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  • only in /netgear-R7000-V1.0.7.12_1.2.5/components/opensource/linux/linux-2.6.36/kernel/trace/
1/*
2 * Infrastructure for statistic tracing (histogram output).
3 *
4 * Copyright (C) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
5 *
6 * Based on the code from trace_branch.c which is
7 * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
8 *
9 */
10
11
12#include <linux/list.h>
13#include <linux/slab.h>
14#include <linux/rbtree.h>
15#include <linux/debugfs.h>
16#include "trace_stat.h"
17#include "trace.h"
18
19
20/*
21 * List of stat red-black nodes from a tracer
22 * We use a such tree to sort quickly the stat
23 * entries from the tracer.
24 */
25struct stat_node {
26	struct rb_node		node;
27	void			*stat;
28};
29
30/* A stat session is the stats output in one file */
31struct stat_session {
32	struct list_head	session_list;
33	struct tracer_stat	*ts;
34	struct rb_root		stat_root;
35	struct mutex		stat_mutex;
36	struct dentry		*file;
37};
38
39/* All of the sessions currently in use. Each stat file embed one session */
40static LIST_HEAD(all_stat_sessions);
41static DEFINE_MUTEX(all_stat_sessions_mutex);
42
43/* The root directory for all stat files */
44static struct dentry		*stat_dir;
45
46/*
47 * Iterate through the rbtree using a post order traversal path
48 * to release the next node.
49 * It won't necessary release one at each iteration
50 * but it will at least advance closer to the next one
51 * to be released.
52 */
53static struct rb_node *release_next(struct tracer_stat *ts,
54				    struct rb_node *node)
55{
56	struct stat_node *snode;
57	struct rb_node *parent = rb_parent(node);
58
59	if (node->rb_left)
60		return node->rb_left;
61	else if (node->rb_right)
62		return node->rb_right;
63	else {
64		if (!parent)
65			;
66		else if (parent->rb_left == node)
67			parent->rb_left = NULL;
68		else
69			parent->rb_right = NULL;
70
71		snode = container_of(node, struct stat_node, node);
72		if (ts->stat_release)
73			ts->stat_release(snode->stat);
74		kfree(snode);
75
76		return parent;
77	}
78}
79
80static void __reset_stat_session(struct stat_session *session)
81{
82	struct rb_node *node = session->stat_root.rb_node;
83
84	while (node)
85		node = release_next(session->ts, node);
86
87	session->stat_root = RB_ROOT;
88}
89
90static void reset_stat_session(struct stat_session *session)
91{
92	mutex_lock(&session->stat_mutex);
93	__reset_stat_session(session);
94	mutex_unlock(&session->stat_mutex);
95}
96
97static void destroy_session(struct stat_session *session)
98{
99	debugfs_remove(session->file);
100	__reset_stat_session(session);
101	mutex_destroy(&session->stat_mutex);
102	kfree(session);
103}
104
105typedef int (*cmp_stat_t)(void *, void *);
106
107static int insert_stat(struct rb_root *root, void *stat, cmp_stat_t cmp)
108{
109	struct rb_node **new = &(root->rb_node), *parent = NULL;
110	struct stat_node *data;
111
112	data = kzalloc(sizeof(*data), GFP_KERNEL);
113	if (!data)
114		return -ENOMEM;
115	data->stat = stat;
116
117	/*
118	 * Figure out where to put new node
119	 * This is a descendent sorting
120	 */
121	while (*new) {
122		struct stat_node *this;
123		int result;
124
125		this = container_of(*new, struct stat_node, node);
126		result = cmp(data->stat, this->stat);
127
128		parent = *new;
129		if (result >= 0)
130			new = &((*new)->rb_left);
131		else
132			new = &((*new)->rb_right);
133	}
134
135	rb_link_node(&data->node, parent, new);
136	rb_insert_color(&data->node, root);
137	return 0;
138}
139
140/*
141 * For tracers that don't provide a stat_cmp callback.
142 * This one will force an insertion as right-most node
143 * in the rbtree.
144 */
145static int dummy_cmp(void *p1, void *p2)
146{
147	return -1;
148}
149
150/*
151 * Initialize the stat rbtree at each trace_stat file opening.
152 * All of these copies and sorting are required on all opening
153 * since the stats could have changed between two file sessions.
154 */
155static int stat_seq_init(struct stat_session *session)
156{
157	struct tracer_stat *ts = session->ts;
158	struct rb_root *root = &session->stat_root;
159	void *stat;
160	int ret = 0;
161	int i;
162
163	mutex_lock(&session->stat_mutex);
164	__reset_stat_session(session);
165
166	if (!ts->stat_cmp)
167		ts->stat_cmp = dummy_cmp;
168
169	stat = ts->stat_start(ts);
170	if (!stat)
171		goto exit;
172
173	ret = insert_stat(root, stat, ts->stat_cmp);
174	if (ret)
175		goto exit;
176
177	/*
178	 * Iterate over the tracer stat entries and store them in an rbtree.
