Line data Source code
1 : // SPDX-License-Identifier: GPL-2.0
2 : /*
3 : * Infrastructure for statistic tracing (histogram output).
4 : *
5 : * Copyright (C) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com>
6 : *
7 : * Based on the code from trace_branch.c which is
8 : * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
9 : *
10 : */
11 :
12 : #include <linux/security.h>
13 : #include <linux/list.h>
14 : #include <linux/slab.h>
15 : #include <linux/rbtree.h>
16 : #include <linux/tracefs.h>
17 : #include "trace_stat.h"
18 : #include "trace.h"
19 :
20 :
21 : /*
22 : * List of stat red-black nodes from a tracer
23 : * We use a such tree to sort quickly the stat
24 : * entries from the tracer.
25 : */
26 : struct stat_node {
27 : struct rb_node node;
28 : void *stat;
29 : };
30 :
31 : /* A stat session is the stats output in one file */
32 : struct stat_session {
33 : struct list_head session_list;
34 : struct tracer_stat *ts;
35 : struct rb_root stat_root;
36 : struct mutex stat_mutex;
37 : struct dentry *file;
38 : };
39 :
40 : /* All of the sessions currently in use. Each stat file embed one session */
41 : static LIST_HEAD(all_stat_sessions);
42 : static DEFINE_MUTEX(all_stat_sessions_mutex);
43 :
44 : /* The root directory for all stat files */
45 : static struct dentry *stat_dir;
46 :
47 0 : static void __reset_stat_session(struct stat_session *session)
48 : {
49 0 : struct stat_node *snode, *n;
50 :
51 0 : rbtree_postorder_for_each_entry_safe(snode, n, &session->stat_root, node) {
52 0 : if (session->ts->stat_release)
53 0 : session->ts->stat_release(snode->stat);
54 0 : kfree(snode);
55 : }
56 :
57 0 : session->stat_root = RB_ROOT;
58 0 : }
59 :
60 0 : static void reset_stat_session(struct stat_session *session)
61 : {
62 0 : mutex_lock(&session->stat_mutex);
63 0 : __reset_stat_session(session);
64 0 : mutex_unlock(&session->stat_mutex);
65 0 : }
66 :
67 0 : static void destroy_session(struct stat_session *session)
68 : {
69 0 : tracefs_remove(session->file);
70 0 : __reset_stat_session(session);
71 0 : mutex_destroy(&session->stat_mutex);
72 0 : kfree(session);
73 0 : }
74 :
75 0 : static int insert_stat(struct rb_root *root, void *stat, cmp_func_t cmp)
76 : {
77 0 : struct rb_node **new = &(root->rb_node), *parent = NULL;
78 0 : struct stat_node *data;
79 :
80 0 : data = kzalloc(sizeof(*data), GFP_KERNEL);
81 0 : if (!data)
82 : return -ENOMEM;
83 0 : data->stat = stat;
84 :
85 : /*
86 : * Figure out where to put new node
87 : * This is a descendent sorting
88 : */
89 0 : while (*new) {
90 0 : struct stat_node *this;
91 0 : int result;
92 :
93 0 : this = container_of(*new, struct stat_node, node);
94 0 : result = cmp(data->stat, this->stat);
95 :
96 0 : parent = *new;
97 0 : if (result >= 0)
98 0 : new = &((*new)->rb_left);
99 : else
100 0 : new = &((*new)->rb_right);
101 : }
102 :
103 0 : rb_link_node(&data->node, parent, new);
104 0 : rb_insert_color(&data->node, root);
105 0 : return 0;
106 : }
107 :
108 : /*
109 : * For tracers that don't provide a stat_cmp callback.
110 : * This one will force an insertion as right-most node
111 : * in the rbtree.
112 : */
113 0 : static int dummy_cmp(const void *p1, const void *p2)
114 : {
115 0 : return -1;
116 : }
117 :
118 : /*
119 : * Initialize the stat rbtree at each trace_stat file opening.
120 : * All of these copies and sorting are required on all opening
121 : * since the stats could have changed between two file sessions.
