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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/tracefs.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
46static void __reset_stat_session(struct stat_session *session)
47{
48 struct stat_node *snode, *n;
49
50 rbtree_postorder_for_each_entry_safe(snode, n, &session->stat_root, node) {
51 if (session->ts->stat_release)
52 session->ts->stat_release(snode->stat);
53 kfree(snode);
54 }
55
56 session->stat_root = RB_ROOT;
57}
58
59static void reset_stat_session(struct stat_session *session)
60{
61 mutex_lock(&session->stat_mutex);
62 __reset_stat_session(session);
63 mutex_unlock(&session->stat_mutex);
64}
65
66static void destroy_session(struct stat_session *session)
67{
68 tracefs_remove(session->file);
69 __reset_stat_session(session);
70 mutex_destroy(&session->stat_mutex);
71 kfree(session);
72}
73
74typedef int (*cmp_stat_t)(void *, void *);
75
76static int insert_stat(struct rb_root *root, void *stat, cmp_stat_t cmp)
77{
78 struct rb_node **new = &(root->rb_node), *parent = NULL;
79 struct stat_node *data;
80
81 data = kzalloc(sizeof(*data), GFP_KERNEL);
82 if (!data)
83 return -ENOMEM;
84 data->stat = stat;
85
86 /*
87 * Figure out where to put new node
88 * This is a descendent sorting
89 */
90 while (*new) {
91 struct stat_node *this;
92 int result;
93
94 this = container_of(*new, struct stat_node, node);
95 result = cmp(data->stat, this->stat);
96
97 parent = *new;
98 if (result >= 0)
99 new = &((*new)->rb_left);
100 else
101 new = &((*new)->rb_right);
102 }
103
104 rb_link_node(&data->node, parent, new);
105 rb_insert_color(&data->node, root);
106 return 0;
107}
108
109/*
110 * For tracers that don't provide a stat_cmp callback.
111 * This one will force an insertion as right-most node
112 * in the rbtree.
113 */
114static int dummy_cmp(void *p1, void *p2)
115{
116 return -1;
117}
118
119/*
120 * Initialize the stat rbtree at each trace_stat file opening.
121 * All of these copies and sorting are required on all opening
122 * since the stats could have changed between two file sessions.
123 */
124static int stat_seq_init(struct stat_session *session)
125{
126 struct tracer_stat *ts = session->ts;
127 struct rb_root *root = &session->stat_root;
128 void *stat;
129 int ret = 0;
130 int i;
131
132 mutex_lock(&session->stat_mutex);
133 __reset_stat_session(session);
134
135 if (!ts->stat_cmp)
136 ts->stat_cmp = dummy_cmp;
137
138 stat = ts->stat_start(ts);
139 if (!stat)
140 goto exit;
141
142 ret = insert_stat(root, stat, ts->stat_cmp);
143 if (ret)
144 goto exit;
145
146 /*
147 * Iterate over the tracer stat entries and store them in an rbtree.
148 */
149 for (i = 1; ; i++) {
150 stat = ts->stat_next(stat, i);
151
152 /* End of insertion */
153 if (!stat)
154 break;
155
156 ret = insert_stat(root, stat, ts->stat_cmp);
157 if (ret)
158 goto exit_free_rbtree;
159 }
160
161exit:
162 mutex_unlock(&session->stat_mutex);
163 return ret;
164
165exit_free_rbtree:
166 __reset_stat_session(session);
167 mutex_unlock(&session->stat_mutex);
168 return ret;
169}
170
171
172static void *stat_seq_start(struct seq_file *s, loff_t *pos)
173{
174 struct stat_session *session = s->private;
175 struct rb_node *node;
176 int n = *pos;
177 int i;
178
179 /* Prevent from tracer switch or rbtree modification */
180 mutex_lock(&session->stat_mutex);
181
182 /* If we are in the beginning of the file, print the headers */
183 if (session->ts->stat_headers) {
184 if (n == 0)
185 return SEQ_START_TOKEN;
186 n--;
187 }
188
189 node = rb_first(&session->stat_root);
190 for (i = 0; node && i < n; i++)
191 node = rb_next(node);
192
193 return node;
194}
195
196static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
197{
198 struct stat_session *session = s->private;
199 struct rb_node *node = p;
200
201 (*pos)++;
202
203 if (p == SEQ_START_TOKEN)
