FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_fail.c
1 /*-
2 * Copyright (c) 2009 Isilon Inc http://www.isilon.com/
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23 * SUCH DAMAGE.
24 */
25 /**
26 * @file
27 *
28 * fail(9) Facility.
29 *
30 * @ingroup failpoint_private
31 */
32 /**
33 * @defgroup failpoint fail(9) Facility
34 *
35 * Failpoints allow for injecting fake errors into running code on the fly,
36 * without modifying code or recompiling with flags. Failpoints are always
37 * present, and are very efficient when disabled. Failpoints are described
38 * in man fail(9).
39 */
40 /**
41 * @defgroup failpoint_private Private fail(9) Implementation functions
42 *
43 * Private implementations for the actual failpoint code.
44 *
45 * @ingroup failpoint
46 */
47 /**
48 * @addtogroup failpoint_private
49 * @{
50 */
51
52 #include <sys/cdefs.h>
53 __FBSDID("$FreeBSD: releng/11.0/sys/kern/kern_fail.c 301727 2016-06-09 13:17:08Z markj $");
54
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
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 *
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
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 *
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
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 *
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
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
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 *
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
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
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
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 fail_point_swap_settings(fp, entries);
405 }
406
407 static inline void
408 fail_point_pause(struct fail_point *fp, enum fail_point_return_code *pret,
409 struct mtx *mtx_sleep)
410 {
411
412 if (fp->fp_pre_sleep_fn)
413 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
414
415 msleep_spin(FP_PAUSE_CHANNEL(fp), mtx_sleep, "failpt", 0);
416
417 if (fp->fp_post_sleep_fn)
418 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg);
419 }
420
421 static inline void
422 fail_point_sleep(struct fail_point *fp, int msecs,
423 enum fail_point_return_code *pret)
424 {
425 int timo;
426
427 /* Convert from millisecs to ticks, rounding up */
428 timo = howmany(msecs * hz, 1000);
429
430 if (timo > 0) {
431 if (!(fp->fp_flags & FAIL_POINT_USE_TIMEOUT_PATH)) {
432 if (fp->fp_pre_sleep_fn)
433 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
434
435 tsleep(FP_SLEEP_CHANNEL(fp), PWAIT, "failpt", timo);
436
437 if (fp->fp_post_sleep_fn)
438 fp->fp_post_sleep_fn(fp->fp_post_sleep_arg);
439 } else {
440 if (fp->fp_pre_sleep_fn)
441 fp->fp_pre_sleep_fn(fp->fp_pre_sleep_arg);
442
443 timeout(fp->fp_post_sleep_fn, fp->fp_post_sleep_arg,
444 timo);
445 *pret = FAIL_POINT_RC_QUEUED;
446 }
447 }
448 }
449
450 static char *parse_fail_point(struct fail_point_setting *, char *);
451 static char *parse_term(struct fail_point_setting *, char *);
452 static char *parse_number(int *out_units, int *out_decimal, char *);
453 static char *parse_type(struct fail_point_entry *, char *);
454
455 /**
456 * Initialize a fail_point. The name is formed in a printf-like fashion
457 * from "fmt" and subsequent arguments. This function is generally used
458 * for custom failpoints located at odd places in the sysctl tree, and is
459 * not explicitly needed for standard in-line-declared failpoints.
460 *
461 * @ingroup failpoint
462 */
463 void
464 fail_point_init(struct fail_point *fp, const char *fmt, ...)
465 {
466 va_list ap;
467 char *name;
468 int n;
469
470 fp->fp_setting = NULL;
471 fp->fp_flags = 0;
472
473 /* Figure out the size of the name. */
474 va_start(ap, fmt);
475 n = vsnprintf(NULL, 0, fmt, ap);
476 va_end(ap);
477
478 /* Allocate the name and fill it in. */
479 name = fp_malloc(n + 1, M_WAITOK);
480 if (name != NULL) {
481 va_start(ap, fmt);
482 vsnprintf(name, n + 1, fmt, ap);
483 va_end(ap);
484 }
485 fp->fp_name = name;
486 fp->fp_location = "";
487 fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME;
488 fp->fp_pre_sleep_fn = NULL;
489 fp->fp_pre_sleep_arg = NULL;
490 fp->fp_post_sleep_fn = NULL;
491 fp->fp_post_sleep_arg = NULL;
492 }
493
494 /**
495 * Free the resources held by a fail_point, and wake any paused threads.