122 : */
123 0 : static int stat_seq_init(struct stat_session *session)
124 : {
125 0 : struct tracer_stat *ts = session->ts;
126 0 : struct rb_root *root = &session->stat_root;
127 0 : void *stat;
128 0 : int ret = 0;
129 0 : int i;
130 :
131 0 : mutex_lock(&session->stat_mutex);
132 0 : __reset_stat_session(session);
133 :
134 0 : if (!ts->stat_cmp)
135 0 : ts->stat_cmp = dummy_cmp;
136 :
137 0 : stat = ts->stat_start(ts);
138 0 : if (!stat)
139 0 : goto exit;
140 :
141 0 : ret = insert_stat(root, stat, ts->stat_cmp);
142 0 : if (ret)
143 0 : goto exit;
144 :
145 : /*
146 : * Iterate over the tracer stat entries and store them in an rbtree.
147 : */
148 0 : for (i = 1; ; i++) {
149 0 : stat = ts->stat_next(stat, i);
150 :
151 : /* End of insertion */
152 0 : if (!stat)
153 : break;
154 :
155 0 : ret = insert_stat(root, stat, ts->stat_cmp);
156 0 : if (ret)
157 0 : goto exit_free_rbtree;
158 : }
159 :
160 0 : exit:
161 0 : mutex_unlock(&session->stat_mutex);
162 0 : return ret;
163 :
164 0 : exit_free_rbtree:
165 0 : __reset_stat_session(session);
166 0 : mutex_unlock(&session->stat_mutex);
167 0 : return ret;
168 : }
169 :
170 :
171 0 : static void *stat_seq_start(struct seq_file *s, loff_t *pos)
172 : {
173 0 : struct stat_session *session = s->private;
174 0 : struct rb_node *node;
175 0 : int n = *pos;
176 0 : int i;
177 :
178 : /* Prevent from tracer switch or rbtree modification */
179 0 : mutex_lock(&session->stat_mutex);
180 :
181 : /* If we are in the beginning of the file, print the headers */
182 0 : if (session->ts->stat_headers) {
183 0 : if (n == 0)
184 : return SEQ_START_TOKEN;
185 0 : n--;
186 : }
187 :
188 0 : node = rb_first(&session->stat_root);
189 0 : for (i = 0; node && i < n; i++)
190 0 : node = rb_next(node);
191 :
192 : return node;
193 : }
194 :
195 0 : static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos)
196 : {
197 0 : struct stat_session *session = s->private;
198 0 : struct rb_node *node = p;
199 :
200 0 : (*pos)++;
201 :
202 0 : if (p == SEQ_START_TOKEN)
203 0 : return rb_first(&session->stat_root);
204 :
205 0 : return rb_next(node);
206 : }
207 :
208 0 : static void stat_seq_stop(struct seq_file *s, void *p)
209 : {
210 0 : struct stat_session *session = s->private;
211 0 : mutex_unlock(&session->stat_mutex);
212 0 : }
213 :
214 0 : static int stat_seq_show(struct seq_file *s, void *v)
215 : {
216 0 : struct stat_session *session = s->private;
217 0 : struct stat_node *l = container_of(v, struct stat_node, node);
218 :
219 0 : if (v == SEQ_START_TOKEN)
220 0 : return session->ts->stat_headers(s);
221 :
222 0 : return session->ts->stat_show(s, l->stat);
223 : }
224 :
225 : static const struct seq_operations trace_stat_seq_ops = {
226 : .start = stat_seq_start,
227 : .next = stat_seq_next,
228 : .stop = stat_seq_stop,
229 : .show = stat_seq_show
230 : };
231 :
232 : /* The session stat is refilled and resorted at each stat file opening */
233 0 : static int tracing_stat_open(struct inode *inode, struct file *file)
234 : {
235 0 : int ret;
236 0 : struct seq_file *m;
237 0 : struct stat_session *session = inode->i_private;
238 :
239 0 : ret = security_locked_down(LOCKDOWN_TRACEFS);
240 0 : if (ret)
241 : return ret;
242 :
243 0 : ret = stat_seq_init(session);
244 0 : if (ret)
245 : return ret;
246 :
247 0 : ret = seq_open(file, &trace_stat_seq_ops);
248 0 : if (ret) {
249 0 : reset_stat_session(session);
250 0 : return ret;
251 : }
252 :
253 0 : m = file->private_data;
254 0 : m->private = session;
255 0 : return ret;
256 : }
257 :
258 : /*
259 : * Avoid consuming memory with our now useless rbtree.
