xref: /freebsd/sys/kern/kern_fail.c (revision b5bd50ae40085c9fa935b1e89f5c70eb0558bbf7)
1cfeb7489SZachary Loafman /*-
2cfeb7489SZachary Loafman  * Copyright (c) 2009 Isilon Inc http://www.isilon.com/
3cfeb7489SZachary Loafman  *
4cfeb7489SZachary Loafman  * Redistribution and use in source and binary forms, with or without
5cfeb7489SZachary Loafman  * modification, are permitted provided that the following conditions
6cfeb7489SZachary Loafman  * are met:
7cfeb7489SZachary Loafman  * 1. Redistributions of source code must retain the above copyright
8cfeb7489SZachary Loafman  *    notice, this list of conditions and the following disclaimer.
9cfeb7489SZachary Loafman  * 2. Redistributions in binary form must reproduce the above copyright
10cfeb7489SZachary Loafman  *    notice, this list of conditions and the following disclaimer in the
11cfeb7489SZachary Loafman  *    documentation and/or other materials provided with the distribution.
12cfeb7489SZachary Loafman  *
13cfeb7489SZachary Loafman  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
14cfeb7489SZachary Loafman  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15cfeb7489SZachary Loafman  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16cfeb7489SZachary Loafman  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
17cfeb7489SZachary Loafman  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18cfeb7489SZachary Loafman  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19cfeb7489SZachary Loafman  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20cfeb7489SZachary Loafman  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21cfeb7489SZachary Loafman  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22cfeb7489SZachary Loafman  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23cfeb7489SZachary Loafman  * SUCH DAMAGE.
24cfeb7489SZachary Loafman  */
25cfeb7489SZachary Loafman /**
26cfeb7489SZachary Loafman  * @file
27cfeb7489SZachary Loafman  *
28cfeb7489SZachary Loafman  * fail(9) Facility.
29cfeb7489SZachary Loafman  *
30cfeb7489SZachary Loafman  * @ingroup failpoint_private
31cfeb7489SZachary Loafman  */
32cfeb7489SZachary Loafman /**
33cfeb7489SZachary Loafman  * @defgroup failpoint fail(9) Facility
34cfeb7489SZachary Loafman  *
35cfeb7489SZachary Loafman  * Failpoints allow for injecting fake errors into running code on the fly,
36cfeb7489SZachary Loafman  * without modifying code or recompiling with flags.  Failpoints are always
37cfeb7489SZachary Loafman  * present, and are very efficient when disabled.  Failpoints are described
38cfeb7489SZachary Loafman  * in man fail(9).
39cfeb7489SZachary Loafman  */
40cfeb7489SZachary Loafman /**
41cfeb7489SZachary Loafman  * @defgroup failpoint_private Private fail(9) Implementation functions
42cfeb7489SZachary Loafman  *
43cfeb7489SZachary Loafman  * Private implementations for the actual failpoint code.
44cfeb7489SZachary Loafman  *
45cfeb7489SZachary Loafman  * @ingroup failpoint
46cfeb7489SZachary Loafman  */
47cfeb7489SZachary Loafman /**
48cfeb7489SZachary Loafman  * @addtogroup failpoint_private
49cfeb7489SZachary Loafman  * @{
50cfeb7489SZachary Loafman  */
51cfeb7489SZachary Loafman 
52cfeb7489SZachary Loafman #include <sys/cdefs.h>
53cfeb7489SZachary Loafman __FBSDID("$FreeBSD$");
54cfeb7489SZachary Loafman 
550894a9bcSMatthew D Fleming #include <sys/ctype.h>
56cfeb7489SZachary Loafman #include <sys/errno.h>
57cfeb7489SZachary Loafman #include <sys/fail.h>
58cfeb7489SZachary Loafman #include <sys/kernel.h>
59cfeb7489SZachary Loafman #include <sys/libkern.h>
60cfeb7489SZachary Loafman #include <sys/lock.h>
61cfeb7489SZachary Loafman #include <sys/malloc.h>
62cfeb7489SZachary Loafman #include <sys/mutex.h>
63*b5bd50aeSMatthew D Fleming #include <sys/proc.h>
64cfeb7489SZachary Loafman #include <sys/sbuf.h>
65cfeb7489SZachary Loafman 
66cfeb7489SZachary Loafman #include <machine/stdarg.h>
67cfeb7489SZachary Loafman 
68cfeb7489SZachary Loafman #ifdef ILOG_DEFINE_FOR_FILE
69cfeb7489SZachary Loafman ILOG_DEFINE_FOR_FILE(L_ISI_FAIL_POINT, L_ILOG, fail_point);
70cfeb7489SZachary Loafman #endif
71cfeb7489SZachary Loafman 
72cfeb7489SZachary Loafman MALLOC_DEFINE(M_FAIL_POINT, "Fail Points", "fail points system");
73cfeb7489SZachary Loafman #define fp_free(ptr) free(ptr, M_FAIL_POINT)
74cfeb7489SZachary Loafman #define fp_malloc(size, flags) malloc((size), M_FAIL_POINT, (flags))
75cfeb7489SZachary Loafman 
76cfeb7489SZachary Loafman static struct mtx g_fp_mtx;
77cfeb7489SZachary Loafman MTX_SYSINIT(g_fp_mtx, &g_fp_mtx, "fail point mtx", MTX_DEF);
78cfeb7489SZachary Loafman #define FP_LOCK()	mtx_lock(&g_fp_mtx)
79cfeb7489SZachary Loafman #define FP_UNLOCK()	mtx_unlock(&g_fp_mtx)
80cfeb7489SZachary Loafman 
81d26b7945SMatthew D Fleming /**
82d26b7945SMatthew D Fleming  * Failpoint types.
