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1 | /* | |
2 | * Copyright (C) 2008 Mathieu Desnoyers | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify | |
5 | * it under the terms of the GNU General Public License as published by | |
6 | * the Free Software Foundation; either version 2 of the License, or | |
7 | * (at your option) any later version. | |
8 | * | |
9 | * This program is distributed in the hope that it will be useful, | |
10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
12 | * GNU General Public License for more details. | |
13 | * | |
14 | * You should have received a copy of the GNU General Public License | |
15 | * along with this program; if not, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | */ | |
18 | #include <linux/module.h> | |
19 | #include <linux/mutex.h> | |
20 | #include <linux/types.h> | |
21 | #include <linux/jhash.h> | |
22 | #include <linux/list.h> | |
23 | #include <linux/rcupdate.h> | |
24 | #include <linux/tracepoint.h> | |
25 | #include <linux/err.h> | |
26 | #include <linux/slab.h> | |
27 | #include <linux/sched.h> | |
28 | #include <linux/jump_label.h> | |
29 | ||
30 | extern struct tracepoint __start___tracepoints[]; | |
31 | extern struct tracepoint __stop___tracepoints[]; | |
32 | ||
33 | /* Set to 1 to enable tracepoint debug output */ | |
34 | static const int tracepoint_debug; | |
35 | ||
36 | /* | |
37 | * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the | |
38 | * builtin and module tracepoints and the hash table. | |
39 | */ | |
40 | static DEFINE_MUTEX(tracepoints_mutex); | |
41 | ||
42 | /* | |
43 | * Tracepoint hash table, containing the active tracepoints. | |
44 | * Protected by tracepoints_mutex. | |
45 | */ | |
46 | #define TRACEPOINT_HASH_BITS 6 | |
47 | #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS) | |
48 | static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE]; | |
49 | ||
50 | /* | |
51 | * Note about RCU : | |
52 | * It is used to delay the free of multiple probes array until a quiescent | |
53 | * state is reached. | |
54 | * Tracepoint entries modifications are protected by the tracepoints_mutex. | |
55 | */ | |
56 | struct tracepoint_entry { | |
57 | struct hlist_node hlist; | |
58 | struct tracepoint_func *funcs; | |
59 | int refcount; /* Number of times armed. 0 if disarmed. */ | |
60 | char name[0]; | |
61 | }; | |
62 | ||
63 | struct tp_probes { | |
64 | union { | |
65 | struct rcu_head rcu; | |
66 | struct list_head list; | |
67 | } u; | |
68 | struct tracepoint_func probes[0]; | |
69 | }; | |
70 | ||
71 | static inline void *allocate_probes(int count) | |
72 | { | |
73 | struct tp_probes *p = kmalloc(count * sizeof(struct tracepoint_func) | |
74 | + sizeof(struct tp_probes), GFP_KERNEL); | |
75 | return p == NULL ? NULL : p->probes; | |
76 | } | |
77 | ||
78 | static void rcu_free_old_probes(struct rcu_head *head) | |
79 | { | |
80 | kfree(container_of(head, struct tp_probes, u.rcu)); | |
81 | } | |
82 | ||
83 | static inline void release_probes(struct tracepoint_func *old) | |
84 | { | |
85 | if (old) { | |
86 | struct tp_probes *tp_probes = container_of(old, | |
87 | struct tp_probes, probes[0]); | |
88 | call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes); | |
89 | } | |
90 | } | |
91 | ||
92 | static void debug_print_probes(struct tracepoint_entry *entry) | |
93 | { | |
94 | int i; | |
95 | ||
96 | if (!tracepoint_debug || !entry->funcs) | |
97 | return; | |
98 | ||
99 | for (i = 0; entry->funcs[i].func; i++) | |
100 | printk(KERN_DEBUG "Probe %d : %p\n", i, entry->funcs[i].func); | |
101 | } | |
102 | ||
103 | static struct tracepoint_func * | |
