xref: /openbmc/linux/lib/dynamic_debug.c (revision 565d76cb)
1 /*
2  * lib/dynamic_debug.c
3  *
4  * make pr_debug()/dev_dbg() calls runtime configurable based upon their
5  * source module.
6  *
7  * Copyright (C) 2008 Jason Baron <jbaron@redhat.com>
8  * By Greg Banks <gnb@melbourne.sgi.com>
9  * Copyright (c) 2008 Silicon Graphics Inc.  All Rights Reserved.
10  * Copyright (C) 2011 Bart Van Assche.  All Rights Reserved.
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/moduleparam.h>
16 #include <linux/kallsyms.h>
17 #include <linux/version.h>
18 #include <linux/types.h>
19 #include <linux/mutex.h>
20 #include <linux/proc_fs.h>
21 #include <linux/seq_file.h>
22 #include <linux/list.h>
23 #include <linux/sysctl.h>
24 #include <linux/ctype.h>
25 #include <linux/string.h>
26 #include <linux/uaccess.h>
27 #include <linux/dynamic_debug.h>
28 #include <linux/debugfs.h>
29 #include <linux/slab.h>
30 #include <linux/jump_label.h>
31 #include <linux/hardirq.h>
32 #include <linux/sched.h>
33 
34 extern struct _ddebug __start___verbose[];
35 extern struct _ddebug __stop___verbose[];
36 
37 struct ddebug_table {
38 	struct list_head link;
39 	char *mod_name;
40 	unsigned int num_ddebugs;
41 	unsigned int num_enabled;
42 	struct _ddebug *ddebugs;
43 };
44 
45 struct ddebug_query {
46 	const char *filename;
47 	const char *module;
48 	const char *function;
49 	const char *format;
50 	unsigned int first_lineno, last_lineno;
51 };
52 
53 struct ddebug_iter {
54 	struct ddebug_table *table;
55 	unsigned int idx;
56 };
57 
58 static DEFINE_MUTEX(ddebug_lock);
59 static LIST_HEAD(ddebug_tables);
60 static int verbose = 0;
61 
62 /* Return the last part of a pathname */
63 static inline const char *basename(const char *path)
64 {
65 	const char *tail = strrchr(path, '/');
66 	return tail ? tail+1 : path;
67 }
68 
69 static struct { unsigned flag:8; char opt_char; } opt_array[] = {
70 	{ _DPRINTK_FLAGS_PRINT, 'p' },
71 	{ _DPRINTK_FLAGS_INCL_MODNAME, 'm' },
72 	{ _DPRINTK_FLAGS_INCL_FUNCNAME, 'f' },
73 	{ _DPRINTK_FLAGS_INCL_LINENO, 'l' },
74 	{ _DPRINTK_FLAGS_INCL_TID, 't' },
75 };
76 
77 /* format a string into buf[] which describes the _ddebug's flags */
78 static char *ddebug_describe_flags(struct _ddebug *dp, char *buf,
79 				    size_t maxlen)
80 {
81 	char *p = buf;
82 	int i;
83 
84 	BUG_ON(maxlen < 4);
85 	for (i = 0; i < ARRAY_SIZE(opt_array); ++i)
86 		if (dp->flags & opt_array[i].flag)
87 			*p++ = opt_array[i].opt_char;
88 	if (p == buf)
89 		*p++ = '-';
90 	*p = '\0';
91 
92 	return buf;
93 }
94 
95 /*
96  * Search the tables for _ddebug's which match the given
97  * `query' and apply the `flags' and `mask' to them.  Tells
98  * the user which ddebug's were changed, or whether none
99  * were matched.