496 * Thou shalt not allow threads to hit this fail point after you enter this
497 * function, nor shall you call this multiple times for a given fp.
498 * @ingroup failpoint
499 */
500 void
501 fail_point_destroy(struct fail_point *fp)
502 {
503
504 fail_point_drain(fp, 0);
505
506 if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) {
507 fp_free(__DECONST(void *, fp->fp_name));
508 fp->fp_name = NULL;
509 }
510 fp->fp_flags = 0;
511
512 sx_xlock(&sx_fp_set);
513 fail_point_garbage_collect();
514 sx_xunlock(&sx_fp_set);
515 }
516
517 /**
518 * This does the real work of evaluating a fail point. If the fail point tells
519 * us to return a value, this function returns 1 and fills in 'return_value'
520 * (return_value is allowed to be null). If the fail point tells us to panic,
521 * we never return. Otherwise we just return 0 after doing some work, which
522 * means "keep going".
523 */
524 enum fail_point_return_code
525 fail_point_eval_nontrivial(struct fail_point *fp, int *return_value)
526 {
527 bool execute = false;
528 struct fail_point_entry *ent;
529 struct fail_point_setting *fp_setting;
530 enum fail_point_return_code ret;
531 int cont;
532 int count;
533 int msecs;
534 int usecs;
535
536 ret = FAIL_POINT_RC_CONTINUE;
537 cont = 0; /* don't continue by default */
538
539 fp_setting = fail_point_setting_get_ref(fp);
540 if (fp_setting == NULL)
541 goto abort;
542
543 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) {
544
545 if (ent->fe_stale)
546 continue;
547
548 if (ent->fe_prob < PROB_MAX &&
549 ent->fe_prob < random() % PROB_MAX)
550 continue;
551
552 if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid)
553 continue;
554
555 if (ent->fe_count != FE_COUNT_UNTRACKED) {
556 count = ent->fe_count;
557 while (count > 0) {
558 if (atomic_cmpset_32(&ent->fe_count, count, count - 1)) {
559 count--;
560 execute = true;
561 break;
562 }
563 count = ent->fe_count;
564 }
565 if (execute == false)
566 /* We lost the race; consider the entry stale and bail now */
567 continue;
568 if (count == 0)
569 ent->fe_stale = true;
570 }
571
572 switch (ent->fe_type) {
573 case FAIL_POINT_PANIC:
574 panic("fail point %s panicking", fp->fp_name);
575 /* NOTREACHED */
576
577 case FAIL_POINT_RETURN:
578 if (return_value != NULL)
579 *return_value = ent->fe_arg;
580 ret = FAIL_POINT_RC_RETURN;
581 break;
582
583 case FAIL_POINT_BREAK:
584 printf("fail point %s breaking to debugger\n",
585 fp->fp_name);
586 breakpoint();
587 break;
588
589 case FAIL_POINT_PRINT:
590 printf("fail point %s executing\n", fp->fp_name);
591 cont = ent->fe_arg;
592 break;
593
594 case FAIL_POINT_SLEEP:
595 msecs = ent->fe_arg;
596 if (msecs)
597 fail_point_sleep(fp, msecs, &ret);
598 break;
599
600 case FAIL_POINT_PAUSE:
601 /**
602 * Pausing is inherently strange with multiple
603 * entries given our design. That is because some
604 * entries could be unreachable, for instance in cases like:
605 * pause->return. We can never reach the return entry.
606 * The sysctl layer actually truncates all entries after
607 * a pause for this reason.
