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 #include <urcu/hlist.h>
  31
  32 //extern struct tracepoint __start___tracepoints[] __attribute__((visibility("hidden")));
  33 //extern struct tracepoint __stop___tracepoints[] __attribute__((visibility("hidden")));
  34
  35 /* Set to 1 to enable tracepoint debug output */
  36 static const int tracepoint_debug;
  37
  38 /* libraries that contain tracepoints (struct tracepoint_lib) */
  39 static CDS_LIST_HEAD(libs);
  40
  41 /*
  42  * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the
  43  * builtin and module tracepoints and the hash table.
  44  */
  45 static DEFINE_MUTEX(tracepoints_mutex);
  46
  47 /*
  48  * Tracepoint hash table, containing the active tracepoints.
  49  * Protected by tracepoints_mutex.
  50  */
  51 #define TRACEPOINT_HASH_BITS 6
  52 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
  53 static struct cds_hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
  54
  55 /*
  56  * Note about RCU :
  57  * It is used to to delay the free of multiple probes array until a quiescent
  58  * state is reached.
  59  * Tracepoint entries modifications are protected by the tracepoints_mutex.
  60  */
  61 struct tracepoint_entry {
  62         struct cds_hlist_node hlist;
  63         struct probe *probes;
  64         int refcount;   /* Number of times armed. 0 if disarmed. */
  65         char name[0];
  66 };
  67
  68 struct tp_probes {
  69         union {
  70 //ust//         struct rcu_head rcu;
  71                 struct cds_list_head list;
  72         } u;
  73         struct probe probes[0];
  74 };
  75
  76 static inline void *allocate_probes(int count)
  77 {
  78         struct tp_probes *p  = zmalloc(count * sizeof(struct probe)
  79                         + sizeof(struct tp_probes));
  80         return p == NULL ? NULL : p->probes;
  81 }
  82
  83 //ust// static void rcu_free_old_probes(struct rcu_head *head)
  84 //ust// {
  85 //ust//         kfree(container_of(head, struct tp_probes, u.rcu));
  86 //ust// }
  87
  88 static inline void release_probes(void *old)
  89 {
  90         if (old) {
  91                 struct tp_probes *tp_probes = _ust_container_of(old,
  92                         struct tp_probes, probes[0]);
  93 //ust//         call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
  94                 synchronize_rcu();
  95                 free(tp_probes);
  96         }
  97 }
  98
  99 static void debug_print_probes(struct tracepoint_entry *entry)
 100 {
 101         int i;
 102
 103         if (!tracepoint_debug || !entry->probes)
 104                 return;
 105
 106         for (i = 0; entry->probes[i].func; i++)
 107                 DBG("Probe %d : %p", i, entry->probes[i].func);
 108 }
 109
 110 static void *
 111 tracepoint_entry_add_probe(struct tracepoint_entry *entry,
 112                            void *probe, void *data)
 113 {
 114         int nr_probes = 0;
 115         struct probe *old, *new;
 116
 117         WARN_ON(!probe);
 118
 119         debug_print_probes(entry);
 120         old = entry->probes;
 121         if (old) {
 122                 /* (N -> N+1), (N != 0, 1) probes */
 123                 for (nr_probes = 0; old[nr_probes].func; nr_probes++)
 124                         if (old[nr_probes].func == probe &&
 125                             old[nr_probes].data == data)
 126                                 return ERR_PTR(-EEXIST);
 127         }
 128         /* + 2 : one for new probe, one for NULL func */
 129         new = allocate_probes(nr_probes + 2);
 130         if (new == NULL)
 131                 return ERR_PTR(-ENOMEM);
 132         if (old)
 133                 memcpy(new, old, nr_probes * sizeof(struct probe));
 134         new[nr_probes].func = probe;
 135         new[nr_probes].data = data;
 136         new[nr_probes + 1].func = NULL;
 137         entry->refcount = nr_probes + 1;
 138         entry->probes = new;
 139         debug_print_probes(entry);
 140         return old;
 141 }
 142
 143 static void *