100  */
101 static void ddebug_change(const struct ddebug_query *query,
102 			   unsigned int flags, unsigned int mask)
103 {
104 	int i;
105 	struct ddebug_table *dt;
106 	unsigned int newflags;
107 	unsigned int nfound = 0;
108 	char flagbuf[8];
109 
110 	/* search for matching ddebugs */
111 	mutex_lock(&ddebug_lock);
112 	list_for_each_entry(dt, &ddebug_tables, link) {
113 
114 		/* match against the module name */
115 		if (query->module != NULL &&
116 		    strcmp(query->module, dt->mod_name))
117 			continue;
118 
119 		for (i = 0 ; i < dt->num_ddebugs ; i++) {
120 			struct _ddebug *dp = &dt->ddebugs[i];
121 
122 			/* match against the source filename */
123 			if (query->filename != NULL &&
124 			    strcmp(query->filename, dp->filename) &&
125 			    strcmp(query->filename, basename(dp->filename)))
126 				continue;
127 
128 			/* match against the function */
129 			if (query->function != NULL &&
130 			    strcmp(query->function, dp->function))
131 				continue;
132 
133 			/* match against the format */
134 			if (query->format != NULL &&
135 			    strstr(dp->format, query->format) == NULL)
136 				continue;
137 
138 			/* match against the line number range */
139 			if (query->first_lineno &&
140 			    dp->lineno < query->first_lineno)
141 				continue;
142 			if (query->last_lineno &&
143 			    dp->lineno > query->last_lineno)
144 				continue;
145 
146 			nfound++;
147 
148 			newflags = (dp->flags & mask) | flags;
149 			if (newflags == dp->flags)
150 				continue;
151 
152 			if (!newflags)
153 				dt->num_enabled--;
154 			else if (!dp->flags)
155 				dt->num_enabled++;
156 			dp->flags = newflags;
157 			if (newflags)
158 				dp->enabled = 1;
159 			else
160 				dp->enabled = 0;
161 			if (verbose)
162 				printk(KERN_INFO
163 					"ddebug: changed %s:%d [%s]%s %s\n",
164 					dp->filename, dp->lineno,
165 					dt->mod_name, dp->function,
166 					ddebug_describe_flags(dp, flagbuf,
167 							sizeof(flagbuf)));
168 		}
169 	}
170 	mutex_unlock(&ddebug_lock);
171 
172 	if (!nfound && verbose)
173 		printk(KERN_INFO "ddebug: no matches for query\n");
174 }
175 
176 /*
177  * Split the buffer `buf' into space-separated words.
178  * Handles simple " and ' quoting, i.e. without nested,
179  * embedded or escaped \".  Return the number of words
180  * or <0 on error.
181  */
182 static int ddebug_tokenize(char *buf, char *words[], int maxwords)
183 {
184 	int nwords = 0;
185 
186 	while (*buf) {
187 		char *end;
188 
189 		/* Skip leading whitespace */
190 		buf = skip_spaces(buf);
191 		if (!*buf)
192 			break;	/* oh, it was trailing whitespace */
193 
194 		/* Run `end' over a word, either whitespace separated or quoted */
195 		if (*buf == '"' || *buf == '\'') {
196 			int quote = *buf++;
197 			for (end = buf ; *end && *end != quote ; end++)
198 				;
199 			if (!*end)
200 				return -EINVAL;	/* unclosed quote */
201 		} else {
202 			for (end = buf ; *end && !isspace(*end) ; end++)
203 				;
204 			BUG_ON(end == buf);
205 		}
206 		/* Here `buf' is the start of the word, `end' is one past the end */
207 
208 		if (nwords == maxwords)
209 			return -EINVAL;	/* ran out of words[] before bytes */
210 		if (*end)
211 			*end++ = '\0';	/* terminate the word */
212 		words[nwords++] = buf;
213 		buf = end;
214 	}
215 
216 	if (verbose) {
217 		int i;
218 		printk(KERN_INFO "%s: split into words:", __func__);
219 		for (i = 0 ; i < nwords ; i++)
220 			printk(" \"%s\"", words[i]);
221 		printk("\n");
222 	}
223 
224 	return nwords;
225 }
226 
227 /*
228  * Parse a single line number.  Note that the empty string ""
229  * is treated as a special case and converted to zero, which
230  * is later treated as a "don't care" value.