104 | tracepoint_entry_add_probe(struct tracepoint_entry *entry, | |
105 | void *probe, void *data) | |
106 | { | |
107 | int nr_probes = 0; | |
108 | struct tracepoint_func *old, *new; | |
109 | ||
110 | WARN_ON(!probe); | |
111 | ||
112 | debug_print_probes(entry); | |
113 | old = entry->funcs; | |
114 | if (old) { | |
115 | /* (N -> N+1), (N != 0, 1) probes */ | |
116 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) | |
117 | if (old[nr_probes].func == probe && | |
118 | old[nr_probes].data == data) | |
119 | return ERR_PTR(-EEXIST); | |
120 | } | |
121 | /* + 2 : one for new probe, one for NULL func */ | |
122 | new = allocate_probes(nr_probes + 2); | |
123 | if (new == NULL) | |
124 | return ERR_PTR(-ENOMEM); | |
125 | if (old) | |
126 | memcpy(new, old, nr_probes * sizeof(struct tracepoint_func)); | |
127 | new[nr_probes].func = probe; | |
128 | new[nr_probes].data = data; | |
129 | new[nr_probes + 1].func = NULL; | |
130 | entry->refcount = nr_probes + 1; | |
131 | entry->funcs = new; | |
132 | debug_print_probes(entry); | |
133 | return old; | |
134 | } | |
135 | ||
136 | static void * | |
137 | tracepoint_entry_remove_probe(struct tracepoint_entry *entry, | |
138 | void *probe, void *data) | |
139 | { | |
140 | int nr_probes = 0, nr_del = 0, i; | |
141 | struct tracepoint_func *old, *new; | |
142 | ||
143 | old = entry->funcs; | |
144 | ||
145 | if (!old) | |
146 | return ERR_PTR(-ENOENT); | |
147 | ||
148 | debug_print_probes(entry); | |
149 | /* (N -> M), (N > 1, M >= 0) probes */ | |
150 | for (nr_probes = 0; old[nr_probes].func; nr_probes++) { | |
151 | if (!probe || | |
152 | (old[nr_probes].func == probe && | |
153 | old[nr_probes].data == data)) | |
154 | nr_del++; | |
155 | } | |
156 | ||
157 | if (nr_probes - nr_del == 0) { | |
158 | /* N -> 0, (N > 1) */ | |
159 | entry->funcs = NULL; | |
160 | entry->refcount = 0; | |
161 | debug_print_probes(entry); | |
162 | return old; | |
163 | } else { | |
164 | int j = 0; | |
165 | /* N -> M, (N > 1, M > 0) */ | |
166 | /* + 1 for NULL */ | |
167 | new = allocate_probes(nr_probes - nr_del + 1); | |
168 | if (new == NULL) | |
169 | return ERR_PTR(-ENOMEM); | |
170 | for (i = 0; old[i].func; i++) | |
171 | if (probe && | |
172 | (old[i].func != probe || old[i].data != data)) | |
173 | new[j++] = old[i]; | |
174 | new[nr_probes - nr_del].func = NULL; | |
175 | entry->refcount = nr_probes - nr_del; | |
176 | entry->funcs = new; | |
177 | } | |
178 | debug_print_probes(entry); | |
179 | return old; | |
180 | } | |
181 | ||
182 | /* | |
183 | * Get tracepoint if the tracepoint is present in the tracepoint hash table. | |
184 | * Must be called with tracepoints_mutex held. | |
185 | * Returns NULL if not present. | |
186 | */ | |
187 | static struct tracepoint_entry *get_tracepoint(const char *name) | |
188 | { | |
189 | struct hlist_head *head; | |
190 | struct hlist_node *node; | |
191 | struct tracepoint_entry *e; | |
192 | u32 hash = jhash(name, strlen(name), 0); | |
193 | ||
194 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; | |
195 | hlist_for_each_entry(e, node, head, hlist) { | |
196 | if (!strcmp(name, e->name)) | |
197 | return e; | |
198 | } | |
199 | return NULL; | |
200 | } | |
201 | ||
202 | /* | |
203 | * Add the tracepoint to the tracepoint hash table. Must be called with | |
204 | * tracepoints_mutex held. | |
205 | */ | |
206 | static struct tracepoint_entry *add_tracepoint(const char *name) | |
207 | { | |
208 | struct hlist_head *head; | |
209 | struct hlist_node *node; | |
210 | struct tracepoint_entry *e; | |
211 | size_t name_len = strlen(name) + 1; | |
212 | u32 hash = jhash(name, name_len-1, 0); | |
213 | ||