608 */
609 mtx_lock_spin(&fp_setting->feq_mtx);
610 fail_point_pause(fp, &ret, &fp_setting->feq_mtx);
611 mtx_unlock_spin(&fp_setting->feq_mtx);
612 break;
613
614 case FAIL_POINT_YIELD:
615 kern_yield(-1);
616 break;
617
618 case FAIL_POINT_DELAY:
619 usecs = ent->fe_arg;
620 DELAY(usecs);
621 break;
622
623 default:
624 break;
625 }
626
627 if (cont == 0)
628 break;
629 }
630
631 if (fail_point_is_off(fp))
632 fail_point_eval_swap_out(fp, fp_setting);
633
634 abort:
635 fail_point_setting_release_ref(fp);
636
637 return (ret);
638 }
639
640 /**
641 * Translate internal fail_point structure into human-readable text.
642 */
643 static void
644 fail_point_get(struct fail_point *fp, struct sbuf *sb,
645 bool verbose)
646 {
647 struct fail_point_entry *ent;
648 struct fail_point_setting *fp_setting;
649 struct fail_point_entry *fp_entry_cpy;
650 int cnt_sleeping;
651 int idx;
652 int printed_entry_count;
653
654 cnt_sleeping = 0;
655 idx = 0;
656 printed_entry_count = 0;
657
658 fp_entry_cpy = fp_malloc(sizeof(struct fail_point_entry) *
659 (FP_MAX_ENTRY_COUNT + 1), M_WAITOK);
660
661 fp_setting = fail_point_setting_get_ref(fp);
662
663 if (fp_setting != NULL) {
664 TAILQ_FOREACH(ent, &fp_setting->fp_entry_queue, fe_entries) {
665 if (ent->fe_stale)
666 continue;
667
668 KASSERT(printed_entry_count < FP_MAX_ENTRY_COUNT,
669 ("FP entry list larger than allowed"));
670
671 fp_entry_cpy[printed_entry_count] = *ent;
672 ++printed_entry_count;
673 }
674 }
675 fail_point_setting_release_ref(fp);
676
677 /* This is our equivalent of a NULL terminator */
678 fp_entry_cpy[printed_entry_count].fe_type = FAIL_POINT_INVALID;
679
680 while (idx < printed_entry_count) {
681 ent = &fp_entry_cpy[idx];
682 ++idx;
683 if (ent->fe_prob < PROB_MAX) {
684 int decimal = ent->fe_prob % (PROB_MAX / 100);
685 int units = ent->fe_prob / (PROB_MAX / 100);
686 sbuf_printf(sb, "%d", units);
687 if (decimal) {
688 int digits = PROB_DIGITS - 2;
689 while (!(decimal % 10)) {
690 digits--;
691 decimal /= 10;
692 }
693 sbuf_printf(sb, ".%0*d", digits, decimal);
694 }
695 sbuf_printf(sb, "%%");
696 }
697 if (ent->fe_count >= 0)
698 sbuf_printf(sb, "%d*", ent->fe_count);
699 sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name);
700 if (ent->fe_arg)
701 sbuf_printf(sb, "(%d)", ent->fe_arg);
702 if (ent->fe_pid != NO_PID)
703 sbuf_printf(sb, "[pid %d]", ent->fe_pid);
704 if (TAILQ_NEXT(ent, fe_entries))
705 sbuf_printf(sb, "->");
706 }
707 if (!printed_entry_count)
708 sbuf_printf(sb, "off");
709
710 fp_free(fp_entry_cpy);
711 if (verbose) {
712 #ifdef STACK
713 /* Print number of sleeping threads. queue=0 is the argument
714 * used by msleep when sending our threads to sleep. */
715 sbuf_printf(sb, "\nsleeping_thread_stacks = {\n");
716 sleepq_sbuf_print_stacks(sb, FP_SLEEP_CHANNEL(fp), 0,
717 &cnt_sleeping);
718
719 sbuf_printf(sb, "},\n");
720 #endif
721 sbuf_printf(sb, "sleeping_thread_count = %d,\n",
722 cnt_sleeping);
723
724 #ifdef STACK
725 sbuf_printf(sb, "paused_thread_stacks = {\n");
726 sleepq_sbuf_print_stacks(sb, FP_PAUSE_CHANNEL(fp), 0,
727 &cnt_sleeping);
728
729 sbuf_printf(sb, "},\n");
730 #endif
731 sbuf_printf(sb, "paused_thread_count = %d\n",
732 cnt_sleeping);
733 }
734 }
735
736 /**
737 * Set an internal fail_point structure from a human-readable failpoint string
738 * in a lock-safe manner.