83d26b7945SMatthew D Fleming  * Don't change these without changing fail_type_strings in fail.c.
84d26b7945SMatthew D Fleming  * @ingroup failpoint_private
85d26b7945SMatthew D Fleming  */
86d26b7945SMatthew D Fleming enum fail_point_t {
87d26b7945SMatthew D Fleming 	FAIL_POINT_OFF,		/**< don't fail */
88d26b7945SMatthew D Fleming 	FAIL_POINT_PANIC,	/**< panic */
89d26b7945SMatthew D Fleming 	FAIL_POINT_RETURN,	/**< return an errorcode */
90d26b7945SMatthew D Fleming 	FAIL_POINT_BREAK,	/**< break into the debugger */
91d26b7945SMatthew D Fleming 	FAIL_POINT_PRINT,	/**< print a message */
92d26b7945SMatthew D Fleming 	FAIL_POINT_SLEEP,	/**< sleep for some msecs */
930894a9bcSMatthew D Fleming 	FAIL_POINT_NUMTYPES
94d26b7945SMatthew D Fleming };
95d26b7945SMatthew D Fleming 
960894a9bcSMatthew D Fleming static struct {
970894a9bcSMatthew D Fleming 	const char *name;
980894a9bcSMatthew D Fleming 	int	nmlen;
990894a9bcSMatthew D Fleming } fail_type_strings[] = {
1000894a9bcSMatthew D Fleming #define	FP_TYPE_NM_LEN(s)	{ s, sizeof(s) - 1 }
1010894a9bcSMatthew D Fleming 	[FAIL_POINT_OFF] =	FP_TYPE_NM_LEN("off"),
1020894a9bcSMatthew D Fleming 	[FAIL_POINT_PANIC] =	FP_TYPE_NM_LEN("panic"),
1030894a9bcSMatthew D Fleming 	[FAIL_POINT_RETURN] =	FP_TYPE_NM_LEN("return"),
1040894a9bcSMatthew D Fleming 	[FAIL_POINT_BREAK] =	FP_TYPE_NM_LEN("break"),
1050894a9bcSMatthew D Fleming 	[FAIL_POINT_PRINT] =	FP_TYPE_NM_LEN("print"),
1060894a9bcSMatthew D Fleming 	[FAIL_POINT_SLEEP] =	FP_TYPE_NM_LEN("sleep"),
107d26b7945SMatthew D Fleming };
108d26b7945SMatthew D Fleming 
109d26b7945SMatthew D Fleming /**
110d26b7945SMatthew D Fleming  * Internal structure tracking a single term of a complete failpoint.
111d26b7945SMatthew D Fleming  * @ingroup failpoint_private
112d26b7945SMatthew D Fleming  */
113d26b7945SMatthew D Fleming struct fail_point_entry {
114d26b7945SMatthew D Fleming 	enum fail_point_t fe_type;	/**< type of entry */
115d26b7945SMatthew D Fleming 	int		fe_arg;		/**< argument to type (e.g. return value) */
116d26b7945SMatthew D Fleming 	int		fe_prob;	/**< likelihood of firing in millionths */
117d26b7945SMatthew D Fleming 	int		fe_count;	/**< number of times to fire, 0 means always */
118*b5bd50aeSMatthew D Fleming 	pid_t		fe_pid;		/**< only fail for this process */
119d26b7945SMatthew D Fleming 	TAILQ_ENTRY(fail_point_entry) fe_entries; /**< next entry in fail point */
120d26b7945SMatthew D Fleming };
121d26b7945SMatthew D Fleming 
122cfeb7489SZachary Loafman static inline void
123cfeb7489SZachary Loafman fail_point_sleep(struct fail_point *fp, struct fail_point_entry *ent,
124cfeb7489SZachary Loafman     int msecs, enum fail_point_return_code *pret)
125cfeb7489SZachary Loafman {
126cfeb7489SZachary Loafman 	/* convert from millisecs to ticks, rounding up */
127cfeb7489SZachary Loafman 	int timo = ((msecs * hz) + 999) / 1000;
128cfeb7489SZachary Loafman 
1290894a9bcSMatthew D Fleming 	if (timo > 0) {
130cfeb7489SZachary Loafman 		if (fp->fp_sleep_fn == NULL) {
131cfeb7489SZachary Loafman 			msleep(fp, &g_fp_mtx, PWAIT, "failpt", timo);
132cfeb7489SZachary Loafman 		} else {
133cfeb7489SZachary Loafman 			timeout(fp->fp_sleep_fn, fp->fp_sleep_arg, timo);
134cfeb7489SZachary Loafman 			*pret = FAIL_POINT_RC_QUEUED;
135cfeb7489SZachary Loafman 		}
136cfeb7489SZachary Loafman 	}
137cfeb7489SZachary Loafman }
138cfeb7489SZachary Loafman 
139cfeb7489SZachary Loafman 
140cfeb7489SZachary Loafman /**
141cfeb7489SZachary Loafman  * Defines stating the equivalent of probablilty one (100%)
142cfeb7489SZachary Loafman  */
143cfeb7489SZachary Loafman enum {
144cfeb7489SZachary Loafman 	PROB_MAX = 1000000,	/* probability between zero and this number */
145cfeb7489SZachary Loafman 	PROB_DIGITS = 6,        /* number of zero's in above number */
146cfeb7489SZachary Loafman };
147cfeb7489SZachary Loafman 
148cfeb7489SZachary Loafman static char *parse_fail_point(struct fail_point_entries *, char *);
149cfeb7489SZachary Loafman static char *parse_term(struct fail_point_entries *, char *);
150cfeb7489SZachary Loafman static char *parse_number(int *out_units, int *out_decimal, char *);
151cfeb7489SZachary Loafman static char *parse_type(struct fail_point_entry *, char *);
152cfeb7489SZachary Loafman static void free_entry(struct fail_point_entries *, struct fail_point_entry *);
153cfeb7489SZachary Loafman static void clear_entries(struct fail_point_entries *);
154cfeb7489SZachary Loafman 
155cfeb7489SZachary Loafman /**
156cfeb7489SZachary Loafman  * Initialize a fail_point.  The name is formed in a printf-like fashion
157cfeb7489SZachary Loafman  * from "fmt" and subsequent arguments.  This function is generally used
158cfeb7489SZachary Loafman  * for custom failpoints located at odd places in the sysctl tree, and is
159cfeb7489SZachary Loafman  * not explicitly needed for standard in-line-declared failpoints.