214 | head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)]; | |
215 | hlist_for_each_entry(e, node, head, hlist) { | |
216 | if (!strcmp(name, e->name)) { | |
217 | printk(KERN_NOTICE | |
218 | "tracepoint %s busy\n", name); | |
219 | return ERR_PTR(-EEXIST); /* Already there */ | |
220 | } | |
221 | } | |
222 | /* | |
223 | * Using kmalloc here to allocate a variable length element. Could | |
224 | * cause some memory fragmentation if overused. | |
225 | */ | |
226 | e = kmalloc(sizeof(struct tracepoint_entry) + name_len, GFP_KERNEL); | |
227 | if (!e) | |
228 | return ERR_PTR(-ENOMEM); | |
229 | memcpy(&e->name[0], name, name_len); | |
230 | e->funcs = NULL; | |
231 | e->refcount = 0; | |
232 | hlist_add_head(&e->hlist, head); | |
233 | return e; | |
234 | } | |
235 | ||
236 | /* | |
237 | * Remove the tracepoint from the tracepoint hash table. Must be called with | |
238 | * mutex_lock held. | |
239 | */ | |
240 | static inline void remove_tracepoint(struct tracepoint_entry *e) | |
241 | { | |
242 | hlist_del(&e->hlist); | |
243 | kfree(e); | |
244 | } | |
245 | ||
246 | /* | |
247 | * Sets the probe callback corresponding to one tracepoint. | |
248 | */ | |
249 | static void set_tracepoint(struct tracepoint_entry **entry, | |
250 | struct tracepoint *elem, int active) | |
251 | { | |
252 | WARN_ON(strcmp((*entry)->name, elem->name) != 0); | |
253 | ||
254 | if (elem->regfunc && !elem->state && active) | |
255 | elem->regfunc(); | |
256 | else if (elem->unregfunc && elem->state && !active) | |
257 | elem->unregfunc(); | |
258 | ||
259 | /* | |
260 | * rcu_assign_pointer has a smp_wmb() which makes sure that the new | |
261 | * probe callbacks array is consistent before setting a pointer to it. | |
262 | * This array is referenced by __DO_TRACE from | |
263 | * include/linux/tracepoints.h. A matching smp_read_barrier_depends() | |
264 | * is used. | |
265 | */ | |
266 | rcu_assign_pointer(elem->funcs, (*entry)->funcs); | |
267 | if (!elem->state && active) { | |
268 | jump_label_enable(&elem->state); | |
269 | elem->state = active; | |
270 | } else if (elem->state && !active) { | |
271 | jump_label_disable(&elem->state); | |
272 | elem->state = active; | |
273 | } | |
274 | } | |
275 | ||
276 | /* | |
277 | * Disable a tracepoint and its probe callback. | |
278 | * Note: only waiting an RCU period after setting elem->call to the empty | |
279 | * function insures that the original callback is not used anymore. This insured | |
280 | * by preempt_disable around the call site. | |
281 | */ | |
282 | static void disable_tracepoint(struct tracepoint *elem) | |
283 | { | |
284 | if (elem->unregfunc && elem->state) | |
285 | elem->unregfunc(); | |
286 | ||
287 | if (elem->state) { | |
288 | jump_label_disable(&elem->state); | |
289 | elem->state = 0; | |
290 | } | |
291 | rcu_assign_pointer(elem->funcs, NULL); | |
292 | } | |
293 | ||
294 | /** | |
295 | * tracepoint_update_probe_range - Update a probe range | |
296 | * @begin: beginning of the range | |
297 | * @end: end of the range | |
298 | * | |
299 | * Updates the probe callback corresponding to a range of tracepoints. | |
300 | */ | |
301 | void | |
302 | tracepoint_update_probe_range(struct tracepoint *begin, struct tracepoint *end) | |
303 | { | |
304 | struct tracepoint *iter; | |
305 | struct tracepoint_entry *mark_entry; | |
306 | ||
307 | if (!begin) | |
308 | return; | |
309 | ||
310 | mutex_lock(&tracepoints_mutex); | |
311 | for (iter = begin; iter < end; iter++) { | |
312 | mark_entry = get_tracepoint(iter->name); | |
313 | if (mark_entry) { | |
314 | set_tracepoint(&mark_entry, iter, | |
315 | !!mark_entry->refcount); | |
316 | } else { | |
