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;
   8  * version 2.1 of the License.
   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 #define _LGPL_SOURCE
  23 #include <errno.h>
  24 #include <ust/tracepoint.h>
  25 #include <ust/tracepoint-internal.h>
  26 #include <ust/core.h>
  27 #include <ust/kcompat/kcompat.h>
  28 #include <urcu-bp.h>
  29 #include <urcu/hlist.h>
  30
  31 #include "usterr_signal_safe.h"
  32
  33 //extern struct tracepoint __start___tracepoints[] __attribute__((visibility("hidden")));
  34 //extern struct tracepoint __stop___tracepoints[] __attribute__((visibility("hidden")));
  35
  36 /* Set to 1 to enable tracepoint debug output */
  37 static const int tracepoint_debug;
  38
  39 /* libraries that contain tracepoints (struct tracepoint_lib) */
  40 static CDS_LIST_HEAD(libs);
  41
  42 /*
  43  * tracepoints_mutex nests inside module_mutex. Tracepoints mutex protects the
  44  * builtin and module tracepoints and the hash table.
  45  */
  46 static DEFINE_MUTEX(tracepoints_mutex);
  47
  48 /*
  49  * Tracepoint hash table, containing the active tracepoints.
  50  * Protected by tracepoints_mutex.
  51  */
  52 #define TRACEPOINT_HASH_BITS 6
  53 #define TRACEPOINT_TABLE_SIZE (1 << TRACEPOINT_HASH_BITS)
  54 static struct cds_hlist_head tracepoint_table[TRACEPOINT_TABLE_SIZE];
  55
  56 /*
  57  * Note about RCU :
  58  * It is used to to delay the free of multiple probes array until a quiescent
  59  * state is reached.
  60  * Tracepoint entries modifications are protected by the tracepoints_mutex.
  61  */
  62 struct tracepoint_entry {
  63         struct cds_hlist_node hlist;
  64         struct tracepoint_probe *probes;
  65         int refcount;   /* Number of times armed. 0 if disarmed. */
  66         char name[0];
  67 };
  68
  69 struct tp_probes {
  70         union {
  71 //ust//         struct rcu_head rcu;
  72                 struct cds_list_head list;
  73         } u;
  74         struct tracepoint_probe probes[0];
  75 };
  76
  77 static inline void *allocate_probes(int count)
  78 {
  79         struct tp_probes *p  = zmalloc(count * sizeof(struct tracepoint_probe)
  80                         + sizeof(struct tp_probes));
  81         return p == NULL ? NULL : p->probes;
  82 }
  83
  84 //ust// static void rcu_free_old_probes(struct rcu_head *head)
  85 //ust// {
  86 //ust//         kfree(container_of(head, struct tp_probes, u.rcu));
  87 //ust// }
  88
  89 static inline void release_probes(void *old)
  90 {
  91         if (old) {
  92                 struct tp_probes *tp_probes = _ust_container_of(old,
  93                         struct tp_probes, probes[0]);
  94 //ust//         call_rcu_sched(&tp_probes->u.rcu, rcu_free_old_probes);
  95                 synchronize_rcu();
  96                 free(tp_probes);
  97         }
  98 }
  99
 100 static void debug_print_probes(struct tracepoint_entry *entry)
 101 {
 102         int i;
 103
 104         if (!tracepoint_debug || !entry->probes)
 105                 return;
 106
 107         for (i = 0; entry->probes[i].func; i++)
 108                 DBG("Probe %d : %p", i, entry->probes[i].func);
 109 }
 110
 111 static void *
 112 tracepoint_entry_add_probe(struct tracepoint_entry *entry,
 113                            void *probe, void *data)
 114 {
 115         int nr_probes = 0;
 116         struct tracepoint_probe *old, *new;
 117
 118         WARN_ON(!probe);
 119
 120         debug_print_probes(entry);
 121         old = entry->probes;
 122         if (old) {
 123                 /* (N -> N+1), (N != 0, 1) probes */
 124                 for (nr_probes = 0; old[nr_probes].func; nr_probes++)
 125                         if (old[nr_probes].func == probe &&
 126                             old[nr_probes].data == data)
 127                                 return ERR_PTR(-EEXIST);
 128         }
 129         /* + 2 : one for new probe, one for NULL func */
 130         new = allocate_probes(nr_probes + 2);
 131         if (new == NULL)
 132                 return ERR_PTR(-ENOMEM);
 133         if (old)
 134                 memcpy(new, old, nr_probes * sizeof(struct tracepoint_probe));
