libust/tracepoint.c

   1 /*
   2  * Copyright (C) 2008 Mathieu Desnoyers
   3  * Copyright (C) 2009 Pierre-Marc Fournier
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, write to the Free Software
  17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
  18  *
  19  * Ported to userspace by Pierre-Marc Fournier.
  20  */
  21
  22 #include <errno.h>
  23 #include <ust/tracepoint.h>
  24 #include <ust/core.h>
  25 #include <ust/kcompat/kcompat.h>
  26 #include "usterr.h"
  27
  28 #define _LGPL_SOURCE
  29 #include <urcu-bp.h>
  30
  31 //extern struct tracepoint __start___tracepoints[] __attribute__((visibility("hidden")));
  32 //extern struct tracepoint __stop___tracepoints[] __attribute__((visibility("hidden")));
  33
  34 /* Set to 1 to enable tracepoint debug output */
  35 static const int tracepoint_debug;
  36
  37 /* libraries that contain tracepoints (struct tracepoint_lib) */
  38 static LIST_HEAD(libs);
  39
  40 /*
  41  * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the
  42  * builtin and module tracepoints and the hash table.
  43  */
  44 static DEFINE_MUTEX(tracepoints_mutex);
  45
  46 /*
  47  * Tracepoint hash table, containing the active tracepoints.
  48  * Protected by tracepoints_mutex.
  49  */
  50 #define TRACEPOINT_HASH_BITS 6
  51 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
  52 static struct hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
  53
  54 /*
  55  * Note about RCU :
  56  * It is used to to delay the free of multiple probes array until a quiescent
  57  * state is reached.
  58  * Tracepoint entries modifications are protected by the tracepoints_mutex.
  59  */
  60 struct tracepoint_entry {
  61         struct hlist_node hlist;
  62         void **funcs;
  63         int refcount;   /* Number of times armed. 0 if disarmed. */
  64         char name[0];
  65 };
  66
  67 struct tp_probes {
  68         union {
  69 //ust//         struct rcu_head rcu;
  70                 struct list_head list;
  71         } u;
  72         void *probes[0];
  73 };
  74
  75 static inline void *allocate_probes(int count)
  76 {
  77         struct tp_probes *p  = malloc(count * sizeof(void *)
  78                         + sizeof(struct tp_probes));
  79         return p == NULL ? NULL : p->probes;
  80 }
  81
  82 //ust// static void rcu_free_old_probes(struct rcu_head *head)
  83 //ust// {
  84 //ust//         kfree(container_of(head, struct tp_probes, u.rcu));
  85 //ust// }
  86
  87 static inline void release_probes(void *old)
  88 {
  89         if (old) {
  90                 struct tp_probes *tp_probes = container_of(old,
  91                         struct tp_probes, probes[0]);
  92 //ust//         call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
  93                 synchronize_rcu();
  94                 free(tp_probes);
  95         }
  96 }
  97
  98 static void debug_print_probes(struct tracepoint_entry *entry)
  99 {
 100         int i;
 101
 102         if (!tracepoint_debug || !entry->funcs)
 103                 return;
 104
 105         for (i = 0; entry->funcs[i]; i++)
 106                 DBG("Probe %d : %p", i, entry->funcs[i]);
 107 }
 108
 109 static void *
 110 tracepoint_entry_add_probe(struct tracepoint_entry *entry, void *probe)
 111 {
 112         int nr_probes = 0;
 113         void **old, **new;
 114
 115         WARN_ON(!probe);
 116
 117         debug_print_probes(entry);
 118         old = entry->funcs;
 119         if (old) {
 120                 /* (N -> N+1), (N != 0, 1) probes */
 121                 for (nr_probes = 0; old[nr_probes]; nr_probes++)
 122                         if (old[nr_probes] == probe)
 123                                 return ERR_PTR(-EEXIST);
 124         }
 125         /* + 2 : one for new probe, one for NULL func */
 126         new = allocate_probes(nr_probes + 2);
 127         if (new == NULL)
 128                 return ERR_PTR(-ENOMEM);
