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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 | */ | |
25 | struct stat_node { | |
26 | struct rb_node node; | |
27 | void *stat; | |
28 | }; | |
29 | ||
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; | |
37 | }; | |
38 | ||
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); | |
42 | ||
43 | /* The root directory for all stat files */ | |
44 | static struct dentry *stat_dir; | |
45 | ||
46 | static 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 | ||
59 | static 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 | ||
66 | static 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 | ||
74 | typedef int (*cmp_stat_t)(void *, void *); | |
75 | ||
76 | static 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 | */ | |
114 | static 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 | */ | |
124 | static 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 | ||
161 | exit: | |
162 | mutex_unlock(&session->stat_mutex); | |
163 | return ret; | |
164 | ||
165 | exit_free_rbtree: | |
166 | __reset_stat_session(session); | |
167 | mutex_unlock(&session->stat_mutex); | |
168 | return ret; | |
169 | } | |
170 | ||
171 | ||
172 | static 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 | ||
196 | static 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 | ||
209 | static 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 | ||
215 | static 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 | ||
226 | static 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 */ | |
234 | static 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 | */ | |
258 | static 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 | ||
267 | static 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 | ||
274 | static 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 | ||
288 | static 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 | ||
301 | int 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 | ||
345 | void 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 | } |