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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
dbd0b4b3 FW |
2 | /* |
3 | * Infrastructure for statistic tracing (histogram output). | |
4 | * | |
8f184f27 | 5 | * Copyright (C) 2008-2009 Frederic Weisbecker <fweisbec@gmail.com> |
dbd0b4b3 FW |
6 | * |
7 | * Based on the code from trace_branch.c which is | |
8 | * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com> | |
9 | * | |
10 | */ | |
11 | ||
17911ff3 | 12 | #include <linux/security.h> |
dbd0b4b3 | 13 | #include <linux/list.h> |
5a0e3ad6 | 14 | #include <linux/slab.h> |
8f184f27 | 15 | #include <linux/rbtree.h> |
8434dc93 | 16 | #include <linux/tracefs.h> |
002bb86d | 17 | #include "trace_stat.h" |
dbd0b4b3 FW |
18 | #include "trace.h" |
19 | ||
20 | ||
8f184f27 FW |
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; | |
55922173 | 28 | void *stat; |
dbd0b4b3 FW |
29 | }; |
30 | ||
034939b6 | 31 | /* A stat session is the stats output in one file */ |
0d64f834 | 32 | struct stat_session { |
002bb86d | 33 | struct list_head session_list; |
55922173 | 34 | struct tracer_stat *ts; |
8f184f27 | 35 | struct rb_root stat_root; |
55922173 | 36 | struct mutex stat_mutex; |
002bb86d | 37 | struct dentry *file; |
034939b6 | 38 | }; |
dbd0b4b3 | 39 | |
73d8b8bc | 40 | /* All of the sessions currently in use. Each stat file embed one session */ |
002bb86d FW |
41 | static LIST_HEAD(all_stat_sessions); |
42 | static DEFINE_MUTEX(all_stat_sessions_mutex); | |
43 | ||
44 | /* The root directory for all stat files */ | |
55922173 | 45 | static struct dentry *stat_dir; |
dbd0b4b3 | 46 | |
9cd804ac | 47 | static void __reset_stat_session(struct stat_session *session) |
8f184f27 | 48 | { |
9cd804ac | 49 | struct stat_node *snode, *n; |
8f184f27 | 50 | |
9cd804ac CS |
51 | rbtree_postorder_for_each_entry_safe(snode, n, &session->stat_root, node) { |
52 | if (session->ts->stat_release) | |
53 | session->ts->stat_release(snode->stat); | |
8f184f27 | 54 | kfree(snode); |
8f184f27 | 55 | } |
dbd0b4b3 | 56 | |
8f184f27 | 57 | session->stat_root = RB_ROOT; |
dbd0b4b3 FW |
58 | } |
59 | ||
636eacee LZ |
60 | static void reset_stat_session(struct stat_session *session) |
61 | { | |
62 | mutex_lock(&session->stat_mutex); | |
63 | __reset_stat_session(session); | |
64 | mutex_unlock(&session->stat_mutex); | |
65 | } | |
66 | ||
0d64f834 | 67 | static void destroy_session(struct stat_session *session) |
dbd0b4b3 | 68 | { |
8434dc93 | 69 | tracefs_remove(session->file); |
636eacee | 70 | __reset_stat_session(session); |
002bb86d FW |
71 | mutex_destroy(&session->stat_mutex); |
72 | kfree(session); | |
73 | } | |
034939b6 | 74 | |
80042c8f | 75 | static int insert_stat(struct rb_root *root, void *stat, cmp_func_t cmp) |
8f184f27 FW |
76 | { |
77 | struct rb_node **new = &(root->rb_node), *parent = NULL; | |
dbd3fbdf LZ |
78 | struct stat_node *data; |
79 | ||
80 | data = kzalloc(sizeof(*data), GFP_KERNEL); | |
81 | if (!data) | |
82 | return -ENOMEM; | |
83 | data->stat = stat; | |
8f184f27 FW |
84 | |
85 | /* | |
86 | * Figure out where to put new node | |