 129         if (old)
 130                 memcpy(new, old, nr_probes * sizeof(void *));
 131         new[nr_probes] = probe;
 132         new[nr_probes + 1] = NULL;
 133         entry->refcount = nr_probes + 1;
 134         entry->funcs = new;
 135         debug_print_probes(entry);
 136         return old;
 137 }
 138
 139 static void *
 140 tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe)
 141 {
 142         int nr_probes = 0, nr_del = 0, i;
 143         void **old, **new;
 144
 145         old = entry->funcs;
 146
 147         if (!old)
 148                 return ERR_PTR(-ENOENT);
 149
 150         debug_print_probes(entry);
 151         /* (N -> M), (N > 1, M >= 0) probes */
 152         for (nr_probes = 0; old[nr_probes]; nr_probes++) {
 153                 if ((!probe || old[nr_probes] == probe))
 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]; i++)
 171                         if ((probe && old[i] != probe))
 172                                 new[j++] = old[i];
 173                 new[nr_probes - nr_del] = NULL;
 174                 entry->refcount = nr_probes - nr_del;
 175                 entry->funcs = new;
 176         }
 177         debug_print_probes(entry);
 178         return old;
 179 }
 180
 181 /*
 182  * Get tracepoint if the tracepoint is present in the tracepoint hash table.
 183  * Must be called with tracepoints_mutex held.
 184  * Returns NULL if not present.
 185  */
 186 static struct tracepoint_entry *get_tracepoint(const char *name)
 187 {
 188         struct hlist_head *head;
 189         struct hlist_node *node;
 190         struct tracepoint_entry *e;
 191         u32 hash = jhash(name, strlen(name), 0);
 192
 193         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 194         hlist_for_each_entry(e, node, head, hlist) {
 195                 if (!strcmp(name, e->name))
 196                         return e;
 197         }
 198         return NULL;
 199 }
 200
 201 /*
 202  * Add the tracepoint to the tracepoint hash table. Must be called with
 203  * tracepoints_mutex held.
 204  */
 205 static struct tracepoint_entry *add_tracepoint(const char *name)
 206 {
 207         struct hlist_head *head;
 208         struct hlist_node *node;
 209         struct tracepoint_entry *e;
 210         size_t name_len = strlen(name) + 1;
 211         u32 hash = jhash(name, name_len-1, 0);
 212
 213         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 214         hlist_for_each_entry(e, node, head, hlist) {
 215                 if (!strcmp(name, e->name)) {
 216                         DBG("tracepoint %s busy", name);
 217                         return ERR_PTR(-EEXIST);        /* Already there */
 218                 }
 219         }
 220         /*
 221          * Using kmalloc here to allocate a variable length element. Could
 222          * cause some memory fragmentation if overused.
 223          */
 224         e = malloc(sizeof(struct tracepoint_entry) + name_len);
 225         if (!e)
 226                 return ERR_PTR(-ENOMEM);
 227         memcpy(&e->name[0], name, name_len);
 228         e->funcs = NULL;
 229         e->refcount = 0;
 230         hlist_add_head(&e->hlist, head);
 231         return e;
 232 }
 233
 234 /*
 235  * Remove the tracepoint from the tracepoint hash table. Must be called with
 236  * mutex_lock held.
 237  */
 238 static inline void remove_tracepoint(struct tracepoint_entry *e)
 239 {
 240         hlist_del(&e->hlist);
 241         free(e);
 242 }
 243
 244 /*
 245  * Sets the probe callback corresponding to one tracepoint.
 246  */
 247 static void set_tracepoint(struct tracepoint_entry **entry,
 248         struct tracepoint *elem, int active)
 249 {
 250         WARN_ON(strcmp((*entry)->name, elem->name) != 0);
 251
 252         /*
 253          * rcu_assign_pointer has a smp_wmb() which makes sure that the new
 254          * probe callbacks array is consistent before setting a pointer to it.
