp->fp_pre_sleep_arg = NULL;
494 fp->fp_post_sleep_fn = NULL;
495 fp->fp_post_sleep_arg = NULL;
496 }
497
498 void
499 fail_point_alloc_callout(struct fail_point *fp)
500 {
501
502 /**
503 * This assumes that calls to fail_point_use_timeout_path()
504 * will not race.
505 */
506 if (fp->fp_callout != NULL)
507 return;
508 fp->fp_callout = fp_malloc(sizeof(*fp->fp_callout), M_WAITOK);
509 callout_init(fp->fp_callout, CALLOUT_MPSAFE);
510 }
511
512 /**
513 * Free the resources held by a fail_point, and wake any paused threads.
514 * Thou shalt not allow threads to hit this fail point after you enter this
515 * function, nor shall you call this multiple times for a given fp.
516 * @ingroup failpoint
517 */
518 void
519 fail_point_destroy(struct fail_point *fp)
520 {
521
522 fail_point_drain(fp, 0);
523
524 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) {
525 fp_free(__DECONST(void *, fp->fp_name));
526 fp->fp_name = NULL;
527 }
528 fp->fp_flags = 0;
529 if (fp->fp_callout) {
530 fp_free(fp->fp_callout);
531 fp->fp_callout = NULL;
532 }
533
534 sx_xlock(&sx_fp_set);
535 fail_point_garbage_collect();
536 sx_xunlock(&sx_fp_set);
537 }
538
539 /**
540 * This does the real work of evaluating a fail point. If the fail point tells
541 * us to return a value, this function returns 1 and fills in 'return_value'
542 * (return_value is allowed to be null). If the fail point tells us to panic,
543 * we never return. Otherwise we just return 0 after doing some work, which
544 * means "keep going".
545 */
546 enum fail_point_return_code
547 fail_point_eval_nontrivial(struct fail_point *fp, int *return_value)
548 {
549 bool execute = false;
550 struct fail_point_entry *ent;
551 struct fail_point_setting *fp_setting;
552 enum fail_point_return_code ret;
553 int cont;
554 int count;
555 int msecs;
556 int usecs;
557
558 ret = FAIL_POINT_RC_CONTINUE;
559 cont = 0; /* don't continue by default */
560
561 fp_setting = fail_point_setting_get_ref(fp);
562 if (fp_setting == NULL)
563 goto abort;
564
565 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) {
566 if (ent->fe_stale)
567 continue;
568
569 if (ent->fe_prob < PROB_MAX &&
570 ent->fe_prob < random() % PROB_MAX)
571 continue;
572
573 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid)
574 continue;
575
576 if (ent->fe_count != FE_COUNT_UNTRACKED) {
577 count = ent->fe_count;
578 while (count > 0) {
579 if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) {
580 count--;
581 execute = true;
582 break;
583 }
584 count = ent->fe_count;
585 }
586 if (execute == false)
587 /* We lost the race; consider the entry stale and bail now */
588 continue;
589 if (count == 0)
590 ent->fe_stale = true;
591 }
592
593 switch (ent->fe_type) {
594 case FAIL_POINT_PANIC:
595 panic("fail point %s panicking", fp->fp_name);
596 /* NOTREACHED */
597
598 case FAIL_POINT_RETURN:
599 if (return_value != NULL)
600 *return_value = ent->fe_arg;
601 ret = FAIL_POINT_RC_RETURN;
602 break;
603
604 case FAIL_POINT_BREAK:
605 printf("fail point %s breaking to debugger\n",
606 fp->fp_name);
607 breakpoint();
608 break;
609
610 case FAIL_POINT_PRINT:
611 printf("fail point %s executing\n", fp->fp_name);
612 cont = ent->fe_arg;
613 break;
614
615 case FAIL_POINT_SLEEP:
616 msecs = ent->fe_arg;
617 if (msecs)
618 fail_point_sleep(fp, msecs, &ret);
619 break;
620
621 case FAIL_POINT_PAUSE:
622 /**
623 * Pausing is inherently strange with multiple
624 * entries given our design. That is because some
625 * entries could be unreachable, for instance in cases like:
626 * pause->return. We can never reach the return entry.
