liblttng-ust/lttng-ust-comm.c

   1 /*
   2  * lttng-ust-comm.c
   3  *
   4  * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
   5  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   6  *
   7  * This library is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU Lesser General Public
   9  * License as published by the Free Software Foundation; only
  10  * version 2.1 of the License.
  11  *
  12  * This library is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15  * Lesser General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU Lesser General Public
  18  * License along with this library; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  20  */
  21
  22 #define _LGPL_SOURCE
  23 #define _GNU_SOURCE
  24 #include <sys/types.h>
  25 #include <sys/socket.h>
  26 #include <sys/mman.h>
  27 #include <sys/stat.h>
  28 #include <sys/types.h>
  29 #include <sys/wait.h>
  30 #include <fcntl.h>
  31 #include <unistd.h>
  32 #include <errno.h>
  33 #include <pthread.h>
  34 #include <semaphore.h>
  35 #include <time.h>
  36 #include <assert.h>
  37 #include <signal.h>
  38 #include <limits.h>
  39 #include <urcu/uatomic.h>
  40 #include <urcu/futex.h>
  41 #include <urcu/compiler.h>
  42
  43 #include <lttng/ust-events.h>
  44 #include <lttng/ust-abi.h>
  45 #include <lttng/ust.h>
  46 #include <lttng/ust-error.h>
  47 #include <lttng/ust-ctl.h>
  48 #include <urcu/tls-compat.h>
  49 #include <ust-comm.h>
  50 #include <ust-fd.h>
  51 #include <usterr-signal-safe.h>
  52 #include <helper.h>
  53 #include "tracepoint-internal.h"
  54 #include "lttng-tracer-core.h"
  55 #include "compat.h"
  56 #include "../libringbuffer/rb-init.h"
  57 #include "lttng-ust-statedump.h"
  58 #include "clock.h"
  59 #include "../libringbuffer/getcpu.h"
  60 #include "getenv.h"
  61
  62 /*
  63  * Has lttng ust comm constructor been called ?
  64  */
  65 static int initialized;
  66
  67 /*
  68  * The ust_lock/ust_unlock lock is used as a communication thread mutex.
  69  * Held when handling a command, also held by fork() to deal with
  70  * removal of threads, and by exit path.
  71  *
  72  * The UST lock is the centralized mutex across UST tracing control and
  73  * probe registration.
  74  *
  75  * ust_exit_mutex must never nest in ust_mutex.
  76  *
  77  * ust_fork_mutex must never nest in ust_mutex.
  78  *
  79  * ust_mutex_nest is a per-thread nesting counter, allowing the perf
  80  * counter lazy initialization called by events within the statedump,
  81  * which traces while the ust_mutex is held.
  82  *
  83  * ust_lock nests within the dynamic loader lock (within glibc) because
  84  * it is taken within the library constructor.
  85  */
  86 static pthread_mutex_t ust_mutex = PTHREAD_MUTEX_INITIALIZER;
  87
  88 /* Allow nesting the ust_mutex within the same thread. */
  89 static DEFINE_URCU_TLS(int, ust_mutex_nest);
  90
  91 /*
  92  * ust_exit_mutex protects thread_active variable wrt thread exit. It
  93  * cannot be done by ust_mutex because pthread_cancel(), which takes an
  94  * internal libc lock, cannot nest within ust_mutex.
  95  *
  96  * It never nests within a ust_mutex.
  97  */
  98 static pthread_mutex_t ust_exit_mutex = PTHREAD_MUTEX_INITIALIZER;
  99
 100 /*
 101  * ust_fork_mutex protects base address statedump tracing against forks. It
 102  * prevents the dynamic loader lock to be taken (by base address statedump
 103  * tracing) while a fork is happening, thus preventing deadlock issues with
 104  * the dynamic loader lock.
 105  */
 106 static pthread_mutex_t ust_fork_mutex = PTHREAD_MUTEX_INITIALIZER;
 107
 108 /* Should the ust comm thread quit ? */
 109 static int lttng_ust_comm_should_quit;
 110
 111 /*
 112  * This variable can be tested by applications to check whether
 113  * lttng-ust is loaded. They simply have to define their own
 114  * "lttng_ust_loaded" weak symbol, and test it. It is set to 1 by the
 115  * library constructor.
 116  */
 117 int lttng_ust_loaded __attribute__((weak));
 118
 119 /*
 120  * Return 0 on success, -1 if should quit.
 121  * The lock is taken in both cases.
 122  * Signal-safe.
 123  */
 124 int ust_lock(void)
 125 {
 126         sigset_t sig_all_blocked, orig_mask;
 127         int ret, oldstate;
 128
 129         ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
 130         if (ret) {
 131                 ERR("pthread_setcancelstate: %s", strerror(ret));
 132         }
 133         if (oldstate != PTHREAD_CANCEL_ENABLE) {
 134                 ERR("pthread_setcancelstate: unexpected oldstate");
 135         }
 136         sigfillset(&sig_all_blocked);
 137         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
 138         if (ret) {
 139                 ERR("pthread_sigmask: %s", strerror(ret));
 140         }
 141         if (!URCU_TLS(ust_mutex_nest)++)
 142                 pthread_mutex_lock(&ust_mutex);
 143         ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
 144         if (ret) {
 145                 ERR("pthread_sigmask: %s", strerror(ret));
 146         }
 147         if (lttng_ust_comm_should_quit) {
 148                 return -1;
 149         } else {
 150                 return 0;
 151         }
 152 }
 153
 154 /*
 155  * ust_lock_nocheck() can be used in constructors/destructors, because
 156  * they are already nested within the dynamic loader lock, and therefore
 157  * have exclusive access against execution of liblttng-ust destructor.
 158  * Signal-safe.
 159  */
 160 void ust_lock_nocheck(void)
 161 {
 162         sigset_t sig_all_blocked, orig_mask;
 163         int ret, oldstate;
 164
 165         ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
 166         if (ret) {
 167                 ERR("pthread_setcancelstate: %s", strerror(ret));
 168         }
 169         if (oldstate != PTHREAD_CANCEL_ENABLE) {
 170                 ERR("pthread_setcancelstate: unexpected oldstate");
 171         }
 172         sigfillset(&sig_all_blocked);
 173         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
 174         if (ret) {
 175                 ERR("pthread_sigmask: %s", strerror(ret));
 176         }
 177         if (!URCU_TLS(ust_mutex_nest)++)
 178                 pthread_mutex_lock(&ust_mutex);
 179         ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
 180         if (ret) {
 181                 ERR("pthread_sigmask: %s", strerror(ret));
 182         }
 183 }
 184
 185 /*
 186  * Signal-safe.
 187  */
 188 void ust_unlock(void)
 189 {
 190         sigset_t sig_all_blocked, orig_mask;
 191         int ret, oldstate;
 192
 193         sigfillset(&sig_all_blocked);
 194         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
 195         if (ret) {
 196                 ERR("pthread_sigmask: %s", strerror(ret));
 197         }
 198         if (!--URCU_TLS(ust_mutex_nest))
 199                 pthread_mutex_unlock(&ust_mutex);
 200         ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
 201         if (ret) {
 202                 ERR("pthread_sigmask: %s", strerror(ret));
 203         }
 204         ret = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldstate);
 205         if (ret) {
 206                 ERR("pthread_setcancelstate: %s", strerror(ret));
 207         }
 208         if (oldstate != PTHREAD_CANCEL_DISABLE) {
 209                 ERR("pthread_setcancelstate: unexpected oldstate");
 210         }
 211 }
 212
 213 /*
 214  * Wait for either of these before continuing to the main
 215  * program:
 216  * - the register_done message from sessiond daemon
 217  *   (will let the sessiond daemon enable sessions before main
 218  *   starts.)
 219  * - sessiond daemon is not reachable.
 220  * - timeout (ensuring applications are resilient to session
 221  *   daemon problems).
 222  */
 223 static sem_t constructor_wait;
 224 /*
 225  * Doing this for both the global and local sessiond.
 226  */
 227 enum {
 228         sem_count_initial_value = 4,
 229 };
 230
 231 static int sem_count = sem_count_initial_value;
 232
 233 /*
 234  * Counting nesting within lttng-ust. Used to ensure that calling fork()
 235  * from liblttng-ust does not execute the pre/post fork handlers.
 236  */
 237 static DEFINE_URCU_TLS(int, lttng_ust_nest_count);
 238
 239 /*
 240  * Info about socket and associated listener thread.