87 | * This is a descendent sorting | |
88 | */ | |
89 | while (*new) { | |
90 | struct stat_node *this; | |
91 | int result; | |
92 | ||
93 | this = container_of(*new, struct stat_node, node); | |
94 | result = cmp(data->stat, this->stat); | |
95 | ||
96 | parent = *new; | |
97 | if (result >= 0) | |
98 | new = &((*new)->rb_left); | |
99 | else | |
100 | new = &((*new)->rb_right); | |
101 | } | |
102 | ||
103 | rb_link_node(&data->node, parent, new); | |
104 | rb_insert_color(&data->node, root); | |
dbd3fbdf | 105 | return 0; |
8f184f27 FW |
106 | } |
107 | ||
dbd0b4b3 FW |
108 | /* |
109 | * For tracers that don't provide a stat_cmp callback. | |
dbd3fbdf LZ |
110 | * This one will force an insertion as right-most node |
111 | * in the rbtree. | |
dbd0b4b3 | 112 | */ |
80042c8f | 113 | static int dummy_cmp(const void *p1, const void *p2) |
dbd0b4b3 | 114 | { |
b3dd7ba7 | 115 | return -1; |
dbd0b4b3 FW |
116 | } |
117 | ||
118 | /* | |
dbd3fbdf | 119 | * Initialize the stat rbtree at each trace_stat file opening. |
dbd0b4b3 FW |
120 | * All of these copies and sorting are required on all opening |
121 | * since the stats could have changed between two file sessions. | |
122 | */ | |
0d64f834 | 123 | static int stat_seq_init(struct stat_session *session) |
dbd0b4b3 | 124 | { |
034939b6 | 125 | struct tracer_stat *ts = session->ts; |
dbd3fbdf | 126 | struct rb_root *root = &session->stat_root; |
09833521 | 127 | void *stat; |
dbd0b4b3 FW |
128 | int ret = 0; |
129 | int i; | |
130 | ||
034939b6 | 131 | mutex_lock(&session->stat_mutex); |
636eacee | 132 | __reset_stat_session(session); |
dbd0b4b3 | 133 | |
034939b6 FW |
134 | if (!ts->stat_cmp) |
135 | ts->stat_cmp = dummy_cmp; | |
dbd0b4b3 | 136 | |
42548008 | 137 | stat = ts->stat_start(ts); |
09833521 SR |
138 | if (!stat) |
139 | goto exit; | |
140 | ||
dbd3fbdf LZ |
141 | ret = insert_stat(root, stat, ts->stat_cmp); |
142 | if (ret) | |
dbd0b4b3 | 143 | goto exit; |
dbd0b4b3 FW |
144 | |
145 | /* | |
dbd3fbdf | 146 | * Iterate over the tracer stat entries and store them in an rbtree. |
dbd0b4b3 FW |
147 | */ |
148 | for (i = 1; ; i++) { | |
09833521 SR |
149 | stat = ts->stat_next(stat, i); |
150 | ||
151 | /* End of insertion */ | |
152 | if (!stat) | |
153 | break; | |
154 | ||
dbd3fbdf LZ |
155 | ret = insert_stat(root, stat, ts->stat_cmp); |
156 | if (ret) | |
157 | goto exit_free_rbtree; | |
dbd0b4b3 | 158 | } |
8f184f27 | 159 | |
dbd0b4b3 | 160 | exit: |
034939b6 | 161 | mutex_unlock(&session->stat_mutex); |
dbd0b4b3 FW |
162 | return ret; |
163 | ||
dbd3fbdf | 164 | exit_free_rbtree: |
636eacee | 165 | __reset_stat_session(session); |
034939b6 | 166 | mutex_unlock(&session->stat_mutex); |
dbd0b4b3 FW |
167 | return ret; |
168 | } | |
169 | ||
170 | ||
171 | static void *stat_seq_start(struct seq_file *s, loff_t *pos) | |
172 | { | |
0d64f834 | 173 | struct stat_session *session = s->private; |
8f184f27 | 174 | struct rb_node *node; |
97d53202 | 175 | int n = *pos; |
8f184f27 | 176 | int i; |
dbd0b4b3 | 177 | |
dbd3fbdf | 178 | /* Prevent from tracer switch or rbtree modification */ |
034939b6 | 179 | mutex_lock(&session->stat_mutex); |
