aboutsummaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace_stat.c
blob: a4bb239eb9874a1a6efe7703a303a7e103c4c977 (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
/*
 * Infrastructure for statistic tracing (histogram output).
 *
 * Copyright (C) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
 *
 * Based on the code from trace_branch.c which is
 * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
 *
 */


#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/debugfs.h>
#include "trace_stat.h"
#include "trace.h"


/*
 * List of stat red-black nodes from a tracer
 * We use a such tree to sort quickly the stat
 * entries from the tracer.
 */
struct stat_node {
	struct rb_node		node;
	void			*stat;
};

/* A stat session is the stats output in one file */
struct stat_session {
	struct list_head	session_list;
	struct tracer_stat	*ts;
	struct rb_root		stat_root;
	struct mutex		stat_mutex;
	struct dentry		*file;
};

/* All of the sessions currently in use. Each stat file embed one session */
static LIST_HEAD(all_stat_sessions);
static DEFINE_MUTEX(all_stat_sessions_mutex);

/* The root directory for all stat files */
static struct dentry		*stat_dir;

/*
 * Iterate through the rbtree using a post order traversal path
 * to release the next node.
 * It won't necessary release one at each iteration
 * but it will at least advance closer to the next one
 * to be released.
 */
static struct rb_node *release_next(struct tracer_stat *ts,
				    struct rb_node *node)
{
	struct stat_node *snode;
	struct rb_node *parent = rb_parent(node);

	if (node->rb_left)
		return node->rb_left;
	else if (node->rb_right)
		return node->rb_right;
	else {
		if (!parent)
			;
		else if (parent->rb_left == node)
			parent->rb_left = NULL;
		else
			parent->rb_right = NULL;

		snode = container_of(node, struct stat_node, node);
		if (ts->stat_release)
			ts->stat_release(snode->stat);
		kfree(snode);

		return parent;
	}
}

static void __reset_stat_session(struct stat_session *session)
{
	struct rb_node *node = session->stat_root.rb_node;

	while (node)
		node = release_next(session->ts, node);

	session->stat_root = RB_ROOT;
}

static void reset_stat_session(struct stat_session *session)
{
	mutex_lock(&session->stat_mutex);
	__reset_stat_session(session);
	mutex_unlock(&session->stat_mutex);
}

static void destroy_session(struct stat_session *session)
{
	debugfs_remove(session->file);
	__reset_stat_session(session);
	mutex_destroy(&session->stat_mutex);
	kfree(session);
}

typedef int (*cmp_stat_t)(void *, void *);

static int insert_stat(struct rb_root *root, void *stat, cmp_stat_t cmp)
{
	struct rb_node **new = &(root->rb_node), *parent = NULL;
	struct stat_node *data;

	data = kzalloc(sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;
	data->stat = stat;

	/*
	 * Figure out where to put new node
	 * This is a descendent sorting
	 */
	while (*new) {
		struct stat_node *this;
		int result;

		this = container_of(*new, struct stat_node, node);
		result = cmp(data->stat, this->stat);

		parent = *new;
		if (result >= 0)
			new = &((*new)->rb_left);
		else
			new = &((*new)->rb_right);
	}

	rb_link_node(&data->node, parent, new);
	rb_insert_color(&data->node, root);
	return 0;
}

/*
 * For tracers that don't provide a stat_cmp callback.
 * This one will force an insertion as right-most node
 * in the rbtree.
 */
static int dummy_cmp(void *p1, void *p2)
{
	return -1;
}

/*
 * Initialize the stat rbtree at each trace_stat file opening.
 * All of these copies and sorting are required on all opening
 * since the stats could have changed between two file sessions.
 */
static int stat_seq_init(struct stat_session *session)
{
	struct tracer_stat *ts = session->ts;
	struct rb_root *root = &session->stat_root;
	void *stat;
	int ret = 0;
	int i;

	mutex_lock(&session->stat_mutex);
	__reset_stat_session(session);

	if (!ts->stat_cmp)
		ts->stat_cmp = dummy_cmp;

	stat = ts->stat_start(ts);
	if (!stat)
		goto exit;

	ret = insert_stat(root, stat, ts->stat_cmp);
	if (ret)
		goto exit;

	/*
	 * Iterate over the tracer stat entries and store them in an rbtree.
	 */
	for (i = 1; ; i++) {
		stat = ts->stat_next(stat, i);

		/* End of insertion */
		if (!stat)
			break;

		ret = insert_stat(root, stat, ts->stat_cmp);
		if (ret)
			goto exit_free_rbtree;
	}

exit:
	mutex_unlock(&session->stat_mutex);
	return ret;

exit_free_rbtree:
	__reset_stat_session(session);
	mutex_unlock(&session->stat_mutex);
	return ret;
}


static void *stat_seq_start(struct seq_file *s, loff_t *pos)
{
	struct stat_session *session = s->private;
	struct rb_node *node;
	int n = *pos;
	int i;