 144 tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe,
 145                               void *data)
 146 {
 147         int nr_probes = 0, nr_del = 0, i;
 148         struct probe *old, *new;
 149
 150         old = entry->probes;
 151
 152         if (!old)
 153                 return ERR_PTR(-ENOENT);
 154
 155         debug_print_probes(entry);
 156         /* (N -> M), (N > 1, M >= 0) probes */
 157         for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
 158                 if (!probe ||
 159                      (old[nr_probes].func == probe &&
 160                      old[nr_probes].data == data))
 161                         nr_del++;
 162         }
 163
 164         if (nr_probes - nr_del == 0) {
 165                 /* N -> 0, (N > 1) */
 166                 entry->probes = NULL;
 167                 entry->refcount = 0;
 168                 debug_print_probes(entry);
 169                 return old;
 170         } else {
 171                 int j = 0;
 172                 /* N -> M, (N > 1, M > 0) */
 173                 /* + 1 for NULL */
 174                 new = allocate_probes(nr_probes - nr_del + 1);
 175                 if (new == NULL)
 176                         return ERR_PTR(-ENOMEM);
 177                 for (i = 0; old[i].func; i++)
 178                         if (probe &&
 179                             (old[i].func != probe || old[i].data != data))
 180                                 new[j++] = old[i];
 181                 new[nr_probes - nr_del].func = NULL;
 182                 entry->refcount = nr_probes - nr_del;
 183                 entry->probes = new;
 184         }
 185         debug_print_probes(entry);
 186         return old;
 187 }
 188
 189 /*
 190  * Get tracepoint if the tracepoint is present in the tracepoint hash table.
 191  * Must be called with tracepoints_mutex held.
 192  * Returns NULL if not present.
 193  */
 194 static struct tracepoint_entry *get_tracepoint(const char *name)
 195 {
 196         struct cds_hlist_head *head;
 197         struct cds_hlist_node *node;
 198         struct tracepoint_entry *e;
 199         u32 hash = jhash(name, strlen(name), 0);
 200
 201         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 202         cds_hlist_for_each_entry(e, node, head, hlist) {
 203                 if (!strcmp(name, e->name))
 204                         return e;
 205         }
 206         return NULL;
 207 }
 208
 209 /*
 210  * Add the tracepoint to the tracepoint hash table. Must be called with
 211  * tracepoints_mutex held.
 212  */
 213 static struct tracepoint_entry *add_tracepoint(const char *name)
 214 {
 215         struct cds_hlist_head *head;
 216         struct cds_hlist_node *node;
 217         struct tracepoint_entry *e;
 218         size_t name_len = strlen(name) + 1;
 219         u32 hash = jhash(name, name_len-1, 0);
 220
 221         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 222         cds_hlist_for_each_entry(e, node, head, hlist) {
 223                 if (!strcmp(name, e->name)) {
 224                         DBG("tracepoint %s busy", name);
 225                         return ERR_PTR(-EEXIST);        /* Already there */
 226                 }
 227         }
 228         /*
 229          * Using zmalloc here to allocate a variable length element. Could
 230          * cause some memory fragmentation if overused.
 231          */
 232         e = zmalloc(sizeof(struct tracepoint_entry) + name_len);
 233         if (!e)
 234                 return ERR_PTR(-ENOMEM);
 235         memcpy(&e->name[0], name, name_len);
 236         e->probes = NULL;
 237         e->refcount = 0;
 238         cds_hlist_add_head(&e->hlist, head);
 239         return e;
 240 }
 241
 242 /*
 243  * Remove the tracepoint from the tracepoint hash table. Must be called with
 244  * mutex_lock held.
 245  */
 246 static inline void remove_tracepoint(struct tracepoint_entry *e)
 247 {
 248         cds_hlist_del(&e->hlist);
 249         free(e);
 250 }
 251
 252 /*
 253  * Sets the probe callback corresponding to one tracepoint.