 241  */
 242 struct sock_info {
 243         const char *name;
 244         pthread_t ust_listener; /* listener thread */
 245         int root_handle;
 246         int registration_done;
 247         int allowed;
 248         int global;
 249         int thread_active;
 250
 251         char sock_path[PATH_MAX];
 252         int socket;
 253         int notify_socket;
 254
 255         char wait_shm_path[PATH_MAX];
 256         char *wait_shm_mmap;
 257         /* Keep track of lazy state dump not performed yet. */
 258         int statedump_pending;
 259         int initial_statedump_done;
 260 };
 261
 262 /* Socket from app (connect) to session daemon (listen) for communication */
 263 struct sock_info global_apps = {
 264         .name = "global",
 265         .global = 1,
 266
 267         .root_handle = -1,
 268         .registration_done = 0,
 269         .allowed = 0,
 270         .thread_active = 0,
 271
 272         .sock_path = LTTNG_DEFAULT_RUNDIR "/" LTTNG_UST_SOCK_FILENAME,
 273         .socket = -1,
 274         .notify_socket = -1,
 275
 276         .wait_shm_path = "/" LTTNG_UST_WAIT_FILENAME,
 277
 278         .statedump_pending = 0,
 279         .initial_statedump_done = 0,
 280 };
 281
 282 /* TODO: allow global_apps_sock_path override */
 283
 284 struct sock_info local_apps = {
 285         .name = "local",
 286         .global = 0,
 287         .root_handle = -1,
 288         .registration_done = 0,
 289         .allowed = 0,   /* Check setuid bit first */
 290         .thread_active = 0,
 291
 292         .socket = -1,
 293         .notify_socket = -1,
 294
 295         .statedump_pending = 0,
 296         .initial_statedump_done = 0,
 297 };
 298
 299 static int wait_poll_fallback;
 300
 301 static const char *cmd_name_mapping[] = {
 302         [ LTTNG_UST_RELEASE ] = "Release",
 303         [ LTTNG_UST_SESSION ] = "Create Session",
 304         [ LTTNG_UST_TRACER_VERSION ] = "Get Tracer Version",
 305
 306         [ LTTNG_UST_TRACEPOINT_LIST ] = "Create Tracepoint List",
 307         [ LTTNG_UST_WAIT_QUIESCENT ] = "Wait for Quiescent State",
 308         [ LTTNG_UST_REGISTER_DONE ] = "Registration Done",
 309         [ LTTNG_UST_TRACEPOINT_FIELD_LIST ] = "Create Tracepoint Field List",
 310
 311         /* Session FD commands */
 312         [ LTTNG_UST_CHANNEL ] = "Create Channel",
 313         [ LTTNG_UST_SESSION_START ] = "Start Session",
 314         [ LTTNG_UST_SESSION_STOP ] = "Stop Session",
 315
 316         /* Channel FD commands */
 317         [ LTTNG_UST_STREAM ] = "Create Stream",
 318         [ LTTNG_UST_EVENT ] = "Create Event",
 319
 320         /* Event and Channel FD commands */
 321         [ LTTNG_UST_CONTEXT ] = "Create Context",
 322         [ LTTNG_UST_FLUSH_BUFFER ] = "Flush Buffer",
 323
 324         /* Event, Channel and Session commands */
 325         [ LTTNG_UST_ENABLE ] = "Enable",
 326         [ LTTNG_UST_DISABLE ] = "Disable",
 327
 328         /* Tracepoint list commands */
 329         [ LTTNG_UST_TRACEPOINT_LIST_GET ] = "List Next Tracepoint",
 330         [ LTTNG_UST_TRACEPOINT_FIELD_LIST_GET ] = "List Next Tracepoint Field",
 331
 332         /* Event FD commands */
 333         [ LTTNG_UST_FILTER ] = "Create Filter",
 334         [ LTTNG_UST_EXCLUSION ] = "Add exclusions to event",
 335 };
 336
 337 static const char *str_timeout;
 338 static int got_timeout_env;
 339
 340 extern void lttng_ring_buffer_client_overwrite_init(void);
 341 extern void lttng_ring_buffer_client_overwrite_rt_init(void);
 342 extern void lttng_ring_buffer_client_discard_init(void);
 343 extern void lttng_ring_buffer_client_discard_rt_init(void);
 344 extern void lttng_ring_buffer_metadata_client_init(void);
 345 extern void lttng_ring_buffer_client_overwrite_exit(void);
 346 extern void lttng_ring_buffer_client_overwrite_rt_exit(void);
 347 extern void lttng_ring_buffer_client_discard_exit(void);
 348 extern void lttng_ring_buffer_client_discard_rt_exit(void);
 349 extern void lttng_ring_buffer_metadata_client_exit(void);
 350
 351 static char *get_map_shm(struct sock_info *sock_info);
 352
 353 ssize_t lttng_ust_read(int fd, void *buf, size_t len)
 354 {
 355         ssize_t ret;
 356         size_t copied = 0, to_copy = len;
 357
 358         do {
 359                 ret = read(fd, buf + copied, to_copy);
 360                 if (ret > 0) {
 361                         copied += ret;
 362                         to_copy -= ret;
 363                 }
 364         } while ((ret > 0 && to_copy > 0)
 365                 || (ret < 0 && errno == EINTR));
 366         if (ret > 0) {
 367                 ret = copied;
 368         }
 369         return ret;
 370 }
 371 /*
 372  * Returns the HOME directory path. Caller MUST NOT free(3) the returned
 373  * pointer.
 374  */
 375 static
 376 const char *get_lttng_home_dir(void)
 377 {
 378        const char *val;
 379
 380        val = (const char *) lttng_getenv("LTTNG_HOME");
 381        if (val != NULL) {
 382                return val;
 383        }
 384        return (const char *) lttng_getenv("HOME");
 385 }
 386
 387 /*
 388  * Force a read (imply TLS fixup for dlopen) of TLS variables.
 389  */
 390 static
 391 void lttng_fixup_nest_count_tls(void)
 392 {
 393         asm volatile ("" : : "m" (URCU_TLS(lttng_ust_nest_count)));
 394 }
 395
 396 static
 397 void lttng_fixup_ust_mutex_nest_tls(void)
 398 {
 399         asm volatile ("" : : "m" (URCU_TLS(ust_mutex_nest)));
 400 }
 401
 402 /*
 403  * Fixup urcu bp TLS.
 404  */
 405 static
 406 void lttng_fixup_urcu_bp_tls(void)
 407 {
 408         rcu_read_lock();
 409         rcu_read_unlock();
 410 }
 411
 412 void lttng_ust_fixup_tls(void)
 413 {
 414         lttng_fixup_urcu_bp_tls();
 415         lttng_fixup_ringbuffer_tls();
 416         lttng_fixup_vtid_tls();
 417         lttng_fixup_nest_count_tls();
 418         lttng_fixup_procname_tls();
 419         lttng_fixup_ust_mutex_nest_tls();
 420         lttng_ust_fixup_fd_tracker_tls();
 421 }
 422
 423 int lttng_get_notify_socket(void *owner)
 424 {
 425         struct sock_info *info = owner;
 426
 427         return info->notify_socket;
 428 }
 429
 430 static
 431 void print_cmd(int cmd, int handle)
 432 {
 433         const char *cmd_name = "Unknown";
 434
 435         if (cmd >= 0 && cmd < LTTNG_ARRAY_SIZE(cmd_name_mapping)
 436                         && cmd_name_mapping[cmd]) {
 437                 cmd_name = cmd_name_mapping[cmd];
 438         }
 439         DBG("Message Received \"%s\" (%d), Handle \"%s\" (%d)",
 440                 cmd_name, cmd,
 441                 lttng_ust_obj_get_name(handle), handle);
 442 }
 443
 444 static
 445 int setup_global_apps(void)
 446 {
 447         int ret = 0;
 448         assert(!global_apps.wait_shm_mmap);
 449
 450         global_apps.wait_shm_mmap = get_map_shm(&global_apps);
 451         if (!global_apps.wait_shm_mmap) {
 452                 WARN("Unable to get map shm for global apps. Disabling LTTng-UST global tracing.");
 453                 global_apps.allowed = 0;
 454                 ret = -EIO;
 455                 goto error;
 456         }
 457
 458         global_apps.allowed = 1;
 459 error:
 460         return ret;
 461 }
 462 static
 463 int setup_local_apps(void)
 464 {
 465         int ret = 0;
 466         const char *home_dir;
 467         uid_t uid;
 468
 469         assert(!local_apps.wait_shm_mmap);
 470
 471         uid = getuid();
 472         /*
 473          * Disallow per-user tracing for setuid binaries.
