Add linux-next specific files for 20110831
[linux-2.6/next.git] / kernel / trace / trace_stat.c
blob96cffb269e7360e131e445c8c0013c90419f0921
1 /*
2 * Infrastructure for statistic tracing (histogram output).
4 * Copyright (C) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
6 * Based on the code from trace_branch.c which is
7 * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
9 */
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"
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.
25 struct stat_node {
26 struct rb_node node;
27 void *stat;
30 /* A stat session is the stats output in one file */
31 struct 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;
39 /* All of the sessions currently in use. Each stat file embed one session */
40 static LIST_HEAD(all_stat_sessions);
41 static DEFINE_MUTEX(all_stat_sessions_mutex);
43 /* The root directory for all stat files */
44 static struct dentry *stat_dir;
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.
53 static struct rb_node *release_next(struct tracer_stat *ts,
54 struct rb_node *node)
56 struct stat_node *snode;
57 struct rb_node *parent = rb_parent(node);
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)
66 else if (parent->rb_left == node)
67 parent->rb_left = NULL;
68 else
69 parent->rb_right = NULL;
71 snode = container_of(node, struct stat_node, node);
72 if (ts->stat_release)
73 ts->stat_release(snode->stat);
74 kfree(snode);
76 return parent;
80 static void __reset_stat_session(struct stat_session *session)
82 struct rb_node *node = session->stat_root.rb_node;
84 while (node)
85 node = release_next(session->ts, node);
87 session->stat_root = RB_ROOT;
90 static void reset_stat_session(struct stat_session *session)
92 mutex_lock(&session->stat_mutex);
93 __reset_stat_session(session);
94 mutex_unlock(&session->stat_mutex);
97 static void destroy_session(struct stat_session *session)
99 debugfs_remove(session->file);
100 __reset_stat_session(session);
101 mutex_destroy(&session->stat_mutex);
102 kfree(session);
105 typedef int (*cmp_stat_t)(void *, void *);
107 static int insert_stat(struct rb_root *root, void *stat, cmp_stat_t cmp)
109 struct rb_node **new = &(root->rb_node), *parent = NULL;
110 struct stat_node *data;
112 data = kzalloc(sizeof(*data), GFP_KERNEL);
113 if (!data)
114 return -ENOMEM;
115 data->stat = stat;
118 * Figure out where to put new node
119 * This is a descendent sorting
121 while (*new) {
122 struct stat_node *this;
123 int result;
125 this = container_of(*new, struct stat_node, node);
126 result = cmp(data->stat, this->stat);
128 parent = *new;
129 if (result >= 0)
130 new = &((*new)->rb_left);
131 else
132 new = &((*new)->rb_right);
135 rb_link_node(&data->node, parent, new);
136 rb_insert_color(&data->node, root);
137 return 0;
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.
145 static int dummy_cmp(void *p1, void *p2)
147 return -1;
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.
155 static int stat_seq_init(struct stat_session *session)
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;
163 mutex_lock(&session->stat_mutex);
164 __reset_stat_session(session);
166 if (!ts->stat_cmp)
167 ts->stat_cmp = dummy_cmp;
169 stat = ts->stat_start(ts);
170 if (!stat)
171 goto exit;
173 ret = insert_stat(root, stat, ts->stat_cmp);
174 if (ret)
175 goto exit;
178 * Iterate over the tracer stat entries and store them in an rbtree.
180 for (i = 1; ; i++) {
181 stat = ts->stat_next(stat, i);
183 /* End of insertion */
184 if (!stat)
185 break;
187 ret = insert_stat(root, stat, ts->stat_cmp);
188 if (ret)
189 goto exit_free_rbtree;
192 exit:
193 mutex_unlock(&session->stat_mutex);
194 return ret;
196 exit_free_rbtree:
197 __reset_stat_session(session);
198 mutex_unlock(&session->stat_mutex);
199 return ret;
203 static void *stat_seq_start(struct seq_file *s, loff_t *pos)
205 struct stat_session *session = s->private;
206 struct rb_node *node;
207 int n = *pos;
208 int i;
210 /* Prevent from tracer switch or rbtree modification */
211 mutex_lock(&session->stat_mutex);
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--;
220 node = rb_first(&session->stat_root);
221 for (i = 0; node && i < n; i++)
222 node = rb_next(node);
224 return node;
227 static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
229 struct stat_session *session = s->private;
230 struct rb_node *node = p;
232 (*pos)++;
234 if (p == SEQ_START_TOKEN)
235 return rb_first(&session->stat_root);
237 return rb_next(node);
240 static void stat_seq_stop(struct seq_file *s, void *p)
242 struct stat_session *session = s->private;
243 mutex_unlock(&session->stat_mutex);
246 static int stat_seq_show(struct seq_file *s, void *v)
248 struct stat_session *session = s->private;
249 struct stat_node *l = container_of(v, struct stat_node, node);
251 if (v == SEQ_START_TOKEN)
252 return session->ts->stat_headers(s);
254 return session->ts->stat_show(s, l->stat);
257 static 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
264 /* The session stat is refilled and resorted at each stat file opening */
265 static int tracing_stat_open(struct inode *inode, struct file *file)
267 int ret;
268 struct seq_file *m;
269 struct stat_session *session = inode->i_private;
271 ret = stat_seq_init(session);
272 if (ret)
273 return ret;
275 ret = seq_open(file, &trace_stat_seq_ops);
276 if (ret) {
277 reset_stat_session(session);
278 return ret;
281 m = file->private_data;
282 m->private = session;
283 return ret;
287 * Avoid consuming memory with our now useless rbtree.
289 static int tracing_stat_release(struct inode *i, struct file *f)
291 struct stat_session *session = i->i_private;
293 reset_stat_session(session);
295 return seq_release(i, f);
298 static 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
305 static int tracing_stat_init(void)
307 struct dentry *d_tracing;
309 d_tracing = tracing_init_dentry();
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;
318 static int init_stat_file(struct stat_session *session)
320 if (!stat_dir && tracing_stat_init())
321 return -ENODEV;
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;
331 int register_stat_tracer(struct tracer_stat *trace)
333 struct stat_session *session, *node;
334 int ret;
336 if (!trace)
337 return -EINVAL;
339 if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
340 return -EINVAL;
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;
350 mutex_unlock(&all_stat_sessions_mutex);
352 /* Init the session */
353 session = kzalloc(sizeof(*session), GFP_KERNEL);
354 if (!session)
355 return -ENOMEM;
357 session->ts = trace;
358 INIT_LIST_HEAD(&session->session_list);
359 mutex_init(&session->stat_mutex);
361 ret = init_stat_file(session);
362 if (ret) {
363 destroy_session(session);
364 return ret;
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);
372 return 0;
375 void unregister_stat_tracer(struct tracer_stat *trace)
377 struct stat_session *node, *tmp;
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;
387 mutex_unlock(&all_stat_sessions_mutex);