231  */
232 static inline int parse_lineno(const char *str, unsigned int *val)
233 {
234 	char *end = NULL;
235 	BUG_ON(str == NULL);
236 	if (*str == '\0') {
237 		*val = 0;
238 		return 0;
239 	}
240 	*val = simple_strtoul(str, &end, 10);
241 	return end == NULL || end == str || *end != '\0' ? -EINVAL : 0;
242 }
243 
244 /*
245  * Undo octal escaping in a string, inplace.  This is useful to
246  * allow the user to express a query which matches a format
247  * containing embedded spaces.
248  */
249 #define isodigit(c)		((c) >= '0' && (c) <= '7')
250 static char *unescape(char *str)
251 {
252 	char *in = str;
253 	char *out = str;
254 
255 	while (*in) {
256 		if (*in == '\\') {
257 			if (in[1] == '\\') {
258 				*out++ = '\\';
259 				in += 2;
260 				continue;
261 			} else if (in[1] == 't') {
262 				*out++ = '\t';
263 				in += 2;
264 				continue;
265 			} else if (in[1] == 'n') {
266 				*out++ = '\n';
267 				in += 2;
268 				continue;
269 			} else if (isodigit(in[1]) &&
270 			         isodigit(in[2]) &&
271 			         isodigit(in[3])) {
272 				*out++ = ((in[1] - '0')<<6) |
273 				          ((in[2] - '0')<<3) |
274 				          (in[3] - '0');
275 				in += 4;
276 				continue;
277 			}
278 		}
279 		*out++ = *in++;
280 	}
281 	*out = '\0';
282 
283 	return str;
284 }
285 
286 /*
287  * Parse words[] as a ddebug query specification, which is a series
288  * of (keyword, value) pairs chosen from these possibilities:
289  *
290  * func <function-name>
291  * file <full-pathname>
292  * file <base-filename>
293  * module <module-name>
294  * format <escaped-string-to-find-in-format>
295  * line <lineno>
296  * line <first-lineno>-<last-lineno> // where either may be empty
297  */
298 static int ddebug_parse_query(char *words[], int nwords,
299 			       struct ddebug_query *query)
300 {
301 	unsigned int i;
302 
303 	/* check we have an even number of words */
304 	if (nwords % 2 != 0)
305 		return -EINVAL;
306 	memset(query, 0, sizeof(*query));
307 
308 	for (i = 0 ; i < nwords ; i += 2) {
309 		if (!strcmp(words[i], "func"))
310 			query->function = words[i+1];
311 		else if (!strcmp(words[i], "file"))
312 			query->filename = words[i+1];
313 		else if (!strcmp(words[i], "module"))
314 			query->module = words[i+1];
315 		else if (!strcmp(words[i], "format"))
316 			query->format = unescape(words[i+1]);
317 		else if (!strcmp(words[i], "line")) {
318 			char *first = words[i+1];
319 			char *last = strchr(first, '-');
320 			if (last)
321 				*last++ = '\0';
322 			if (parse_lineno(first, &query->first_lineno) < 0)
323 				return -EINVAL;
324 			if (last != NULL) {
325 				/* range <first>-<last> */
326 				if (parse_lineno(last, &query->last_lineno) < 0)
327 					return -EINVAL;
328 			} else {
329 				query->last_lineno = query->first_lineno;
330 			}
331 		} else {
332 			if (verbose)
333 				printk(KERN_ERR "%s: unknown keyword \"%s\"\n",
334 					__func__, words[i]);
335 			return -EINVAL;
336 		}
337 	}
338 
339 	if (verbose)
340 		printk(KERN_INFO "%s: q->function=\"%s\" q->filename=\"%s\" "
341 		       "q->module=\"%s\" q->format=\"%s\" q->lineno=%u-%u\n",
342 			__func__, query->function, query->filename,
343 			query->module, query->format, query->first_lineno,
344 			query->last_lineno);
345 
346 	return 0;
347 }
348 
349 /*
350  * Parse `str' as a flags specification, format [-+=][p]+.
351  * Sets up *maskp and *flagsp to be used when changing the
352  * flags fields of matched _ddebug's.  Returns 0 on success
353  * or <0 on error.