 474          */
 475         if (uid != geteuid()) {
 476                 assert(local_apps.allowed == 0);
 477                 ret = 0;
 478                 goto end;
 479         }
 480         home_dir = get_lttng_home_dir();
 481         if (!home_dir) {
 482                 WARN("HOME environment variable not set. Disabling LTTng-UST per-user tracing.");
 483                 assert(local_apps.allowed == 0);
 484                 ret = -ENOENT;
 485                 goto end;
 486         }
 487         local_apps.allowed = 1;
 488         snprintf(local_apps.sock_path, PATH_MAX, "%s/%s/%s",
 489                 home_dir,
 490                 LTTNG_DEFAULT_HOME_RUNDIR,
 491                 LTTNG_UST_SOCK_FILENAME);
 492         snprintf(local_apps.wait_shm_path, PATH_MAX, "/%s-%u",
 493                 LTTNG_UST_WAIT_FILENAME,
 494                 uid);
 495
 496         local_apps.wait_shm_mmap = get_map_shm(&local_apps);
 497         if (!local_apps.wait_shm_mmap) {
 498                 WARN("Unable to get map shm for local apps. Disabling LTTng-UST per-user tracing.");
 499                 local_apps.allowed = 0;
 500                 ret = -EIO;
 501                 goto end;
 502         }
 503 end:
 504         return ret;
 505 }
 506
 507 /*
 508  * Get socket timeout, in ms.
 509  * -1: wait forever. 0: don't wait. >0: timeout, in ms.
 510  */
 511 static
 512 long get_timeout(void)
 513 {
 514         long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
 515
 516         if (!got_timeout_env) {
 517                 str_timeout = lttng_getenv("LTTNG_UST_REGISTER_TIMEOUT");
 518                 got_timeout_env = 1;
 519         }
 520         if (str_timeout)
 521                 constructor_delay_ms = strtol(str_timeout, NULL, 10);
 522         /* All negative values are considered as "-1". */
 523         if (constructor_delay_ms < -1)
 524                 constructor_delay_ms = -1;
 525         return constructor_delay_ms;
 526 }
 527
 528 /* Timeout for notify socket send and recv. */
 529 static
 530 long get_notify_sock_timeout(void)
 531 {
 532         return get_timeout();
 533 }
 534
 535 /* Timeout for connecting to cmd and notify sockets. */
 536 static
 537 long get_connect_sock_timeout(void)
 538 {
 539         return get_timeout();
 540 }
 541
 542 /*
 543  * Return values: -1: wait forever. 0: don't wait. 1: timeout wait.
 544  */
 545 static
 546 int get_constructor_timeout(struct timespec *constructor_timeout)
 547 {
 548         long constructor_delay_ms;
 549         int ret;
 550
 551         constructor_delay_ms = get_timeout();
 552
 553         switch (constructor_delay_ms) {
 554         case -1:/* fall-through */
 555         case 0:
 556                 return constructor_delay_ms;
 557         default:
 558                 break;
 559         }
 560
 561         /*
 562          * If we are unable to find the current time, don't wait.
 563          */
 564         ret = clock_gettime(CLOCK_REALTIME, constructor_timeout);
 565         if (ret) {
 566                 /* Don't wait. */
 567                 return 0;
 568         }
 569         constructor_timeout->tv_sec += constructor_delay_ms / 1000UL;
 570         constructor_timeout->tv_nsec +=
 571                 (constructor_delay_ms % 1000UL) * 1000000UL;
 572         if (constructor_timeout->tv_nsec >= 1000000000UL) {
 573                 constructor_timeout->tv_sec++;
 574                 constructor_timeout->tv_nsec -= 1000000000UL;
 575         }
 576         /* Timeout wait (constructor_delay_ms). */
 577         return 1;
 578 }
 579
 580 static
 581 void get_allow_blocking(void)
 582 {
 583         const char *str_allow_blocking =
 584                 lttng_getenv("LTTNG_UST_ALLOW_BLOCKING");
 585
 586         if (str_allow_blocking) {
 587                 DBG("%s environment variable is set",
 588                         "LTTNG_UST_ALLOW_BLOCKING");
 589                 lttng_ust_ringbuffer_set_allow_blocking();
 590         }
 591 }
 592
 593 static
 594 int register_to_sessiond(int socket, enum ustctl_socket_type type)
 595 {
 596         return ustcomm_send_reg_msg(socket,
 597                 type,
 598                 CAA_BITS_PER_LONG,
 599                 lttng_alignof(uint8_t) * CHAR_BIT,
 600                 lttng_alignof(uint16_t) * CHAR_BIT,
 601                 lttng_alignof(uint32_t) * CHAR_BIT,
 602                 lttng_alignof(uint64_t) * CHAR_BIT,
 603                 lttng_alignof(unsigned long) * CHAR_BIT);
 604 }
 605
 606 static
 607 int send_reply(int sock, struct ustcomm_ust_reply *lur)
 608 {
 609         ssize_t len;
 610
 611         len = ustcomm_send_unix_sock(sock, lur, sizeof(*lur));
 612         switch (len) {
 613         case sizeof(*lur):
 614                 DBG("message successfully sent");
 615                 return 0;
 616         default:
 617                 if (len == -ECONNRESET) {
 618                         DBG("remote end closed connection");
 619                         return 0;
 620                 }
 621                 if (len < 0)
 622                         return len;
 623                 DBG("incorrect message size: %zd", len);
 624                 return -EINVAL;
 625         }
 626 }
 627
 628 static
 629 void decrement_sem_count(unsigned int count)
 630 {
 631         int ret;
 632
 633         assert(uatomic_read(&sem_count) >= count);
 634
 635         if (uatomic_read(&sem_count) <= 0) {
 636                 return;
 637         }
 638
 639         ret = uatomic_add_return(&sem_count, -count);
 640         if (ret == 0) {
 641                 ret = sem_post(&constructor_wait);
 642                 assert(!ret);
 643         }
 644 }
 645
 646 static
 647 int handle_register_done(struct sock_info *sock_info)
 648 {
 649         if (sock_info->registration_done)
 650                 return 0;
 651         sock_info->registration_done = 1;
 652
 653         decrement_sem_count(1);
 654
 655         return 0;
 656 }
 657
 658 static
 659 int handle_register_failed(struct sock_info *sock_info)
 660 {
 661         if (sock_info->registration_done)
 662                 return 0;
 663         sock_info->registration_done = 1;
 664         sock_info->initial_statedump_done = 1;
 665
 666         decrement_sem_count(2);
 667
 668         return 0;
 669 }
 670
 671 /*
 672  * Only execute pending statedump after the constructor semaphore has
 673  * been posted by the current listener thread. This means statedump will
 674  * only be performed after the "registration done" command is received
 675  * from this thread's session daemon.
 676  *
 677  * This ensures we don't run into deadlock issues with the dynamic
 678  * loader mutex, which is held while the constructor is called and
 679  * waiting on the constructor semaphore. All operations requiring this
 680  * dynamic loader lock need to be postponed using this mechanism.
 681  *
 682  * In a scenario with two session daemons connected to the application,
 683  * it is possible that the first listener thread which receives the
 684  * registration done command issues its statedump while the dynamic
 685  * loader lock is still held by the application constructor waiting on
 686  * the semaphore. It will however be allowed to proceed when the
 687  * second session daemon sends the registration done command to the
 688  * second listener thread. This situation therefore does not produce
 689  * a deadlock.