 254  */
 255 static void set_tracepoint(struct tracepoint_entry **entry,
 256         struct tracepoint *elem, int active)
 257 {
 258         WARN_ON(strcmp((*entry)->name, elem->name) != 0);
 259
 260         /*
 261          * rcu_assign_pointer has a cmm_smp_wmb() which makes sure that the new
 262          * probe callbacks array is consistent before setting a pointer to it.
 263          * This array is referenced by __DO_TRACE from
 264          * include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends()
 265          * is used.
 266          */
 267         rcu_assign_pointer(elem->probes, (*entry)->probes);
 268         elem->state__imv = active;
 269 }
 270
 271 /*
 272  * Disable a tracepoint and its probe callback.
 273  * Note: only waiting an RCU period after setting elem->call to the empty
 274  * function insures that the original callback is not used anymore. This insured
 275  * by preempt_disable around the call site.
 276  */
 277 static void disable_tracepoint(struct tracepoint *elem)
 278 {
 279         elem->state__imv = 0;
 280         rcu_assign_pointer(elem->probes, NULL);
 281 }
 282
 283 /**
 284  * tracepoint_update_probe_range - Update a probe range
 285  * @begin: beginning of the range
 286  * @end: end of the range
 287  *
 288  * Updates the probe callback corresponding to a range of tracepoints.
 289  */
 290 void tracepoint_update_probe_range(struct tracepoint * const *begin,
 291                                    struct tracepoint * const *end)
 292 {
 293         struct tracepoint * const *iter;
 294         struct tracepoint_entry *mark_entry;
 295
 296         pthread_mutex_lock(&tracepoints_mutex);
 297         for (iter = begin; iter < end; iter++) {
 298                 if (!(*iter)->name) {
 299                         disable_tracepoint(*iter);
 300                         continue;
 301                 }
 302                 mark_entry = get_tracepoint((*iter)->name);
 303                 if (mark_entry) {
 304                         set_tracepoint(&mark_entry, *iter,
 305                                         !!mark_entry->refcount);
 306                 } else {
 307                         disable_tracepoint(*iter);
 308                 }
 309         }
 310         pthread_mutex_unlock(&tracepoints_mutex);
 311 }
 312
 313 static void lib_update_tracepoints(void)
 314 {
 315         struct tracepoint_lib *lib;
 316
 317 //ust// pthread_mutex_lock(&module_mutex);
 318         cds_list_for_each_entry(lib, &libs, list)
 319                 tracepoint_update_probe_range(lib->tracepoints_start,
 320                                 lib->tracepoints_start + lib->tracepoints_count);
 321 //ust// pthread_mutex_unlock(&module_mutex);
 322 }
 323
 324 /*
 325  * Update probes, removing the faulty probes.
 326  */
 327 static void tracepoint_update_probes(void)
 328 {
 329         /* Core kernel tracepoints */
 330 //ust// tracepoint_update_probe_range(__start___tracepoints,
 331 //ust//         __stop___tracepoints);
 332         /* tracepoints in modules. */
 333         lib_update_tracepoints();
 334         /* Update immediate values */
 335         core_imv_update();
 336 //ust// module_imv_update();
 337 }
 338
 339 static struct probe *
 340 tracepoint_add_probe(const char *name, void *probe, void *data)
 341 {
 342         struct tracepoint_entry *entry;
 343         struct probe *old;
 344
 345         entry = get_tracepoint(name);
 346         if (!entry) {
 347                 entry = add_tracepoint(name);
 348                 if (IS_ERR(entry))
 349                         return (struct probe *)entry;
 350         }
 351         old = tracepoint_entry_add_probe(entry, probe, data);
 352         if (IS_ERR(old) && !entry->refcount)
 353                 remove_tracepoint(entry);
 354         return old;
 355 }
 356
 357 /**
 358  * tracepoint_probe_register -  Connect a probe to a tracepoint
 359  * @name: tracepoint name
 360  * @probe: probe handler
 361  *
 362  * Returns 0 if ok, error value on error.
 363  * The probe address must at least be aligned on the architecture pointer size.