160cfeb7489SZachary Loafman  *
161cfeb7489SZachary Loafman  * @ingroup failpoint
162cfeb7489SZachary Loafman  */
163cfeb7489SZachary Loafman void
164cfeb7489SZachary Loafman fail_point_init(struct fail_point *fp, const char *fmt, ...)
165cfeb7489SZachary Loafman {
166cfeb7489SZachary Loafman 	va_list ap;
167cfeb7489SZachary Loafman 	char *name;
168cfeb7489SZachary Loafman 	int n;
169cfeb7489SZachary Loafman 
170cfeb7489SZachary Loafman 	TAILQ_INIT(&fp->fp_entries);
171cfeb7489SZachary Loafman 	fp->fp_flags = 0;
172cfeb7489SZachary Loafman 
173cfeb7489SZachary Loafman 	/* Figure out the size of the name. */
174cfeb7489SZachary Loafman 	va_start(ap, fmt);
175cfeb7489SZachary Loafman 	n = vsnprintf(NULL, 0, fmt, ap);
176cfeb7489SZachary Loafman 	va_end(ap);
177cfeb7489SZachary Loafman 
178cfeb7489SZachary Loafman 	/* Allocate the name and fill it in. */
179cfeb7489SZachary Loafman 	name = fp_malloc(n + 1, M_WAITOK);
180cfeb7489SZachary Loafman 	if (name != NULL) {
181cfeb7489SZachary Loafman 		va_start(ap, fmt);
182cfeb7489SZachary Loafman 		vsnprintf(name, n + 1, fmt, ap);
183cfeb7489SZachary Loafman 		va_end(ap);
184cfeb7489SZachary Loafman 	}
185cfeb7489SZachary Loafman 	fp->fp_name = name;
1864b7c6844SMatthew D Fleming 	fp->fp_location = "";
187cfeb7489SZachary Loafman 	fp->fp_flags |= FAIL_POINT_DYNAMIC_NAME;
188cfeb7489SZachary Loafman 	fp->fp_sleep_fn = NULL;
189cfeb7489SZachary Loafman 	fp->fp_sleep_arg = NULL;
190cfeb7489SZachary Loafman }
191cfeb7489SZachary Loafman 
192cfeb7489SZachary Loafman /**
193cfeb7489SZachary Loafman  * Free the resources held by a fail_point.
194cfeb7489SZachary Loafman  *
195cfeb7489SZachary Loafman  * @ingroup failpoint
196cfeb7489SZachary Loafman  */
197cfeb7489SZachary Loafman void
198cfeb7489SZachary Loafman fail_point_destroy(struct fail_point *fp)
199cfeb7489SZachary Loafman {
200cfeb7489SZachary Loafman 
2010894a9bcSMatthew D Fleming 	if ((fp->fp_flags & FAIL_POINT_DYNAMIC_NAME) != 0) {
2020894a9bcSMatthew D Fleming 		fp_free(__DECONST(void *, fp->fp_name));
203cfeb7489SZachary Loafman 		fp->fp_name = NULL;
204cfeb7489SZachary Loafman 	}
205cfeb7489SZachary Loafman 	fp->fp_flags = 0;
2060894a9bcSMatthew D Fleming 	clear_entries(&fp->fp_entries);
207cfeb7489SZachary Loafman }
208cfeb7489SZachary Loafman 
209cfeb7489SZachary Loafman /**
210cfeb7489SZachary Loafman  * This does the real work of evaluating a fail point. If the fail point tells
211cfeb7489SZachary Loafman  * us to return a value, this function returns 1 and fills in 'return_value'
212cfeb7489SZachary Loafman  * (return_value is allowed to be null). If the fail point tells us to panic,
213cfeb7489SZachary Loafman  * we never return. Otherwise we just return 0 after doing some work, which
214cfeb7489SZachary Loafman  * means "keep going".