 690  */
 691 static
 692 void handle_pending_statedump(struct sock_info *sock_info)
 693 {
 694         if (sock_info->registration_done && sock_info->statedump_pending) {
 695                 sock_info->statedump_pending = 0;
 696                 pthread_mutex_lock(&ust_fork_mutex);
 697                 lttng_handle_pending_statedump(sock_info);
 698                 pthread_mutex_unlock(&ust_fork_mutex);
 699
 700                 if (!sock_info->initial_statedump_done) {
 701                         sock_info->initial_statedump_done = 1;
 702                         decrement_sem_count(1);
 703                 }
 704         }
 705 }
 706
 707 static
 708 int handle_message(struct sock_info *sock_info,
 709                 int sock, struct ustcomm_ust_msg *lum)
 710 {
 711         int ret = 0;
 712         const struct lttng_ust_objd_ops *ops;
 713         struct ustcomm_ust_reply lur;
 714         union ust_args args;
 715         char ctxstr[LTTNG_UST_SYM_NAME_LEN];    /* App context string. */
 716         ssize_t len;
 717
 718         memset(&lur, 0, sizeof(lur));
 719
 720         if (ust_lock()) {
 721                 ret = -LTTNG_UST_ERR_EXITING;
 722                 goto error;
 723         }
 724
 725         ops = objd_ops(lum->handle);
 726         if (!ops) {
 727                 ret = -ENOENT;
 728                 goto error;
 729         }
 730
 731         switch (lum->cmd) {
 732         case LTTNG_UST_REGISTER_DONE:
 733                 if (lum->handle == LTTNG_UST_ROOT_HANDLE)
 734                         ret = handle_register_done(sock_info);
 735                 else
 736                         ret = -EINVAL;
 737                 break;
 738         case LTTNG_UST_RELEASE:
 739                 if (lum->handle == LTTNG_UST_ROOT_HANDLE)
 740                         ret = -EPERM;
 741                 else
 742                         ret = lttng_ust_objd_unref(lum->handle, 1);
 743                 break;
 744         case LTTNG_UST_FILTER:
 745         {
 746                 /* Receive filter data */
 747                 struct lttng_ust_filter_bytecode_node *bytecode;
 748
 749                 if (lum->u.filter.data_size > FILTER_BYTECODE_MAX_LEN) {
 750                         ERR("Filter data size is too large: %u bytes",
 751                                 lum->u.filter.data_size);
 752                         ret = -EINVAL;
 753                         goto error;
 754                 }
 755
 756                 if (lum->u.filter.reloc_offset > lum->u.filter.data_size) {
 757                         ERR("Filter reloc offset %u is not within data",
 758                                 lum->u.filter.reloc_offset);
 759                         ret = -EINVAL;
 760                         goto error;
 761                 }
 762
 763                 bytecode = zmalloc(sizeof(*bytecode) + lum->u.filter.data_size);
 764                 if (!bytecode) {
 765                         ret = -ENOMEM;
 766                         goto error;
 767                 }
 768                 len = ustcomm_recv_unix_sock(sock, bytecode->bc.data,
 769                                 lum->u.filter.data_size);
 770                 switch (len) {
 771                 case 0: /* orderly shutdown */
 772                         ret = 0;
 773                         free(bytecode);
 774                         goto error;
 775                 default:
 776                         if (len == lum->u.filter.data_size) {
 777                                 DBG("filter data received");
 778                                 break;
 779                         } else if (len < 0) {
 780                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 781                                 if (len == -ECONNRESET) {
 782                                         ERR("%s remote end closed connection", sock_info->name);
 783                                         ret = len;
 784                                         free(bytecode);
 785                                         goto error;
 786                                 }
 787                                 ret = len;
 788                                 free(bytecode);
 789                                 goto error;
 790                         } else {
 791                                 DBG("incorrect filter data message size: %zd", len);
 792                                 ret = -EINVAL;
 793                                 free(bytecode);
 794                                 goto error;
 795                         }
 796                 }
 797                 bytecode->bc.len = lum->u.filter.data_size;
 798                 bytecode->bc.reloc_offset = lum->u.filter.reloc_offset;
 799                 bytecode->bc.seqnum = lum->u.filter.seqnum;
 800                 if (ops->cmd) {
 801                         ret = ops->cmd(lum->handle, lum->cmd,
 802                                         (unsigned long) bytecode,
 803                                         &args, sock_info);
 804                         if (ret) {
 805                                 free(bytecode);
 806                         }
 807                         /* don't free bytecode if everything went fine. */
 808                 } else {
 809                         ret = -ENOSYS;
 810                         free(bytecode);
 811                 }
 812                 break;
 813         }
 814         case LTTNG_UST_EXCLUSION:
 815         {
 816                 /* Receive exclusion names */
 817                 struct lttng_ust_excluder_node *node;
 818                 unsigned int count;
 819
 820                 count = lum->u.exclusion.count;
 821                 if (count == 0) {
 822                         /* There are no names to read */
 823                         ret = 0;
 824                         goto error;
 825                 }
 826                 node = zmalloc(sizeof(*node) +
 827                                 count * LTTNG_UST_SYM_NAME_LEN);
 828                 if (!node) {
 829                         ret = -ENOMEM;
 830                         goto error;
 831                 }
 832                 node->excluder.count = count;
 833                 len = ustcomm_recv_unix_sock(sock, node->excluder.names,
 834                                 count * LTTNG_UST_SYM_NAME_LEN);
 835                 switch (len) {
 836                 case 0: /* orderly shutdown */
 837                         ret = 0;
 838                         free(node);
 839                         goto error;
 840                 default:
 841                         if (len == count * LTTNG_UST_SYM_NAME_LEN) {
 842                                 DBG("Exclusion data received");
 843                                 break;
 844                         } else if (len < 0) {
 845                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 846                                 if (len == -ECONNRESET) {
 847                                         ERR("%s remote end closed connection", sock_info->name);
 848                                         ret = len;
 849                                         free(node);
 850                                         goto error;
 851                                 }
 852                                 ret = len;
 853                                 free(node);
 854                                 goto error;
 855                         } else {
 856                                 DBG("Incorrect exclusion data message size: %zd", len);
 857                                 ret = -EINVAL;
 858                                 free(node);
 859                                 goto error;
 860                         }
 861                 }
 862                 if (ops->cmd) {
 863                         ret = ops->cmd(lum->handle, lum->cmd,
 864                                         (unsigned long) node,
 865                                         &args, sock_info);
 866                         if (ret) {
 867                                 free(node);
 868                         }
 869                         /* Don't free exclusion data if everything went fine. */
 870                 } else {
 871                         ret = -ENOSYS;
 872                         free(node);
 873                 }
 874                 break;
 875         }
 876         case LTTNG_UST_CHANNEL:
 877         {
 878                 void *chan_data;
 879                 int wakeup_fd;
 880
 881                 len = ustcomm_recv_channel_from_sessiond(sock,
 882                                 &chan_data, lum->u.channel.len,
 883                                 &wakeup_fd);
 884                 switch (len) {
 885                 case 0: /* orderly shutdown */
 886                         ret = 0;
 887                         goto error;
 888                 default:
 889                         if (len == lum->u.channel.len) {
 890                                 DBG("channel data received");
 891                                 break;
 892                         } else if (len < 0) {
 893                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 894                                 if (len == -ECONNRESET) {
 895                                         ERR("%s remote end closed connection", sock_info->name);
 896                                         ret = len;
 897                                         goto error;
 898                                 }
 899                                 ret = len;
 900                                 goto error;
 901                         } else {
 902                                 DBG("incorrect channel data message size: %zd", len);
 903                                 ret = -EINVAL;
 904                                 goto error;
 905                         }
 906                 }
 907                 args.channel.chan_data = chan_data;
 908                 args.channel.wakeup_fd = wakeup_fd;
 909                 if (ops->cmd)
 910                         ret = ops->cmd(lum->handle, lum->cmd,
 911                                         (unsigned long) &lum->u,
 912                                         &args, sock_info);
 913                 else
 914                         ret = -ENOSYS;
 915                 break;
 916         }
 917         case LTTNG_UST_STREAM:
 918         {
 919                 /* Receive shm_fd, wakeup_fd */
 920                 ret = ustcomm_recv_stream_from_sessiond(sock,
 921                         NULL,
 922                         &args.stream.shm_fd,
 923                         &args.stream.wakeup_fd);
 924                 if (ret) {
 925                         goto error;
 926                 }
 927
 928                 if (ops->cmd)
 929                         ret = ops->cmd(lum->handle, lum->cmd,
 930                                         (unsigned long) &lum->u,
 931                                         &args, sock_info);
 932                 else
 933                         ret = -ENOSYS;
 934                 break;
 935         }
 936         case LTTNG_UST_CONTEXT:
 937                 switch (lum->u.context.ctx) {
 938                 case LTTNG_UST_CONTEXT_APP_CONTEXT:
 939                 {
 940                         char *p;
 941                         size_t ctxlen, recvlen;
 942
 943                         ctxlen = strlen("$app.") + lum->u.context.u.app_ctx.provider_name_len - 1
 944                                         + strlen(":") + lum->u.context.u.app_ctx.ctx_name_len;
 945                         if (ctxlen >= LTTNG_UST_SYM_NAME_LEN) {
 946                                 ERR("Application context string length size is too large: %zu bytes",
 947                                         ctxlen);
 948                                 ret = -EINVAL;
 949                                 goto error;
 950                         }
 951                         strcpy(ctxstr, "$app.");
 952                         p = &ctxstr[strlen("$app.")];
 953                         recvlen = ctxlen - strlen("$app.");
 954                         len = ustcomm_recv_unix_sock(sock, p, recvlen);
 955                         switch (len) {
 956                         case 0: /* orderly shutdown */
 957                                 ret = 0;
 958                                 goto error;
 959                         default:
 960                                 if (len == recvlen) {
 961                                         DBG("app context data received");
 962                                         break;
 963                                 } else if (len < 0) {
 964                                         DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 965                                         if (len == -ECONNRESET) {
 966                                                 ERR("%s remote end closed connection", sock_info->name);
 967                                                 ret = len;
 968                                                 goto error;
 969                                         }
 970                                         ret = len;
 971                                         goto error;
 972                                 } else {
 973                                         DBG("incorrect app context data message size: %zd", len);
 974                                         ret = -EINVAL;
 975                                         goto error;
 976                                 }
 977                         }
 978                         /* Put : between provider and ctxname. */
 979                         p[lum->u.context.u.app_ctx.provider_name_len - 1] = ':';
 980                         args.app_context.ctxname = ctxstr;
 981                         break;
 982                 }
 983                 default:
 984                         break;
 985                 }
 986                 if (ops->cmd) {
 987                         ret = ops->cmd(lum->handle, lum->cmd,
 988                                         (unsigned long) &lum->u,
 989                                         &args, sock_info);
 990                 } else {
 991                         ret = -ENOSYS;
 992                 }
 993                 break;
 994         default:
 995                 if (ops->cmd)
 996                         ret = ops->cmd(lum->handle, lum->cmd,
 997                                         (unsigned long) &lum->u,
 998                                         &args, sock_info);
 999                 else
1000                         ret = -ENOSYS;
1001                 break;
1002         }
1003
1004         lur.handle = lum->handle;
1005         lur.cmd = lum->cmd;
1006         lur.ret_val = ret;
1007         if (ret >= 0) {
1008                 lur.ret_code = LTTNG_UST_OK;
1009         } else {
1010                 /*
1011                  * Use -LTTNG_UST_ERR as wildcard for UST internal
1012                  * error that are not caused by the transport, except if
1013                  * we already have a more precise error message to
1014                  * report.