 255          * This array is referenced by __DO_TRACE from
 256          * include/linux/tracepoints.h. A matching smp_read_barrier_depends()
 257          * is used.
 258          */
 259         rcu_assign_pointer(elem->funcs, (*entry)->funcs);
 260         elem->state__imv = active;
 261 }
 262
 263 /*
 264  * Disable a tracepoint and its probe callback.
 265  * Note: only waiting an RCU period after setting elem->call to the empty
 266  * function insures that the original callback is not used anymore. This insured
 267  * by preempt_disable around the call site.
 268  */
 269 static void disable_tracepoint(struct tracepoint *elem)
 270 {
 271         elem->state__imv = 0;
 272         rcu_assign_pointer(elem->funcs, NULL);
 273 }
 274
 275 /**
 276  * tracepoint_update_probe_range - Update a probe range
 277  * @begin: beginning of the range
 278  * @end: end of the range
 279  *
 280  * Updates the probe callback corresponding to a range of tracepoints.
 281  */
 282 void tracepoint_update_probe_range(struct tracepoint *begin,
 283         struct tracepoint *end)
 284 {
 285         struct tracepoint *iter;
 286         struct tracepoint_entry *mark_entry;
 287
 288         pthread_mutex_lock(&tracepoints_mutex);
 289         for (iter = begin; iter < end; iter++) {
 290                 mark_entry = get_tracepoint(iter->name);
 291                 if (mark_entry) {
 292                         set_tracepoint(&mark_entry, iter,
 293                                         !!mark_entry->refcount);
 294                 } else {
 295                         disable_tracepoint(iter);
 296                 }
 297         }
 298         pthread_mutex_unlock(&tracepoints_mutex);
 299 }
 300
 301 static void lib_update_tracepoints(void)
 302 {
 303         struct tracepoint_lib *lib;
 304
 305 //ust// pthread_mutex_lock(&module_mutex);
 306         list_for_each_entry(lib, &libs, list)
 307                 tracepoint_update_probe_range(lib->tracepoints_start,
 308                                 lib->tracepoints_start + lib->tracepoints_count);
 309 //ust// pthread_mutex_unlock(&module_mutex);
 310 }
 311
 312 /*
 313  * Update probes, removing the faulty probes.
 314  */
 315 static void tracepoint_update_probes(void)
 316 {
 317         /* Core kernel tracepoints */
 318 //ust// tracepoint_update_probe_range(__start___tracepoints,
 319 //ust//         __stop___tracepoints);
 320         /* tracepoints in modules. */
 321         lib_update_tracepoints();
 322         /* Update immediate values */
 323         core_imv_update();
 324 //ust// module_imv_update();
 325 }
 326
 327 static void *tracepoint_add_probe(const char *name, void *probe)
 328 {
 329         struct tracepoint_entry *entry;
 330         void *old;
 331
 332         entry = get_tracepoint(name);
 333         if (!entry) {
 334                 entry = add_tracepoint(name);
 335                 if (IS_ERR(entry))
 336                         return entry;
 337         }
 338         old = tracepoint_entry_add_probe(entry, probe);
 339         if (IS_ERR(old) && !entry->refcount)
 340                 remove_tracepoint(entry);
 341         return old;
 342 }
 343
 344 /**
 345  * tracepoint_probe_register -  Connect a probe to a tracepoint
 346  * @name: tracepoint name
 347  * @probe: probe handler
 348  *
 349  * Returns 0 if ok, error value on error.
 350  * The probe address must at least be aligned on the architecture pointer size.