627 * The sysctl layer actually truncates all entries after
628 * a pause for this reason.
629 */
630 mtx_lock_spin(&fp_setting->feq_mtx);
631 fail_point_pause(fp, &ret, &fp_setting->feq_mtx);
632 mtx_unlock_spin(&fp_setting->feq_mtx);
633 break;
634
635 case FAIL_POINT_YIELD:
636 kern_yield(PRI_UNCHANGED);
637 break;
638
639 case FAIL_POINT_DELAY:
640 usecs = ent->fe_arg;
641 DELAY(usecs);
642 break;
643
644 default:
645 break;
646 }
647
648 if (cont == 0)
649 break;
650 }
651
652 if (fail_point_is_off(fp))
653 fail_point_eval_swap_out(fp, fp_setting);
654
655 abort:
656 fail_point_setting_release_ref(fp);
657
658 return (ret);
659 }
660
661 /**
662 * Translate internal fail_point structure into human-readable text.
663 */
664 static void
665 fail_point_get(struct fail_point *fp, struct sbuf *sb,
666 bool verbose)
667 {
668 struct fail_point_entry *ent;
669 struct fail_point_setting *fp_setting;
670 struct fail_point_entry *fp_entry_cpy;
671 int cnt_sleeping;
672 int idx;
673 int printed_entry_count;
674
675 cnt_sleeping = 0;
676 idx = 0;
677 printed_entry_count = 0;
678
679 fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) *
680 (FP_MAX_ENTRY_COUNT + 1), M_WAITOK);
681
682 fp_setting = fail_point_setting_get_ref(fp);
683
684 if (fp_setting != NULL) {
685 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) {
686 if (ent->fe_stale)
687 continue;
688
689 KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT,
690 ("FP entry list larger than allowed"));
691
692 fp_entry_cpy[printed_entry_count] = *ent;
693 ++printed_entry_count;
694 }
695 }
696 fail_point_setting_release_ref(fp);
697
698 /* This is our equivalent of a NULL terminator */
699 fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID;
700
701 while (idx < printed_entry_count) {
702 ent = &fp_entry_cpy[idx];
703 ++idx;
704 if (ent->fe_prob < PROB_MAX) {
705 int decimal = ent->fe_prob % (PROB_MAX / 100);
706 int units = ent->fe_prob / (PROB_MAX / 100);
707 sbuf_printf(sb, "%d", units);
708 if (decimal) {
709 int digits = PROB_DIGITS - 2;
710 while (!(decimal % 10)) {
711 digits--;
712 decimal /= 10;
713 }
714 sbuf_printf(sb, ".%0*d", digits, decimal);
715 }
716 sbuf_printf(sb, "%%");
717 }
718 if (ent->fe_count >= 0)
719 sbuf_printf(sb, "%d*", ent->fe_count);
720 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name);
721 if (ent->fe_arg)
722 sbuf_printf(sb, "(%d)", ent->fe_arg);
723 if (ent->fe_pid != NO_PID)
724 sbuf_printf(sb, "[pid %d]", ent->fe_pid);
725 if (TAILQ_NEXT(ent, fe_entries))
726 sbuf_printf(sb, "->");
727 }
728 if (!printed_entry_count)
729 sbuf_printf(sb, "off");
730
731 fp_free(fp_entry_cpy);
732 if (verbose) {
733 #ifdef STACK
734 /* Print number of sleeping threads. queue=0 is the argument
735 * used by msleep when sending our threads to sleep. */
736 sbuf_printf(sb, "\nsleeping_thread_stacks = {\n");
737 sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0,
738 &cnt_sleeping);
739
740 sbuf_printf(sb, "},\n");
741 #endif
742 sbuf_printf(sb, "sleeping_thread_count = %d,\n",
743 cnt_sleeping);
744
745 #ifdef STACK
746 sbuf_printf(sb, "paused_thread_stacks = {\n");
747 sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0,
748 &cnt_sleeping);
749
750 sbuf_printf(sb, "},\n");
751 #endif
752 sbuf_printf(sb, "paused_thread_count = %d\n",
753 cnt_sleeping);
754 }
755 }
756
757 /**
758 * Set an internal fail_point structure from a human-readable failpoint string
759 * in a lock-safe manner.