 135         new[nr_probes].func = probe;
 136         new[nr_probes].data = data;
 137         new[nr_probes + 1].func = NULL;
 138         entry->refcount = nr_probes + 1;
 139         entry->probes = new;
 140         debug_print_probes(entry);
 141         return old;
 142 }
 143
 144 static void *
 145 tracepoint_entry_remove_probe(struct tracepoint_entry *entry, void *probe,
 146                               void *data)
 147 {
 148         int nr_probes = 0, nr_del = 0, i;
 149         struct tracepoint_probe *old, *new;
 150
 151         old = entry->probes;
 152
 153         if (!old)
 154                 return ERR_PTR(-ENOENT);
 155
 156         debug_print_probes(entry);
 157         /* (N -> M), (N > 1, M >= 0) probes */
 158         for (nr_probes = 0; old[nr_probes].func; nr_probes++) {
 159                 if (!probe ||
 160                      (old[nr_probes].func == probe &&
 161                      old[nr_probes].data == data))
 162                         nr_del++;
 163         }
 164
 165         if (nr_probes - nr_del == 0) {
 166                 /* N -> 0, (N > 1) */
 167                 entry->probes = NULL;
 168                 entry->refcount = 0;
 169                 debug_print_probes(entry);
 170                 return old;
 171         } else {
 172                 int j = 0;
 173                 /* N -> M, (N > 1, M > 0) */
 174                 /* + 1 for NULL */
 175                 new = allocate_probes(nr_probes - nr_del + 1);
 176                 if (new == NULL)
 177                         return ERR_PTR(-ENOMEM);
 178                 for (i = 0; old[i].func; i++)
 179                         if (probe &&
 180                             (old[i].func != probe || old[i].data != data))
 181                                 new[j++] = old[i];
 182                 new[nr_probes - nr_del].func = NULL;
 183                 entry->refcount = nr_probes - nr_del;
 184                 entry->probes = new;
 185         }
 186         debug_print_probes(entry);
 187         return old;
 188 }
 189
 190 /*
 191  * Get tracepoint if the tracepoint is present in the tracepoint hash table.
 192  * Must be called with tracepoints_mutex held.
 193  * Returns NULL if not present.
 194  */
 195 static struct tracepoint_entry *get_tracepoint(const char *name)
 196 {
 197         struct cds_hlist_head *head;
 198         struct cds_hlist_node *node;
 199         struct tracepoint_entry *e;
 200         u32 hash = jhash(name, strlen(name), 0);
 201
 202         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 203         cds_hlist_for_each_entry(e, node, head, hlist) {
 204                 if (!strcmp(name, e->name))
 205                         return e;
 206         }
 207         return NULL;
 208 }
 209
 210 /*
 211  * Add the tracepoint to the tracepoint hash table. Must be called with
 212  * tracepoints_mutex held.
 213  */
 214 static struct tracepoint_entry *add_tracepoint(const char *name)
 215 {
 216         struct cds_hlist_head *head;
 217         struct cds_hlist_node *node;
 218         struct tracepoint_entry *e;
 219         size_t name_len = strlen(name) + 1;
 220         u32 hash = jhash(name, name_len-1, 0);
 221
 222         head = &tracepoint_table[hash & (TRACEPOINT_TABLE_SIZE - 1)];
 223         cds_hlist_for_each_entry(e, node, head, hlist) {
 224                 if (!strcmp(name, e->name)) {
 225                         DBG("tracepoint %s busy", name);
 226                         return ERR_PTR(-EEXIST);        /* Already there */
 227                 }
 228         }
 229         /*
 230          * Using zmalloc here to allocate a variable length element. Could
 231          * cause some memory fragmentation if overused.
 232          */
 233         e = zmalloc(sizeof(struct tracepoint_entry) + name_len);
 234         if (!e)
 235                 return ERR_PTR(-ENOMEM);
 236         memcpy(&e->name[0], name, name_len);
 237         e->probes = NULL;
 238         e->refcount = 0;
 239         cds_hlist_add_head(&e->hlist, head);
 240         return e;
 241 }
 242
 243 /*
 244  * Remove the tracepoint from the tracepoint hash table. Must be called with
 245  * mutex_lock held.