 351  */
 352 int tracepoint_probe_register(const char *name, void *probe)
 353 {
 354         void *old;
 355
 356         pthread_mutex_lock(&tracepoints_mutex);
 357         old = tracepoint_add_probe(name, probe);
 358         pthread_mutex_unlock(&tracepoints_mutex);
 359         if (IS_ERR(old))
 360                 return PTR_ERR(old);
 361
 362         tracepoint_update_probes();             /* may update entry */
 363         release_probes(old);
 364         return 0;
 365 }
 366 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register);
 367
 368 static void *tracepoint_remove_probe(const char *name, void *probe)
 369 {
 370         struct tracepoint_entry *entry;
 371         void *old;
 372
 373         entry = get_tracepoint(name);
 374         if (!entry)
 375                 return ERR_PTR(-ENOENT);
 376         old = tracepoint_entry_remove_probe(entry, probe);
 377         if (IS_ERR(old))
 378                 return old;
 379         if (!entry->refcount)
 380                 remove_tracepoint(entry);
 381         return old;
 382 }
 383
 384 /**
 385  * tracepoint_probe_unregister -  Disconnect a probe from a tracepoint
 386  * @name: tracepoint name
 387  * @probe: probe function pointer
 388  *
 389  * We do not need to call a synchronize_sched to make sure the probes have
 390  * finished running before doing a module unload, because the module unload
 391  * itself uses stop_machine(), which insures that every preempt disabled section
 392  * have finished.
 393  */
 394 int tracepoint_probe_unregister(const char *name, void *probe)
 395 {
 396         void *old;
 397
 398         pthread_mutex_lock(&tracepoints_mutex);
 399         old = tracepoint_remove_probe(name, probe);
 400         pthread_mutex_unlock(&tracepoints_mutex);
 401         if (IS_ERR(old))
 402                 return PTR_ERR(old);
 403
 404         tracepoint_update_probes();             /* may update entry */
 405         release_probes(old);
 406         return 0;
 407 }
 408 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
 409
 410 static LIST_HEAD(old_probes);
 411 static int need_update;
 412
 413 static void tracepoint_add_old_probes(void *old)
 414 {
 415         need_update = 1;
 416         if (old) {
 417                 struct tp_probes *tp_probes = container_of(old,
 418                         struct tp_probes, probes[0]);
 419                 list_add(&tp_probes->u.list, &old_probes);
 420         }
 421 }
 422
 423 /**
 424  * tracepoint_probe_register_noupdate -  register a probe but not connect
 425  * @name: tracepoint name
 426  * @probe: probe handler
 427  *
 428  * caller must call tracepoint_probe_update_all()
 429  */
 430 int tracepoint_probe_register_noupdate(const char *name, void *probe)
 431 {
 432         void *old;
 433
 434         pthread_mutex_lock(&tracepoints_mutex);
 435         old = tracepoint_add_probe(name, probe);
 436         if (IS_ERR(old)) {
 437                 pthread_mutex_unlock(&tracepoints_mutex);
 438                 return PTR_ERR(old);
 439         }
 440         tracepoint_add_old_probes(old);
 441         pthread_mutex_unlock(&tracepoints_mutex);
 442         return 0;
 443 }
 444 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
 445
 446 /**
 447  * tracepoint_probe_unregister_noupdate -  remove a probe but not disconnect
 448  * @name: tracepoint name
 449  * @probe: probe function pointer
 450  *
 451  * caller must call tracepoint_probe_update_all()
 452  */
 453 int tracepoint_probe_unregister_noupdate(const char *name, void *probe)
 454 {
 455         void *old;
 456
 457         pthread_mutex_lock(&tracepoints_mutex);
 458         old = tracepoint_remove_probe(name, probe);
 459         if (IS_ERR(old)) {
 460                 pthread_mutex_unlock(&tracepoints_mutex);
 461                 return PTR_ERR(old);
 462         }
 463         tracepoint_add_old_probes(old);
 464         pthread_mutex_unlock(&tracepoints_mutex);
 465         return 0;
 466 }
 467 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
 468
 469 /**
 470  * tracepoint_probe_update_all -  update tracepoints
 471  */
 472 void tracepoint_probe_update_all(void)
 473 {
 474         LIST_HEAD(release_probes);
 475         struct tp_probes *pos, *next;
 476
 477         pthread_mutex_lock(&tracepoints_mutex);
 478         if (!need_update) {
 479                 pthread_mutex_unlock(&tracepoints_mutex);
 480                 return;
 481         }
 482         if (!list_empty(&old_probes))
 483                 list_replace_init(&old_probes, &release_probes);
 484         need_update = 0;
 485         pthread_mutex_unlock(&tracepoints_mutex);
 486
 487         tracepoint_update_probes();
 488         list_for_each_entry_safe(pos, next, &release_probes, u.list) {
 489                 list_del(&pos->u.list);
 490 //ust//         call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
 491                 synchronize_rcu();
 492                 free(pos);
 493         }
 494 }
 495 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
 496
 497 /*
 498  * Returns 0 if current not found.
