summaryrefslogtreecommitdiffstats
path: root/kernel/gcov/fs.c
blob: 6e40ff6be083dab77ad46edc01dbd95e4c0a854f (plain)
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
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
// SPDX-License-Identifier: GPL-2.0
/*
 *  This code exports profiling data as debugfs files to userspace.
 *
 *    Copyright IBM Corp. 2009
 *    Author(s): Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
 *
 *    Uses gcc-internal data definitions.
 *    Based on the gcov-kernel patch by:
 *		 Hubertus Franke <frankeh@us.ibm.com>
 *		 Nigel Hinds <nhinds@us.ibm.com>
 *		 Rajan Ravindran <rajancr@us.ibm.com>
 *		 Peter Oberparleiter <oberpar@linux.vnet.ibm.com>
 *		 Paul Larson
 *		 Yi CDL Yang
 */

#define pr_fmt(fmt)	"gcov: " fmt

#include <linux/init.h>
#include <linux/module.h>
#include <linux/debugfs.h>
#include <linux/fs.h>
#include <linux/list.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include "gcov.h"

/**
 * struct gcov_node - represents a debugfs entry
 * @list: list head for child node list
 * @children: child nodes
 * @all: list head for list of all nodes
 * @parent: parent node
 * @loaded_info: array of pointers to profiling data sets for loaded object
 *   files.
 * @num_loaded: number of profiling data sets for loaded object files.
 * @unloaded_info: accumulated copy of profiling data sets for unloaded
 *   object files. Used only when gcov_persist=1.
 * @dentry: main debugfs entry, either a directory or data file
 * @links: associated symbolic links
 * @name: data file basename
 *
 * struct gcov_node represents an entity within the gcov/ subdirectory
 * of debugfs. There are directory and data file nodes. The latter represent
 * the actual synthesized data file plus any associated symbolic links which
 * are needed by the gcov tool to work correctly.
 */
struct gcov_node {
	struct list_head list;
	struct list_head children;
	struct list_head all;
	struct gcov_node *parent;
	struct gcov_info **loaded_info;
	struct gcov_info *unloaded_info;
	struct dentry *dentry;
	struct dentry **links;
	int num_loaded;
	char name[0];
};

static const char objtree[] = OBJTREE;
static const char srctree[] = SRCTREE;
static struct gcov_node root_node;
static struct dentry *reset_dentry;
static LIST_HEAD(all_head);
static DEFINE_MUTEX(node_lock);

/* If non-zero, keep copies of profiling data for unloaded modules. */
static int gcov_persist = 1;

static int __init gcov_persist_setup(char *str)
{
	unsigned long val;

	if (kstrtoul(str, 0, &val)) {
		pr_warn("invalid gcov_persist parameter '%s'\n", str);
		return 0;
	}
	gcov_persist = val;
	pr_info("setting gcov_persist to %d\n", gcov_persist);

	return 1;
}
__setup("gcov_persist=", gcov_persist_setup);

/*
 * seq_file.start() implementation for gcov data files. Note that the
 * gcov_iterator interface is designed to be more restrictive than seq_file
 * (no start from arbitrary position, etc.), to simplify the iterator
 * implementation.
 */
static void *gcov_seq_start(struct seq_file *seq, loff_t *pos)
{
	loff_t i;

	gcov_iter_start(seq->private);
	for (i = 0; i < *pos; i++) {
		if (gcov_iter_next(seq->private))
			return NULL;
	}
	return seq->private;
}

/* seq_file.next() implementation for gcov data files. */
static void *gcov_seq_next(struct seq_file *seq, void *data, loff_t *pos)
{
	struct gcov_iterator *iter = data;

	if (gcov_iter_next(iter))
		return NULL;
	(*pos)++;

	return iter;
}

/* seq_file.show() implementation for gcov data files. */
static int gcov_seq_show(struct seq_file *seq, void *data)
{
	struct gcov_iterator *iter = data;

	if (gcov_iter_write(iter, seq))
		return -EINVAL;
	return 0;
}

static void gcov_seq_stop(struct seq_file *seq, void *data)
{
	/* Unused. */
}

static const struct seq_operations gcov_seq_ops = {
	.start	= gcov_seq_start,
	.next	= gcov_seq_next,
	.show	= gcov_seq_show,
	.stop	= gcov_seq_stop,
};