1015                  */
1016                 if (ret > -LTTNG_UST_ERR) {
1017                         /* Translate code to UST error. */
1018                         switch (ret) {
1019                         case -EEXIST:
1020                                 lur.ret_code = -LTTNG_UST_ERR_EXIST;
1021                                 break;
1022                         case -EINVAL:
1023                                 lur.ret_code = -LTTNG_UST_ERR_INVAL;
1024                                 break;
1025                         case -ENOENT:
1026                                 lur.ret_code = -LTTNG_UST_ERR_NOENT;
1027                                 break;
1028                         case -EPERM:
1029                                 lur.ret_code = -LTTNG_UST_ERR_PERM;
1030                                 break;
1031                         case -ENOSYS:
1032                                 lur.ret_code = -LTTNG_UST_ERR_NOSYS;
1033                                 break;
1034                         default:
1035                                 lur.ret_code = -LTTNG_UST_ERR;
1036                                 break;
1037                         }
1038                 } else {
1039                         lur.ret_code = ret;
1040                 }
1041         }
1042         if (ret >= 0) {
1043                 switch (lum->cmd) {
1044                 case LTTNG_UST_TRACER_VERSION:
1045                         lur.u.version = lum->u.version;
1046                         break;
1047                 case LTTNG_UST_TRACEPOINT_LIST_GET:
1048                         memcpy(&lur.u.tracepoint, &lum->u.tracepoint, sizeof(lur.u.tracepoint));
1049                         break;
1050                 }
1051         }
1052         DBG("Return value: %d", lur.ret_val);
1053
1054         ust_unlock();
1055
1056         /*
1057          * Performed delayed statedump operations outside of the UST
1058          * lock. We need to take the dynamic loader lock before we take
1059          * the UST lock internally within handle_pending_statedump().
1060           */
1061         handle_pending_statedump(sock_info);
1062
1063         if (ust_lock()) {
1064                 ret = -LTTNG_UST_ERR_EXITING;
1065                 goto error;
1066         }
1067
1068         ret = send_reply(sock, &lur);
1069         if (ret < 0) {
1070                 DBG("error sending reply");
1071                 goto error;
1072         }
1073
1074         /*
1075          * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
1076          * after the reply.
1077          */
1078         if (lur.ret_code == LTTNG_UST_OK) {
1079                 switch (lum->cmd) {
1080                 case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
1081                         len = ustcomm_send_unix_sock(sock,
1082                                 &args.field_list.entry,
1083                                 sizeof(args.field_list.entry));
1084                         if (len < 0) {
1085                                 ret = len;
1086                                 goto error;
1087                         }
1088                         if (len != sizeof(args.field_list.entry)) {
1089                                 ret = -EINVAL;
1090                                 goto error;
1091                         }
1092                 }
1093         }
1094
1095 error:
1096         ust_unlock();
1097
1098         return ret;
1099 }
1100
1101 static
1102 void cleanup_sock_info(struct sock_info *sock_info, int exiting)
1103 {
1104         int ret;
1105
1106         if (sock_info->root_handle != -1) {
1107                 ret = lttng_ust_objd_unref(sock_info->root_handle, 1);
1108                 if (ret) {
1109                         ERR("Error unref root handle");
1110                 }
1111                 sock_info->root_handle = -1;
1112         }
1113         sock_info->registration_done = 0;
1114         sock_info->initial_statedump_done = 0;
1115
1116         /*
1117          * wait_shm_mmap, socket and notify socket are used by listener
1118          * threads outside of the ust lock, so we cannot tear them down
1119          * ourselves, because we cannot join on these threads. Leave
1120          * responsibility of cleaning up these resources to the OS
1121          * process exit.
1122          */
1123         if (exiting)
1124                 return;
1125
1126         if (sock_info->socket != -1) {
1127                 ret = ustcomm_close_unix_sock(sock_info->socket);
1128                 if (ret) {
1129                         ERR("Error closing ust cmd socket");
1130                 }
1131                 sock_info->socket = -1;
1132         }
1133         if (sock_info->notify_socket != -1) {
1134                 ret = ustcomm_close_unix_sock(sock_info->notify_socket);
1135                 if (ret) {
1136                         ERR("Error closing ust notify socket");
1137                 }
1138                 sock_info->notify_socket = -1;
1139         }
1140         if (sock_info->wait_shm_mmap) {
1141                 long page_size;
1142
1143                 page_size = sysconf(_SC_PAGE_SIZE);
1144                 if (page_size <= 0) {
1145                         if (!page_size) {
1146                                 errno = EINVAL;
1147                         }
1148                         PERROR("Error in sysconf(_SC_PAGE_SIZE)");
1149                 } else {
1150                         ret = munmap(sock_info->wait_shm_mmap, page_size);
1151                         if (ret) {
1152                                 ERR("Error unmapping wait shm");
1153                         }
1154                 }
1155                 sock_info->wait_shm_mmap = NULL;
1156         }
1157 }
1158
1159 /*
1160  * Using fork to set umask in the child process (not multi-thread safe).
1161  * We deal with the shm_open vs ftruncate race (happening when the
1162  * sessiond owns the shm and does not let everybody modify it, to ensure
1163  * safety against shm_unlink) by simply letting the mmap fail and
1164  * retrying after a few seconds.
1165  * For global shm, everybody has rw access to it until the sessiond
1166  * starts.
1167  */
1168 static
1169 int get_wait_shm(struct sock_info *sock_info, size_t mmap_size)
1170 {
1171         int wait_shm_fd, ret;
1172         pid_t pid;
1173
1174         /*
1175          * Try to open read-only.
1176          */
1177         wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
1178         if (wait_shm_fd >= 0) {
1179                 int32_t tmp_read;
1180                 ssize_t len;
1181                 size_t bytes_read = 0;
1182
1183                 /*
1184                  * Try to read the fd. If unable to do so, try opening
1185                  * it in write mode.
1186                  */
1187                 do {
1188                         len = read(wait_shm_fd,
1189                                 &((char *) &tmp_read)[bytes_read],
1190                                 sizeof(tmp_read) - bytes_read);
1191                         if (len > 0) {
1192                                 bytes_read += len;
1193                         }
1194                 } while ((len < 0 && errno == EINTR)
1195                         || (len > 0 && bytes_read < sizeof(tmp_read)));
1196                 if (bytes_read != sizeof(tmp_read)) {
1197                         ret = close(wait_shm_fd);
1198                         if (ret) {
1199                                 ERR("close wait_shm_fd");
1200                         }
1201                         goto open_write;
1202                 }
1203                 goto end;
1204         } else if (wait_shm_fd < 0 && errno != ENOENT) {
1205                 /*
1206                  * Real-only open did not work, and it's not because the
1207                  * entry was not present. It's a failure that prohibits
1208                  * using shm.
1209                  */
1210                 ERR("Error opening shm %s", sock_info->wait_shm_path);
1211                 goto end;
1212         }
1213
1214 open_write:
1215         /*
1216          * If the open failed because the file did not exist, or because
1217          * the file was not truncated yet, try creating it ourself.
1218          */
1219         URCU_TLS(lttng_ust_nest_count)++;
1220         pid = fork();
1221         URCU_TLS(lttng_ust_nest_count)--;
1222         if (pid > 0) {
1223                 int status;
1224
1225                 /*
1226                  * Parent: wait for child to return, in which case the
1227                  * shared memory map will have been created.
1228                  */
1229                 pid = wait(&status);
1230                 if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
1231                         wait_shm_fd = -1;
1232                         goto end;
1233                 }
1234                 /*
1235                  * Try to open read-only again after creation.
1236                  */
1237                 wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
1238                 if (wait_shm_fd < 0) {
1239                         /*
1240                          * Real-only open did not work. It's a failure
1241                          * that prohibits using shm.
1242                          */
1243                         ERR("Error opening shm %s", sock_info->wait_shm_path);
1244                         goto end;
1245                 }
1246                 goto end;
1247         } else if (pid == 0) {
1248                 int create_mode;
1249
1250                 /* Child */
1251                 create_mode = S_IRUSR | S_IWUSR | S_IRGRP;
1252                 if (sock_info->global)
1253                         create_mode |= S_IROTH | S_IWGRP | S_IWOTH;
1254                 /*
1255                  * We're alone in a child process, so we can modify the
1256                  * process-wide umask.
