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)
 299                         continue;       /* skip dummy */
 300                 if (!(*iter)->name) {
 301                         disable_tracepoint(*iter);
 302                         continue;
 303                 }
 304                 mark_entry = get_tracepoint((*iter)->name);
 305                 if (mark_entry) {
 306                         set_tracepoint(&mark_entry, *iter,
 307                                         !!mark_entry->refcount);
 308                 } else {
 309                         disable_tracepoint(*iter);
 310                 }
 311         }
 312         pthread_mutex_unlock(&tracepoints_mutex);
 313 }
 314
 315 static void lib_update_tracepoints(void)
 316 {
 317         struct tracepoint_lib *lib;
 318
 319 //ust// pthread_mutex_lock(&module_mutex);
 320         cds_list_for_each_entry(lib, &libs, list)
 321                 tracepoint_update_probe_range(lib->tracepoints_start,
 322                                 lib->tracepoints_start + lib->tracepoints_count);
 323 //ust// pthread_mutex_unlock(&module_mutex);
 324 }
 325
 326 /*
 327  * Update probes, removing the faulty probes.
 328  */
 329 static void tracepoint_update_probes(void)
 330 {
 331         /* Core kernel tracepoints */
 332 //ust// tracepoint_update_probe_range(__start___tracepoints,
 333 //ust//         __stop___tracepoints);
 334         /* tracepoints in modules. */
 335         lib_update_tracepoints();
 336         /* Update immediate values */
 337         core_imv_update();
 338 //ust// module_imv_update();
 339 }
 340
 341 static struct probe *
 342 tracepoint_add_probe(const char *name, void *probe, void *data)
 343 {
 344         struct tracepoint_entry *entry;
 345         struct probe *old;
 346
 347         entry = get_tracepoint(name);
 348         if (!entry) {
 349                 entry = add_tracepoint(name);
 350                 if (IS_ERR(entry))
 351                         return (struct probe *)entry;
 352         }
 353         old = tracepoint_entry_add_probe(entry, probe, data);
 354         if (IS_ERR(old) && !entry->refcount)
 355                 remove_tracepoint(entry);
 356         return old;
 357 }
 358
 359 /**
 360  * tracepoint_probe_register -  Connect a probe to a tracepoint
 361  * @name: tracepoint name
 362  * @probe: probe handler
 363  *
 364  * Returns 0 if ok, error value on error.
 365  * The probe address must at least be aligned on the architecture pointer size.
 366  */
 367 int tracepoint_probe_register(const char *name, void *probe, void *data)
 368 {
 369         void *old;
 370
 371         pthread_mutex_lock(&tracepoints_mutex);
 372         old = tracepoint_add_probe(name, probe, data);
 373         pthread_mutex_unlock(&tracepoints_mutex);
 374         if (IS_ERR(old))
 375                 return PTR_ERR(old);
 376
 377         tracepoint_update_probes();             /* may update entry */
 378         release_probes(old);
 379         return 0;
 380 }
 381 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register);
 382
 383 static void *tracepoint_remove_probe(const char *name, void *probe, void *data)
 384 {
 385         struct tracepoint_entry *entry;
 386         void *old;
 387
 388         entry = get_tracepoint(name);
 389         if (!entry)
 390                 return ERR_PTR(-ENOENT);
 391         old = tracepoint_entry_remove_probe(entry, probe, data);
 392         if (IS_ERR(old))
 393                 return old;
 394         if (!entry->refcount)
 395                 remove_tracepoint(entry);
 396         return old;
 397 }
 398
 399 /**
 400  * tracepoint_probe_unregister -  Disconnect a probe from a tracepoint
 401  * @name: tracepoint name
 402  * @probe: probe function pointer
 403  * @probe: probe data pointer
 404  *
 405  * We do not need to call a synchronize_sched to make sure the probes have
 406  * finished running before doing a module unload, because the module unload
 407  * itself uses stop_machine(), which insures that every preempt disabled section
 408  * have finished.