/*
 * Return a profiling data set associated with the given node. This is
 * either a data set for a loaded object file or a data set copy in case
 * all associated object files have been unloaded.
 */
static struct gcov_info *get_node_info(struct gcov_node *node)
{
	if (node->num_loaded > 0)
		return node->loaded_info[0];

	return node->unloaded_info;
}

/*
 * Return a newly allocated profiling data set which contains the sum of
 * all profiling data associated with the given node.
 */
static struct gcov_info *get_accumulated_info(struct gcov_node *node)
{
	struct gcov_info *info;
	int i = 0;

	if (node->unloaded_info)
		info = gcov_info_dup(node->unloaded_info);
	else
		info = gcov_info_dup(node->loaded_info[i++]);
	if (!info)
		return NULL;
	for (; i < node->num_loaded; i++)
		gcov_info_add(info, node->loaded_info[i]);

	return info;
}

/*
 * open() implementation for gcov data files. Create a copy of the profiling
 * data set and initialize the iterator and seq_file interface.
 */
static int gcov_seq_open(struct inode *inode, struct file *file)
{
	struct gcov_node *node = inode->i_private;
	struct gcov_iterator *iter;
	struct seq_file *seq;
	struct gcov_info *info;
	int rc = -ENOMEM;

	mutex_lock(&node_lock);
	/*
	 * Read from a profiling data copy to minimize reference tracking
	 * complexity and concurrent access and to keep accumulating multiple
	 * profiling data sets associated with one node simple.
	 */
	info = get_accumulated_info(node);
	if (!info)
		goto out_unlock;
	iter = gcov_iter_new(info);
	if (!iter)
		goto err_free_info;
	rc = seq_open(file, &gcov_seq_ops);
	if (rc)
		goto err_free_iter_info;
	seq = file->private_data;
	seq->private = iter;
out_unlock:
	mutex_unlock(&node_lock);
	return rc;

err_free_iter_info:
	gcov_iter_free(iter);
err_free_info:
	gcov_info_free(info);
	goto out_unlock;
}

/*
 * release() implementation for gcov data files. Release resources allocated
 * by open().
 */
static int gcov_seq_release(struct inode *inode, struct file *file)
{
	struct gcov_iterator *iter;
	struct gcov_info *info;
	struct seq_file *seq;

	seq = file->private_data;
	iter = seq->private;
	info = gcov_iter_get_info(iter);
	gcov_iter_free(iter);
	gcov_info_free(info);
	seq_release(inode, file);

	return 0;
}

/*
 * Find a node by the associated data file name. Needs to be called with
 * node_lock held.
 */
static struct gcov_node *get_node_by_name(const char *name)
{
	struct gcov_node *node;
	struct gcov_info *info;

	list_for_each_entry(node, &all_head, all) {
		info = get_node_info(node);
		if (info && (strcmp(gcov_info_filename(info), name) == 0))
			return node;
	}

	return NULL;
}

/*
 * Reset all profiling data associated with the specified node.
 */
static void reset_node(struct gcov_node *node)
{
	int i;

	if (node->unloaded_info)
		gcov_info_reset(node->unloaded_info);
	for (i = 0; i < node->num_loaded; i++)
		gcov_info_reset(node->loaded_info[i]);
}

static void remove_node(struct gcov_node *node);

/*
 * write() implementation for gcov data files. Reset profiling data for the
 * corresponding file. If all associated object files have been unloaded,
 * remove the debug fs node as well.
 */
static ssize_t gcov_seq_write(struct file *file, const char __user *addr,
			      size_t len, loff_t *pos)
{
	struct seq_file *seq;
	struct gcov_info *info;
	struct gcov_node *node;

	seq = file->private_data;
	info = gcov_iter_get_info(seq->private);
	mutex_lock(&node_lock);
	node = get_node_by_name(gcov_info_filename(info));
	if (node) {
		/* Reset counts or remove node for unloaded modules. */
		if (node->num_loaded == 0)
			remove_node(node);
		else
			reset_node(node);
	}
	/* Reset counts for open file. */
	gcov_info_reset(info);
	mutex_unlock(&node_lock);

	return len;
}

/*
 * Given a string <path> representing a file path of format:
 *   path/to/file.gcda
 * construct and return a new string:
 *   <dir/>path/to/file.<ext>
 */
static char *link_target(const char *dir, const char *path, const char *ext)
{
	char *target;
	char *old_ext;
	char *copy;