 499  * Returns 1 if current found.
 500  */
 501 int lib_get_iter_tracepoints(struct tracepoint_iter *iter)
 502 {
 503         struct tracepoint_lib *iter_lib;
 504         int found = 0;
 505
 506 //ust// pthread_mutex_lock(&module_mutex);
 507         list_for_each_entry(iter_lib, &libs, list) {
 508                 if (iter_lib < iter->lib)
 509                         continue;
 510                 else if (iter_lib > iter->lib)
 511                         iter->tracepoint = NULL;
 512                 found = tracepoint_get_iter_range(&iter->tracepoint,
 513                         iter_lib->tracepoints_start,
 514                         iter_lib->tracepoints_start + iter_lib->tracepoints_count);
 515                 if (found) {
 516                         iter->lib = iter_lib;
 517                         break;
 518                 }
 519         }
 520 //ust// pthread_mutex_unlock(&module_mutex);
 521         return found;
 522 }
 523
 524 /**
 525  * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
 526  * @tracepoint: current tracepoints (in), next tracepoint (out)
 527  * @begin: beginning of the range
 528  * @end: end of the range
 529  *
 530  * Returns whether a next tracepoint has been found (1) or not (0).
 531  * Will return the first tracepoint in the range if the input tracepoint is
 532  * NULL.
 533  */
 534 int tracepoint_get_iter_range(struct tracepoint **tracepoint,
 535         struct tracepoint *begin, struct tracepoint *end)
 536 {
 537         if (!*tracepoint && begin != end) {
 538                 *tracepoint = begin;
 539                 return 1;
 540         }
 541         if (*tracepoint >= begin && *tracepoint < end)
 542                 return 1;
 543         return 0;
 544 }
 545 //ust// EXPORT_SYMBOL_GPL(tracepoint_get_iter_range);
 546
 547 static void tracepoint_get_iter(struct tracepoint_iter *iter)
 548 {
 549         int found = 0;
 550
 551 //ust// /* Core kernel tracepoints */
 552 //ust// if (!iter->module) {
 553 //ust//         found = tracepoint_get_iter_range(&iter->tracepoint,
 554 //ust//                         __start___tracepoints, __stop___tracepoints);
 555 //ust//         if (found)
 556 //ust//                 goto end;
 557 //ust// }
 558         /* tracepoints in libs. */
 559         found = lib_get_iter_tracepoints(iter);
 560 //ust// end:
 561         if (!found)
 562                 tracepoint_iter_reset(iter);
 563 }
 564
 565 void tracepoint_iter_start(struct tracepoint_iter *iter)
 566 {
 567         tracepoint_get_iter(iter);
 568 }
 569 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_start);
 570
 571 void tracepoint_iter_next(struct tracepoint_iter *iter)
 572 {
 573         iter->tracepoint++;
 574         /*
 575          * iter->tracepoint may be invalid because we blindly incremented it.
 576          * Make sure it is valid by marshalling on the tracepoints, getting the
 577          * tracepoints from following modules if necessary.