 409  */
 410 int tracepoint_probe_unregister(const char *name, void *probe, void *data)
 411 {
 412         void *old;
 413
 414         pthread_mutex_lock(&tracepoints_mutex);
 415         old = tracepoint_remove_probe(name, probe, data);
 416         pthread_mutex_unlock(&tracepoints_mutex);
 417         if (IS_ERR(old))
 418                 return PTR_ERR(old);
 419
 420         tracepoint_update_probes();             /* may update entry */
 421         release_probes(old);
 422         return 0;
 423 }
 424 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister);
 425
 426 static CDS_LIST_HEAD(old_probes);
 427 static int need_update;
 428
 429 static void tracepoint_add_old_probes(void *old)
 430 {
 431         need_update = 1;
 432         if (old) {
 433                 struct tp_probes *tp_probes = _ust_container_of(old,
 434                         struct tp_probes, probes[0]);
 435                 cds_list_add(&tp_probes->u.list, &old_probes);
 436         }
 437 }
 438
 439 /**
 440  * tracepoint_probe_register_noupdate -  register a probe but not connect
 441  * @name: tracepoint name
 442  * @probe: probe handler
 443  *
 444  * caller must call tracepoint_probe_update_all()
 445  */
 446 int tracepoint_probe_register_noupdate(const char *name, void *probe,
 447                                        void *data)
 448 {
 449         void *old;
 450
 451         pthread_mutex_lock(&tracepoints_mutex);
 452         old = tracepoint_add_probe(name, probe, data);
 453         if (IS_ERR(old)) {
 454                 pthread_mutex_unlock(&tracepoints_mutex);
 455                 return PTR_ERR(old);
 456         }
 457         tracepoint_add_old_probes(old);
 458         pthread_mutex_unlock(&tracepoints_mutex);
 459         return 0;
 460 }
 461 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
 462
 463 /**
 464  * tracepoint_probe_unregister_noupdate -  remove a probe but not disconnect
 465  * @name: tracepoint name
 466  * @probe: probe function pointer
 467  *
 468  * caller must call tracepoint_probe_update_all()
 469  */
 470 int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
 471                                          void *data)
 472 {
 473         void *old;
 474
 475         pthread_mutex_lock(&tracepoints_mutex);
 476         old = tracepoint_remove_probe(name, probe, data);
 477         if (IS_ERR(old)) {
 478                 pthread_mutex_unlock(&tracepoints_mutex);
 479                 return PTR_ERR(old);
 480         }
 481         tracepoint_add_old_probes(old);
 482         pthread_mutex_unlock(&tracepoints_mutex);
 483         return 0;
 484 }
 485 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
 486
 487 /**
 488  * tracepoint_probe_update_all -  update tracepoints
 489  */
 490 void tracepoint_probe_update_all(void)
 491 {
 492         CDS_LIST_HEAD(release_probes);
 493         struct tp_probes *pos, *next;
 494
 495         pthread_mutex_lock(&tracepoints_mutex);
 496         if (!need_update) {
 497                 pthread_mutex_unlock(&tracepoints_mutex);
 498                 return;
 499         }
 500         if (!cds_list_empty(&old_probes))
 501                 cds_list_replace_init(&old_probes, &release_probes);
 502         need_update = 0;
 503         pthread_mutex_unlock(&tracepoints_mutex);
 504
 505         tracepoint_update_probes();
 506         cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) {
 507                 cds_list_del(&pos->u.list);
 508 //ust//         call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
 509                 synchronize_rcu();
 510                 free(pos);
 511         }
 512 }
 513 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
 514
 515 /*
 516  * Returns 0 if current not found.
 517  * Returns 1 if current found.
 518  */
 519 int lib_get_iter_tracepoints(struct tracepoint_iter *iter)
 520 {
 521         struct tracepoint_lib *iter_lib;
 522         int found = 0;
 523
 524 //ust// pthread_mutex_lock(&module_mutex);
 525         cds_list_for_each_entry(iter_lib, &libs, list) {
 526                 if (iter_lib < iter->lib)
 527                         continue;
 528                 else if (iter_lib > iter->lib)
 529                         iter->tracepoint = NULL;
 530                 found = tracepoint_get_iter_range(&iter->tracepoint,
 531                         iter_lib->tracepoints_start,
 532                         iter_lib->tracepoints_start + iter_lib->tracepoints_count);
 533                 if (found) {
 534                         iter->lib = iter_lib;
 535                         break;
 536                 }
 537         }
 538 //ust// pthread_mutex_unlock(&module_mutex);
 539         return found;
 540 }
 541
 542 /**
 543  * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
 544  * @tracepoint: current tracepoints (in), next tracepoint (out)
 545  * @begin: beginning of the range
 546  * @end: end of the range
 547  *
 548  * Returns whether a next tracepoint has been found (1) or not (0).
 549  * Will return the first tracepoint in the range if the input tracepoint is
 550  * NULL.
 551  */
 552 int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
 553         struct tracepoint * const *begin, struct tracepoint * const *end)
 554 {
 555         if (!*tracepoint && begin != end)
 556                 *tracepoint = begin;
 557         while (*tracepoint >= begin && *tracepoint < end) {
 558                 if (!**tracepoint)
 559                         (*tracepoint)++;        /* skip dummy */
 560                 else
 561                         return 1;
 562         }
 563         return 0;
 564 }
 565 //ust// EXPORT_SYMBOL_GPL(tracepoint_get_iter_range);
 566
 567 static void tracepoint_get_iter(struct tracepoint_iter *iter)
 568 {
 569         int found = 0;
 570
 571 //ust// /* Core kernel tracepoints */
 572 //ust// if (!iter->module) {
 573 //ust//         found = tracepoint_get_iter_range(&iter->tracepoint,
 574 //ust//                         __start___tracepoints, __stop___tracepoints);
 575 //ust//         if (found)
 576 //ust//                 goto end;
 577 //ust// }
 578         /* tracepoints in libs. */
 579         found = lib_get_iter_tracepoints(iter);
 580 //ust// end:
 581         if (!found)
 582                 tracepoint_iter_reset(iter);
 583 }
 584
 585 void tracepoint_iter_start(struct tracepoint_iter *iter)
 586 {
 587         tracepoint_get_iter(iter);
 588 }
 589 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_start);
 590
 591 void tracepoint_iter_next(struct tracepoint_iter *iter)
 592 {
 593         iter->tracepoint++;
 594         /*
 595          * iter->tracepoint may be invalid because we blindly incremented it.