	copy = kstrdup(path, GFP_KERNEL);
	if (!copy)
		return NULL;
	old_ext = strrchr(copy, '.');
	if (old_ext)
		*old_ext = '\0';
	if (dir)
		target = kasprintf(GFP_KERNEL, "%s/%s.%s", dir, copy, ext);
	else
		target = kasprintf(GFP_KERNEL, "%s.%s", copy, ext);
	kfree(copy);

	return target;
}

/*
 * Construct a string representing the symbolic link target for the given
 * gcov data file name and link type. Depending on the link type and the
 * location of the data file, the link target can either point to a
 * subdirectory of srctree, objtree or in an external location.
 */
static char *get_link_target(const char *filename, const struct gcov_link *ext)
{
	const char *rel;
	char *result;

	if (strncmp(filename, objtree, strlen(objtree)) == 0) {
		rel = filename + strlen(objtree) + 1;
		if (ext->dir == SRC_TREE)
			result = link_target(srctree, rel, ext->ext);
		else
			result = link_target(objtree, rel, ext->ext);
	} else {
		/* External compilation. */
		result = link_target(NULL, filename, ext->ext);
	}

	return result;
}

#define SKEW_PREFIX	".tmp_"

/*
 * For a filename .tmp_filename.ext return filename.ext. Needed to compensate
 * for filename skewing caused by the mod-versioning mechanism.
 */
static const char *deskew(const char *basename)
{
	if (strncmp(basename, SKEW_PREFIX, sizeof(SKEW_PREFIX) - 1) == 0)
		return basename + sizeof(SKEW_PREFIX) - 1;
	return basename;
}

/*
 * Create links to additional files (usually .c and .gcno files) which the
 * gcov tool expects to find in the same directory as the gcov data file.
 */
static void add_links(struct gcov_node *node, struct dentry *parent)
{
	const char *basename;
	char *target;
	int num;
	int i;

	for (num = 0; gcov_link[num].ext; num++)
		/* Nothing. */;
	node->links = kcalloc(num, sizeof(struct dentry *), GFP_KERNEL);
	if (!node->links)
		return;
	for (i = 0; i < num; i++) {
		target = get_link_target(
				gcov_info_filename(get_node_info(node)),
				&gcov_link[i]);
		if (!target)
			goto out_err;
		basename = kbasename(target);
		if (basename == target)
			goto out_err;
		node->links[i] = debugfs_create_symlink(deskew(basename),
							parent,	target);
		if (!node->links[i])
			goto out_err;
		kfree(target);
	}

	return;
out_err:
	kfree(target);
	while (i-- > 0)
		debugfs_remove(node->links[i]);
	kfree(node->links);
	node->links = NULL;
}

static const struct file_operations gcov_data_fops = {
	.open		= gcov_seq_open,
	.release	= gcov_seq_release,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.write		= gcov_seq_write,
};

/* Basic initialization of a new node. */
static void init_node(struct gcov_node *node, struct gcov_info *info,
		      const char *name, struct gcov_node *parent)
{
	INIT_LIST_HEAD(&node->list);
	INIT_LIST_HEAD(&node->children);
	INIT_LIST_HEAD(&node->all);
	if (node->loaded_info) {
		node->loaded_info[0] = info;
		node->num_loaded = 1;
	}
	node->parent = parent;
	if (name)
		strcpy(node->name, name);
}

/*
 * Create a new node and associated debugfs entry. Needs to be called with
 * node_lock held.
 */
static struct gcov_node *new_node(struct gcov_node *parent,
				  struct gcov_info *info, const char *name)
{
	struct gcov_node *node;

	node = kzalloc(sizeof(struct gcov_node) + strlen(name) + 1, GFP_KERNEL);
	if (!node)
		goto err_nomem;
	if (info) {
		node->loaded_info = kcalloc(1, sizeof(struct gcov_info *),
					   GFP_KERNEL);
		if (!node->loaded_info)
			goto err_nomem;
	}
	init_node(node, info, name, parent);
	/* Differentiate between gcov data file nodes and directory nodes. */
	if (info) {
		node->dentry = debugfs_create_file(deskew(node->name), 0600,
					parent->dentry, node, &gcov_data_fops);
	} else
		node->dentry = debugfs_create_dir(node->name, parent->dentry);
	if (!node->dentry) {
		pr_warn("could not create file\n");
		kfree(node);
		return NULL;
	}
	if (info)
		add_links(node, parent->dentry);
	list_add(&node->list, &parent->children);
	list_add(&node->all, &all_head);

	return node;

err_nomem:
	kfree(node);
	pr_warn("out of memory\n");
	return NULL;
}

/* Remove symbolic links associated with node. */
static void remove_links(struct gcov_node *node)
{
	int i;

	if (!node->links)
		return;
	for (i = 0; gcov_link[i].ext; i++)
		debugfs_remove(node->links[i]);
	kfree(node->links);
	node->links = NULL;
}