354  */
355 static int ddebug_parse_flags(const char *str, unsigned int *flagsp,
356 			       unsigned int *maskp)
357 {
358 	unsigned flags = 0;
359 	int op = '=', i;
360 
361 	switch (*str) {
362 	case '+':
363 	case '-':
364 	case '=':
365 		op = *str++;
366 		break;
367 	default:
368 		return -EINVAL;
369 	}
370 	if (verbose)
371 		printk(KERN_INFO "%s: op='%c'\n", __func__, op);
372 
373 	for ( ; *str ; ++str) {
374 		for (i = ARRAY_SIZE(opt_array) - 1; i >= 0; i--) {
375 			if (*str == opt_array[i].opt_char) {
376 				flags |= opt_array[i].flag;
377 				break;
378 			}
379 		}
380 		if (i < 0)
381 			return -EINVAL;
382 	}
383 	if (flags == 0)
384 		return -EINVAL;
385 	if (verbose)
386 		printk(KERN_INFO "%s: flags=0x%x\n", __func__, flags);
387 
388 	/* calculate final *flagsp, *maskp according to mask and op */
389 	switch (op) {
390 	case '=':
391 		*maskp = 0;
392 		*flagsp = flags;
393 		break;
394 	case '+':
395 		*maskp = ~0U;
396 		*flagsp = flags;
397 		break;
398 	case '-':
399 		*maskp = ~flags;
400 		*flagsp = 0;
401 		break;
402 	}
403 	if (verbose)
404 		printk(KERN_INFO "%s: *flagsp=0x%x *maskp=0x%x\n",
405 			__func__, *flagsp, *maskp);
406 	return 0;
407 }
408 
409 static int ddebug_exec_query(char *query_string)
410 {
411 	unsigned int flags = 0, mask = 0;
412 	struct ddebug_query query;
413 #define MAXWORDS 9
414 	int nwords;
415 	char *words[MAXWORDS];
416 
417 	nwords = ddebug_tokenize(query_string, words, MAXWORDS);
418 	if (nwords <= 0)
419 		return -EINVAL;
420 	if (ddebug_parse_query(words, nwords-1, &query))
421 		return -EINVAL;
422 	if (ddebug_parse_flags(words[nwords-1], &flags, &mask))
423 		return -EINVAL;
424 
425 	/* actually go and implement the change */
426 	ddebug_change(&query, flags, mask);
427 	return 0;
428 }
429 
430 int __dynamic_pr_debug(struct _ddebug *descriptor, const char *fmt, ...)
431 {
432 	va_list args;
433 	int res;
434 
435 	BUG_ON(!descriptor);
436 	BUG_ON(!fmt);
437 
438 	va_start(args, fmt);
439 	res = printk(KERN_DEBUG);
440 	if (descriptor->flags & _DPRINTK_FLAGS_INCL_TID) {
441 		if (in_interrupt())
442 			res += printk(KERN_CONT "<intr> ");
443 		else
444 			res += printk(KERN_CONT "[%d] ", task_pid_vnr(current));
445 	}
446 	if (descriptor->flags & _DPRINTK_FLAGS_INCL_MODNAME)
447 		res += printk(KERN_CONT "%s:", descriptor->modname);
448 	if (descriptor->flags & _DPRINTK_FLAGS_INCL_FUNCNAME)
449 		res += printk(KERN_CONT "%s:", descriptor->function);
450 	if (descriptor->flags & _DPRINTK_FLAGS_INCL_LINENO)
451 		res += printk(KERN_CONT "%d ", descriptor->lineno);
452 	res += vprintk(fmt, args);
453 	va_end(args);
454 
455 	return res;
456 }
457 EXPORT_SYMBOL(__dynamic_pr_debug);
458 
459 static __initdata char ddebug_setup_string[1024];
460 static __init int ddebug_setup_query(char *str)
461 {
462 	if (strlen(str) >= 1024) {
463 		pr_warning("ddebug boot param string too large\n");
464 		return 0;
465 	}
466 	strcpy(ddebug_setup_string, str);
467 	return 1;
468 }
469 
470 __setup("ddebug_query=", ddebug_setup_query);
471 
472 /*
473  * File_ops->write method for <debugfs>/dynamic_debug/conrol.  Gathers the
474  * command text from userspace, parses and executes it.