 364  */
 365 int tracepoint_probe_register(const char *name, void *probe, void *data)
 366 {
 367         void *old;
 368
 369         pthread_mutex_lock(&tracepoints_mutex);
 370         old = tracepoint_add_probe(name, probe, data);
 371         pthread_mutex_unlock(&tracepoints_mutex);
 372         if (IS_ERR(old))
 373                 return PTR_ERR(old);
 374
 375         tracepoint_update_probes();             /* may update entry */
 376         release_probes(old);
 377         return 0;
 378 }
 379 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register);
 380
 381 static void *tracepoint_remove_probe(const char *name, void *probe, void *data)
 382 {
 383         struct tracepoint_entry *entry;
 384         void *old;
 385
 386         entry = get_tracepoint(name);
 387         if (!entry)
 388                 return ERR_PTR(-ENOENT);
 389         old = tracepoint_entry_remove_probe(entry, probe, data);
 390         if (IS_ERR(old))
 391                 return old;
 392         if (!entry->refcount)
 393                 remove_tracepoint(entry);
 394         return old;
 395 }
 396
 397 /**
 398  * tracepoint_probe_unregister -  Disconnect a probe from a tracepoint
 399  * @name: tracepoint name
 400  * @probe: probe function pointer
 401  * @probe: probe data pointer
 402  *
 403  * We do not need to call a synchronize_sched to make sure the probes have
 404  * finished running before doing a module unload, because the module unload
 405  * itself uses stop_machine(), which insures that every preempt disabled section
 406  * have finished.
 407  */
 408 int tracepoint_probe_unregister(const char *name, void *probe, void *data)
 409 {
 410         void *old;
 411
 412         pthread_mutex_lock(&tracepoints_mutex);
 413         old = tracepoint_remove_probe(name, probe, data);
 414         pthread_mutex_unlock(&tracepoints_mutex);
 415         if (IS_ERR(old))
 416                 return PTR_ERR(old);
 417
 418         tracepoint_update_probes();             /* may update entry */
 419         release_probes(old);
 420         return 0;
 421 }
 422 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
 423
 424 static CDS_LIST_HEAD(old_probes);
 425 static int need_update;
 426
 427 static void tracepoint_add_old_probes(void *old)
 428 {
 429         need_update = 1;
 430         if (old) {
 431                 struct tp_probes *tp_probes = _ust_container_of(old,
 432                         struct tp_probes, probes[0]);
 433                 cds_list_add(&tp_probes->u.list, &old_probes);
 434         }
 435 }
 436
 437 /**
 438  * tracepoint_probe_register_noupdate -  register a probe but not connect
 439  * @name: tracepoint name
 440  * @probe: probe handler
 441  *
 442  * caller must call tracepoint_probe_update_all()
 443  */
 444 int tracepoint_probe_register_noupdate(const char *name, void *probe,
 445                                        void *data)
 446 {
 447         void *old;
 448
 449         pthread_mutex_lock(&tracepoints_mutex);
 450         old = tracepoint_add_probe(name, probe, data);
 451         if (IS_ERR(old)) {
 452                 pthread_mutex_unlock(&tracepoints_mutex);
 453                 return PTR_ERR(old);
 454         }
 455         tracepoint_add_old_probes(old);
 456         pthread_mutex_unlock(&tracepoints_mutex);
 457         return 0;
 458 }
 459 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
 460
 461 /**
 462  * tracepoint_probe_unregister_noupdate -  remove a probe but not disconnect
 463  * @name: tracepoint name
 464  * @probe: probe function pointer
 465  *
 466  * caller must call tracepoint_probe_update_all()
 467  */
 468 int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
 469                                          void *data)
 470 {
 471         void *old;
 472
 473         pthread_mutex_lock(&tracepoints_mutex);
 474         old = tracepoint_remove_probe(name, probe, data);
 475         if (IS_ERR(old)) {
 476                 pthread_mutex_unlock(&tracepoints_mutex);
 477                 return PTR_ERR(old);
 478         }
 479         tracepoint_add_old_probes(old);
 480         pthread_mutex_unlock(&tracepoints_mutex);
 481         return 0;
 482 }
 483 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
 484
 485 /**
 486  * tracepoint_probe_update_all -  update tracepoints
 487  */
 488 void tracepoint_probe_update_all(void)
 489 {
 490         CDS_LIST_HEAD(release_probes);
 491         struct tp_probes *pos, *next;
 492
 493         pthread_mutex_lock(&tracepoints_mutex);
 494         if (!need_update) {
 495                 pthread_mutex_unlock(&tracepoints_mutex);
 496                 return;
 497         }
 498         if (!cds_list_empty(&old_probes))
 499                 cds_list_replace_init(&old_probes, &release_probes);
 500         need_update = 0;
 501         pthread_mutex_unlock(&tracepoints_mutex);
 502
 503         tracepoint_update_probes();
 504         cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) {
 505                 cds_list_del(&pos->u.list);
 506 //ust//         call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
 507                 synchronize_rcu();
 508                 free(pos);
 509         }
 510 }
 511 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
 512
 513 /*
 514  * Returns 0 if current not found.