760 */
761 static int
762 fail_point_set(struct fail_point *fp, char *buf)
763 {
764 struct fail_point_entry *ent, *ent_next;
765 struct fail_point_setting *entries;
766 bool should_wake_paused;
767 bool should_truncate;
768 int error;
769
770 error = 0;
771 should_wake_paused = false;
772 should_truncate = false;
773
774 /* Parse new entries. */
775 /**
776 * ref protects our new malloc'd stuff from being garbage collected
777 * before we link it.
778 */
779 fail_point_setting_get_ref(fp);
780 entries = fail_point_setting_new(fp);
781 if (parse_fail_point(entries, buf) == NULL) {
782 STAILQ_REMOVE(&fp_setting_garbage, entries,
783 fail_point_setting, fs_garbage_link);
784 fail_point_setting_destroy(entries);
785 error = EINVAL;
786 goto end;
787 }
788
789 /**
790 * Transfer the entries we are going to keep to a new list.
791 * Get rid of useless zero probability entries, and entries with hit
792 * count 0.
793 * If 'off' is present, and it has no hit count set, then all entries
794 * after it are discarded since they are unreachable.
795 */
796 TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) {
797 if (ent->fe_prob == 0 || ent->fe_count == 0) {
798 printf("Discarding entry which cannot execute %s\n",
799 fail_type_strings[ent->fe_type].name);
800 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
801 fe_entries);
802 fp_free(ent);
803 continue;
804 } else if (should_truncate) {
805 printf("Discarding unreachable entry %s\n",
806 fail_type_strings[ent->fe_type].name);
807 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
808 fe_entries);
809 fp_free(ent);
810 continue;
811 }
812
813 if (ent->fe_type == FAIL_POINT_OFF) {
814 should_wake_paused = true;
815 if (ent->fe_count == FE_COUNT_UNTRACKED) {
816 should_truncate = true;
817 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
818 fe_entries);
819 fp_free(ent);
820 }
821 } else if (ent->fe_type == FAIL_POINT_PAUSE) {
822 should_truncate = true;
823 } else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags &
824 FAIL_POINT_NONSLEEPABLE)) {
825 /**
826 * If this fail point is annotated as being in a
827 * non-sleepable ctx, convert sleep to delay and
828 * convert the msec argument to usecs.
829 */
830 printf("Sleep call request on fail point in "
831 "non-sleepable context; using delay instead "
832 "of sleep\n");
833 ent->fe_type = FAIL_POINT_DELAY;
834 ent->fe_arg *= 1000;
835 }
836 }
837
838 if (TAILQ_EMPTY(&entries->fp_entry_queue)) {
839 entries = fail_point_swap_settings(fp, NULL);
840 if (entries != NULL)
841 wakeup(FP_PAUSE_CHANNEL(fp));
842 } else {
843 if (should_wake_paused)
844 wakeup(FP_PAUSE_CHANNEL(fp));
845 fail_point_swap_settings(fp, entries);
846 }
847
848 end:
849 #ifdef IWARNING
850 if (error)
851 IWARNING("Failed to set %s %s to %s",
852 fp->fp_name, fp->fp_location, buf);
853 else
854 INOTICE("Set %s %s to %s",
855 fp->fp_name, fp->fp_location, buf);
856 #endif /* IWARNING */
857
858 fail_point_setting_release_ref(fp);
859 return (error);
860 }
861
862 #define MAX_FAIL_POINT_BUF 1023
863
864 /**
865 * Handle kernel failpoint set/get.