/*
 * Remove node from all lists and debugfs and release associated resources.
 * Needs to be called with node_lock held.
 */
static void release_node(struct gcov_node *node)
{
	list_del(&node->list);
	list_del(&node->all);
	debugfs_remove(node->dentry);
	remove_links(node);
	kfree(node->loaded_info);
	if (node->unloaded_info)
		gcov_info_free(node->unloaded_info);
	kfree(node);
}

/* Release node and empty parents. Needs to be called with node_lock held. */
static void remove_node(struct gcov_node *node)
{
	struct gcov_node *parent;

	while ((node != &root_node) && list_empty(&node->children)) {
		parent = node->parent;
		release_node(node);
		node = parent;
	}
}

/*
 * Find child node with given basename. Needs to be called with node_lock
 * held.
 */
static struct gcov_node *get_child_by_name(struct gcov_node *parent,
					   const char *name)
{
	struct gcov_node *node;

	list_for_each_entry(node, &parent->children, list) {
		if (strcmp(node->name, name) == 0)
			return node;
	}

	return NULL;
}

/*
 * write() implementation for reset file. Reset all profiling data to zero
 * and remove nodes for which all associated object files are unloaded.
 */
static ssize_t reset_write(struct file *file, const char __user *addr,
			   size_t len, loff_t *pos)
{
	struct gcov_node *node;

	mutex_lock(&node_lock);
restart:
	list_for_each_entry(node, &all_head, all) {
		if (node->num_loaded > 0)
			reset_node(node);
		else if (list_empty(&node->children)) {
			remove_node(node);
			/* Several nodes may have gone - restart loop. */
			goto restart;
		}
	}
	mutex_unlock(&node_lock);

	return len;
}

/* read() implementation for reset file. Unused. */
static ssize_t reset_read(struct file *file, char __user *addr, size_t len,
			  loff_t *pos)
{
	/* Allow read operation so that a recursive copy won't fail. */
	return 0;
}

static const struct file_operations gcov_reset_fops = {
	.write	= reset_write,
	.read	= reset_read,
	.llseek = noop_llseek,
};

/*
 * Create a node for a given profiling data set and add it to all lists and
 * debugfs. Needs to be called with node_lock held.
 */
static void add_node(struct gcov_info *info)
{
	char *filename;
	char *curr;
	char *next;
	struct gcov_node *parent;
	struct gcov_node *node;

	filename = kstrdup(gcov_info_filename(info), GFP_KERNEL);
	if (!filename)
		return;
	parent = &root_node;
	/* Create directory nodes along the path. */
	for (curr = filename; (next = strchr(curr, '/')); curr = next + 1) {
		if (curr == next)
			continue;
		*next = 0;
		if (strcmp(curr, ".") == 0)
			continue;
		if (strcmp(curr, "..") == 0) {
			if (!parent->parent)
				goto err_remove;
			parent = parent->parent;
			continue;
		}
		node = get_child_by_name(parent, curr);
		if (!node) {
			node = new_node(parent, NULL, curr);
			if (!node)
				goto err_remove;
		}
		parent = node;
	}
	/* Create file node. */
	node = new_node(parent, info, curr);
	if (!node)
		goto err_remove;
out:
	kfree(filename);
	return;

err_remove:
	remove_node(parent);
	goto out;
}

/*
 * Associate a profiling data set with an existing node. Needs to be called
 * with node_lock held.
 */
static void add_info(struct gcov_node *node, struct gcov_info *info)
{
	struct gcov_info **loaded_info;
	int num = node->num_loaded;