1257                  */
1258                 umask(~create_mode);
1259                 /*
1260                  * Try creating shm (or get rw access).
1261                  * We don't do an exclusive open, because we allow other
1262                  * processes to create+ftruncate it concurrently.
1263                  */
1264                 wait_shm_fd = shm_open(sock_info->wait_shm_path,
1265                                 O_RDWR | O_CREAT, create_mode);
1266                 if (wait_shm_fd >= 0) {
1267                         ret = ftruncate(wait_shm_fd, mmap_size);
1268                         if (ret) {
1269                                 PERROR("ftruncate");
1270                                 _exit(EXIT_FAILURE);
1271                         }
1272                         _exit(EXIT_SUCCESS);
1273                 }
1274                 /*
1275                  * For local shm, we need to have rw access to accept
1276                  * opening it: this means the local sessiond will be
1277                  * able to wake us up. For global shm, we open it even
1278                  * if rw access is not granted, because the root.root
1279                  * sessiond will be able to override all rights and wake
1280                  * us up.
1281                  */
1282                 if (!sock_info->global && errno != EACCES) {
1283                         ERR("Error opening shm %s", sock_info->wait_shm_path);
1284                         _exit(EXIT_FAILURE);
1285                 }
1286                 /*
1287                  * The shm exists, but we cannot open it RW. Report
1288                  * success.
1289                  */
1290                 _exit(EXIT_SUCCESS);
1291         } else {
1292                 return -1;
1293         }
1294 end:
1295         if (wait_shm_fd >= 0 && !sock_info->global) {
1296                 struct stat statbuf;
1297
1298                 /*
1299                  * Ensure that our user is the owner of the shm file for
1300                  * local shm. If we do not own the file, it means our
1301                  * sessiond will not have access to wake us up (there is
1302                  * probably a rogue process trying to fake our
1303                  * sessiond). Fallback to polling method in this case.
1304                  */
1305                 ret = fstat(wait_shm_fd, &statbuf);
1306                 if (ret) {
1307                         PERROR("fstat");
1308                         goto error_close;
1309                 }
1310                 if (statbuf.st_uid != getuid())
1311                         goto error_close;
1312         }
1313         return wait_shm_fd;
1314
1315 error_close:
1316         ret = close(wait_shm_fd);
1317         if (ret) {
1318                 PERROR("Error closing fd");
1319         }
1320         return -1;
1321 }
1322
1323 static
1324 char *get_map_shm(struct sock_info *sock_info)
1325 {
1326         long page_size;
1327         int wait_shm_fd, ret;
1328         char *wait_shm_mmap;
1329
1330         page_size = sysconf(_SC_PAGE_SIZE);
1331         if (page_size <= 0) {
1332                 if (!page_size) {
1333                         errno = EINVAL;
1334                 }
1335                 PERROR("Error in sysconf(_SC_PAGE_SIZE)");
1336                 goto error;
1337         }
1338
1339         lttng_ust_lock_fd_tracker();
1340         wait_shm_fd = get_wait_shm(sock_info, page_size);
1341         if (wait_shm_fd < 0) {
1342                 lttng_ust_unlock_fd_tracker();
1343                 goto error;
1344         }
1345
1346         ret = lttng_ust_add_fd_to_tracker(wait_shm_fd);
1347         if (ret < 0) {
1348                 ret = close(wait_shm_fd);
1349                 if (!ret) {
1350                         PERROR("Error closing fd");
1351                 }
1352                 lttng_ust_unlock_fd_tracker();
1353                 goto error;
1354         }
1355
1356         wait_shm_fd = ret;
1357         lttng_ust_unlock_fd_tracker();
1358
1359         wait_shm_mmap = mmap(NULL, page_size, PROT_READ,
1360                   MAP_SHARED, wait_shm_fd, 0);
1361
1362         /* close shm fd immediately after taking the mmap reference */
1363         lttng_ust_lock_fd_tracker();
1364         ret = close(wait_shm_fd);
1365         if (!ret) {
1366                 lttng_ust_delete_fd_from_tracker(wait_shm_fd);
1367         } else {
1368                 PERROR("Error closing fd");
1369         }
1370         lttng_ust_unlock_fd_tracker();
1371
1372         if (wait_shm_mmap == MAP_FAILED) {
1373                 DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
1374                 goto error;
1375         }
1376         return wait_shm_mmap;
1377
1378 error:
1379         return NULL;
1380 }
1381
1382 static
1383 void wait_for_sessiond(struct sock_info *sock_info)
1384 {
1385         /* Use ust_lock to check if we should quit. */
1386         if (ust_lock()) {
1387                 goto quit;
1388         }
1389         if (wait_poll_fallback) {
1390                 goto error;
1391         }
1392         ust_unlock();
1393
1394         assert(sock_info->wait_shm_mmap);
1395
1396         DBG("Waiting for %s apps sessiond", sock_info->name);
1397         /* Wait for futex wakeup */
1398         if (uatomic_read((int32_t *) sock_info->wait_shm_mmap))
1399                 goto end_wait;
1400
1401         while (futex_async((int32_t *) sock_info->wait_shm_mmap,
1402                         FUTEX_WAIT, 0, NULL, NULL, 0)) {
1403                 switch (errno) {
1404                 case EWOULDBLOCK:
1405                         /* Value already changed. */
1406                         goto end_wait;
1407                 case EINTR:
1408                         /* Retry if interrupted by signal. */
1409                         break;  /* Get out of switch. */
1410                 case EFAULT:
1411                         wait_poll_fallback = 1;
1412                         DBG(
1413 "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
1414 "do not support FUTEX_WAKE on read-only memory mappings correctly. "
1415 "Please upgrade your kernel "
1416 "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
1417 "mainline). LTTng-UST will use polling mode fallback.");
1418                         if (ust_debug())
1419                                 PERROR("futex");
1420                         goto end_wait;
1421                 }
1422         }
1423 end_wait:
1424         return;
1425
1426 quit:
1427         ust_unlock();
1428         return;
1429
1430 error:
1431         ust_unlock();
1432         return;
1433 }
1434
1435 /*
1436  * This thread does not allocate any resource, except within
1437  * handle_message, within mutex protection. This mutex protects against
1438  * fork and exit.
1439  * The other moment it allocates resources is at socket connection, which
1440  * is also protected by the mutex.
1441  */
1442 static
1443 void *ust_listener_thread(void *arg)
1444 {
1445         struct sock_info *sock_info = arg;
1446         int sock, ret, prev_connect_failed = 0, has_waited = 0, fd;
1447         long timeout;
1448
1449         lttng_ust_fixup_tls();
1450         /*
1451          * If available, add '-ust' to the end of this thread's
1452          * process name
1453          */
1454         ret = lttng_ust_setustprocname();
1455         if (ret) {
1456                 ERR("Unable to set UST process name");
1457         }
1458
1459         /* Restart trying to connect to the session daemon */
1460 restart:
1461         if (prev_connect_failed) {
1462                 /* Wait for sessiond availability with pipe */
1463                 wait_for_sessiond(sock_info);
1464                 if (has_waited) {
1465                         has_waited = 0;
1466                         /*
1467                          * Sleep for 5 seconds before retrying after a
1468                          * sequence of failure / wait / failure. This
1469                          * deals with a killed or broken session daemon.
1470                          */
1471                         sleep(5);
1472                 } else {
1473                         has_waited = 1;
1474                 }
1475                 prev_connect_failed = 0;
1476         }
1477
1478         if (ust_lock()) {
1479                 goto quit;
1480         }
1481
1482         if (sock_info->socket != -1) {
1483                 /* FD tracker is updated by ustcomm_close_unix_sock() */
1484                 ret = ustcomm_close_unix_sock(sock_info->socket);
1485                 if (ret) {
1486                         ERR("Error closing %s ust cmd socket",
1487                                 sock_info->name);
1488                 }
1489                 sock_info->socket = -1;
1490         }
1491         if (sock_info->notify_socket != -1) {
1492                 /* FD tracker is updated by ustcomm_close_unix_sock() */
1493                 ret = ustcomm_close_unix_sock(sock_info->notify_socket);
1494                 if (ret) {
1495                         ERR("Error closing %s ust notify socket",
1496                                 sock_info->name);
1497                 }
1498                 sock_info->notify_socket = -1;
1499         }
1500
1501
1502         /*
1503          * Register. We need to perform both connect and sending
1504          * registration message before doing the next connect otherwise
1505          * we may reach unix socket connect queue max limits and block
1506          * on the 2nd connect while the session daemon is awaiting the
1507          * first connect registration message.