475  */
476 static ssize_t ddebug_proc_write(struct file *file, const char __user *ubuf,
477 				  size_t len, loff_t *offp)
478 {
479 	char tmpbuf[256];
480 	int ret;
481 
482 	if (len == 0)
483 		return 0;
484 	/* we don't check *offp -- multiple writes() are allowed */
485 	if (len > sizeof(tmpbuf)-1)
486 		return -E2BIG;
487 	if (copy_from_user(tmpbuf, ubuf, len))
488 		return -EFAULT;
489 	tmpbuf[len] = '\0';
490 	if (verbose)
491 		printk(KERN_INFO "%s: read %d bytes from userspace\n",
492 			__func__, (int)len);
493 
494 	ret = ddebug_exec_query(tmpbuf);
495 	if (ret)
496 		return ret;
497 
498 	*offp += len;
499 	return len;
500 }
501 
502 /*
503  * Set the iterator to point to the first _ddebug object
504  * and return a pointer to that first object.  Returns
505  * NULL if there are no _ddebugs at all.
506  */
507 static struct _ddebug *ddebug_iter_first(struct ddebug_iter *iter)
508 {
509 	if (list_empty(&ddebug_tables)) {
510 		iter->table = NULL;
511 		iter->idx = 0;
512 		return NULL;
513 	}
514 	iter->table = list_entry(ddebug_tables.next,
515 				 struct ddebug_table, link);
516 	iter->idx = 0;
517 	return &iter->table->ddebugs[iter->idx];
518 }
519 
520 /*
521  * Advance the iterator to point to the next _ddebug
522  * object from the one the iterator currently points at,
523  * and returns a pointer to the new _ddebug.  Returns
524  * NULL if the iterator has seen all the _ddebugs.
525  */
526 static struct _ddebug *ddebug_iter_next(struct ddebug_iter *iter)
527 {
528 	if (iter->table == NULL)
529 		return NULL;
530 	if (++iter->idx == iter->table->num_ddebugs) {
531 		/* iterate to next table */
532 		iter->idx = 0;
533 		if (list_is_last(&iter->table->link, &ddebug_tables)) {
534 			iter->table = NULL;
535 			return NULL;
536 		}
537 		iter->table = list_entry(iter->table->link.next,
538 					 struct ddebug_table, link);
539 	}
540 	return &iter->table->ddebugs[iter->idx];
541 }
542 
543 /*
544  * Seq_ops start method.  Called at the start of every
545  * read() call from userspace.  Takes the ddebug_lock and
546  * seeks the seq_file's iterator to the given position.
547  */
548 static void *ddebug_proc_start(struct seq_file *m, loff_t *pos)
549 {
550 	struct ddebug_iter *iter = m->private;
551 	struct _ddebug *dp;
552 	int n = *pos;
553 
554 	if (verbose)
555 		printk(KERN_INFO "%s: called m=%p *pos=%lld\n",
556 			__func__, m, (unsigned long long)*pos);
557 
558 	mutex_lock(&ddebug_lock);
559 
560 	if (!n)
561 		return SEQ_START_TOKEN;
562 	if (n < 0)
563 		return NULL;
564 	dp = ddebug_iter_first(iter);
565 	while (dp != NULL && --n > 0)
566 		dp = ddebug_iter_next(iter);
567 	return dp;
568 }
569 
570 /*
571  * Seq_ops next method.  Called several times within a read()
572  * call from userspace, with ddebug_lock held.  Walks to the
573  * next _ddebug object with a special case for the header line.
574  */
575 static void *ddebug_proc_next(struct seq_file *m, void *p, loff_t *pos)
576 {
577 	struct ddebug_iter *iter = m->private;
578 	struct _ddebug *dp;
579 
580 	if (verbose)
581 		printk(KERN_INFO "%s: called m=%p p=%p *pos=%lld\n",
582 			__func__, m, p, (unsigned long long)*pos);
583 
584 	if (p == SEQ_START_TOKEN)
585 		dp = ddebug_iter_first(iter);
586 	else
587 		dp = ddebug_iter_next(iter);
588 	++*pos;
589 	return dp;
590 }
591 
592 /*
593  * Seq_ops show method.  Called several times within a read()
594  * call from userspace, with ddebug_lock held.  Formats the
595  * current _ddebug as a single human-readable line, with a
596  * special case for the header line.