 246  */
 247 static inline void remove_tracepoint(struct tracepoint_entry *e)
 248 {
 249         cds_hlist_del(&e->hlist);
 250         free(e);
 251 }
 252
 253 /*
 254  * Sets the probe callback corresponding to one tracepoint.
 255  */
 256 static void set_tracepoint(struct tracepoint_entry **entry,
 257         struct tracepoint *elem, int active)
 258 {
 259         WARN_ON(strcmp((*entry)->name, elem->name) != 0);
 260
 261         /*
 262          * rcu_assign_pointer has a cmm_smp_wmb() which makes sure that the new
 263          * probe callbacks array is consistent before setting a pointer to it.
 264          * This array is referenced by __DO_TRACE from
 265          * include/linux/tracepoints.h. A matching cmm_smp_read_barrier_depends()
 266          * is used.
 267          */
 268         rcu_assign_pointer(elem->probes, (*entry)->probes);
 269         elem->state = active;
 270 }
 271
 272 /*
 273  * Disable a tracepoint and its probe callback.
 274  * Note: only waiting an RCU period after setting elem->call to the empty
 275  * function insures that the original callback is not used anymore. This insured
 276  * by preempt_disable around the call site.
 277  */
 278 static void disable_tracepoint(struct tracepoint *elem)
 279 {
 280         elem->state = 0;
 281         rcu_assign_pointer(elem->probes, NULL);
 282 }
 283
 284 /**
 285  * tracepoint_update_probe_range - Update a probe range
 286  * @begin: beginning of the range
 287  * @end: end of the range
 288  *
 289  * Updates the probe callback corresponding to a range of tracepoints.
 290  */
 291 void tracepoint_update_probe_range(struct tracepoint * const *begin,
 292                                    struct tracepoint * const *end)
 293 {
 294         struct tracepoint * const *iter;
 295         struct tracepoint_entry *mark_entry;
 296
 297         pthread_mutex_lock(&tracepoints_mutex);
 298         for (iter = begin; iter < end; iter++) {
 299                 if (!*iter)
 300                         continue;       /* skip dummy */
 301                 if (!(*iter)->name) {
 302                         disable_tracepoint(*iter);
 303                         continue;
 304                 }
 305                 mark_entry = get_tracepoint((*iter)->name);
 306                 if (mark_entry) {
 307                         set_tracepoint(&mark_entry, *iter,
 308                                         !!mark_entry->refcount);
 309                 } else {
 310                         disable_tracepoint(*iter);
 311                 }
 312         }
 313         pthread_mutex_unlock(&tracepoints_mutex);
 314 }
 315
 316 static void lib_update_tracepoints(void)
 317 {
 318         struct tracepoint_lib *lib;
 319
 320 //ust// pthread_mutex_lock(&module_mutex);
 321         cds_list_for_each_entry(lib, &libs, list)
 322                 tracepoint_update_probe_range(lib->tracepoints_start,
 323                                 lib->tracepoints_start + lib->tracepoints_count);
 324 //ust// pthread_mutex_unlock(&module_mutex);
 325 }
 326
 327 /*
 328  * Update probes, removing the faulty probes.
 329  */
 330 static void tracepoint_update_probes(void)
 331 {
 332         /* Core kernel tracepoints */
 333 //ust// tracepoint_update_probe_range(__start___tracepoints,
 334 //ust//         __stop___tracepoints);
 335         /* tracepoints in modules. */
 336         lib_update_tracepoints();
 337 }
 338
 339 static struct tracepoint_probe *
 340 tracepoint_add_probe(const char *name, void *probe, void *data)
 341 {
 342         struct tracepoint_entry *entry;
 343         struct tracepoint_probe *old;
 344
 345         entry = get_tracepoint(name);
 346         if (!entry) {
 347                 entry = add_tracepoint(name);
 348                 if (IS_ERR(entry))
 349                         return (struct tracepoint_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
 380 static void *tracepoint_remove_probe(const char *name, void *probe, void *data)
 381 {
 382         struct tracepoint_entry *entry;
 383         void *old;
 384
 385         entry = get_tracepoint(name);
 386         if (!entry)
 387                 return ERR_PTR(-ENOENT);
 388         old = tracepoint_entry_remove_probe(entry, probe, data);
 389         if (IS_ERR(old))
 390                 return old;
 391         if (!entry->refcount)
 392                 remove_tracepoint(entry);
 393         return old;
 394 }
 395
 396 /**
 397  * tracepoint_probe_unregister -  Disconnect a probe from a tracepoint
 398  * @name: tracepoint name
 399  * @probe: probe function pointer
 400  * @probe: probe data pointer
 401  *
 402  * We do not need to call a synchronize_sched to make sure the probes have
 403  * finished running before doing a module unload, because the module unload
 404  * itself uses stop_machine(), which insures that every preempt disabled section
 405  * have finished.