 578          */
 579         tracepoint_get_iter(iter);
 580 }
 581 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_next);
 582
 583 void tracepoint_iter_stop(struct tracepoint_iter *iter)
 584 {
 585 }
 586 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_stop);
 587
 588 void tracepoint_iter_reset(struct tracepoint_iter *iter)
 589 {
 590 //ust// iter->module = NULL;
 591         iter->tracepoint = NULL;
 592 }
 593 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_reset);
 594
 595 //ust// #ifdef CONFIG_MODULES
 596
 597 //ust// int tracepoint_module_notify(struct notifier_block *self,
 598 //ust//                              unsigned long val, void *data)
 599 //ust// {
 600 //ust//         struct module *mod = data;
 601 //ust//
 602 //ust//         switch (val) {
 603 //ust//         case MODULE_STATE_COMING:
 604 //ust//                 tracepoint_update_probe_range(mod->tracepoints,
 605 //ust//                         mod->tracepoints + mod->num_tracepoints);
 606 //ust//                 break;
 607 //ust//         case MODULE_STATE_GOING:
 608 //ust//                 tracepoint_update_probe_range(mod->tracepoints,
 609 //ust//                         mod->tracepoints + mod->num_tracepoints);
 610 //ust//                 break;
 611 //ust//         }
 612 //ust//         return 0;
 613 //ust// }
 614
 615 //ust// struct notifier_block tracepoint_module_nb = {
 616 //ust//         .notifier_call = tracepoint_module_notify,
 617 //ust//         .priority = 0,
 618 //ust// };
 619
 620 //ust// static int init_tracepoints(void)
 621 //ust// {
 622 //ust//         return register_module_notifier(&tracepoint_module_nb);
 623 //ust// }
 624 //ust// __initcall(init_tracepoints);
 625
 626 //ust// #endif /* CONFIG_MODULES */
 627
 628 static void (*new_tracepoint_cb)(struct tracepoint *) = NULL;
 629
 630 void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *))
 631 {
 632         new_tracepoint_cb = cb;
 633 }
 634
 635 static void new_tracepoints(struct tracepoint *start, struct tracepoint *end)
 636 {
 637         if(new_tracepoint_cb) {
 638                 struct tracepoint *t;
 639                 for(t=start; t < end; t++) {
 640                         new_tracepoint_cb(t);
 641                 }
 642         }
 643 }
 644
 645 int tracepoint_register_lib(struct tracepoint *tracepoints_start, int tracepoints_count)
 646 {
 647         struct tracepoint_lib *pl;
 648
 649         pl = (struct tracepoint_lib *) malloc(sizeof(struct tracepoint_lib));
 650
 651         pl->tracepoints_start = tracepoints_start;
 652         pl->tracepoints_count = tracepoints_count;
 653
 654         /* FIXME: maybe protect this with its own mutex? */
 655         pthread_mutex_lock(&tracepoints_mutex);
 656         list_add(&pl->list, &libs);
 657         pthread_mutex_unlock(&tracepoints_mutex);
 658
 659         new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count);
 660
 661         /* FIXME: update just the loaded lib */
 662         lib_update_tracepoints();
 663
 664         DBG("just registered a tracepoints section from %p and having %d tracepoints", tracepoints_start, tracepoints_count);
 665
 666         return 0;
 667 }
 668
 669 int tracepoint_unregister_lib(struct tracepoint *tracepoints_start)
 670 {
 671         struct tracepoint_lib *lib;
 672
 673         pthread_mutex_lock(&tracepoints_mutex);
 674
 675         list_for_each_entry(lib, &libs, list) {
 676                 if(lib->tracepoints_start == tracepoints_start) {
 677                         struct tracepoint_lib *lib2free = lib;
 678                         list_del(&lib->list);
 679                         free(lib2free);
 680                         break;
 681                 }
 682         }
 683
 684         pthread_mutex_unlock(&tracepoints_mutex);
 685
 686         return 0;
 687 }