597  */
598 static int ddebug_proc_show(struct seq_file *m, void *p)
599 {
600 	struct ddebug_iter *iter = m->private;
601 	struct _ddebug *dp = p;
602 	char flagsbuf[8];
603 
604 	if (verbose)
605 		printk(KERN_INFO "%s: called m=%p p=%p\n",
606 			__func__, m, p);
607 
608 	if (p == SEQ_START_TOKEN) {
609 		seq_puts(m,
610 			"# filename:lineno [module]function flags format\n");
611 		return 0;
612 	}
613 
614 	seq_printf(m, "%s:%u [%s]%s %s \"",
615 		   dp->filename, dp->lineno,
616 		   iter->table->mod_name, dp->function,
617 		   ddebug_describe_flags(dp, flagsbuf, sizeof(flagsbuf)));
618 	seq_escape(m, dp->format, "\t\r\n\"");
619 	seq_puts(m, "\"\n");
620 
621 	return 0;
622 }
623 
624 /*
625  * Seq_ops stop method.  Called at the end of each read()
626  * call from userspace.  Drops ddebug_lock.
627  */
628 static void ddebug_proc_stop(struct seq_file *m, void *p)
629 {
630 	if (verbose)
631 		printk(KERN_INFO "%s: called m=%p p=%p\n",
632 			__func__, m, p);
633 	mutex_unlock(&ddebug_lock);
634 }
635 
636 static const struct seq_operations ddebug_proc_seqops = {
637 	.start = ddebug_proc_start,
638 	.next = ddebug_proc_next,
639 	.show = ddebug_proc_show,
640 	.stop = ddebug_proc_stop
641 };
642 
643 /*
644  * File_ops->open method for <debugfs>/dynamic_debug/control.  Does the seq_file
645  * setup dance, and also creates an iterator to walk the _ddebugs.
646  * Note that we create a seq_file always, even for O_WRONLY files
647  * where it's not needed, as doing so simplifies the ->release method.
648  */
649 static int ddebug_proc_open(struct inode *inode, struct file *file)
650 {
651 	struct ddebug_iter *iter;
652 	int err;
653 
654 	if (verbose)
655 		printk(KERN_INFO "%s: called\n", __func__);
656 
657 	iter = kzalloc(sizeof(*iter), GFP_KERNEL);
658 	if (iter == NULL)
659 		return -ENOMEM;
660 
661 	err = seq_open(file, &ddebug_proc_seqops);
662 	if (err) {
663 		kfree(iter);
664 		return err;
665 	}
666 	((struct seq_file *) file->private_data)->private = iter;
667 	return 0;
668 }
669 
670 static const struct file_operations ddebug_proc_fops = {
671 	.owner = THIS_MODULE,
672 	.open = ddebug_proc_open,
673 	.read = seq_read,
674 	.llseek = seq_lseek,
675 	.release = seq_release_private,
676 	.write = ddebug_proc_write
677 };
678 
679 /*
680  * Allocate a new ddebug_table for the given module
681  * and add it to the global list.
682  */
683 int ddebug_add_module(struct _ddebug *tab, unsigned int n,
684 			     const char *name)
685 {
686 	struct ddebug_table *dt;
687 	char *new_name;
688 
689 	dt = kzalloc(sizeof(*dt), GFP_KERNEL);
690 	if (dt == NULL)
691 		return -ENOMEM;
692 	new_name = kstrdup(name, GFP_KERNEL);
693 	if (new_name == NULL) {
694 		kfree(dt);
695 		return -ENOMEM;
696 	}
697 	dt->mod_name = new_name;
698 	dt->num_ddebugs = n;
699 	dt->num_enabled = 0;
700 	dt->ddebugs = tab;
701 
702 	mutex_lock(&ddebug_lock);
703 	list_add_tail(&dt->link, &ddebug_tables);
704 	mutex_unlock(&ddebug_lock);
705 
706 	if (verbose)
707 		printk(KERN_INFO "%u debug prints in module %s\n",
708 				 n, dt->mod_name);
709 	return 0;
710 }
711 EXPORT_SYMBOL_GPL(ddebug_add_module);
712 
713 static void ddebug_table_free(struct ddebug_table *dt)
714 {
715 	list_del_init(&dt->link);
716 	kfree(dt->mod_name);
717 	kfree(dt);
718 }
719 
720 /*
721  * Called in response to a module being unloaded.  Removes
722  * any ddebug_table's which point at the module.