204 return rb_first(&session->stat_root);
205
206 return rb_next(node);
207}
208
209static void stat_seq_stop(struct seq_file *s, void *p)
210{
211 struct stat_session *session = s->private;
212 mutex_unlock(&session->stat_mutex);
213}
214
215static int stat_seq_show(struct seq_file *s, void *v)
216{
217 struct stat_session *session = s->private;
218 struct stat_node *l = container_of(v, struct stat_node, node);
219
220 if (v == SEQ_START_TOKEN)
221 return session->ts->stat_headers(s);
222
223 return session->ts->stat_show(s, l->stat);
224}
225
226static const struct seq_operations trace_stat_seq_ops = {
227 .start = stat_seq_start,
228 .next = stat_seq_next,
229 .stop = stat_seq_stop,
230 .show = stat_seq_show
231};
232
233/* The session stat is refilled and resorted at each stat file opening */
234static int tracing_stat_open(struct inode *inode, struct file *file)
235{
236 int ret;
237 struct seq_file *m;
238 struct stat_session *session = inode->i_private;
239
240 ret = stat_seq_init(session);
241 if (ret)
242 return ret;
243
244 ret = seq_open(file, &trace_stat_seq_ops);
245 if (ret) {
246 reset_stat_session(session);
247 return ret;
248 }
249
250 m = file->private_data;
251 m->private = session;
252 return ret;
253}
254
255/*
256 * Avoid consuming memory with our now useless rbtree.
257 */
258static int tracing_stat_release(struct inode *i, struct file *f)
259{
260 struct stat_session *session = i->i_private;
261
262 reset_stat_session(session);
263
264 return seq_release(i, f);
265}
266
267static const struct file_operations tracing_stat_fops = {
268 .open = tracing_stat_open,
269 .read = seq_read,
270 .llseek = seq_lseek,
271 .release = tracing_stat_release
272};
273
274static int tracing_stat_init(void)
275{
276 struct dentry *d_tracing;
277
278 d_tracing = tracing_init_dentry();
279 if (IS_ERR(d_tracing))
280 return 0;
281
282 stat_dir = tracefs_create_dir("trace_stat", d_tracing);
283 if (!stat_dir)
284 pr_warn("Could not create tracefs 'trace_stat' entry\n");
285 return 0;
286}
287
288static int init_stat_file(struct stat_session *session)
289{
290 if (!stat_dir && tracing_stat_init())
291 return -ENODEV;
292
293 session->file = tracefs_create_file(session->ts->name, 0644,
294 stat_dir,
295 session, &tracing_stat_fops);
296 if (!session->file)
297 return -ENOMEM;
298 return 0;
299}
300
301int register_stat_tracer(struct tracer_stat *trace)
302{
303 struct stat_session *session, *node;
304 int ret;
305
306 if (!trace)
307 return -EINVAL;
308
309 if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
310 return -EINVAL;
311
312 /* Already registered? */
313 mutex_lock(&all_stat_sessions_mutex);
314 list_for_each_entry(node, &all_stat_sessions, session_list) {
315 if (node->ts == trace) {
316 mutex_unlock(&all_stat_sessions_mutex);
317 return -EINVAL;
318 }
319 }
320 mutex_unlock(&all_stat_sessions_mutex);
321
322 /* Init the session */
323 session = kzalloc(sizeof(*session), GFP_KERNEL);
324 if (!session)
325 return -ENOMEM;
326
327 session->ts = trace;
328 INIT_LIST_HEAD(&session->session_list);
329 mutex_init(&session->stat_mutex);
330
331 ret = init_stat_file(session);
332 if (ret) {
333 destroy_session(session);
334 return ret;
335 }
336
337 /* Register */
338 mutex_lock(&all_stat_sessions_mutex);
339 list_add_tail(&session->session_list, &all_stat_sessions);
340 mutex_unlock(&all_stat_sessions_mutex);
341
342 return 0;
343}
344
345void unregister_stat_tracer(struct tracer_stat *trace)
346{
347 struct stat_session *node, *tmp;
348
349 mutex_lock(&all_stat_sessions_mutex);
350 list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
351 if (node->ts == trace) {
352 list_del(&node->session_list);
353 destroy_session(node);
354 break;
355 }
356 }
357 mutex_unlock(&all_stat_sessions_mutex);
358}
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}