739 */
740 static int
741 fail_point_set(struct fail_point *fp, char *buf)
742 {
743 struct fail_point_entry *ent, *ent_next;
744 struct fail_point_setting *entries;
745 bool should_wake_paused;
746 bool should_truncate;
747 int error;
748
749 error = 0;
750 should_wake_paused = false;
751 should_truncate = false;
752
753 /* Parse new entries. */
754 /**
755 * ref protects our new malloc'd stuff from being garbage collected
756 * before we link it.
757 */
758 fail_point_setting_get_ref(fp);
759 entries = fail_point_setting_new(fp);
760 if (parse_fail_point(entries, buf) == NULL) {
761 STAILQ_REMOVE(&fp_setting_garbage, entries,
762 fail_point_setting, fs_garbage_link);
763 fail_point_setting_destroy(entries);
764 error = EINVAL;
765 goto end;
766 }
767
768 /**
769 * Transfer the entries we are going to keep to a new list.
770 * Get rid of useless zero probability entries, and entries with hit
771 * count 0.
772 * If 'off' is present, and it has no hit count set, then all entries
773 * after it are discarded since they are unreachable.
774 */
775 TAILQ_FOREACH_SAFE(ent, &entries->fp_entry_queue, fe_entries, ent_next) {
776 if (ent->fe_prob == 0 || ent->fe_count == 0) {
777 printf("Discarding entry which cannot execute %s\n",
778 fail_type_strings[ent->fe_type].name);
779 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
780 fe_entries);
781 fp_free(ent);
782 continue;
783 } else if (should_truncate) {
784 printf("Discarding unreachable entry %s\n",
785 fail_type_strings[ent->fe_type].name);
786 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
787 fe_entries);
788 fp_free(ent);
789 continue;
790 }
791
792 if (ent->fe_type == FAIL_POINT_OFF) {
793 should_wake_paused = true;
794 if (ent->fe_count == FE_COUNT_UNTRACKED) {
795 should_truncate = true;
796 TAILQ_REMOVE(&entries->fp_entry_queue, ent,
797 fe_entries);
798 fp_free(ent);
799 }
800 } else if (ent->fe_type == FAIL_POINT_PAUSE) {
801 should_truncate = true;
802 } else if (ent->fe_type == FAIL_POINT_SLEEP && (fp->fp_flags &
803 FAIL_POINT_NONSLEEPABLE)) {
804 /**
805 * If this fail point is annotated as being in a
806 * non-sleepable ctx, convert sleep to delay and
807 * convert the msec argument to usecs.
808 */
809 printf("Sleep call request on fail point in "
810 "non-sleepable context; using delay instead "
811 "of sleep\n");
812 ent->fe_type = FAIL_POINT_DELAY;
813 ent->fe_arg *= 1000;
814 }
815 }
816
817 if (TAILQ_EMPTY(&entries->fp_entry_queue)) {
818 entries = fail_point_swap_settings(fp, NULL);
819 if (entries != NULL)
820 wakeup(FP_PAUSE_CHANNEL(fp));
821 } else {
822 if (should_wake_paused)
823 wakeup(FP_PAUSE_CHANNEL(fp));
824 fail_point_swap_settings(fp, entries);
825 }
826
827 end:
828 #ifdef IWARNING
829 if (error)
830 IWARNING("Failed to set %s %s to %s",
831 fp->fp_name, fp->fp_location, buf);
832 else
833 INOTICE("Set %s %s to %s",
834 fp->fp_name, fp->fp_location, buf);
835 #endif /* IWARNING */
836
837 fail_point_setting_release_ref(fp);
838 return (error);
839 }
840
841 #define MAX_FAIL_POINT_BUF 1023
842
843 /**
844 * Handle kernel failpoint set/get.