 515  * Returns 1 if current found.
 516  */
 517 int lib_get_iter_tracepoints(struct tracepoint_iter *iter)
 518 {
 519         struct tracepoint_lib *iter_lib;
 520         int found = 0;
 521
 522 //ust// pthread_mutex_lock(&module_mutex);
 523         cds_list_for_each_entry(iter_lib, &libs, list) {
 524                 if (iter_lib < iter->lib)
 525                         continue;
 526                 else if (iter_lib > iter->lib)
 527                         iter->tracepoint = NULL;
 528                 found = tracepoint_get_iter_range(&iter->tracepoint,
 529                         iter_lib->tracepoints_start,
 530                         iter_lib->tracepoints_start + iter_lib->tracepoints_count);
 531                 if (found) {
 532                         iter->lib = iter_lib;
 533                         break;
 534                 }
 535         }
 536 //ust// pthread_mutex_unlock(&module_mutex);
 537         return found;
 538 }
 539
 540 /**
 541  * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
 542  * @tracepoint: current tracepoints (in), next tracepoint (out)
 543  * @begin: beginning of the range
 544  * @end: end of the range
 545  *
 546  * Returns whether a next tracepoint has been found (1) or not (0).
 547  * Will return the first tracepoint in the range if the input tracepoint is
 548  * NULL.
 549  */
 550 int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
 551         struct tracepoint * const *begin, struct tracepoint * const *end)
 552 {
 553         if (!*tracepoint && begin != end) {
 554                 *tracepoint = begin;
 555                 return 1;
 556         }
 557         if (*tracepoint >= begin && *tracepoint < end)
 558                 return 1;
 559         return 0;
 560 }
 561 //ust// EXPORT_SYMBOL_GPL(tracepoint_get_iter_range);
 562
 563 static void tracepoint_get_iter(struct tracepoint_iter *iter)
 564 {
 565         int found = 0;
 566
 567 //ust// /* Core kernel tracepoints */
 568 //ust// if (!iter->module) {
 569 //ust//         found = tracepoint_get_iter_range(&iter->tracepoint,
 570 //ust//                         __start___tracepoints, __stop___tracepoints);
 571 //ust//         if (found)
 572 //ust//                 goto end;
 573 //ust// }
 574         /* tracepoints in libs. */
 575         found = lib_get_iter_tracepoints(iter);
 576 //ust// end:
 577         if (!found)
 578                 tracepoint_iter_reset(iter);
 579 }
 580
 581 void tracepoint_iter_start(struct tracepoint_iter *iter)
 582 {
 583         tracepoint_get_iter(iter);
 584 }
 585 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_start);
 586
 587 void tracepoint_iter_next(struct tracepoint_iter *iter)
 588 {
 589         iter->tracepoint++;
 590         /*
 591          * iter->tracepoint may be invalid because we blindly incremented it.
