aboutsummaryrefslogtreecommitdiffstats
path: root/lib/dynamic_debug.c
blob: 02afc25337284329d23a998e636240d5a41d337d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
/*
 * lib/dynamic_debug.c
 *
 * make pr_debug()/dev_dbg() calls runtime configurable based upon their
 * source module.
 *
 * Copyright (C) 2008 Jason Baron <jbaron@redhat.com>
 * By Greg Banks <gnb@melbourne.sgi.com>
 * Copyright (c) 2008 Silicon Graphics Inc.  All Rights Reserved.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kallsyms.h>
#include <linux/version.h>
#include <linux/types.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/list.h>
#include <linux/sysctl.h>
#include <linux/ctype.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/dynamic_debug.h>
#include <linux/debugfs.h>
#include <linux/slab.h>

extern struct _ddebug __start___verbose[];
extern struct _ddebug __stop___verbose[];

/* dynamic_debug_enabled, and dynamic_debug_enabled2 are bitmasks in which
 * bit n is set to 1 if any modname hashes into the bucket n, 0 otherwise. They
 * use independent hash functions, to reduce the chance of false positives.
 */
long long dynamic_debug_enabled;
EXPORT_SYMBOL_GPL(dynamic_debug_enabled);
long long dynamic_debug_enabled2;
EXPORT_SYMBOL_GPL(dynamic_debug_enabled2);

struct ddebug_table {
	struct list_head link;
	char *mod_name;
	unsigned int num_ddebugs;
	unsigned int num_enabled;
	struct _ddebug *ddebugs;
};

struct ddebug_query {
	const char *filename;
	const char *module;
	const char *function;
	const char *format;
	unsigned int first_lineno, last_lineno;
};

struct ddebug_iter {
	struct ddebug_table *table;
	unsigned int idx;
};

static DEFINE_MUTEX(ddebug_lock);
static LIST_HEAD(ddebug_tables);
static int verbose = 0;

/* Return the last part of a pathname */
static inline const char *basename(const char *path)
{
	const char *tail = strrchr(path, '/');
	return tail ? tail+1 : path;
}

/* format a string into buf[] which describes the _ddebug's flags */
static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
				    size_t maxlen)
{
	char *p = buf;

	BUG_ON(maxlen < 4);
	if (dp->flags & _DPRINTK_FLAGS_PRINT)
		*p++ = 'p';
	if (p == buf)
		*p++ = '-';
	*p = '\0';

	return buf;
}

/*
 * must be called with ddebug_lock held
 */

static int disabled_hash(char hash, bool first_table)
{
	struct ddebug_table *dt;
	char table_hash_value;

	list_for_each_entry(dt, &ddebug_tables, link) {
		if (first_table)
			table_hash_value = dt->ddebugs->primary_hash;
		else
			table_hash_value = dt->ddebugs->secondary_hash;
		if (dt->num_enabled && (hash == table_hash_value))
			return 0;
	}
	return 1;
}

/*
 * Search the tables for _ddebug's which match the given
 * `query' and apply the `flags' and `mask' to them.  Tells
 * the user which ddebug's were changed, or whether none
 * were matched.
 */
static void ddebug_change(const struct ddebug_query *query,
			   unsigned int flags, unsigned int mask)
{
	int i;
	struct ddebug_table *dt;
	unsigned int newflags;
	unsigned int nfound = 0;
	char flagbuf[8];

	/* search for matching ddebugs */
	mutex_lock(&ddebug_lock);
	list_for_each_entry(dt, &ddebug_tables, link) {

		/* match against the module name */
		if (query->module != NULL &&
		    strcmp(query->module, dt->mod_name))
			continue;

		for (i = 0 ; i < dt->num_ddebugs ; i++) {
			struct _ddebug *dp = &dt->ddebugs[i];

			/* match against the source filename */
			if (query->filename != NULL &&
			    strcmp(query->filename, dp->filename) &&
			    strcmp(query->filename, basename(dp->filename)))
				continue;

			/* match against the function */
			if (query->function != NULL &&
			    strcmp(query->function, dp->function))
				continue;

			/* match against the format */
			if (query->format != NULL &&
			    strstr(dp->format, query->format) == NULL)
				continue;