845 */
846 int
847 fail_point_sysctl(SYSCTL_HANDLER_ARGS)
848 {
849 struct fail_point *fp;
850 char *buf;
851 struct sbuf sb, *sb_check;
852 int error;
853
854 buf = NULL;
855 error = 0;
856 fp = arg1;
857
858 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND);
859 if (sb_check != &sb)
860 return (ENOMEM);
861
862 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req);
863
864 /* Setting */
865 /**
866 * Lock protects any new entries from being garbage collected before we
867 * can link them to the fail point.
868 */
869 sx_xlock(&sx_fp_set);
870 if (req->newptr) {
871 if (req->newlen > MAX_FAIL_POINT_BUF) {
872 error = EINVAL;
873 goto out;
874 }
875
876 buf = fp_malloc(req->newlen + 1, M_WAITOK);
877
878 error = SYSCTL_IN(req, buf, req->newlen);
879 if (error)
880 goto out;
881 buf[req->newlen] = '\0';
882
883 error = fail_point_set(fp, buf);
884 }
885
886 fail_point_garbage_collect();
887 sx_xunlock(&sx_fp_set);
888
889 /* Retrieving. */
890 fail_point_get(fp, &sb, false);
891
892 out:
893 sbuf_finish(&sb);
894 sbuf_delete(&sb);
895
896 if (buf)
897 fp_free(buf);
898
899 return (error);
900 }
901
902 int
903 fail_point_sysctl_status(SYSCTL_HANDLER_ARGS)
904 {
905 struct fail_point *fp;
906 struct sbuf sb, *sb_check;
907
908 fp = arg1;
909
910 sb_check = sbuf_new(&sb, NULL, 1024, SBUF_AUTOEXTEND);
911 if (sb_check != &sb)
912 return (ENOMEM);
913
914 sbuf_set_drain(&sb, (sbuf_drain_func *)fail_sysctl_drain_func, req);
915
916 /* Retrieving. */
917 fail_point_get(fp, &sb, true);
918
919 sbuf_finish(&sb);
920 sbuf_delete(&sb);
921
922 /**
923 * Lock protects any new entries from being garbage collected before we
924 * can link them to the fail point.
925 */
926 sx_xlock(&sx_fp_set);
927 fail_point_garbage_collect();
928 sx_xunlock(&sx_fp_set);
929
930 return (0);
931 }
932
933 int
934 fail_sysctl_drain_func(void *sysctl_args, const char *buf, int len)
935 {
936 struct sysctl_req *sa;
937 int error;
938
939 sa = sysctl_args;
940
941 error = SYSCTL_OUT(sa, buf, len);
942
943 if (error == ENOMEM)
944 return (-1);
945 else
946 return (len);
947 }
948
949 /**
950 * Internal helper function to translate a human-readable failpoint string
951 * into a internally-parsable fail_point structure.
952 */
953 static char *
954 parse_fail_point(struct fail_point_setting *ents, char *p)
955 {
956 /* <fail_point> ::
957 * <term> ( "->" <term> )*
958 */
959 uint8_t term_count;
960
961 term_count = 1;
962
963 p = parse_term(ents, p);
964 if (p == NULL)
965 return (NULL);
966
967 while (*p != '\0') {
968 term_count++;
969 if (p[0] != '-' || p[1] != '>' ||
970 (p = parse_term(ents, p+2)) == NULL ||
971 term_count > FP_MAX_ENTRY_COUNT)
972 return (NULL);
973 }
974 return (p);
975 }
976
977 /**
978 * Internal helper function to parse an individual term from a failpoint.