215cfeb7489SZachary Loafman  */
216cfeb7489SZachary Loafman enum fail_point_return_code
217cfeb7489SZachary Loafman fail_point_eval_nontrivial(struct fail_point *fp, int *return_value)
218cfeb7489SZachary Loafman {
219cfeb7489SZachary Loafman 	enum fail_point_return_code ret = FAIL_POINT_RC_CONTINUE;
220cfeb7489SZachary Loafman 	struct fail_point_entry *ent, *next;
221cfeb7489SZachary Loafman 	int msecs;
222cfeb7489SZachary Loafman 
223cfeb7489SZachary Loafman 	FP_LOCK();
224cfeb7489SZachary Loafman 
2250894a9bcSMatthew D Fleming 	TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, next) {
226cfeb7489SZachary Loafman 		int cont = 0; /* don't continue by default */
227cfeb7489SZachary Loafman 
228cfeb7489SZachary Loafman 		if (ent->fe_prob < PROB_MAX &&
2290894a9bcSMatthew D Fleming 		    ent->fe_prob < random() % PROB_MAX)
2300894a9bcSMatthew D Fleming 			continue;
231*b5bd50aeSMatthew D Fleming 		if (ent->fe_pid != NO_PID && ent->fe_pid != curproc->p_pid)
232*b5bd50aeSMatthew D Fleming 			continue;
233cfeb7489SZachary Loafman 
234cfeb7489SZachary Loafman 		switch (ent->fe_type) {
235cfeb7489SZachary Loafman 		case FAIL_POINT_PANIC:
236cfeb7489SZachary Loafman 			panic("fail point %s panicking", fp->fp_name);
237cfeb7489SZachary Loafman 			/* NOTREACHED */
238cfeb7489SZachary Loafman 
239cfeb7489SZachary Loafman 		case FAIL_POINT_RETURN:
2400894a9bcSMatthew D Fleming 			if (return_value != NULL)
241cfeb7489SZachary Loafman 				*return_value = ent->fe_arg;
242cfeb7489SZachary Loafman 			ret = FAIL_POINT_RC_RETURN;
243cfeb7489SZachary Loafman 			break;
244cfeb7489SZachary Loafman 
245cfeb7489SZachary Loafman 		case FAIL_POINT_BREAK:
2460894a9bcSMatthew D Fleming 			printf("fail point %s breaking to debugger\n",
2470894a9bcSMatthew D Fleming 			    fp->fp_name);
248cfeb7489SZachary Loafman 			breakpoint();
249cfeb7489SZachary Loafman 			break;
250cfeb7489SZachary Loafman 
251cfeb7489SZachary Loafman 		case FAIL_POINT_PRINT:
252cfeb7489SZachary Loafman 			printf("fail point %s executing\n", fp->fp_name);
253cfeb7489SZachary Loafman 			cont = ent->fe_arg;
254cfeb7489SZachary Loafman 			break;
255cfeb7489SZachary Loafman 
256cfeb7489SZachary Loafman 		case FAIL_POINT_SLEEP:
257cfeb7489SZachary Loafman 			/*
258cfeb7489SZachary Loafman 			 * Free the entry now if necessary, since
259cfeb7489SZachary Loafman 			 * we're about to drop the mutex and sleep.
260cfeb7489SZachary Loafman 			 */
261cfeb7489SZachary Loafman 			msecs = ent->fe_arg;
262cfeb7489SZachary Loafman 			if (ent->fe_count > 0 && --ent->fe_count == 0) {
263cfeb7489SZachary Loafman 				free_entry(&fp->fp_entries, ent);
264cfeb7489SZachary Loafman 				ent = NULL;
265cfeb7489SZachary Loafman 			}
266cfeb7489SZachary Loafman 
267cfeb7489SZachary Loafman 			if (msecs)
268cfeb7489SZachary Loafman 				fail_point_sleep(fp, ent, msecs, &ret);
269cfeb7489SZachary Loafman 			break;
270cfeb7489SZachary Loafman 
271cfeb7489SZachary Loafman 		default:
272cfeb7489SZachary Loafman 			break;
273cfeb7489SZachary Loafman 		}
274cfeb7489SZachary Loafman 
2750894a9bcSMatthew D Fleming 		if (ent != NULL && ent->fe_count > 0 && --ent->fe_count == 0)
276cfeb7489SZachary Loafman 			free_entry(&fp->fp_entries, ent);
2770894a9bcSMatthew D Fleming 		if (cont == 0)
278cfeb7489SZachary Loafman 			break;
279cfeb7489SZachary Loafman 	}
280cfeb7489SZachary Loafman 
281cfeb7489SZachary Loafman 	/* Get rid of "off"s at the end. */
282cfeb7489SZachary Loafman 	while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) &&
283cfeb7489SZachary Loafman 	       ent->fe_type == FAIL_POINT_OFF)
284cfeb7489SZachary Loafman 		free_entry(&fp->fp_entries, ent);
285cfeb7489SZachary Loafman 
286cfeb7489SZachary Loafman 	FP_UNLOCK();
287cfeb7489SZachary Loafman 
2880894a9bcSMatthew D Fleming 	return (ret);
289cfeb7489SZachary Loafman }
290cfeb7489SZachary Loafman 
291cfeb7489SZachary Loafman /**
292cfeb7489SZachary Loafman  * Translate internal fail_point structure into human-readable text.