 596          * Make sure it is valid by marshalling on the tracepoints, getting the
 597          * tracepoints from following modules if necessary.
 598          */
 599         tracepoint_get_iter(iter);
 600 }
 601 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_next);
 602
 603 void tracepoint_iter_stop(struct tracepoint_iter *iter)
 604 {
 605 }
 606 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_stop);
 607
 608 void tracepoint_iter_reset(struct tracepoint_iter *iter)
 609 {
 610 //ust// iter->module = NULL;
 611         iter->tracepoint = NULL;
 612 }
 613 //ust// EXPORT_SYMBOL_GPL(tracepoint_iter_reset);
 614
 615 //ust// #ifdef CONFIG_MODULES
 616
 617 //ust// int tracepoint_module_notify(struct notifier_block *self,
 618 //ust//                              unsigned long val, void *data)
 619 //ust// {
 620 //ust//         struct module *mod = data;
 621 //ust//
 622 //ust//         switch (val) {
 623 //ust//         case MODULE_STATE_COMING:
 624 //ust//                 tracepoint_update_probe_range(mod->tracepoints,
 625 //ust//                         mod->tracepoints + mod->num_tracepoints);
 626 //ust//                 break;
 627 //ust//         case MODULE_STATE_GOING:
 628 //ust//                 tracepoint_update_probe_range(mod->tracepoints,
 629 //ust//                         mod->tracepoints + mod->num_tracepoints);
 630 //ust//                 break;
 631 //ust//         }
 632 //ust//         return 0;
 633 //ust// }
 634
 635 //ust// struct notifier_block tracepoint_module_nb = {
 636 //ust//         .notifier_call = tracepoint_module_notify,
 637 //ust//         .priority = 0,
 638 //ust// };
 639
 640 //ust// static int init_tracepoints(void)
 641 //ust// {
 642 //ust//         return register_module_notifier(&tracepoint_module_nb);
 643 //ust// }
 644 //ust// __initcall(init_tracepoints);
 645
 646 //ust// #endif /* CONFIG_MODULES */
 647
 648 static void (*new_tracepoint_cb)(struct tracepoint *) = NULL;
 649
 650 void tracepoint_set_new_tracepoint_cb(void (*cb)(struct tracepoint *))
 651 {
 652         new_tracepoint_cb = cb;
 653 }
 654
 655 static void new_tracepoints(struct tracepoint * const *start, struct tracepoint * const *end)
 656 {
 657         if (new_tracepoint_cb) {
 658                 struct tracepoint * const *t;
 659
 660                 for(t = start; t < end; t++) {
 661                         if (*t)
 662                                 new_tracepoint_cb(*t);
 663                 }
 664         }
 665 }
 666
 667 int tracepoint_register_lib(struct tracepoint * const *tracepoints_start, int tracepoints_count)
 668 {
 669         struct tracepoint_lib *pl, *iter;
 670
 671         pl = (struct tracepoint_lib *) zmalloc(sizeof(struct tracepoint_lib));
 672
 673         pl->tracepoints_start = tracepoints_start;
 674         pl->tracepoints_count = tracepoints_count;
 675
 676         /* FIXME: maybe protect this with its own mutex? */
 677         pthread_mutex_lock(&tracepoints_mutex);
 678         /*
 679          * We sort the libs by struct lib pointer address.
 680          */
 681         cds_list_for_each_entry_reverse(iter, &libs, list) {
 682                 BUG_ON(iter == pl);    /* Should never be in the list twice */
 683                 if (iter < pl) {
 684                         /* We belong to the location right after iter. */
 685                         cds_list_add(&pl->list, &iter->list);
 686                         goto lib_added;
 687                 }
 688         }
 689         /* We should be added at the head of the list */
 690         cds_list_add(&pl->list, &libs);
 691 lib_added:
 692         pthread_mutex_unlock(&tracepoints_mutex);
 693
 694         new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count);
 695
 696         /* FIXME: update just the loaded lib */
 697         lib_update_tracepoints();
 698
 699         /* tracepoints_count - 1: skip dummy */
 700         DBG("just registered a tracepoints section from %p and having %d tracepoints (minus dummy tracepoints)", tracepoints_start, tracepoints_count);
 701
 702         return 0;
 703 }
 704
 705 int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start)
 706 {
 707         struct tracepoint_lib *lib;
 708
 709         pthread_mutex_lock(&tracepoints_mutex);
 710
 711         cds_list_for_each_entry(lib, &libs, list) {
 712                 if (lib->tracepoints_start == tracepoints_start) {
 713                         struct tracepoint_lib *lib2free = lib;
 714                         cds_list_del(&lib->list);
 715                         free(lib2free);
 716                         break;
 717                 }
 718         }
 719
 720         pthread_mutex_unlock(&tracepoints_mutex);
 721
 722         return 0;
 723 }