317 | disable_tracepoint(iter); | |
318 | } | |
319 | } | |
320 | mutex_unlock(&tracepoints_mutex); | |
321 | } | |
322 | ||
323 | /* | |
324 | * Update probes, removing the faulty probes. | |
325 | */ | |
326 | static void tracepoint_update_probes(void) | |
327 | { | |
328 | /* Core kernel tracepoints */ | |
329 | tracepoint_update_probe_range(__start___tracepoints, | |
330 | __stop___tracepoints); | |
331 | /* tracepoints in modules. */ | |
332 | module_update_tracepoints(); | |
333 | } | |
334 | ||
335 | static struct tracepoint_func * | |
336 | tracepoint_add_probe(const char *name, void *probe, void *data) | |
337 | { | |
338 | struct tracepoint_entry *entry; | |
339 | struct tracepoint_func *old; | |
340 | ||
341 | entry = get_tracepoint(name); | |
342 | if (!entry) { | |
343 | entry = add_tracepoint(name); | |
344 | if (IS_ERR(entry)) | |
345 | return (struct tracepoint_func *)entry; | |
346 | } | |
347 | old = tracepoint_entry_add_probe(entry, probe, data); | |
348 | if (IS_ERR(old) && !entry->refcount) | |
349 | remove_tracepoint(entry); | |
350 | return old; | |
351 | } | |
352 | ||
353 | /** | |
354 | * tracepoint_probe_register - Connect a probe to a tracepoint | |
355 | * @name: tracepoint name | |
356 | * @probe: probe handler | |
357 | * | |
358 | * Returns 0 if ok, error value on error. | |
359 | * The probe address must at least be aligned on the architecture pointer size. | |
360 | */ | |
361 | int tracepoint_probe_register(const char *name, void *probe, void *data) | |
362 | { | |
363 | struct tracepoint_func *old; | |
364 | ||
365 | mutex_lock(&tracepoints_mutex); | |
366 | old = tracepoint_add_probe(name, probe, data); | |
367 | mutex_unlock(&tracepoints_mutex); | |
368 | if (IS_ERR(old)) | |
369 | return PTR_ERR(old); | |
370 | ||
371 | tracepoint_update_probes(); /* may update entry */ | |
372 | release_probes(old); | |
373 | return 0; | |
374 | } | |
375 | EXPORT_SYMBOL_GPL(tracepoint_probe_register); | |
376 | ||
377 | static struct tracepoint_func * | |
378 | tracepoint_remove_probe(const char *name, void *probe, void *data) | |
379 | { | |
380 | struct tracepoint_entry *entry; | |
381 | struct tracepoint_func *old; | |
382 | ||
383 | entry = get_tracepoint(name); | |
384 | if (!entry) | |
385 | return ERR_PTR(-ENOENT); | |
386 | old = tracepoint_entry_remove_probe(entry, probe, data); | |
387 | if (IS_ERR(old)) | |
388 | return old; | |
389 | if (!entry->refcount) | |
390 | remove_tracepoint(entry); | |
391 | return old; | |
392 | } | |
393 | ||
394 | /** | |
395 | * tracepoint_probe_unregister - Disconnect a probe from a tracepoint | |
396 | * @name: tracepoint name | |
397 | * @probe: probe function pointer | |
398 | * | |
399 | * We do not need to call a synchronize_sched to make sure the probes have | |
400 | * finished running before doing a module unload, because the module unload | |
401 | * itself uses stop_machine(), which insures that every preempt disabled section | |
402 | * have finished. | |
403 | */ | |
404 | int tracepoint_probe_unregister(const char *name, void *probe, void *data) | |
405 | { | |
406 | struct tracepoint_func *old; | |
407 | ||
408 | mutex_lock(&tracepoints_mutex); | |
409 | old = tracepoint_remove_probe(name, probe, data); | |
410 | mutex_unlock(&tracepoints_mutex); | |
411 | if (IS_ERR(old)) | |
412 | return PTR_ERR(old); | |
413 | ||
414 | tracepoint_update_probes(); /* may update entry */ | |
415 | release_probes(old); | |
416 | return 0; | |
417 | } | |
418 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister); | |
419 | ||
420 | static LIST_HEAD(old_probes); | |
421 | static int need_update; | |
422 | ||
423 | static void tracepoint_add_old_probes(void *old) | |