	/* Prevent from tracer switch or rbtree modification */
	mutex_lock(&session->stat_mutex);

	/* If we are in the beginning of the file, print the headers */
	if (session->ts->stat_headers) {
		if (n == 0)
			return SEQ_START_TOKEN;
		n--;
	}

	node = rb_first(&session->stat_root);
	for (i = 0; node && i < n; i++)
		node = rb_next(node);

	return node;
}

static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
{
	struct stat_session *session = s->private;
	struct rb_node *node = p;

	(*pos)++;

	if (p == SEQ_START_TOKEN)
		return rb_first(&session->stat_root);

	return rb_next(node);
}

static void stat_seq_stop(struct seq_file *s, void *p)
{
	struct stat_session *session = s->private;
	mutex_unlock(&session->stat_mutex);
}

static int stat_seq_show(struct seq_file *s, void *v)
{
	struct stat_session *session = s->private;
	struct stat_node *l = container_of(v, struct stat_node, node);

	if (v == SEQ_START_TOKEN)
		return session->ts->stat_headers(s);

	return session->ts->stat_show(s, l->stat);
}

static const struct seq_operations trace_stat_seq_ops = {
	.start		= stat_seq_start,
	.next		= stat_seq_next,
	.stop		= stat_seq_stop,
	.show		= stat_seq_show
};

/* The session stat is refilled and resorted at each stat file opening */
static int tracing_stat_open(struct inode *inode, struct file *file)
{
	int ret;
	struct seq_file *m;
	struct stat_session *session = inode->i_private;

	ret = stat_seq_init(session);
	if (ret)
		return ret;

	ret = seq_open(file, &trace_stat_seq_ops);
	if (ret) {
		reset_stat_session(session);
		return ret;
	}

	m = file->private_data;
	m->private = session;
	return ret;
}

/*
 * Avoid consuming memory with our now useless rbtree.
 */
static int tracing_stat_release(struct inode *i, struct file *f)
{
	struct stat_session *session = i->i_private;

	reset_stat_session(session);

	return seq_release(i, f);
}

static const struct file_operations tracing_stat_fops = {
	.open		= tracing_stat_open,
	.read		= seq_read,
	.llseek		= seq_lseek,
	.release	= tracing_stat_release
};

static int tracing_stat_init(void)
{
	struct dentry *d_tracing;

	d_tracing = tracing_init_dentry();

	stat_dir = debugfs_create_dir("trace_stat", d_tracing);
	if (!stat_dir)
		pr_warning("Could not create debugfs "
			   "'trace_stat' entry\n");
	return 0;
}

static int init_stat_file(struct stat_session *session)
{
	if (!stat_dir && tracing_stat_init())
		return -ENODEV;

	session->file = debugfs_create_file(session->ts->name, 0644,
					    stat_dir,
					    session, &tracing_stat_fops);
	if (!session->file)
		return -ENOMEM;
	return 0;
}

int register_stat_tracer(struct tracer_stat *trace)
{
	struct stat_session *session, *node;
	int ret;

	if (!trace)
		return -EINVAL;

	if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
		return -EINVAL;

	/* Already registered? */
	mutex_lock(&all_stat_sessions_mutex);
	list_for_each_entry(node, &all_stat_sessions, session_list) {
		if (node->ts == trace) {
			mutex_unlock(&all_stat_sessions_mutex);
			return -EINVAL;
		}
	}
	mutex_unlock(&all_stat_sessions_mutex);

	/* Init the session */
	session = kzalloc(sizeof(*session), GFP_KERNEL);
	if (!session)
		return -ENOMEM;

	session->ts = trace;
	INIT_LIST_HEAD(&session->session_list);
	mutex_init(&session->stat_mutex);

	ret = init_stat_file(session);
	if (ret) {
		destroy_session(session);
		return ret;
	}

	/* Register */
	mutex_lock(&all_stat_sessions_mutex);
	list_add_tail(&session->session_list, &all_stat_sessions);
	mutex_unlock(&all_stat_sessions_mutex);

	return 0;
}

void unregister_stat_tracer(struct tracer_stat *trace)
{
	struct stat_session *node, *tmp;

	mutex_lock(&all_stat_sessions_mutex);
	list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
		if (node->ts == trace) {
			list_del(&node->session_list);
			destroy_session(node);
			break;
		}
	}
	mutex_unlock(&all_stat_sessions_mutex);
}