			/* match against the line number range */
			if (query->first_lineno &&
			    dp->lineno < query->first_lineno)
				continue;
			if (query->last_lineno &&
			    dp->lineno > query->last_lineno)
				continue;

			nfound++;

			newflags = (dp->flags & mask) | flags;
			if (newflags == dp->flags)
				continue;

			if (!newflags)
				dt->num_enabled--;
			else if (!dp->flags)
				dt->num_enabled++;
			dp->flags = newflags;
			if (newflags) {
				dynamic_debug_enabled |=
						(1LL << dp->primary_hash);
				dynamic_debug_enabled2 |=
						(1LL << dp->secondary_hash);
			} else {
				if (disabled_hash(dp->primary_hash, true))
					dynamic_debug_enabled &=
						~(1LL << dp->primary_hash);
				if (disabled_hash(dp->secondary_hash, false))
					dynamic_debug_enabled2 &=
						~(1LL << dp->secondary_hash);
			}
			if (verbose)
				printk(KERN_INFO
					"ddebug: changed %s:%d [%s]%s %s\n",
					dp->filename, dp->lineno,
					dt->mod_name, dp->function,
					ddebug_describe_flags(dp, flagbuf,
							sizeof(flagbuf)));
		}
	}
	mutex_unlock(&ddebug_lock);

	if (!nfound && verbose)
		printk(KERN_INFO "ddebug: no matches for query\n");
}

/*
 * Split the buffer `buf' into space-separated words.
 * Handles simple " and ' quoting, i.e. without nested,
 * embedded or escaped \".  Return the number of words
 * or <0 on error.
 */
static int ddebug_tokenize(char *buf, char *words[], int maxwords)
{
	int nwords = 0;

	while (*buf) {
		char *end;

		/* Skip leading whitespace */
		buf = skip_spaces(buf);
		if (!*buf)
			break;	/* oh, it was trailing whitespace */

		/* Run `end' over a word, either whitespace separated or quoted */
		if (*buf == '"' || *buf == '\'') {
			int quote = *buf++;
			for (end = buf ; *end && *end != quote ; end++)
				;
			if (!*end)
				return -EINVAL;	/* unclosed quote */
		} else {
			for (end = buf ; *end && !isspace(*end) ; end++)
				;
			BUG_ON(end == buf);
		}
		/* Here `buf' is the start of the word, `end' is one past the end */

		if (nwords == maxwords)
			return -EINVAL;	/* ran out of words[] before bytes */
		if (*end)
			*end++ = '\0';	/* terminate the word */
		words[nwords++] = buf;
		buf = end;
	}

	if (verbose) {
		int i;
		printk(KERN_INFO "%s: split into words:", __func__);
		for (i = 0 ; i < nwords ; i++)
			printk(" \"%s\"", words[i]);
		printk("\n");
	}

	return nwords;
}

/*
 * Parse a single line number.  Note that the empty string ""
 * is treated as a special case and converted to zero, which
 * is later treated as a "don't care" value.
 */
static inline int parse_lineno(const char *str, unsigned int *val)
{
	char *end = NULL;
	BUG_ON(str == NULL);
	if (*str == '\0') {
		*val = 0;
		return 0;
	}
	*val = simple_strtoul(str, &end, 10);
	return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
}

/*
 * Undo octal escaping in a string, inplace.  This is useful to
 * allow the user to express a query which matches a format
 * containing embedded spaces.
 */
#define isodigit(c)		((c) >= '0' && (c) <= '7')
static char *unescape(char *str)
{
	char *in = str;
	char *out = str;

	while (*in) {
		if (*in == '\\') {
			if (in[1] == '\\') {
				*out++ = '\\';
				in += 2;
				continue;
			} else if (in[1] == 't') {
				*out++ = '\t';
				in += 2;
				continue;
			} else if (in[1] == 'n') {
				*out++ = '\n';
				in += 2;
				continue;
			} else if (isodigit(in[1]) &&
			         isodigit(in[2]) &&
			         isodigit(in[3])) {
				*out++ = ((in[1] - '0')<<6) |
				          ((in[2] - '0')<<3) |
				          (in[3] - '0');
				in += 4;
				continue;
			}
		}
		*out++ = *in++;
	}
	*out = '\0';

	return str;
}

/*
 * Parse words[] as a ddebug query specification, which is a series
 * of (keyword, value) pairs chosen from these possibilities:
 *
 * func <function-name>
 * file <full-pathname>
 * file <base-filename>
 * module <module-name>
 * format <escaped-string-to-find-in-format>
 * line <lineno>
 * line <first-lineno>-<last-lineno> // where either may be empty
 */
static int ddebug_parse_query(char *words[], int nwords,
			       struct ddebug_query *query)
{
	unsigned int i;