 406  */
 407 int __tracepoint_probe_unregister(const char *name, void *probe, void *data)
 408 {
 409         void *old;
 410
 411         pthread_mutex_lock(&tracepoints_mutex);
 412         old = tracepoint_remove_probe(name, probe, data);
 413         pthread_mutex_unlock(&tracepoints_mutex);
 414         if (IS_ERR(old))
 415                 return PTR_ERR(old);
 416
 417         tracepoint_update_probes();             /* may update entry */
 418         release_probes(old);
 419         return 0;
 420 }
 421
 422 static CDS_LIST_HEAD(old_probes);
 423 static int need_update;
 424
 425 static void tracepoint_add_old_probes(void *old)
 426 {
 427         need_update = 1;
 428         if (old) {
 429                 struct tp_probes *tp_probes = _ust_container_of(old,
 430                         struct tp_probes, probes[0]);
 431                 cds_list_add(&tp_probes->u.list, &old_probes);
 432         }
 433 }
 434
 435 /**
 436  * tracepoint_probe_register_noupdate -  register a probe but not connect
 437  * @name: tracepoint name
 438  * @probe: probe handler
 439  *
 440  * caller must call tracepoint_probe_update_all()
 441  */
 442 int tracepoint_probe_register_noupdate(const char *name, void *probe,
 443                                        void *data)
 444 {
 445         void *old;
 446
 447         pthread_mutex_lock(&tracepoints_mutex);
 448         old = tracepoint_add_probe(name, probe, data);
 449         if (IS_ERR(old)) {
 450                 pthread_mutex_unlock(&tracepoints_mutex);
 451                 return PTR_ERR(old);
 452         }
 453         tracepoint_add_old_probes(old);
 454         pthread_mutex_unlock(&tracepoints_mutex);
 455         return 0;
 456 }
 457 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_register_noupdate);
 458
 459 /**
 460  * tracepoint_probe_unregister_noupdate -  remove a probe but not disconnect
 461  * @name: tracepoint name
 462  * @probe: probe function pointer
 463  *
 464  * caller must call tracepoint_probe_update_all()
 465  */
 466 int tracepoint_probe_unregister_noupdate(const char *name, void *probe,
 467                                          void *data)
 468 {
 469         void *old;
 470
 471         pthread_mutex_lock(&tracepoints_mutex);
 472         old = tracepoint_remove_probe(name, probe, data);
 473         if (IS_ERR(old)) {
 474                 pthread_mutex_unlock(&tracepoints_mutex);
 475                 return PTR_ERR(old);
 476         }
 477         tracepoint_add_old_probes(old);
 478         pthread_mutex_unlock(&tracepoints_mutex);
 479         return 0;
 480 }
 481 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_unregister_noupdate);
 482
 483 /**
 484  * tracepoint_probe_update_all -  update tracepoints
 485  */
 486 void tracepoint_probe_update_all(void)
 487 {
 488         CDS_LIST_HEAD(release_probes);
 489         struct tp_probes *pos, *next;
 490
 491         pthread_mutex_lock(&tracepoints_mutex);
 492         if (!need_update) {
 493                 pthread_mutex_unlock(&tracepoints_mutex);
 494                 return;
 495         }
 496         if (!cds_list_empty(&old_probes))
 497                 cds_list_replace_init(&old_probes, &release_probes);
 498         need_update = 0;
 499         pthread_mutex_unlock(&tracepoints_mutex);
 500
 501         tracepoint_update_probes();
 502         cds_list_for_each_entry_safe(pos, next, &release_probes, u.list) {
 503                 cds_list_del(&pos->u.list);
 504 //ust//         call_rcu_sched(&pos->u.rcu, rcu_free_old_probes);
 505                 synchronize_rcu();
 506                 free(pos);
 507         }
 508 }
 509 //ust// EXPORT_SYMBOL_GPL(tracepoint_probe_update_all);
 510
 511 /*
 512  * Returns 0 if current not found.