979 */
980 static char *
981 parse_term(struct fail_point_setting *ents, char *p)
982 {
983 struct fail_point_entry *ent;
984
985 ent = fail_point_entry_new(ents);
986
987 /*
988 * <term> ::
989 * ( (<float> "%") | (<integer> "*" ) )*
990 * <type>
991 * [ "(" <integer> ")" ]
992 * [ "[pid " <integer> "]" ]
993 */
994
995 /* ( (<float> "%") | (<integer> "*" ) )* */
996 while (isdigit(*p) || *p == '.') {
997 int units, decimal;
998
999 p = parse_number(&units, &decimal, p);
1000 if (p == NULL)
1001 return (NULL);
1002
1003 if (*p == '%') {
1004 if (units > 100) /* prevent overflow early */
1005 units = 100;
1006 ent->fe_prob = units * (PROB_MAX / 100) + decimal;
1007 if (ent->fe_prob > PROB_MAX)
1008 ent->fe_prob = PROB_MAX;
1009 } else if (*p == '*') {
1010 if (!units || units < 0 || decimal)
1011 return (NULL);
1012 ent->fe_count = units;
1013 } else
1014 return (NULL);
1015 p++;
1016 }
1017
1018 /* <type> */
1019 p = parse_type(ent, p);
1020 if (p == NULL)
1021 return (NULL);
1022 if (*p == '\0')
1023 return (p);
1024
1025 /* [ "(" <integer> ")" ] */
1026 if (*p != '(')
1027 return (p);
1028 p++;
1029 if (!isdigit(*p) && *p != '-')
1030 return (NULL);
1031 ent->fe_arg = strtol(p, &p, 0);
1032 if (*p++ != ')')
1033 return (NULL);
1034
1035 /* [ "[pid " <integer> "]" ] */
1036 #define PID_STRING "[pid "
1037 if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0)
1038 return (p);
1039 p += sizeof(PID_STRING) - 1;
1040 if (!isdigit(*p))
1041 return (NULL);
1042 ent->fe_pid = strtol(p, &p, 0);
1043 if (*p++ != ']')
1044 return (NULL);
1045
1046 return (p);
1047 }
1048
1049 /**
1050 * Internal helper function to parse a numeric for a failpoint term.
1051 */
1052 static char *
1053 parse_number(int *out_units, int *out_decimal, char *p)
1054 {
1055 char *old_p;
1056
1057 /**
1058 * <number> ::
1059 * <integer> [ "." <integer> ] |
1060 * "." <integer>
1061 */
1062
1063 /* whole part */
1064 old_p = p;
1065 *out_units = strtol(p, &p, 10);
1066 if (p == old_p && *p != '.')
1067 return (NULL);
1068
1069 /* fractional part */
1070 *out_decimal = 0;
1071 if (*p == '.') {
1072 int digits = 0;
1073 p++;
1074 while (isdigit(*p)) {
1075 int digit = *p - '';
1076 if (digits < PROB_DIGITS - 2)
1077 *out_decimal = *out_decimal * 10 + digit;
1078 else if (digits == PROB_DIGITS - 2 && digit >= 5)
1079 (*out_decimal)++;
1080 digits++;
1081 p++;
1082 }
1083 if (!digits) /* need at least one digit after '.' */
1084 return (NULL);
1085 while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */
1086 *out_decimal *= 10;
1087 }
1088
1089 return (p); /* success */
1090 }
1091
1092 /**
1093 * Internal helper function to parse an individual type for a failpoint term.
1094 */
1095 static char *
1096 parse_type(struct fail_point_entry *ent, char *beg)
1097 {
1098 enum fail_point_t type;
1099 int len;
1100
1101 for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) {
1102 len = fail_type_strings[type].nmlen;
1103 if (strncmp(fail_type_strings[type].name, beg, len) == 0) {
1104 ent->fe_type = type;
1105 return (beg + len);
1106 }
1107 }
1108 return (NULL);
1109 }
1110
1111 /* The fail point sysctl tree. */
1112 SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW, 0, "fail points");
1113
1114 /* Debugging/testing stuff for fail point */
1115 static int
1116 sysctl_test_fail_point(SYSCTL_HANDLER_ARGS)
1117 {
1118
1119 KFAIL_POINT_RETURN(DEBUG_FP, test_fail_point);
1120 return (0);
1121 }
1122 SYSCTL_OID(_debug_fail_point, OID_AUTO, test_trigger_fail_point,
1123 CTLTYPE_STRING | CTLFLAG_RD, NULL, 0, sysctl_test_fail_point, "A",
1124 "Trigger test fail points");
Cache object: 245d3a27b086addaeb2b31527a52fef7
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