293cfeb7489SZachary Loafman  */
294cfeb7489SZachary Loafman static void
295cfeb7489SZachary Loafman fail_point_get(struct fail_point *fp, struct sbuf *sb)
296cfeb7489SZachary Loafman {
297cfeb7489SZachary Loafman 	struct fail_point_entry *ent;
298cfeb7489SZachary Loafman 
299cfeb7489SZachary Loafman 	FP_LOCK();
300cfeb7489SZachary Loafman 
301cfeb7489SZachary Loafman 	TAILQ_FOREACH(ent, &fp->fp_entries, fe_entries) {
302cfeb7489SZachary Loafman 		if (ent->fe_prob < PROB_MAX) {
303cfeb7489SZachary Loafman 			int decimal = ent->fe_prob % (PROB_MAX / 100);
304cfeb7489SZachary Loafman 			int units = ent->fe_prob / (PROB_MAX / 100);
305cfeb7489SZachary Loafman 			sbuf_printf(sb, "%d", units);
306cfeb7489SZachary Loafman 			if (decimal) {
307cfeb7489SZachary Loafman 				int digits = PROB_DIGITS - 2;
308cfeb7489SZachary Loafman 				while (!(decimal % 10)) {
309cfeb7489SZachary Loafman 					digits--;
310cfeb7489SZachary Loafman 					decimal /= 10;
311cfeb7489SZachary Loafman 				}
312cfeb7489SZachary Loafman 				sbuf_printf(sb, ".%0*d", digits, decimal);
313cfeb7489SZachary Loafman 			}
314cfeb7489SZachary Loafman 			sbuf_printf(sb, "%%");
315cfeb7489SZachary Loafman 		}
316cfeb7489SZachary Loafman 		if (ent->fe_count > 0)
317cfeb7489SZachary Loafman 			sbuf_printf(sb, "%d*", ent->fe_count);
3180894a9bcSMatthew D Fleming 		sbuf_printf(sb, "%s", fail_type_strings[ent->fe_type].name);
319cfeb7489SZachary Loafman 		if (ent->fe_arg)
320cfeb7489SZachary Loafman 			sbuf_printf(sb, "(%d)", ent->fe_arg);
321*b5bd50aeSMatthew D Fleming 		if (ent->fe_pid != NO_PID)
322*b5bd50aeSMatthew D Fleming 			sbuf_printf(sb, "[pid %d]", ent->fe_pid);
323cfeb7489SZachary Loafman 		if (TAILQ_NEXT(ent, fe_entries))
324cfeb7489SZachary Loafman 			sbuf_printf(sb, "->");
325cfeb7489SZachary Loafman 	}
326cfeb7489SZachary Loafman 	if (TAILQ_EMPTY(&fp->fp_entries))
327cfeb7489SZachary Loafman 		sbuf_printf(sb, "off");
328cfeb7489SZachary Loafman 
329cfeb7489SZachary Loafman 	FP_UNLOCK();
330cfeb7489SZachary Loafman }
331cfeb7489SZachary Loafman 
332cfeb7489SZachary Loafman /**
333cfeb7489SZachary Loafman  * Set an internal fail_point structure from a human-readable failpoint string
334cfeb7489SZachary Loafman  * in a lock-safe manner.
335cfeb7489SZachary Loafman  */
336cfeb7489SZachary Loafman static int
337cfeb7489SZachary Loafman fail_point_set(struct fail_point *fp, char *buf)
338cfeb7489SZachary Loafman {
339cfeb7489SZachary Loafman 	int error = 0;
340cfeb7489SZachary Loafman 	struct fail_point_entry *ent, *ent_next;
341cfeb7489SZachary Loafman 	struct fail_point_entries new_entries;
342cfeb7489SZachary Loafman 
343cfeb7489SZachary Loafman 	/* Parse new entries. */
344cfeb7489SZachary Loafman 	TAILQ_INIT(&new_entries);
345cfeb7489SZachary Loafman 	if (!parse_fail_point(&new_entries, buf)) {
346cfeb7489SZachary Loafman 	        clear_entries(&new_entries);
347cfeb7489SZachary Loafman 		error = EINVAL;
348cfeb7489SZachary Loafman 		goto end;
349cfeb7489SZachary Loafman 	}
350cfeb7489SZachary Loafman 
351cfeb7489SZachary Loafman 	FP_LOCK();
352cfeb7489SZachary Loafman 
353cfeb7489SZachary Loafman 	/* Move new entries in. */
354cfeb7489SZachary Loafman 	TAILQ_SWAP(&fp->fp_entries, &new_entries, fail_point_entry, fe_entries);
355cfeb7489SZachary Loafman 	clear_entries(&new_entries);
356cfeb7489SZachary Loafman 
357cfeb7489SZachary Loafman 	/* Get rid of useless zero probability entries. */
358cfeb7489SZachary Loafman 	TAILQ_FOREACH_SAFE(ent, &fp->fp_entries, fe_entries, ent_next) {
359cfeb7489SZachary Loafman 		if (ent->fe_prob == 0)
360cfeb7489SZachary Loafman 			free_entry(&fp->fp_entries, ent);
361cfeb7489SZachary Loafman 	}
362cfeb7489SZachary Loafman 
363cfeb7489SZachary Loafman 	/* Get rid of "off"s at the end. */
364cfeb7489SZachary Loafman 	while ((ent = TAILQ_LAST(&fp->fp_entries, fail_point_entries)) &&
365cfeb7489SZachary Loafman 		ent->fe_type == FAIL_POINT_OFF)
366cfeb7489SZachary Loafman 		free_entry(&fp->fp_entries, ent);
367cfeb7489SZachary Loafman 
368cfeb7489SZachary Loafman 	FP_UNLOCK();
369cfeb7489SZachary Loafman 
370cfeb7489SZachary Loafman  end:
371cfeb7489SZachary Loafman #ifdef IWARNING
372cfeb7489SZachary Loafman 	if (error)
3734b7c6844SMatthew D Fleming 		IWARNING("Failed to set %s %s to %s",
374cfeb7489SZachary Loafman 		    fp->fp_name, fp->fp_location, buf);
375cfeb7489SZachary Loafman 	else
3764b7c6844SMatthew D Fleming 		INOTICE("Set %s %s to %s",
377cfeb7489SZachary Loafman 		    fp->fp_name, fp->fp_location, buf);
378cfeb7489SZachary Loafman #endif /* IWARNING */
379cfeb7489SZachary Loafman 
3800894a9bcSMatthew D Fleming 	return (error);
381cfeb7489SZachary Loafman }
382cfeb7489SZachary Loafman 
383cfeb7489SZachary Loafman #define MAX_FAIL_POINT_BUF	1023
384cfeb7489SZachary Loafman 
385cfeb7489SZachary Loafman /**
386cfeb7489SZachary Loafman  * Handle kernel failpoint set/get.