260 : */
261 0 : static int tracing_stat_release(struct inode *i, struct file *f)
262 : {
263 0 : struct stat_session *session = i->i_private;
264 :
265 0 : reset_stat_session(session);
266 :
267 0 : return seq_release(i, f);
268 : }
269 :
270 : static const struct file_operations tracing_stat_fops = {
271 : .open = tracing_stat_open,
272 : .read = seq_read,
273 : .llseek = seq_lseek,
274 : .release = tracing_stat_release
275 : };
276 :
277 0 : static int tracing_stat_init(void)
278 : {
279 0 : int ret;
280 :
281 0 : ret = tracing_init_dentry();
282 0 : if (ret)
283 : return -ENODEV;
284 :
285 0 : stat_dir = tracefs_create_dir("trace_stat", NULL);
286 0 : if (!stat_dir) {
287 0 : pr_warn("Could not create tracefs 'trace_stat' entry\n");
288 0 : return -ENOMEM;
289 : }
290 : return 0;
291 : }
292 :
293 0 : static int init_stat_file(struct stat_session *session)
294 : {
295 0 : int ret;
296 :
297 0 : if (!stat_dir && (ret = tracing_stat_init()))
298 : return ret;
299 :
300 0 : session->file = tracefs_create_file(session->ts->name, 0644,
301 : stat_dir,
302 : session, &tracing_stat_fops);
303 0 : if (!session->file)
304 0 : return -ENOMEM;
305 : return 0;
306 : }
307 :
308 0 : int register_stat_tracer(struct tracer_stat *trace)
309 : {
310 0 : struct stat_session *session, *node;
311 0 : int ret = -EINVAL;
312 :
313 0 : if (!trace)
314 : return -EINVAL;
315 :
316 0 : if (!trace->stat_start || !trace->stat_next || !trace->stat_show)
317 : return -EINVAL;
318 :
319 : /* Already registered? */
320 0 : mutex_lock(&all_stat_sessions_mutex);
321 0 : list_for_each_entry(node, &all_stat_sessions, session_list) {
322 0 : if (node->ts == trace)
323 0 : goto out;
324 : }
325 :
326 0 : ret = -ENOMEM;
327 : /* Init the session */
328 0 : session = kzalloc(sizeof(*session), GFP_KERNEL);
329 0 : if (!session)
330 0 : goto out;
331 :
332 0 : session->ts = trace;
333 0 : INIT_LIST_HEAD(&session->session_list);
334 0 : mutex_init(&session->stat_mutex);
335 :
336 0 : ret = init_stat_file(session);
337 0 : if (ret) {
338 0 : destroy_session(session);
339 0 : goto out;
340 : }
341 :
342 0 : ret = 0;
343 : /* Register */
344 0 : list_add_tail(&session->session_list, &all_stat_sessions);
345 0 : out:
346 0 : mutex_unlock(&all_stat_sessions_mutex);
347 :
348 0 : return ret;
349 : }
350 :
351 0 : void unregister_stat_tracer(struct tracer_stat *trace)
352 : {
353 0 : struct stat_session *node, *tmp;
354 :
355 0 : mutex_lock(&all_stat_sessions_mutex);
356 0 : list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) {
357 0 : if (node->ts == trace) {
358 0 : list_del(&node->session_list);
359 0 : destroy_session(node);
360 0 : break;
361 : }
362 : }
363 0 : mutex_unlock(&all_stat_sessions_mutex);
364 0 : }
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