	/* check we have an even number of words */
	if (nwords % 2 != 0)
		return -EINVAL;
	memset(query, 0, sizeof(*query));

	for (i = 0 ; i < nwords ; i += 2) {
		if (!strcmp(words[i], "func"))
			query->function = words[i+1];
		else if (!strcmp(words[i], "file"))
			query->filename = words[i+1];
		else if (!strcmp(words[i], "module"))
			query->module = words[i+1];
		else if (!strcmp(words[i], "format"))
			query->format = unescape(words[i+1]);
		else if (!strcmp(words[i], "line")) {
			char *first = words[i+1];
			char *last = strchr(first, '-');
			if (last)
				*last++ = '\0';
			if (parse_lineno(first, &query->first_lineno) < 0)
				return -EINVAL;
			if (last != NULL) {
				/* range <first>-<last> */
				if (parse_lineno(last, &query->last_lineno) < 0)
					return -EINVAL;
			} else {
				query->last_lineno = query->first_lineno;
			}
		} else {
			if (verbose)
				printk(KERN_ERR "%s: unknown keyword \"%s\"\n",
					__func__, words[i]);
			return -EINVAL;
		}
	}

	if (verbose)
		printk(KERN_INFO "%s: q->function=\"%s\" q->filename=\"%s\" "
		       "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
			__func__, query->function, query->filename,
			query->module, query->format, query->first_lineno,
			query->last_lineno);

	return 0;
}

/*
 * Parse `str' as a flags specification, format [-+=][p]+.
 * Sets up *maskp and *flagsp to be used when changing the
 * flags fields of matched _ddebug's.  Returns 0 on success
 * or <0 on error.
 */
static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
			       unsigned int *maskp)
{
	unsigned flags = 0;
	int op = '=';

	switch (*str) {
	case '+':
	case '-':
	case '=':
		op = *str++;
		break;
	default:
		return -EINVAL;
	}
	if (verbose)
		printk(KERN_INFO "%s: op='%c'\n", __func__, op);

	for ( ; *str ; ++str) {
		switch (*str) {
		case 'p':
			flags |= _DPRINTK_FLAGS_PRINT;
			break;
		default:
			return -EINVAL;
		}
	}
	if (flags == 0)
		return -EINVAL;
	if (verbose)
		printk(KERN_INFO "%s: flags=0x%x\n", __func__, flags);

	/* calculate final *flagsp, *maskp according to mask and op */
	switch (op) {
	case '=':
		*maskp = 0;
		*flagsp = flags;
		break;
	case '+':
		*maskp = ~0U;
		*flagsp = flags;
		break;
	case '-':
		*maskp = ~flags;
		*flagsp = 0;
		break;
	}
	if (verbose)
		printk(KERN_INFO "%s: *flagsp=0x%x *maskp=0x%x\n",
			__func__, *flagsp, *maskp);
	return 0;
}

/*
 * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
 * command text from userspace, parses and executes it.
 */
static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
				  size_t len, loff_t *offp)
{
	unsigned int flags = 0, mask = 0;
	struct ddebug_query query;
#define MAXWORDS 9
	int nwords;
	char *words[MAXWORDS];
	char tmpbuf[256];

	if (len == 0)
		return 0;
	/* we don't check *offp -- multiple writes() are allowed */
	if (len > sizeof(tmpbuf)-1)
		return -E2BIG;
	if (copy_from_user(tmpbuf, ubuf, len))
		return -EFAULT;
	tmpbuf[len] = '\0';
	if (verbose)
		printk(KERN_INFO "%s: read %d bytes from userspace\n",
			__func__, (int)len);

	nwords = ddebug_tokenize(tmpbuf, words, MAXWORDS);
	if (nwords <= 0)
		return -EINVAL;
	if (ddebug_parse_query(words, nwords-1, &query))
		return -EINVAL;
	if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
		return -EINVAL;

	/* actually go and implement the change */
	ddebug_change(&query, flags, mask);