424 | { | |
425 | need_update = 1; | |
426 | if (old) { | |
427 | struct tp_probes *tp_probes = container_of(old, | |
428 | struct tp_probes, probes[0]); | |
429 | list_add(&tp_probes->u.list, &old_probes); | |
430 | } | |
431 | } | |
432 | ||
433 | /** | |
434 | * tracepoint_probe_register_noupdate - register a probe but not connect | |
435 | * @name: tracepoint name | |
436 | * @probe: probe handler | |
437 | * | |
438 | * caller must call tracepoint_probe_update_all() | |
439 | */ | |
440 | int tracepoint_probe_register_noupdate(const char *name, void *probe, | |
441 | void *data) | |
442 | { | |
443 | struct tracepoint_func *old; | |
444 | ||
445 | mutex_lock(&tracepoints_mutex); | |
446 | old = tracepoint_add_probe(name, probe, data); | |
447 | if (IS_ERR(old)) { | |
448 | mutex_unlock(&tracepoints_mutex); | |
449 | return PTR_ERR(old); | |
450 | } | |
451 | tracepoint_add_old_probes(old); | |
452 | mutex_unlock(&tracepoints_mutex); | |
453 | return 0; | |
454 | } | |
455 | EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate); | |
456 | ||
457 | /** | |
458 | * tracepoint_probe_unregister_noupdate - remove a probe but not disconnect | |
459 | * @name: tracepoint name | |
460 | * @probe: probe function pointer | |
461 | * | |
462 | * caller must call tracepoint_probe_update_all() | |
463 | */ | |
464 | int tracepoint_probe_unregister_noupdate(const char *name, void *probe, | |
465 | void *data) | |
466 | { | |
467 | struct tracepoint_func *old; | |
468 | ||
469 | mutex_lock(&tracepoints_mutex); | |
470 | old = tracepoint_remove_probe(name, probe, data); | |
471 | if (IS_ERR(old)) { | |
472 | mutex_unlock(&tracepoints_mutex); | |
473 | return PTR_ERR(old); | |
474 | } | |
475 | tracepoint_add_old_probes(old); | |
476 | mutex_unlock(&tracepoints_mutex); | |
477 | return 0; | |
478 | } | |
479 | EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate); | |
480 | ||
481 | /** | |
482 | * tracepoint_probe_update_all - update tracepoints | |
483 | */ | |
484 | void tracepoint_probe_update_all(void) | |
485 | { | |
486 | LIST_HEAD(release_probes); | |
487 | struct tp_probes *pos, *next; | |
488 | ||
489 | mutex_lock(&tracepoints_mutex); | |
490 | if (!need_update) { | |
491 | mutex_unlock(&tracepoints_mutex); | |
492 | return; | |
493 | } | |
494 | if (!list_empty(&old_probes)) | |
495 | list_replace_init(&old_probes, &release_probes); | |
496 | need_update = 0; | |
497 | mutex_unlock(&tracepoints_mutex); | |
498 | ||
499 | tracepoint_update_probes(); | |
500 | list_for_each_entry_safe(pos, next, &release_probes, u.list) { | |
501 | list_del(&pos->u.list); | |
502 | call_rcu_sched(&pos->u.rcu, rcu_free_old_probes); | |
503 | } | |
504 | } | |
505 | EXPORT_SYMBOL_GPL(tracepoint_probe_update_all); | |
506 | ||
507 | /** | |
508 | * tracepoint_get_iter_range - Get a next tracepoint iterator given a range. | |
509 | * @tracepoint: current tracepoints (in), next tracepoint (out) | |
510 | * @begin: beginning of the range | |
511 | * @end: end of the range | |
512 | * | |
513 | * Returns whether a next tracepoint has been found (1) or not (0). | |
514 | * Will return the first tracepoint in the range if the input tracepoint is | |
515 | * NULL. | |
516 | */ | |
517 | int tracepoint_get_iter_range(struct tracepoint **tracepoint, | |
518 | struct tracepoint *begin, struct tracepoint *end) | |
519 | { | |
520 | if (!*tracepoint && begin != end) { | |
521 | *tracepoint = begin; | |
522 | return 1; | |
523 | } | |
524 | if (*tracepoint >= begin && *tracepoint < end) | |
525 | return 1; | |
526 | return 0; | |
527 | } | |
528 | EXPORT_SYMBOL_GPL(tracepoint_get_iter_range); | |
529 | ||