387cfeb7489SZachary Loafman  */
388cfeb7489SZachary Loafman int
389cfeb7489SZachary Loafman fail_point_sysctl(SYSCTL_HANDLER_ARGS)
390cfeb7489SZachary Loafman {
391cfeb7489SZachary Loafman 	struct fail_point *fp = arg1;
392cfeb7489SZachary Loafman 	char *buf = NULL;
393cfeb7489SZachary Loafman 	struct sbuf sb;
394cfeb7489SZachary Loafman 	int error;
395cfeb7489SZachary Loafman 
396cfeb7489SZachary Loafman 	/* Retrieving */
397cfeb7489SZachary Loafman 	sbuf_new(&sb, NULL, 128, SBUF_AUTOEXTEND);
398cfeb7489SZachary Loafman 	fail_point_get(fp, &sb);
399cfeb7489SZachary Loafman 	sbuf_trim(&sb);
400cfeb7489SZachary Loafman 	sbuf_finish(&sb);
401cfeb7489SZachary Loafman 	error = SYSCTL_OUT(req, sbuf_data(&sb), sbuf_len(&sb));
402cfeb7489SZachary Loafman 	sbuf_delete(&sb);
403cfeb7489SZachary Loafman 
404cfeb7489SZachary Loafman 	/* Setting */
405cfeb7489SZachary Loafman 	if (!error && req->newptr) {
406cfeb7489SZachary Loafman 		if (req->newlen > MAX_FAIL_POINT_BUF) {
407cfeb7489SZachary Loafman 			error = EINVAL;
408cfeb7489SZachary Loafman 			goto out;
409cfeb7489SZachary Loafman 		}
410cfeb7489SZachary Loafman 
411cfeb7489SZachary Loafman 		buf = fp_malloc(req->newlen + 1, M_WAITOK);
412cfeb7489SZachary Loafman 
413cfeb7489SZachary Loafman 		error = SYSCTL_IN(req, buf, req->newlen);
414cfeb7489SZachary Loafman 		if (error)
415cfeb7489SZachary Loafman 			goto out;
416cfeb7489SZachary Loafman 		buf[req->newlen] = '\0';
417cfeb7489SZachary Loafman 
418cfeb7489SZachary Loafman 		error = fail_point_set(fp, buf);
419cfeb7489SZachary Loafman         }
420cfeb7489SZachary Loafman 
421cfeb7489SZachary Loafman out:
422cfeb7489SZachary Loafman 	fp_free(buf);
4230894a9bcSMatthew D Fleming 	return (error);
424cfeb7489SZachary Loafman }
425cfeb7489SZachary Loafman 
426cfeb7489SZachary Loafman /**
427cfeb7489SZachary Loafman  * Internal helper function to translate a human-readable failpoint string
428cfeb7489SZachary Loafman  * into a internally-parsable fail_point structure.
429cfeb7489SZachary Loafman  */
430cfeb7489SZachary Loafman static char *
431cfeb7489SZachary Loafman parse_fail_point(struct fail_point_entries *ents, char *p)
432cfeb7489SZachary Loafman {
433cfeb7489SZachary Loafman 	/*  <fail_point> ::
434cfeb7489SZachary Loafman 	 *      <term> ( "->" <term> )*
435cfeb7489SZachary Loafman 	 */
4360894a9bcSMatthew D Fleming 	p = parse_term(ents, p);
4370894a9bcSMatthew D Fleming 	if (p == NULL)
4380894a9bcSMatthew D Fleming 		return (NULL);
4390894a9bcSMatthew D Fleming 	while (*p != '\0') {
4400894a9bcSMatthew D Fleming 		if (p[0] != '-' || p[1] != '>')
4410894a9bcSMatthew D Fleming 			return (NULL);
4420894a9bcSMatthew D Fleming 		p = parse_term(ents, p + 2);
4430894a9bcSMatthew D Fleming 		if (p == NULL)
4440894a9bcSMatthew D Fleming 			return (NULL);
4450894a9bcSMatthew D Fleming 	}
4460894a9bcSMatthew D Fleming 	return (p);
447cfeb7489SZachary Loafman }
448cfeb7489SZachary Loafman 
449cfeb7489SZachary Loafman /**
450cfeb7489SZachary Loafman  * Internal helper function to parse an individual term from a failpoint.