723  */
724 int ddebug_remove_module(const char *mod_name)
725 {
726 	struct ddebug_table *dt, *nextdt;
727 	int ret = -ENOENT;
728 
729 	if (verbose)
730 		printk(KERN_INFO "%s: removing module \"%s\"\n",
731 				__func__, mod_name);
732 
733 	mutex_lock(&ddebug_lock);
734 	list_for_each_entry_safe(dt, nextdt, &ddebug_tables, link) {
735 		if (!strcmp(dt->mod_name, mod_name)) {
736 			ddebug_table_free(dt);
737 			ret = 0;
738 		}
739 	}
740 	mutex_unlock(&ddebug_lock);
741 	return ret;
742 }
743 EXPORT_SYMBOL_GPL(ddebug_remove_module);
744 
745 static void ddebug_remove_all_tables(void)
746 {
747 	mutex_lock(&ddebug_lock);
748 	while (!list_empty(&ddebug_tables)) {
749 		struct ddebug_table *dt = list_entry(ddebug_tables.next,
750 						      struct ddebug_table,
751 						      link);
752 		ddebug_table_free(dt);
753 	}
754 	mutex_unlock(&ddebug_lock);
755 }
756 
757 static __initdata int ddebug_init_success;
758 
759 static int __init dynamic_debug_init_debugfs(void)
760 {
761 	struct dentry *dir, *file;
762 
763 	if (!ddebug_init_success)
764 		return -ENODEV;
765 
766 	dir = debugfs_create_dir("dynamic_debug", NULL);
767 	if (!dir)
768 		return -ENOMEM;
769 	file = debugfs_create_file("control", 0644, dir, NULL,
770 					&ddebug_proc_fops);
771 	if (!file) {
772 		debugfs_remove(dir);
773 		return -ENOMEM;
774 	}
775 	return 0;
776 }
777 
778 static int __init dynamic_debug_init(void)
779 {
780 	struct _ddebug *iter, *iter_start;
781 	const char *modname = NULL;
782 	int ret = 0;
783 	int n = 0;
784 
785 	if (__start___verbose != __stop___verbose) {
786 		iter = __start___verbose;
787 		modname = iter->modname;
788 		iter_start = iter;
789 		for (; iter < __stop___verbose; iter++) {
790 			if (strcmp(modname, iter->modname)) {
791 				ret = ddebug_add_module(iter_start, n, modname);
792 				if (ret)
793 					goto out_free;
794 				n = 0;
795 				modname = iter->modname;
796 				iter_start = iter;
797 			}
798 			n++;
799 		}
800 		ret = ddebug_add_module(iter_start, n, modname);
801 	}
802 
803 	/* ddebug_query boot param got passed -> set it up */
804 	if (ddebug_setup_string[0] != '\0') {
805 		ret = ddebug_exec_query(ddebug_setup_string);
806 		if (ret)
807 			pr_warning("Invalid ddebug boot param %s",
808 				   ddebug_setup_string);
809 		else
810 			pr_info("ddebug initialized with string %s",
811 				ddebug_setup_string);
812 	}
813 
814 out_free:
815 	if (ret)
816 		ddebug_remove_all_tables();
817 	else
818 		ddebug_init_success = 1;
819 	return 0;
820 }
821 /* Allow early initialization for boot messages via boot param */
822 arch_initcall(dynamic_debug_init);
823 /* Debugfs setup must be done later */
824 module_init(dynamic_debug_init_debugfs);
825