	/*
	 * Prepare new array. This is done first to simplify cleanup in
	 * case the new data set is incompatible, the node only contains
	 * unloaded data sets and there's not enough memory for the array.
	 */
	loaded_info = kcalloc(num + 1, sizeof(struct gcov_info *), GFP_KERNEL);
	if (!loaded_info) {
		pr_warn("could not add '%s' (out of memory)\n",
			gcov_info_filename(info));
		return;
	}
	memcpy(loaded_info, node->loaded_info,
	       num * sizeof(struct gcov_info *));
	loaded_info[num] = info;
	/* Check if the new data set is compatible. */
	if (num == 0) {
		/*
		 * A module was unloaded, modified and reloaded. The new
		 * data set replaces the copy of the last one.
		 */
		if (!gcov_info_is_compatible(node->unloaded_info, info)) {
			pr_warn("discarding saved data for %s "
				"(incompatible version)\n",
				gcov_info_filename(info));
			gcov_info_free(node->unloaded_info);
			node->unloaded_info = NULL;
		}
	} else {
		/*
		 * Two different versions of the same object file are loaded.
		 * The initial one takes precedence.
		 */
		if (!gcov_info_is_compatible(node->loaded_info[0], info)) {
			pr_warn("could not add '%s' (incompatible "
				"version)\n", gcov_info_filename(info));
			kfree(loaded_info);
			return;
		}
	}
	/* Overwrite previous array. */
	kfree(node->loaded_info);
	node->loaded_info = loaded_info;
	node->num_loaded = num + 1;
}

/*
 * Return the index of a profiling data set associated with a node.
 */
static int get_info_index(struct gcov_node *node, struct gcov_info *info)
{
	int i;

	for (i = 0; i < node->num_loaded; i++) {
		if (node->loaded_info[i] == info)
			return i;
	}
	return -ENOENT;
}

/*
 * Save the data of a profiling data set which is being unloaded.
 */
static void save_info(struct gcov_node *node, struct gcov_info *info)
{
	if (node->unloaded_info)
		gcov_info_add(node->unloaded_info, info);
	else {
		node->unloaded_info = gcov_info_dup(info);
		if (!node->unloaded_info) {
			pr_warn("could not save data for '%s' "
				"(out of memory)\n",
				gcov_info_filename(info));
		}
	}
}

/*
 * Disassociate a profiling data set from a node. Needs to be called with
 * node_lock held.
 */
static void remove_info(struct gcov_node *node, struct gcov_info *info)
{
	int i;

	i = get_info_index(node, info);
	if (i < 0) {
		pr_warn("could not remove '%s' (not found)\n",
			gcov_info_filename(info));
		return;
	}
	if (gcov_persist)
		save_info(node, info);
	/* Shrink array. */
	node->loaded_info[i] = node->loaded_info[node->num_loaded - 1];
	node->num_loaded--;
	if (node->num_loaded > 0)
		return;
	/* Last loaded data set was removed. */
	kfree(node->loaded_info);
	node->loaded_info = NULL;
	node->num_loaded = 0;
	if (!node->unloaded_info)
		remove_node(node);
}

/*
 * Callback to create/remove profiling files when code compiled with
 * -fprofile-arcs is loaded/unloaded.
 */
void gcov_event(enum gcov_action action, struct gcov_info *info)
{
	struct gcov_node *node;

	mutex_lock(&node_lock);
	node = get_node_by_name(gcov_info_filename(info));
	switch (action) {
	case GCOV_ADD:
		if (node)
			add_info(node, info);
		else
			add_node(info);
		break;
	case GCOV_REMOVE:
		if (node)
			remove_info(node, info);
		else {
			pr_warn("could not remove '%s' (not found)\n",
				gcov_info_filename(info));
		}
		break;
	}
	mutex_unlock(&node_lock);
}

/* Create debugfs entries. */
static __init int gcov_fs_init(void)
{
	int rc = -EIO;

	init_node(&root_node, NULL, NULL, NULL);
	/*
	 * /sys/kernel/debug/gcov will be parent for the reset control file
	 * and all profiling files.
	 */
	root_node.dentry = debugfs_create_dir("gcov", NULL);
	if (!root_node.dentry)
		goto err_remove;
	/*
	 * Create reset file which resets all profiling counts when written
	 * to.
	 */
	reset_dentry = debugfs_create_file("reset", 0600, root_node.dentry,
					   NULL, &gcov_reset_fops);
	if (!reset_dentry)
		goto err_remove;
	/* Replay previous events to get our fs hierarchy up-to-date. */
	gcov_enable_events();
	return 0;

err_remove:
	pr_err("init failed\n");
	debugfs_remove(root_node.dentry);

	return rc;
}
device_initcall(gcov_fs_init);
OpenPOWER on IntegriCloud