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>
12 #include <linux/list.h>
13 #include <linux/rbtree.h>
14 #include <linux/debugfs.h>
15 #include "trace_stat.h"
20 * List of stat red-black nodes from a tracer
21 * We use a such tree to sort quickly the stat
22 * entries from the tracer.
29 /* A stat session is the stats output in one file */
31 struct list_head session_list;
32 struct tracer_stat *ts;
33 struct rb_root stat_root;
34 struct mutex stat_mutex;
38 /* All of the sessions currently in use. Each stat file embed one session */
39 static LIST_HEAD(all_stat_sessions);
40 static DEFINE_MUTEX(all_stat_sessions_mutex);
42 /* The root directory for all stat files */
43 static struct dentry *stat_dir;
46 * Iterate through the rbtree using a post order traversal path
47 * to release the next node.
48 * It won't necessary release one at each iteration
49 * but it will at least advance closer to the next one
52 static struct rb_node *release_next(struct tracer_stat *ts,
55 struct stat_node *snode;
56 struct rb_node *parent = rb_parent(node);
60 else if (node->rb_right)
61 return node->rb_right;
65 else if (parent->rb_left == node)
66 parent->rb_left = NULL;
68 parent->rb_right = NULL;
70 snode = container_of(node, struct stat_node, node);
72 ts->stat_release(snode->stat);
79 static void __reset_stat_session(struct stat_session *session)
81 struct rb_node *node = session->stat_root.rb_node;
84 node = release_next(session->ts, node);
86 session->stat_root = RB_ROOT;
89 static void reset_stat_session(struct stat_session *session)
91 mutex_lock(&session->stat_mutex);
92 __reset_stat_session(session);
93 mutex_unlock(&session->stat_mutex);
96 static void destroy_session(struct stat_session *session)
98 debugfs_remove(session->file);
99 __reset_stat_session(session);
100 mutex_destroy(&session->stat_mutex);
104 typedef int (*cmp_stat_t)(void *, void *);
106 static int insert_stat(struct rb_root *root, void *stat, cmp_stat_t cmp)
108 struct rb_node **new = &(root->rb_node), *parent = NULL;
109 struct stat_node *data;
111 data = kzalloc(sizeof(*data), GFP_KERNEL);
117 * Figure out where to put new node
118 * This is a descendent sorting
121 struct stat_node *this;
124 this = container_of(*new, struct stat_node, node);
125 result = cmp(data->stat, this->stat);
129 new = &((*new)->rb_left);
131 new = &((*new)->rb_right);
134 rb_link_node(&data->node, parent, new);
135 rb_insert_color(&data->node, root);
140 * For tracers that don't provide a stat_cmp callback.
141 * This one will force an insertion as right-most node
144 static int dummy_cmp(void *p1, void *p2)
150 * Initialize the stat rbtree at each trace_stat file opening.
151 * All of these copies and sorting are required on all opening
152 * since the stats could have changed between two file sessions.
154 static int stat_seq_init(struct stat_session *session)
156 struct tracer_stat *ts = session->ts;
157 struct rb_root *root = &session->stat_root;
162 mutex_lock(&session->stat_mutex);
163 __reset_stat_session(session);
166 ts->stat_cmp = dummy_cmp;
168 stat = ts->stat_start(ts);
172 ret = insert_stat(root, stat, ts->stat_cmp);
177 * Iterate over the tracer stat entries and store them in an rbtree.
180 stat = ts->stat_next(stat, i);
182 /* End of insertion */
186 ret = insert_stat(root, stat, ts->stat_cmp);
188 goto exit_free_rbtree;
192 mutex_unlock(&session->stat_mutex);
196 __reset_stat_session(session);
197 mutex_unlock(&session->stat_mutex);
202 static void *stat_seq_start(struct seq_file *s, loff_t *pos)
204 struct stat_session *session = s->private;
205 struct rb_node *node;
209 /* Prevent from tracer switch or rbtree modification */
210 mutex_lock(&session->stat_mutex);
212 /* If we are in the beginning of the file, print the headers */
213 if (session->ts->stat_headers) {
215 return SEQ_START_TOKEN;
219 node = rb_first(&session->stat_root);
220 for (i = 0; node && i < n; i++)
221 node = rb_next(node);
226 static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
228 struct stat_session *session = s->private;
229 struct rb_node *node = p;
233 if (p == SEQ_START_TOKEN)
234 return rb_first(&session->stat_root);
236 return rb_next(node);
239 static void stat_seq_stop(struct seq_file *s, void *p)
241 struct stat_session *session = s->private;
242 mutex_unlock(&session->stat_mutex);
245 static int stat_seq_show(struct seq_file *s, void *v)
247 struct stat_session *session = s->private;
248 struct stat_node *l = container_of(v, struct stat_node, node);
250 if (v == SEQ_START_TOKEN)
251 return session->ts->stat_headers(s);
253 return session->ts->stat_show(s, l->stat);
256 static const struct seq_operations trace_stat_seq_ops = {
257 .start = stat_seq_start,
258 .next = stat_seq_next,
259 .stop = stat_seq_stop,
260 .show = stat_seq_show
263 /* The session stat is refilled and resorted at each stat file opening */
264 static int tracing_stat_open(struct inode *inode, struct file *file)
268 struct stat_session *session = inode->i_private;
270 ret = stat_seq_init(session);
274 ret = seq_open(file, &trace_stat_seq_ops);
276 reset_stat_session(session);
280 m = file->private_data;
281 m->private = session;
286 * Avoid consuming memory with our now useless rbtree.
288 static int tracing_stat_release(struct inode *i, struct file *f)
290 struct stat_session *session = i->i_private;
292 reset_stat_session(session);
294 return seq_release(i, f);
297 static const struct file_operations tracing_stat_fops = {
298 .open = tracing_stat_open,
301 .release = tracing_stat_release
304 static int tracing_stat_init(void)
306 struct dentry *d_tracing;
308 d_tracing = tracing_init_dentry();
310 stat_dir = debugfs_create_dir("trace_stat", d_tracing);
312 pr_warning("Could not create debugfs "
313 "'trace_stat' entry\n");
317 static int init_stat_file(struct stat_session *session)
319 if (!stat_dir && tracing_stat_init())
322 session->file = debugfs_create_file(session->ts->name, 0644,
324 session, &tracing_stat_fops);
330 int register_stat_tracer(struct tracer_stat *trace)
332 struct stat_session *session, *node;
338 if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
341 /* Already registered? */
342 mutex_lock(&all_stat_sessions_mutex);
343 list_for_each_entry(node, &all_stat_sessions, session_list) {
344 if (node->ts == trace) {
345 mutex_unlock(&all_stat_sessions_mutex);
349 mutex_unlock(&all_stat_sessions_mutex);
351 /* Init the session */
352 session = kzalloc(sizeof(*session), GFP_KERNEL);
357 INIT_LIST_HEAD(&session->session_list);
358 mutex_init(&session->stat_mutex);
360 ret = init_stat_file(session);
362 destroy_session(session);
367 mutex_lock(&all_stat_sessions_mutex);
368 list_add_tail(&session->session_list, &all_stat_sessions);
369 mutex_unlock(&all_stat_sessions_mutex);
374 void unregister_stat_tracer(struct tracer_stat *trace)
376 struct stat_session *node, *tmp;
378 mutex_lock(&all_stat_sessions_mutex);
379 list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
380 if (node->ts == trace) {
381 list_del(&node->session_list);
382 destroy_session(node);
386 mutex_unlock(&all_stat_sessions_mutex);