	*offp += len;
	return len;
}

/*
 * Set the iterator to point to the first _ddebug object
 * and return a pointer to that first object.  Returns
 * NULL if there are no _ddebugs at all.
 */
static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
{
	if (list_empty(&ddebug_tables)) {
		iter->table = NULL;
		iter->idx = 0;
		return NULL;
	}
	iter->table = list_entry(ddebug_tables.next,
				 struct ddebug_table, link);
	iter->idx = 0;
	return &iter->table->ddebugs[iter->idx];
}

/*
 * Advance the iterator to point to the next _ddebug
 * object from the one the iterator currently points at,
 * and returns a pointer to the new _ddebug.  Returns
 * NULL if the iterator has seen all the _ddebugs.
 */
static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
{
	if (iter->table == NULL)
		return NULL;
	if (++iter->idx == iter->table->num_ddebugs) {
		/* iterate to next table */
		iter->idx = 0;
		if (list_is_last(&iter->table->link, &ddebug_tables)) {
			iter->table = NULL;
			return NULL;
		}
		iter->table = list_entry(iter->table->link.next,
					 struct ddebug_table, link);
	}
	return &iter->table->ddebugs[iter->idx];
}

/*
 * Seq_ops start method.  Called at the start of every
 * read() call from userspace.  Takes the ddebug_lock and
 * seeks the seq_file's iterator to the given position.
 */
static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
{
	struct ddebug_iter *iter = m->private;
	struct _ddebug *dp;
	int n = *pos;

	if (verbose)
		printk(KERN_INFO "%s: called m=%p *pos=%lld\n",
			__func__, m, (unsigned long long)*pos);

	mutex_lock(&ddebug_lock);

	if (!n)
		return SEQ_START_TOKEN;
	if (n < 0)
		return NULL;
	dp = ddebug_iter_first(iter);
	while (dp != NULL && --n > 0)
		dp = ddebug_iter_next(iter);
	return dp;
}

/*
 * Seq_ops next method.  Called several times within a read()
 * call from userspace, with ddebug_lock held.  Walks to the
 * next _ddebug object with a special case for the header line.
 */
static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
{
	struct ddebug_iter *iter = m->private;
	struct _ddebug *dp;

	if (verbose)
		printk(KERN_INFO "%s: called m=%p p=%p *pos=%lld\n",
			__func__, m, p, (unsigned long long)*pos);

	if (p == SEQ_START_TOKEN)
		dp = ddebug_iter_first(iter);
	else
		dp = ddebug_iter_next(iter);
	++*pos;
	return dp;
}

/*
 * Seq_ops show method.  Called several times within a read()
 * call from userspace, with ddebug_lock held.  Formats the
 * current _ddebug as a single human-readable line, with a
 * special case for the header line.
 */
static int ddebug_proc_show(struct seq_file *m, void *p)
{
	struct ddebug_iter *iter = m->private;
	struct _ddebug *dp = p;
	char flagsbuf[8];

	if (verbose)
		printk(KERN_INFO "%s: called m=%p p=%p\n",
			__func__, m, p);

	if (p == SEQ_START_TOKEN) {
		seq_puts(m,
			"# filename:lineno [module]function flags format\n");
		return 0;
	}

	seq_printf(m, "%s:%u [%s]%s %s \"",
		   dp->filename, dp->lineno,
		   iter->table->mod_name, dp->function,
		   ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
	seq_escape(m, dp->format, "\t\r\n\"");
	seq_puts(m, "\"\n");

	return 0;
}

/*
 * Seq_ops stop method.  Called at the end of each read()
 * call from userspace.  Drops ddebug_lock.
 */
static void ddebug_proc_stop(struct seq_file *m, void *p)
{
	if (verbose)
		printk(KERN_INFO "%s: called m=%p p=%p\n",
			__func__, m, p);
	mutex_unlock(&ddebug_lock);
}

static const struct seq_operations ddebug_proc_seqops = {
	.start = ddebug_proc_start,
	.next = ddebug_proc_next,
	.show = ddebug_proc_show,
	.stop = ddebug_proc_stop
};