866 */
867 int
868 fail_point_sysctl(SYSCTL_HANDLER_ARGS)
869 {
870 struct fail_point *fp;
871 char *buf;
872 struct sbuf sb, *sb_check;
873 int error;
874
875 buf = NULL;
876 error = 0;
877 fp = arg1;
878
879 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND);
880 if (sb_check != &sb)
881 return (ENOMEM);
882
883 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req);
884
885 /* Setting */
886 /**
887 * Lock protects any new entries from being garbage collected before we
888 * can link them to the fail point.
889 */
890 sx_xlock(&sx_fp_set);
891 if (req->newptr) {
892 if (req->newlen > MAX_FAIL_POINT_BUF) {
893 error = EINVAL;
894 goto out;
895 }
896
897 buf = fp_malloc(req->newlen + 1, M_WAITOK);
898
899 error = SYSCTL_IN(req, buf, req->newlen);
900 if (error)
901 goto out;
902 buf[req->newlen] = '\0';
903
904 error = fail_point_set(fp, buf);
905 }
906
907 fail_point_garbage_collect();
908 sx_xunlock(&sx_fp_set);
909
910 /* Retrieving. */
911 fail_point_get(fp, &sb, false);
912
913 out:
914 sbuf_finish(&sb);
915 sbuf_delete(&sb);
916
917 if (buf)
918 fp_free(buf);
919
920 return (error);
921 }
922
923 int
924 fail_point_sysctl_status(SYSCTL_HANDLER_ARGS)
925 {
926 struct fail_point *fp;
927 struct sbuf sb, *sb_check;
928
929 fp = arg1;
930
931 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND);
932 if (sb_check != &sb)
933 return (ENOMEM);
934
935 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req);
936
937 /* Retrieving. */
938 fail_point_get(fp, &sb, true);
939
940 sbuf_finish(&sb);
941 sbuf_delete(&sb);
942
943 /**
944 * Lock protects any new entries from being garbage collected before we
945 * can link them to the fail point.
946 */
947 sx_xlock(&sx_fp_set);
948 fail_point_garbage_collect();
949 sx_xunlock(&sx_fp_set);
950
951 return (0);
952 }
953
954 int
955 fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len)
956 {
957 struct sysctl_req *sa;
958 int error;
959
960 sa = sysctl_args;
961
962 error = SYSCTL_OUT(sa, buf, len);
963
964 if (error == ENOMEM)
965 return (-1);
966 else
967 return (len);
968 }
969
970 /**
971 * Internal helper function to translate a human-readable failpoint string
972 * into a internally-parsable fail_point structure.
973 */
974 static char *
975 parse_fail_point(struct fail_point_setting *ents, char *p)
976 {
977 /* <fail_point> ::
978 * <term> ( "->" <term> )*
979 */
980 uint8_t term_count;
981
982 term_count = 1;
983
984 p = parse_term(ents, p);
985 if (p == NULL)
986 return (NULL);
987
988 while (*p != '\0') {
989 term_count++;
990 if (p[0] != '-' || p[1] != '>' ||
991 (p = parse_term(ents, p+2)) == NULL ||
992 term_count > FP_MAX_ENTRY_COUNT)
993 return (NULL);
994 }
995 return (p);
996 }
997
998 /**
999 * Internal helper function to parse an individual term from a failpoint.