451cfeb7489SZachary Loafman  */
452cfeb7489SZachary Loafman static char *
453cfeb7489SZachary Loafman parse_term(struct fail_point_entries *ents, char *p)
454cfeb7489SZachary Loafman {
455cfeb7489SZachary Loafman 	struct fail_point_entry *ent;
456cfeb7489SZachary Loafman 
457cfeb7489SZachary Loafman 	ent = fp_malloc(sizeof *ent, M_WAITOK | M_ZERO);
458cfeb7489SZachary Loafman 	ent->fe_prob = PROB_MAX;
459*b5bd50aeSMatthew D Fleming 	ent->fe_pid = NO_PID;
460cfeb7489SZachary Loafman 	TAILQ_INSERT_TAIL(ents, ent, fe_entries);
461cfeb7489SZachary Loafman 
462cfeb7489SZachary Loafman 	/*
463cfeb7489SZachary Loafman 	 * <term> ::
464cfeb7489SZachary Loafman 	 *     ( (<float> "%") | (<integer> "*" ) )*
465cfeb7489SZachary Loafman 	 *     <type>
466cfeb7489SZachary Loafman 	 *     [ "(" <integer> ")" ]
467*b5bd50aeSMatthew D Fleming 	 *     [ "[pid " <integer> "]" ]
468cfeb7489SZachary Loafman 	 */
469cfeb7489SZachary Loafman 
470cfeb7489SZachary Loafman 	/* ( (<float> "%") | (<integer> "*" ) )* */
4710894a9bcSMatthew D Fleming 	while (isdigit(*p) || *p == '.') {
472cfeb7489SZachary Loafman 		int units, decimal;
473cfeb7489SZachary Loafman 
4740894a9bcSMatthew D Fleming 		p = parse_number(&units, &decimal, p);
4750894a9bcSMatthew D Fleming 		if (p == NULL)
4760894a9bcSMatthew D Fleming 			return (NULL);
477cfeb7489SZachary Loafman 
478cfeb7489SZachary Loafman 		if (*p == '%') {
479cfeb7489SZachary Loafman 			if (units > 100) /* prevent overflow early */
480cfeb7489SZachary Loafman 				units = 100;
481cfeb7489SZachary Loafman 			ent->fe_prob = units * (PROB_MAX / 100) + decimal;
482cfeb7489SZachary Loafman 			if (ent->fe_prob > PROB_MAX)
483cfeb7489SZachary Loafman 				ent->fe_prob = PROB_MAX;
484cfeb7489SZachary Loafman 		} else if (*p == '*') {
485cfeb7489SZachary Loafman 			if (!units || decimal)
4860894a9bcSMatthew D Fleming 				return (NULL);
487c2ede4b3SMartin Blapp 			ent->fe_count = units;
4880894a9bcSMatthew D Fleming 		} else
4890894a9bcSMatthew D Fleming 			return (NULL);
490cfeb7489SZachary Loafman 		p++;
491cfeb7489SZachary Loafman 	}
492cfeb7489SZachary Loafman 
493cfeb7489SZachary Loafman 	/* <type> */
4940894a9bcSMatthew D Fleming 	p = parse_type(ent, p);
4950894a9bcSMatthew D Fleming 	if (p == NULL)
4960894a9bcSMatthew D Fleming 		return (NULL);
497cfeb7489SZachary Loafman 	if (*p == '\0')
4980894a9bcSMatthew D Fleming 		return (p);
499cfeb7489SZachary Loafman 
500cfeb7489SZachary Loafman 	/* [ "(" <integer> ")" ] */
501cfeb7489SZachary Loafman 	if (*p != '(')
502cfeb7489SZachary Loafman 		return p;
503cfeb7489SZachary Loafman 	p++;
5040894a9bcSMatthew D Fleming 	if (!isdigit(*p) && *p != '-')
5050894a9bcSMatthew D Fleming 		return (NULL);
506cfeb7489SZachary Loafman 	ent->fe_arg = strtol(p, &p, 0);
507cfeb7489SZachary Loafman 	if (*p++ != ')')
5080894a9bcSMatthew D Fleming 		return (NULL);
509cfeb7489SZachary Loafman 
510*b5bd50aeSMatthew D Fleming 	/* [ "[pid " <integer> "]" ] */
511*b5bd50aeSMatthew D Fleming #define	PID_STRING	"[pid "
512*b5bd50aeSMatthew D Fleming 	if (strncmp(p, PID_STRING, sizeof(PID_STRING) - 1) != 0)
513*b5bd50aeSMatthew D Fleming 		return (p);
514*b5bd50aeSMatthew D Fleming 	p += sizeof(PID_STRING) - 1;
515*b5bd50aeSMatthew D Fleming 	if (!isdigit(*p))
516*b5bd50aeSMatthew D Fleming 		return (NULL);
517*b5bd50aeSMatthew D Fleming 	ent->fe_pid = strtol(p, &p, 0);
518*b5bd50aeSMatthew D Fleming 	if (*p++ != ']')
519*b5bd50aeSMatthew D Fleming 		return (NULL);
520*b5bd50aeSMatthew D Fleming 
5210894a9bcSMatthew D Fleming 	return (p);
522cfeb7489SZachary Loafman }
523cfeb7489SZachary Loafman 
524cfeb7489SZachary Loafman /**
525cfeb7489SZachary Loafman  * Internal helper function to parse a numeric for a failpoint term.