dbd0b4b3 FW |
180 | |
181 | /* If we are in the beginning of the file, print the headers */ | |
97d53202 LZ |
182 | if (session->ts->stat_headers) { |
183 | if (n == 0) | |
184 | return SEQ_START_TOKEN; | |
185 | n--; | |
186 | } | |
dbd0b4b3 | 187 | |
8f184f27 | 188 | node = rb_first(&session->stat_root); |
97d53202 | 189 | for (i = 0; node && i < n; i++) |
8f184f27 FW |
190 | node = rb_next(node); |
191 | ||
8f184f27 | 192 | return node; |
dbd0b4b3 FW |
193 | } |
194 | ||
195 | static void *stat_seq_next(struct seq_file *s, void *p, loff_t *pos) | |
196 | { | |
0d64f834 | 197 | struct stat_session *session = s->private; |
8f184f27 FW |
198 | struct rb_node *node = p; |
199 | ||
200 | (*pos)++; | |
dbd0b4b3 | 201 | |
e6f48901 | 202 | if (p == SEQ_START_TOKEN) |
8f184f27 | 203 | return rb_first(&session->stat_root); |
e6f48901 | 204 | |
8f184f27 | 205 | return rb_next(node); |
dbd0b4b3 FW |
206 | } |
207 | ||
034939b6 | 208 | static void stat_seq_stop(struct seq_file *s, void *p) |
dbd0b4b3 | 209 | { |
0d64f834 | 210 | struct stat_session *session = s->private; |
034939b6 | 211 | mutex_unlock(&session->stat_mutex); |
dbd0b4b3 FW |
212 | } |
213 | ||
214 | static int stat_seq_show(struct seq_file *s, void *v) | |
215 | { | |
0d64f834 | 216 | struct stat_session *session = s->private; |
8f184f27 | 217 | struct stat_node *l = container_of(v, struct stat_node, node); |
ff288b27 | 218 | |
e6f48901 LJ |
219 | if (v == SEQ_START_TOKEN) |
220 | return session->ts->stat_headers(s); | |
221 | ||
034939b6 | 222 | return session->ts->stat_show(s, l->stat); |
dbd0b4b3 FW |
223 | } |
224 | ||
225 | static const struct seq_operations trace_stat_seq_ops = { | |
55922173 IM |
226 | .start = stat_seq_start, |
227 | .next = stat_seq_next, | |
228 | .stop = stat_seq_stop, | |
229 | .show = stat_seq_show | |
dbd0b4b3 FW |
230 | }; |
231 | ||
034939b6 | 232 | /* The session stat is refilled and resorted at each stat file opening */ |
dbd0b4b3 FW |
233 | static int tracing_stat_open(struct inode *inode, struct file *file) |
234 | { | |
235 | int ret; | |
636eacee | 236 | struct seq_file *m; |
0d64f834 | 237 | struct stat_session *session = inode->i_private; |
034939b6 | 238 | |
17911ff3 SRV |
239 | ret = security_locked_down(LOCKDOWN_TRACEFS); |
240 | if (ret) | |
241 | return ret; | |
242 | ||
636eacee LZ |
243 | ret = stat_seq_init(session); |
244 | if (ret) | |
245 | return ret; | |
246 | ||
dbd0b4b3 | 247 | ret = seq_open(file, &trace_stat_seq_ops); |
636eacee LZ |
248 | if (ret) { |
249 | reset_stat_session(session); | |
250 | return ret; | |
dbd0b4b3 FW |
251 | } |
252 | ||
636eacee LZ |
253 | m = file->private_data; |
254 | m->private = session; | |
dbd0b4b3 FW |
255 | return ret; |
256 | } | |
257 | ||
dbd0b4b3 | 258 | /* |
dbd3fbdf | 259 | * Avoid consuming memory with our now useless rbtree. |
dbd0b4b3 FW |
260 | */ |
261 | static int tracing_stat_release(struct inode *i, struct file *f) | |
262 | { | |
0d64f834 | 263 | struct stat_session *session = i->i_private; |
034939b6 | 264 | |
034939b6 | 265 | reset_stat_session(session); |
034939b6 | 266 | |