/*
 * File_ops->open method for <debugfs>/dynamic_debug/control.  Does the seq_file
 * setup dance, and also creates an iterator to walk the _ddebugs.
 * Note that we create a seq_file always, even for O_WRONLY files
 * where it's not needed, as doing so simplifies the ->release method.
 */
static int ddebug_proc_open(struct inode *inode, struct file *file)
{
	struct ddebug_iter *iter;
	int err;

	if (verbose)
		printk(KERN_INFO "%s: called\n", __func__);

	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
	if (iter == NULL)
		return -ENOMEM;

	err = seq_open(file, &ddebug_proc_seqops);
	if (err) {
		kfree(iter);
		return err;
	}
	((struct seq_file *) file->private_data)->private = iter;
	return 0;
}

static const struct file_operations ddebug_proc_fops = {
	.owner = THIS_MODULE,
	.open = ddebug_proc_open,
	.read = seq_read,
	.llseek = seq_lseek,
	.release = seq_release_private,
	.write = ddebug_proc_write
};

/*
 * Allocate a new ddebug_table for the given module
 * and add it to the global list.
 */
int ddebug_add_module(struct _ddebug *tab, unsigned int n,
			     const char *name)
{
	struct ddebug_table *dt;
	char *new_name;

	dt = kzalloc(sizeof(*dt), GFP_KERNEL);
	if (dt == NULL)
		return -ENOMEM;
	new_name = kstrdup(name, GFP_KERNEL);
	if (new_name == NULL) {
		kfree(dt);
		return -ENOMEM;
	}
	dt->mod_name = new_name;
	dt->num_ddebugs = n;
	dt->num_enabled = 0;
	dt->ddebugs = tab;

	mutex_lock(&ddebug_lock);
	list_add_tail(&dt->link, &ddebug_tables);
	mutex_unlock(&ddebug_lock);

	if (verbose)
		printk(KERN_INFO "%u debug prints in module %s\n",
				 n, dt->mod_name);
	return 0;
}
EXPORT_SYMBOL_GPL(ddebug_add_module);

static void ddebug_table_free(struct ddebug_table *dt)
{
	list_del_init(&dt->link);
	kfree(dt->mod_name);
	kfree(dt);
}

/*
 * Called in response to a module being unloaded.  Removes
 * any ddebug_table's which point at the module.
 */
int ddebug_remove_module(const char *mod_name)
{
	struct ddebug_table *dt, *nextdt;
	int ret = -ENOENT;

	if (verbose)
		printk(KERN_INFO "%s: removing module \"%s\"\n",
				__func__, mod_name);

	mutex_lock(&ddebug_lock);
	list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
		if (!strcmp(dt->mod_name, mod_name)) {
			ddebug_table_free(dt);
			ret = 0;
		}
	}
	mutex_unlock(&ddebug_lock);
	return ret;
}
EXPORT_SYMBOL_GPL(ddebug_remove_module);

static void ddebug_remove_all_tables(void)
{
	mutex_lock(&ddebug_lock);
	while (!list_empty(&ddebug_tables)) {
		struct ddebug_table *dt = list_entry(ddebug_tables.next,
						      struct ddebug_table,
						      link);
		ddebug_table_free(dt);
	}
	mutex_unlock(&ddebug_lock);
}

static int __init dynamic_debug_init(void)
{
	struct dentry *dir, *file;
	struct _ddebug *iter, *iter_start;
	const char *modname = NULL;
	int ret = 0;
	int n = 0;

	dir = debugfs_create_dir("dynamic_debug", NULL);
	if (!dir)
		return -ENOMEM;
	file = debugfs_create_file("control", 0644, dir, NULL,
					&ddebug_proc_fops);
	if (!file) {
		debugfs_remove(dir);
		return -ENOMEM;
	}
	if (__start___verbose != __stop___verbose) {
		iter = __start___verbose;
		modname = iter->modname;
		iter_start = iter;
		for (; iter < __stop___verbose; iter++) {
			if (strcmp(modname, iter->modname)) {
				ret = ddebug_add_module(iter_start, n, modname);
				if (ret)
					goto out_free;
				n = 0;
				modname = iter->modname;
				iter_start = iter;
			}
			n++;
		}
		ret = ddebug_add_module(iter_start, n, modname);
	}
out_free:
	if (ret) {
		ddebug_remove_all_tables();
		debugfs_remove(dir);
		debugfs_remove(file);
	}
	return 0;
}
module_init(dynamic_debug_init);