530 | static void tracepoint_get_iter(struct tracepoint_iter *iter) | |
531 | { | |
532 | int found = 0; | |
533 | ||
534 | /* Core kernel tracepoints */ | |
535 | if (!iter->module) { | |
536 | found = tracepoint_get_iter_range(&iter->tracepoint, | |
537 | __start___tracepoints, __stop___tracepoints); | |
538 | if (found) | |
539 | goto end; | |
540 | } | |
541 | /* tracepoints in modules. */ | |
542 | found = module_get_iter_tracepoints(iter); | |
543 | end: | |
544 | if (!found) | |
545 | tracepoint_iter_reset(iter); | |
546 | } | |
547 | ||
548 | void tracepoint_iter_start(struct tracepoint_iter *iter) | |
549 | { | |
550 | tracepoint_get_iter(iter); | |
551 | } | |
552 | EXPORT_SYMBOL_GPL(tracepoint_iter_start); | |
553 | ||
554 | void tracepoint_iter_next(struct tracepoint_iter *iter) | |
555 | { | |
556 | iter->tracepoint++; | |
557 | /* | |
558 | * iter->tracepoint may be invalid because we blindly incremented it. | |
559 | * Make sure it is valid by marshalling on the tracepoints, getting the | |
560 | * tracepoints from following modules if necessary. | |
561 | */ | |
562 | tracepoint_get_iter(iter); | |
563 | } | |
564 | EXPORT_SYMBOL_GPL(tracepoint_iter_next); | |
565 | ||
566 | void tracepoint_iter_stop(struct tracepoint_iter *iter) | |
567 | { | |
568 | } | |
569 | EXPORT_SYMBOL_GPL(tracepoint_iter_stop); | |
570 | ||
571 | void tracepoint_iter_reset(struct tracepoint_iter *iter) | |
572 | { | |
573 | iter->module = NULL; | |
574 | iter->tracepoint = NULL; | |
575 | } | |
576 | EXPORT_SYMBOL_GPL(tracepoint_iter_reset); | |
577 | ||
578 | #ifdef CONFIG_MODULES | |
579 | ||
580 | int tracepoint_module_notify(struct notifier_block *self, | |
581 | unsigned long val, void *data) | |
582 | { | |
583 | struct module *mod = data; | |
584 | ||
585 | switch (val) { | |
586 | case MODULE_STATE_COMING: | |
587 | case MODULE_STATE_GOING: | |
588 | tracepoint_update_probe_range(mod->tracepoints, | |
589 | mod->tracepoints + mod->num_tracepoints); | |
590 | break; | |
591 | } | |
592 | return 0; | |
593 | } | |
594 | ||
595 | struct notifier_block tracepoint_module_nb = { | |
596 | .notifier_call = tracepoint_module_notify, | |
597 | .priority = 0, | |
598 | }; | |
599 | ||
600 | static int init_tracepoints(void) | |
601 | { | |
602 | return register_module_notifier(&tracepoint_module_nb); | |
603 | } | |
604 | __initcall(init_tracepoints); | |
605 | ||
606 | #endif /* CONFIG_MODULES */ | |
607 | ||
608 | #ifdef CONFIG_HAVE_SYSCALL_TRACEPOINTS | |
609 | ||
610 | /* NB: reg/unreg are called while guarded with the tracepoints_mutex */ | |
611 | static int sys_tracepoint_refcount; | |
612 | ||
613 | void syscall_regfunc(void) | |
614 | { | |
615 | unsigned long flags; | |
616 | struct task_struct *g, *t; | |
617 | ||
618 | if (!sys_tracepoint_refcount) { | |
619 | read_lock_irqsave(&tasklist_lock, flags); | |
620 | do_each_thread(g, t) { | |
621 | /* Skip kernel threads. */ | |
622 | if (t->mm) | |
623 | set_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); | |
624 | } while_each_thread(g, t); | |
625 | read_unlock_irqrestore(&tasklist_lock, flags); | |
626 | } | |
627 | sys_tracepoint_refcount++; | |
628 | } | |
629 | ||
630 | void syscall_unregfunc(void) | |
631 | { | |
632 | unsigned long flags; | |
633 | struct task_struct *g, *t; | |
634 | ||
635 | sys_tracepoint_refcount--; | |
636 | if (!sys_tracepoint_refcount) { | |
637 | read_lock_irqsave(&tasklist_lock, flags); | |
638 | do_each_thread(g, t) { | |
639 | clear_tsk_thread_flag(t, TIF_SYSCALL_TRACEPOINT); | |
640 | } while_each_thread(g, t); | |
641 | read_unlock_irqrestore(&tasklist_lock, flags); | |
642 | } | |
643 | } | |
644 | #endif |