179	 */
180	for (i = 1; ; i++) {
181		stat = ts->stat_next(stat, i);
182
183		/* End of insertion */
184		if (!stat)
185			break;
186
187		ret = insert_stat(root, stat, ts->stat_cmp);
188		if (ret)
189			goto exit_free_rbtree;
190	}
191
192exit:
193	mutex_unlock(&session->stat_mutex);
194	return ret;
195
196exit_free_rbtree:
197	__reset_stat_session(session);
198	mutex_unlock(&session->stat_mutex);
199	return ret;
200}
201
202
203static void *stat_seq_start(struct seq_file *s, loff_t *pos)
204{
205	struct stat_session *session = s->private;
206	struct rb_node *node;
207	int n = *pos;
208	int i;
209
210	/* Prevent from tracer switch or rbtree modification */
211	mutex_lock(&session->stat_mutex);
212
213	/* If we are in the beginning of the file, print the headers */
214	if (session->ts->stat_headers) {
215		if (n == 0)
216			return SEQ_START_TOKEN;
217		n--;
218	}
219
220	node = rb_first(&session->stat_root);
221	for (i = 0; node && i < n; i++)
222		node = rb_next(node);
223
224	return node;
225}
226
227static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
228{
229	struct stat_session *session = s->private;
230	struct rb_node *node = p;
231
232	(*pos)++;
233
234	if (p == SEQ_START_TOKEN)
235		return rb_first(&session->stat_root);
236
237	return rb_next(node);
238}
239
240static void stat_seq_stop(struct seq_file *s, void *p)
241{
242	struct stat_session *session = s->private;
243	mutex_unlock(&session->stat_mutex);
244}
245
246static int stat_seq_show(struct seq_file *s, void *v)
247{
248	struct stat_session *session = s->private;
249	struct stat_node *l = container_of(v, struct stat_node, node);
250
251	if (v == SEQ_START_TOKEN)
252		return session->ts->stat_headers(s);
253
254	return session->ts->stat_show(s, l->stat);
255}
256
257static const struct seq_operations trace_stat_seq_ops = {
258	.start		= stat_seq_start,
259	.next		= stat_seq_next,
260	.stop		= stat_seq_stop,
261	.show		= stat_seq_show
262};
263
264/* The session stat is refilled and resorted at each stat file opening */
265static int tracing_stat_open(struct inode *inode, struct file *file)
266{
267	int ret;
268	struct seq_file *m;
269	struct stat_session *session = inode->i_private;
270
271	ret = stat_seq_init(session);
272	if (ret)
273		return ret;
274
275	ret = seq_open(file, &trace_stat_seq_ops);
276	if (ret) {
277		reset_stat_session(session);
278		return ret;
279	}
280
281	m = file->private_data;
282	m->private = session;
283	return ret;
284}
285
286/*
287 * Avoid consuming memory with our now useless rbtree.
288 */
289static int tracing_stat_release(struct inode *i, struct file *f)
290{
291	struct stat_session *session = i->i_private;
292
293	reset_stat_session(session);
294
295	return seq_release(i, f);
296}
297
298static const struct file_operations tracing_stat_fops = {
299	.open		= tracing_stat_open,
300	.read		= seq_read,
301	.llseek		= seq_lseek,
302	.release	= tracing_stat_release
303};
304
305static int tracing_stat_init(void)
306{
307	struct dentry *d_tracing;
308
309	d_tracing = tracing_init_dentry();
310
311	stat_dir = debugfs_create_dir("trace_stat", d_tracing);
312	if (!stat_dir)
313		pr_warning("Could not create debugfs "
314			   "'trace_stat' entry\n");
315	return 0;
316}
317
318static int init_stat_file(struct stat_session *session)
319{
320	if (!stat_dir && tracing_stat_init())
321		return -ENODEV;
322
323	session->file = debugfs_create_file(session->ts->name, 0644,
324					    stat_dir,
325					    session, &tracing_stat_fops);
326	if (!session->file)
327		return -ENOMEM;
328	return 0;
329}
330
331int register_stat_tracer(struct tracer_stat *trace)
332{
333	struct stat_session *session, *node;
334	int ret;
335
336	if (!trace)
337		return -EINVAL;
338
339	if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
340		return -EINVAL;
341
342	/* Already registered? */
343	mutex_lock(&all_stat_sessions_mutex);
344	list_for_each_entry(node, &all_stat_sessions, session_list) {
345		if (node->ts == trace) {
346			mutex_unlock(&all_stat_sessions_mutex);
347			return -EINVAL;
348		}
349	}
350	mutex_unlock(&all_stat_sessions_mutex);
351
352	/* Init the session */
353	session = kzalloc(sizeof(*session), GFP_KERNEL);
354	if (!session)
355		return -ENOMEM;
356
357	session->ts = trace;
358	INIT_LIST_HEAD(&session->session_list);
359	mutex_init(&session->stat_mutex);
360
361	ret = init_stat_file(session);
362	if (ret) {
363		destroy_session(session);
364		return ret;
365	}
366
367	/* Register */
368	mutex_lock(&all_stat_sessions_mutex);
369	list_add_tail(&session->session_list, &all_stat_sessions);
370	mutex_unlock(&all_stat_sessions_mutex);
371
372	return 0;
373}
374
375void unregister_stat_tracer(struct tracer_stat *trace)
376{
377	struct stat_session *node, *tmp;
378
379	mutex_lock(&all_stat_sessions_mutex);
380	list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
381		if (node->ts == trace) {
382			list_del(&node->session_list);
383			destroy_session(node);
384			break;
385		}
386	}
387	mutex_unlock(&all_stat_sessions_mutex);
388}
389