636eacee | 267 | return seq_release(i, f); |
dbd0b4b3 FW |
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 | ||
002bb86d | 277 | static int tracing_stat_init(void) |
dbd0b4b3 | 278 | { |
22c36b18 | 279 | int ret; |
dbd0b4b3 | 280 | |
22c36b18 WY |
281 | ret = tracing_init_dentry(); |
282 | if (ret) | |
afccc00f | 283 | return -ENODEV; |
dbd0b4b3 | 284 | |
22c36b18 | 285 | stat_dir = tracefs_create_dir("trace_stat", NULL); |
afccc00f | 286 | if (!stat_dir) { |
a395d6a7 | 287 | pr_warn("Could not create tracefs 'trace_stat' entry\n"); |
afccc00f LH |
288 | return -ENOMEM; |
289 | } | |
dbd0b4b3 FW |
290 | return 0; |
291 | } | |
002bb86d | 292 | |
0d64f834 | 293 | static int init_stat_file(struct stat_session *session) |
002bb86d | 294 | { |
afccc00f LH |
295 | int ret; |
296 | ||
297 | if (!stat_dir && (ret = tracing_stat_init())) | |
298 | return ret; | |
002bb86d | 299 | |
8434dc93 | 300 | session->file = tracefs_create_file(session->ts->name, 0644, |
002bb86d FW |
301 | stat_dir, |
302 | session, &tracing_stat_fops); | |
303 | if (!session->file) | |
304 | return -ENOMEM; | |
305 | return 0; | |
306 | } | |
55922173 IM |
307 | |
308 | int register_stat_tracer(struct tracer_stat *trace) | |
309 | { | |
43bd1236 | 310 | struct stat_session *session, *node; |
dfb6cd1e | 311 | int ret = -EINVAL; |
55922173 IM |
312 | |
313 | if (!trace) | |
314 | return -EINVAL; | |
315 | ||
316 | if (!trace->stat_start || !trace->stat_next || !trace->stat_show) | |
317 | return -EINVAL; | |
318 | ||
319 | /* Already registered? */ | |
320 | mutex_lock(&all_stat_sessions_mutex); | |
43bd1236 | 321 | list_for_each_entry(node, &all_stat_sessions, session_list) { |
dfb6cd1e SRV |
322 | if (node->ts == trace) |
323 | goto out; | |
55922173 | 324 | } |
55922173 | 325 | |
dfb6cd1e | 326 | ret = -ENOMEM; |
55922173 | 327 | /* Init the session */ |
8f184f27 | 328 | session = kzalloc(sizeof(*session), GFP_KERNEL); |
55922173 | 329 | if (!session) |
dfb6cd1e | 330 | goto out; |
55922173 IM |
331 | |
332 | session->ts = trace; | |
333 | INIT_LIST_HEAD(&session->session_list); | |
55922173 | 334 | mutex_init(&session->stat_mutex); |
55922173 IM |
335 | |
336 | ret = init_stat_file(session); | |
337 | if (ret) { | |
338 | destroy_session(session); | |
dfb6cd1e | 339 | goto out; |
55922173 IM |
340 | } |
341 | ||
dfb6cd1e | 342 | ret = 0; |
55922173 | 343 | /* Register */ |
55922173 | 344 | list_add_tail(&session->session_list, &all_stat_sessions); |
dfb6cd1e | 345 | out: |
55922173 IM |
346 | mutex_unlock(&all_stat_sessions_mutex); |
347 | ||
dfb6cd1e | 348 | return ret; |
55922173 IM |
349 | } |
350 | ||
351 | void unregister_stat_tracer(struct tracer_stat *trace) | |
352 | { | |
0d64f834 | 353 | struct stat_session *node, *tmp; |
55922173 IM |
354 | |
355 | mutex_lock(&all_stat_sessions_mutex); | |
356 | list_for_each_entry_safe(node, tmp, &all_stat_sessions, session_list) { | |
357 | if (node->ts == trace) { | |
358 | list_del(&node->session_list); | |
359 | destroy_session(node); | |
360 | break; | |
361 | } | |
362 | } | |
363 | mutex_unlock(&all_stat_sessions_mutex); | |
364 | } |