1508          */
1509         /* Connect cmd socket */
1510         lttng_ust_lock_fd_tracker();
1511         ret = ustcomm_connect_unix_sock(sock_info->sock_path,
1512                 get_connect_sock_timeout());
1513         if (ret < 0) {
1514                 lttng_ust_unlock_fd_tracker();
1515                 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
1516                 prev_connect_failed = 1;
1517
1518                 /*
1519                  * If we cannot find the sessiond daemon, don't delay
1520                  * constructor execution.
1521                  */
1522                 ret = handle_register_failed(sock_info);
1523                 assert(!ret);
1524                 ust_unlock();
1525                 goto restart;
1526         }
1527         fd = ret;
1528         ret = lttng_ust_add_fd_to_tracker(fd);
1529         if (ret < 0) {
1530                 ret = close(fd);
1531                 if (ret) {
1532                         PERROR("close on sock_info->socket");
1533                 }
1534                 ret = -1;
1535                 lttng_ust_unlock_fd_tracker();
1536                 ust_unlock();
1537                 goto quit;
1538         }
1539
1540         sock_info->socket = ret;
1541         lttng_ust_unlock_fd_tracker();
1542
1543         ust_unlock();
1544         /*
1545          * Unlock/relock ust lock because connect is blocking (with
1546          * timeout). Don't delay constructors on the ust lock for too
1547          * long.
1548          */
1549         if (ust_lock()) {
1550                 goto quit;
1551         }
1552
1553         /*
1554          * Create only one root handle per listener thread for the whole
1555          * process lifetime, so we ensure we get ID which is statically
1556          * assigned to the root handle.
1557          */
1558         if (sock_info->root_handle == -1) {
1559                 ret = lttng_abi_create_root_handle();
1560                 if (ret < 0) {
1561                         ERR("Error creating root handle");
1562                         goto quit;
1563                 }
1564                 sock_info->root_handle = ret;
1565         }
1566
1567         ret = register_to_sessiond(sock_info->socket, USTCTL_SOCKET_CMD);
1568         if (ret < 0) {
1569                 ERR("Error registering to %s ust cmd socket",
1570                         sock_info->name);
1571                 prev_connect_failed = 1;
1572                 /*
1573                  * If we cannot register to the sessiond daemon, don't
1574                  * delay constructor execution.
1575                  */
1576                 ret = handle_register_failed(sock_info);
1577                 assert(!ret);
1578                 ust_unlock();
1579                 goto restart;
1580         }
1581
1582         ust_unlock();
1583         /*
1584          * Unlock/relock ust lock because connect is blocking (with
1585          * timeout). Don't delay constructors on the ust lock for too
1586          * long.
1587          */
1588         if (ust_lock()) {
1589                 goto quit;
1590         }
1591
1592         /* Connect notify socket */
1593         lttng_ust_lock_fd_tracker();
1594         ret = ustcomm_connect_unix_sock(sock_info->sock_path,
1595                 get_connect_sock_timeout());
1596         if (ret < 0) {
1597                 lttng_ust_unlock_fd_tracker();
1598                 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
1599                 prev_connect_failed = 1;
1600
1601                 /*
1602                  * If we cannot find the sessiond daemon, don't delay
1603                  * constructor execution.
1604                  */
1605                 ret = handle_register_failed(sock_info);
1606                 assert(!ret);
1607                 ust_unlock();
1608                 goto restart;
1609         }
1610
1611         fd = ret;
1612         ret = lttng_ust_add_fd_to_tracker(fd);
1613         if (ret < 0) {
1614                 ret = close(fd);
1615                 if (ret) {
1616                         PERROR("close on sock_info->notify_socket");
1617                 }
1618                 ret = -1;
1619                 lttng_ust_unlock_fd_tracker();
1620                 ust_unlock();
1621                 goto quit;
1622         }
1623
1624         sock_info->notify_socket = ret;
1625         lttng_ust_unlock_fd_tracker();
1626
1627         ust_unlock();
1628         /*
1629          * Unlock/relock ust lock because connect is blocking (with
1630          * timeout). Don't delay constructors on the ust lock for too
1631          * long.
1632          */
1633         if (ust_lock()) {
1634                 goto quit;
1635         }
1636
1637         timeout = get_notify_sock_timeout();
1638         if (timeout >= 0) {
1639                 /*
1640                  * Give at least 10ms to sessiond to reply to
1641                  * notifications.
1642                  */
1643                 if (timeout < 10)
1644                         timeout = 10;
1645                 ret = ustcomm_setsockopt_rcv_timeout(sock_info->notify_socket,
1646                                 timeout);
1647                 if (ret < 0) {
1648                         WARN("Error setting socket receive timeout");
1649                 }
1650                 ret = ustcomm_setsockopt_snd_timeout(sock_info->notify_socket,
1651                                 timeout);
1652                 if (ret < 0) {
1653                         WARN("Error setting socket send timeout");
1654                 }
1655         } else if (timeout < -1) {
1656                 WARN("Unsupported timeout value %ld", timeout);
1657         }
1658
1659         ret = register_to_sessiond(sock_info->notify_socket,
1660                         USTCTL_SOCKET_NOTIFY);
1661         if (ret < 0) {
1662                 ERR("Error registering to %s ust notify socket",
1663                         sock_info->name);
1664                 prev_connect_failed = 1;
1665                 /*
1666                  * If we cannot register to the sessiond daemon, don't
1667                  * delay constructor execution.
1668                  */
1669                 ret = handle_register_failed(sock_info);
1670                 assert(!ret);
1671                 ust_unlock();
1672                 goto restart;
1673         }
1674         sock = sock_info->socket;
1675
1676         ust_unlock();
1677
1678         for (;;) {
1679                 ssize_t len;
1680                 struct ustcomm_ust_msg lum;
1681
1682                 len = ustcomm_recv_unix_sock(sock, &lum, sizeof(lum));
1683                 switch (len) {
1684                 case 0: /* orderly shutdown */
1685                         DBG("%s lttng-sessiond has performed an orderly shutdown", sock_info->name);
1686                         if (ust_lock()) {
1687                                 goto quit;
1688                         }
1689                         /*
1690                          * Either sessiond has shutdown or refused us by closing the socket.
1691                          * In either case, we don't want to delay construction execution,
1692                          * and we need to wait before retry.
1693                          */
1694                         prev_connect_failed = 1;
1695                         /*
1696                          * If we cannot register to the sessiond daemon, don't
1697                          * delay constructor execution.
1698                          */
1699                         ret = handle_register_failed(sock_info);
1700                         assert(!ret);
1701                         ust_unlock();
1702                         goto end;
1703                 case sizeof(lum):
1704                         print_cmd(lum.cmd, lum.handle);
1705                         ret = handle_message(sock_info, sock, &lum);
1706                         if (ret) {
1707                                 ERR("Error handling message for %s socket",
1708                                         sock_info->name);
1709                                 /*
1710                                  * Close socket if protocol error is
1711                                  * detected.
1712                                  */
1713                                 goto end;
1714                         }
1715                         continue;
1716                 default:
1717                         if (len < 0) {
1718                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
1719                         } else {
1720                                 DBG("incorrect message size (%s socket): %zd", sock_info->name, len);
1721                         }
1722                         if (len == -ECONNRESET) {
1723                                 DBG("%s remote end closed connection", sock_info->name);
1724                                 goto end;
1725                         }
1726                         goto end;
1727                 }
1728
1729         }
1730 end:
1731         if (ust_lock()) {
1732                 goto quit;
1733         }
1734         /* Cleanup socket handles before trying to reconnect */
1735         lttng_ust_objd_table_owner_cleanup(sock_info);
1736         ust_unlock();
1737         goto restart;   /* try to reconnect */
1738
1739 quit:
1740         ust_unlock();
1741
1742         pthread_mutex_lock(&ust_exit_mutex);
1743         sock_info->thread_active = 0;
1744         pthread_mutex_unlock(&ust_exit_mutex);
1745         return NULL;
1746 }
1747
1748 /*
1749  * Weak symbol to call when the ust malloc wrapper is not loaded.
1750  */
1751 __attribute__((weak))
1752 void lttng_ust_malloc_wrapper_init(void)
1753 {
1754 }
1755
1756 /*
1757  * sessiond monitoring thread: monitor presence of global and per-user
1758  * sessiond by polling the application common named pipe.
1759  */
1760 void __attribute__((constructor)) lttng_ust_init(void)
1761 {
1762         struct timespec constructor_timeout;
1763         sigset_t sig_all_blocked, orig_parent_mask;
1764         pthread_attr_t thread_attr;
1765         int timeout_mode;
1766         int ret;
1767
1768         if (uatomic_xchg(&initialized, 1) == 1)
1769                 return;
1770
1771         /*
1772          * Fixup interdependency between TLS fixup mutex (which happens
1773          * to be the dynamic linker mutex) and ust_lock, taken within
1774          * the ust lock.