526cfeb7489SZachary Loafman  */
527cfeb7489SZachary Loafman static char *
528cfeb7489SZachary Loafman parse_number(int *out_units, int *out_decimal, char *p)
529cfeb7489SZachary Loafman {
530cfeb7489SZachary Loafman 	char *old_p;
531cfeb7489SZachary Loafman 
532cfeb7489SZachary Loafman 	/*
533cfeb7489SZachary Loafman 	 *  <number> ::
534cfeb7489SZachary Loafman 	 *      <integer> [ "." <integer> ] |
535cfeb7489SZachary Loafman 	 *      "." <integer>
536cfeb7489SZachary Loafman 	 */
537cfeb7489SZachary Loafman 
538cfeb7489SZachary Loafman 	/* whole part */
539cfeb7489SZachary Loafman 	old_p = p;
540c2ede4b3SMartin Blapp 	*out_units = strtol(p, &p, 10);
541cfeb7489SZachary Loafman 	if (p == old_p && *p != '.')
5420894a9bcSMatthew D Fleming 		return (NULL);
543cfeb7489SZachary Loafman 
544cfeb7489SZachary Loafman 	/* fractional part */
545cfeb7489SZachary Loafman 	*out_decimal = 0;
546cfeb7489SZachary Loafman 	if (*p == '.') {
547cfeb7489SZachary Loafman 		int digits = 0;
548cfeb7489SZachary Loafman 		p++;
5490894a9bcSMatthew D Fleming 		while (isdigit(*p)) {
550cfeb7489SZachary Loafman 			int digit = *p - '0';
551cfeb7489SZachary Loafman 			if (digits < PROB_DIGITS - 2)
552cfeb7489SZachary Loafman 				*out_decimal = *out_decimal * 10 + digit;
553cfeb7489SZachary Loafman 			else if (digits == PROB_DIGITS - 2 && digit >= 5)
554cfeb7489SZachary Loafman 				(*out_decimal)++;
555cfeb7489SZachary Loafman 			digits++;
556cfeb7489SZachary Loafman 			p++;
557cfeb7489SZachary Loafman 		}
558cfeb7489SZachary Loafman 		if (!digits) /* need at least one digit after '.' */
5590894a9bcSMatthew D Fleming 			return (NULL);
560cfeb7489SZachary Loafman 		while (digits++ < PROB_DIGITS - 2) /* add implicit zeros */
561cfeb7489SZachary Loafman 			*out_decimal *= 10;
562cfeb7489SZachary Loafman 	}
563cfeb7489SZachary Loafman 
5640894a9bcSMatthew D Fleming 	return (p); /* success */
565cfeb7489SZachary Loafman }
566cfeb7489SZachary Loafman 
567cfeb7489SZachary Loafman /**
568cfeb7489SZachary Loafman  * Internal helper function to parse an individual type for a failpoint term.
569cfeb7489SZachary Loafman  */
570cfeb7489SZachary Loafman static char *
571cfeb7489SZachary Loafman parse_type(struct fail_point_entry *ent, char *beg)
572cfeb7489SZachary Loafman {
573cfeb7489SZachary Loafman 	enum fail_point_t type;
5740894a9bcSMatthew D Fleming 	int len;
5750894a9bcSMatthew D Fleming 
5760894a9bcSMatthew D Fleming 	for (type = FAIL_POINT_OFF; type < FAIL_POINT_NUMTYPES; type++) {
5770894a9bcSMatthew D Fleming 		len = fail_type_strings[type].nmlen;
5780894a9bcSMatthew D Fleming 		if (strncmp(fail_type_strings[type].name, beg, len) == 0) {
579cfeb7489SZachary Loafman 			ent->fe_type = type;
5800894a9bcSMatthew D Fleming 			return (beg + len);
581cfeb7489SZachary Loafman 		}
582cfeb7489SZachary Loafman 	}
5830894a9bcSMatthew D Fleming 	return (NULL);
584cfeb7489SZachary Loafman }
585cfeb7489SZachary Loafman 
586cfeb7489SZachary Loafman /**
587cfeb7489SZachary Loafman  * Internal helper function to free an individual failpoint term.
588cfeb7489SZachary Loafman  */
589cfeb7489SZachary Loafman static void
590cfeb7489SZachary Loafman free_entry(struct fail_point_entries *ents, struct fail_point_entry *ent)
591cfeb7489SZachary Loafman {
592cfeb7489SZachary Loafman 	TAILQ_REMOVE(ents, ent, fe_entries);
593cfeb7489SZachary Loafman 	fp_free(ent);
594cfeb7489SZachary Loafman }
595cfeb7489SZachary Loafman 
596cfeb7489SZachary Loafman /**
597cfeb7489SZachary Loafman  * Internal helper function to clear out all failpoint terms for a single
598cfeb7489SZachary Loafman  * failpoint.
599cfeb7489SZachary Loafman  */
600cfeb7489SZachary Loafman static void
601cfeb7489SZachary Loafman clear_entries(struct fail_point_entries *ents)
602cfeb7489SZachary Loafman {
603cfeb7489SZachary Loafman 	struct fail_point_entry *ent, *ent_next;
6040894a9bcSMatthew D Fleming 
605cfeb7489SZachary Loafman 	TAILQ_FOREACH_SAFE(ent, ents, fe_entries, ent_next)
606cfeb7489SZachary Loafman 		fp_free(ent);
607cfeb7489SZachary Loafman 	TAILQ_INIT(ents);
608cfeb7489SZachary Loafman }
609cfeb7489SZachary Loafman 
610cfeb7489SZachary Loafman /* The fail point sysctl tree. */
611cfeb7489SZachary Loafman SYSCTL_NODE(_debug, OID_AUTO, fail_point, CTLFLAG_RW, 0, "fail points");
612