 513  * Returns 1 if current found.
 514  */
 515 int lib_get_iter_tracepoints(struct tracepoint_iter *iter)
 516 {
 517         struct tracepoint_lib *iter_lib;
 518         int found = 0;
 519
 520 //ust// pthread_mutex_lock(&module_mutex);
 521         cds_list_for_each_entry(iter_lib, &libs, list) {
 522                 if (iter_lib < iter->lib)
 523                         continue;
 524                 else if (iter_lib > iter->lib)
 525                         iter->tracepoint = NULL;
 526                 found = tracepoint_get_iter_range(&iter->tracepoint,
 527                         iter_lib->tracepoints_start,
 528                         iter_lib->tracepoints_start + iter_lib->tracepoints_count);
 529                 if (found) {
 530                         iter->lib = iter_lib;
 531                         break;
 532                 }
 533         }
 534 //ust// pthread_mutex_unlock(&module_mutex);
 535         return found;
 536 }
 537
 538 /**
 539  * tracepoint_get_iter_range - Get a next tracepoint iterator given a range.
 540  * @tracepoint: current tracepoints (in), next tracepoint (out)
 541  * @begin: beginning of the range
 542  * @end: end of the range
 543  *
 544  * Returns whether a next tracepoint has been found (1) or not (0).
 545  * Will return the first tracepoint in the range if the input tracepoint is
 546  * NULL.
 547  */
 548 int tracepoint_get_iter_range(struct tracepoint * const **tracepoint,
 549         struct tracepoint * const *begin, struct tracepoint * const *end)
 550 {
 551         if (!*tracepoint && begin != end)
 552                 *tracepoint = begin;
 553         while (*tracepoint >= begin && *tracepoint < end) {
 554                 if (!**tracepoint)
 555                         (*tracepoint)++;        /* skip dummy */
 556                 else
 557                         return 1;
 558         }
 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
 656                 for(t = start; t < end; t++) {
 657                         if (*t)
 658                                 new_tracepoint_cb(*t);
 659                 }
 660         }
 661 }
 662
 663 int tracepoint_register_lib(struct tracepoint * const *tracepoints_start, int tracepoints_count)
 664 {
 665         struct tracepoint_lib *pl, *iter;
 666
 667         pl = (struct tracepoint_lib *) zmalloc(sizeof(struct tracepoint_lib));
 668
 669         pl->tracepoints_start = tracepoints_start;
 670         pl->tracepoints_count = tracepoints_count;
 671
 672         /* FIXME: maybe protect this with its own mutex? */
 673         pthread_mutex_lock(&tracepoints_mutex);
 674         /*
 675          * We sort the libs by struct lib pointer address.
 676          */
 677         cds_list_for_each_entry_reverse(iter, &libs, list) {
 678                 BUG_ON(iter == pl);    /* Should never be in the list twice */
 679                 if (iter < pl) {
 680                         /* We belong to the location right after iter. */
 681                         cds_list_add(&pl->list, &iter->list);
 682                         goto lib_added;
 683                 }
 684         }
 685         /* We should be added at the head of the list */
 686         cds_list_add(&pl->list, &libs);
 687 lib_added:
 688         pthread_mutex_unlock(&tracepoints_mutex);
 689
 690         new_tracepoints(tracepoints_start, tracepoints_start + tracepoints_count);
 691
 692         /* FIXME: update just the loaded lib */
 693         lib_update_tracepoints();
 694
 695         /* tracepoints_count - 1: skip dummy */
 696         DBG("just registered a tracepoints section from %p and having %d tracepoints (minus dummy tracepoints)", tracepoints_start, tracepoints_count);
 697
 698         return 0;
 699 }
 700
 701 int tracepoint_unregister_lib(struct tracepoint * const *tracepoints_start)
 702 {
 703         struct tracepoint_lib *lib;
 704
 705         pthread_mutex_lock(&tracepoints_mutex);
 706
 707         cds_list_for_each_entry(lib, &libs, list) {
 708                 if (lib->tracepoints_start == tracepoints_start) {
 709                         struct tracepoint_lib *lib2free = lib;
 710                         cds_list_del(&lib->list);
 711                         free(lib2free);
 712                         break;
 713                 }
 714         }
 715
 716         pthread_mutex_unlock(&tracepoints_mutex);
 717
 718         return 0;
 719 }