 592          * Make sure it is valid by marshalling on the tracepoints, getting the
 593          * tracepoints from following modules if necessary.
 594          */
 595         tracepoint_get_iter(iter);
 596 }
 597 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_next);
 598
 599 void tracepoint_iter_stop(struct tracepoint_iter *iter)
 600 {
 601 }
 602 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_stop);
 603
 604 void tracepoint_iter_reset(struct tracepoint_iter *iter)
 605 {
 606 //ust// iter->module = NULL;
 607         iter->tracepoint = NULL;
 608 }
 609 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_reset);
 610
 611 //ust// #ifdef CONFIG_MODULES
 612
 613 //ust// int tracepoint_module_notify(struct notifier_block *self,
 614 //ust//                              unsigned long val, void *data)
 615 //ust// {
 616 //ust//         struct module *mod = data;
 617 //ust//
 618 //ust//         switch (val) {
 619 //ust//         case MODULE_STATE_COMING:
 620 //ust//                 tracepoint_update_probe_range(mod->tracepoints,
 621 //ust//                         mod->tracepoints + mod->num_tracepoints);
 622 //ust//                 break;
 623 //ust//         case MODULE_STATE_GOING:
 624 //ust//                 tracepoint_update_probe_range(mod->tracepoints,
 625 //ust//                         mod->tracepoints + mod->num_tracepoints);
 626 //ust//                 break;
 627 //ust//         }
 628 //ust//         return 0;
 629 //ust// }
 630
 631 //ust// struct notifier_block tracepoint_module_nb = {
 632 //ust//         .notifier_call = tracepoint_module_notify,
 633 //ust//         .priority = 0,
 634 //ust// };
 635
 636 //ust// static int init_tracepoints(void)
 637 //ust// {
 638 //ust//         return register_module_notifier(&tracepoint_module_nb);
 639 //ust// }
 640 //ust// __initcall(init_tracepoints);
 641
 642 //ust// #endif /* CONFIG_MODULES */
 643
 644 static void (*new_tracepoint_cb)(struct tracepoint *) = NULL;
 645
 646 void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *))
 647 {
 648         new_tracepoint_cb = cb;
 649 }
 650
 651 static void new_tracepoints(struct tracepoint * const *start, struct tracepoint * const *end)
 652 {
 653         if (new_tracepoint_cb) {
 654                 struct tracepoint * const *t;
 655                 for(t=start; t < end; t++) {
 656                         new_tracepoint_cb(*t);
 657                 }
 658         }
 659 }
 660
 661 int tracepoint_register_lib(struct tracepoint * const *tracepoints_start, int tracepoints_count)
 662 {
 663         struct tracepoint_lib *pl;
 664
 665         pl = (struct tracepoint_lib *) zmalloc(sizeof(struct tracepoint_lib));
 666
 667         pl->tracepoints_start = tracepoints_start;
 668         pl->tracepoints_count = tracepoints_count;
 669
 670         /* FIXME: maybe protect this with its own mutex? */
 671         pthread_mutex_lock(&tracepoints_mutex);
 672         cds_list_add(&pl->list, &libs);
 673         pthread_mutex_unlock(&tracepoints_mutex);
 674
 675         new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count);
 676
 677         /* FIXME: update just the loaded lib */
 678         lib_update_tracepoints();
 679
 680         DBG("just registered a tracepoints section from %p and having %d tracepoints", tracepoints_start, tracepoints_count);
 681
 682         return 0;
 683 }
 684
 685 int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start)
 686 {
 687         struct tracepoint_lib *lib;
 688
 689         pthread_mutex_lock(&tracepoints_mutex);
 690
 691         cds_list_for_each_entry(lib, &libs, list) {
 692                 if (lib->tracepoints_start == tracepoints_start) {
 693                         struct tracepoint_lib *lib2free = lib;
 694                         cds_list_del(&lib->list);
 695                         free(lib2free);
 696                         break;
 697                 }
 698         }
 699
 700         pthread_mutex_unlock(&tracepoints_mutex);
 701
 702         return 0;
 703 }