1000 */
1001 static char *
1002 parse_term(struct fail_point_setting *ents, char *p)
1003 {
1004 struct fail_point_entry *ent;
1005
1006 ent = fail_point_entry_new(ents);
1007
1008 /*
1009 * <term> ::
1010 * ( (<float> "%") | (<integer> "*" ) )*
1011 * <type>
1012 * [ "(" <integer> ")" ]
1013 * [ "[pid " <integer> "]" ]
1014 */
1015
1016 /* ( (<float> "%") | (<integer> "*" ) )* */
1017 while (isdigit(*p) || *p == '.') {
1018 int units, decimal;
1019
1020 p = parse_number(&units, &decimal, p);
1021 if (p == NULL)
1022 return (NULL);
1023
1024 if (*p == '%') {
1025 if (units > 100) /* prevent overflow early */
1026 units = 100;
1027 ent->fe_prob = units * (PROB_MAX / 100) + decimal;
1028 if (ent->fe_prob > PROB_MAX)
1029 ent->fe_prob = PROB_MAX;
1030 } else if (*p == '*') {
1031 if (!units || units < 0 || decimal)
1032 return (NULL);
1033 ent->fe_count = units;
1034 } else
1035 return (NULL);
1036 p++;
1037 }
1038
1039 /* <type> */
1040 p = parse_type(ent, p);
1041 if (p == NULL)
1042 return (NULL);
1043 if (*p == '\0')
1044 return (p);
1045
1046 /* [ "(" <integer> ")" ] */
1047 if (*p != '(')
1048 return (p);
1049 p++;
1050 if (!isdigit(*p) && *p != '-')
1051 return (NULL);
1052 ent->fe_arg = strtol(p, &p, 0);
1053 if (*p++ != ')')
1054 return (NULL);
1055
1056 /* [ "[pid " <integer> "]" ] */
1057 #define PID_STRING "[pid "
1058 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0)
1059 return (p);
1060 p += sizeof(PID_STRING) - 1;
1061 if (!isdigit(*p))
1062 return (NULL);
1063 ent->fe_pid = strtol(p, &p, 0);
1064 if (*p++ != ']')
1065 return (NULL);
1066
1067 return (p);
1068 }
1069
1070 /**
1071 * Internal helper function to parse a numeric for a failpoint term.
1072 */
1073 static char *
1074 parse_number(int *out_units, int *out_decimal, char *p)
1075 {
1076 char *old_p;
1077
1078 /**
1079 * <number> ::
1080 * <integer> [ "." <integer> ] |
1081 * "." <integer>
1082 */
1083
1084 /* whole part */
1085 old_p = p;
1086 *out_units = strtol(p, &p, 10);
1087 if (p == old_p && *p != '.')
1088 return (NULL);
1089
1090 /* fractional part */
1091 *out_decimal = 0;
1092 if (*p == '.') {
1093 int digits = 0;
1094 p++;
1095 while (isdigit(*p)) {
1096 int digit = *p - '';
1097 if (digits < PROB_DIGITS - 2)
1098 *out_decimal = *out_decimal * 10 + digit;
1099 else if (digits == PROB_DIGITS - 2 && digit >= 5)
1100 (*out_decimal)++;
1101 digits++;
1102 p++;
1103 }
1104 if (!digits) /* need at least one digit after '.' */
1105 return (NULL);
1106 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */
1107 *out_decimal *= 10;
1108 }
1109
1110 return (p); /* success */
1111 }
1112
1113 /**
1114 * Internal helper function to parse an individual type for a failpoint term.
1115 */
1116 static char *
1117 parse_type(struct fail_point_entry *ent, char *beg)
1118 {
1119 enum fail_point_t type;
1120 int len;
1121
1122 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) {
1123 len = fail_type_strings[type].nmlen;
1124 if (strncmp(fail_type_strings[type].name, beg, len) == 0) {
1125 ent->fe_type = type;
1126 return (beg + len);
1127 }
1128 }
1129 return (NULL);
1130 }
1131
1132 /* The fail point sysctl tree. */
1133 SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
1134 "fail points");
1135
1136 /* Debugging/testing stuff for fail point */
1137 static int
1138 sysctl_test_fail_point(SYSCTL_HANDLER_ARGS)
1139 {
1140
1141 KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point);
1142 return (0);
1143 }
1144 SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point,
1145 CTLTYPE_STRING | CTLFLAG_RD | CTLFLAG_NEEDGIANT, NULL, 0,
1146 sysctl_test_fail_point, "A",
1147 "Trigger test fail points");
Cache object: 522146602ccadf813a5e99ea49d058dd
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