1775          */
1776         lttng_ust_fixup_tls();
1777
1778         lttng_ust_loaded = 1;
1779
1780         /*
1781          * We want precise control over the order in which we construct
1782          * our sub-libraries vs starting to receive commands from
1783          * sessiond (otherwise leading to errors when trying to create
1784          * sessiond before the init functions are completed).
1785          */
1786         init_usterr();
1787         lttng_ust_getenv_init();        /* Needs init_usterr() to be completed. */
1788         init_tracepoint();
1789         lttng_ust_init_fd_tracker();
1790         lttng_ust_clock_init();
1791         lttng_ust_getcpu_init();
1792         lttng_ust_statedump_init();
1793         lttng_ring_buffer_metadata_client_init();
1794         lttng_ring_buffer_client_overwrite_init();
1795         lttng_ring_buffer_client_overwrite_rt_init();
1796         lttng_ring_buffer_client_discard_init();
1797         lttng_ring_buffer_client_discard_rt_init();
1798         lttng_perf_counter_init();
1799         /*
1800          * Invoke ust malloc wrapper init before starting other threads.
1801          */
1802         lttng_ust_malloc_wrapper_init();
1803
1804         timeout_mode = get_constructor_timeout(&constructor_timeout);
1805
1806         get_allow_blocking();
1807
1808         ret = sem_init(&constructor_wait, 0, 0);
1809         if (ret) {
1810                 PERROR("sem_init");
1811         }
1812
1813         ret = setup_global_apps();
1814         if (ret) {
1815                 assert(global_apps.allowed == 0);
1816                 DBG("global apps setup returned %d", ret);
1817         }
1818
1819         ret = setup_local_apps();
1820         if (ret) {
1821                 assert(local_apps.allowed == 0);
1822                 DBG("local apps setup returned %d", ret);
1823         }
1824
1825         /* A new thread created by pthread_create inherits the signal mask
1826          * from the parent. To avoid any signal being received by the
1827          * listener thread, we block all signals temporarily in the parent,
1828          * while we create the listener thread.
1829          */
1830         sigfillset(&sig_all_blocked);
1831         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
1832         if (ret) {
1833                 ERR("pthread_sigmask: %s", strerror(ret));
1834         }
1835
1836         ret = pthread_attr_init(&thread_attr);
1837         if (ret) {
1838                 ERR("pthread_attr_init: %s", strerror(ret));
1839         }
1840         ret = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
1841         if (ret) {
1842                 ERR("pthread_attr_setdetachstate: %s", strerror(ret));
1843         }
1844
1845         if (global_apps.allowed) {
1846                 pthread_mutex_lock(&ust_exit_mutex);
1847                 ret = pthread_create(&global_apps.ust_listener, &thread_attr,
1848                                 ust_listener_thread, &global_apps);
1849                 if (ret) {
1850                         ERR("pthread_create global: %s", strerror(ret));
1851                 }
1852                 global_apps.thread_active = 1;
1853                 pthread_mutex_unlock(&ust_exit_mutex);
1854         } else {
1855                 handle_register_done(&global_apps);
1856         }
1857
1858         if (local_apps.allowed) {
1859                 pthread_mutex_lock(&ust_exit_mutex);
1860                 ret = pthread_create(&local_apps.ust_listener, &thread_attr,
1861                                 ust_listener_thread, &local_apps);
1862                 if (ret) {
1863                         ERR("pthread_create local: %s", strerror(ret));
1864                 }
1865                 local_apps.thread_active = 1;
1866                 pthread_mutex_unlock(&ust_exit_mutex);
1867         } else {
1868                 handle_register_done(&local_apps);
1869         }
1870         ret = pthread_attr_destroy(&thread_attr);
1871         if (ret) {
1872                 ERR("pthread_attr_destroy: %s", strerror(ret));
1873         }
1874
1875         /* Restore original signal mask in parent */
1876         ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
1877         if (ret) {
1878                 ERR("pthread_sigmask: %s", strerror(ret));
1879         }
1880
1881         switch (timeout_mode) {
1882         case 1: /* timeout wait */
1883                 do {
1884                         ret = sem_timedwait(&constructor_wait,
1885                                         &constructor_timeout);
1886                 } while (ret < 0 && errno == EINTR);
1887                 if (ret < 0) {
1888                         switch (errno) {
1889                         case ETIMEDOUT:
1890                                 ERR("Timed out waiting for lttng-sessiond");
1891                                 break;
1892                         case EINVAL:
1893                                 PERROR("sem_timedwait");
1894                                 break;
1895                         default:
1896                                 ERR("Unexpected error \"%s\" returned by sem_timedwait",
1897                                         strerror(errno));
1898                         }
1899                 }
1900                 break;
1901         case -1:/* wait forever */
1902                 do {
1903                         ret = sem_wait(&constructor_wait);
1904                 } while (ret < 0 && errno == EINTR);
1905                 if (ret < 0) {
1906                         switch (errno) {
1907                         case EINVAL:
1908                                 PERROR("sem_wait");
1909                                 break;
1910                         default:
1911                                 ERR("Unexpected error \"%s\" returned by sem_wait",
1912                                         strerror(errno));
1913                         }
1914                 }
1915                 break;
1916         case 0: /* no timeout */
1917                 break;
1918         }
1919 }
1920
1921 static
1922 void lttng_ust_cleanup(int exiting)
1923 {
1924         cleanup_sock_info(&global_apps, exiting);
1925         cleanup_sock_info(&local_apps, exiting);
1926         local_apps.allowed = 0;
1927         global_apps.allowed = 0;
1928         /*
1929          * The teardown in this function all affect data structures
1930          * accessed under the UST lock by the listener thread. This
1931          * lock, along with the lttng_ust_comm_should_quit flag, ensure
1932          * that none of these threads are accessing this data at this
1933          * point.
1934          */
1935         lttng_ust_abi_exit();
1936         lttng_ust_events_exit();
1937         lttng_perf_counter_exit();
1938         lttng_ring_buffer_client_discard_rt_exit();
1939         lttng_ring_buffer_client_discard_exit();
1940         lttng_ring_buffer_client_overwrite_rt_exit();
1941         lttng_ring_buffer_client_overwrite_exit();
1942         lttng_ring_buffer_metadata_client_exit();
1943         lttng_ust_statedump_destroy();
1944         exit_tracepoint();
1945         if (!exiting) {
1946                 /* Reinitialize values for fork */
1947                 sem_count = sem_count_initial_value;
1948                 lttng_ust_comm_should_quit = 0;
1949                 initialized = 0;
1950         }
1951 }
1952
1953 void __attribute__((destructor)) lttng_ust_exit(void)
1954 {
1955         int ret;
1956
1957         /*
1958          * Using pthread_cancel here because:
1959          * A) we don't want to hang application teardown.
1960          * B) the thread is not allocating any resource.
1961          */
1962
1963         /*
1964          * Require the communication thread to quit. Synchronize with
1965          * mutexes to ensure it is not in a mutex critical section when
1966          * pthread_cancel is later called.
1967          */
1968         ust_lock_nocheck();
1969         lttng_ust_comm_should_quit = 1;
1970         ust_unlock();
1971
1972         pthread_mutex_lock(&ust_exit_mutex);
1973         /* cancel threads */
1974         if (global_apps.thread_active) {
1975                 ret = pthread_cancel(global_apps.ust_listener);
1976                 if (ret) {
1977                         ERR("Error cancelling global ust listener thread: %s",
1978                                 strerror(ret));
1979                 } else {
1980                         global_apps.thread_active = 0;
1981                 }
1982         }
1983         if (local_apps.thread_active) {
1984                 ret = pthread_cancel(local_apps.ust_listener);
1985                 if (ret) {
1986                         ERR("Error cancelling local ust listener thread: %s",
1987                                 strerror(ret));
1988                 } else {
1989                         local_apps.thread_active = 0;
1990                 }
1991         }
1992         pthread_mutex_unlock(&ust_exit_mutex);
1993
1994         /*
1995          * Do NOT join threads: use of sys_futex makes it impossible to
1996          * join the threads without using async-cancel, but async-cancel
1997          * is delivered by a signal, which could hit the target thread
1998          * anywhere in its code path, including while the ust_lock() is
1999          * held, causing a deadlock for the other thread. Let the OS
2000          * cleanup the threads if there are stalled in a syscall.
2001          */
2002         lttng_ust_cleanup(1);
2003 }
2004
2005 /*
2006  * We exclude the worker threads across fork and clone (except
2007  * CLONE_VM), because these system calls only keep the forking thread
2008  * running in the child.  Therefore, we don't want to call fork or clone
2009  * in the middle of an tracepoint or ust tracing state modification.
2010  * Holding this mutex protects these structures across fork and clone.
2011  */
2012 void ust_before_fork(sigset_t *save_sigset)
2013 {
2014         /*
2015          * Disable signals. This is to avoid that the child intervenes
2016          * before it is properly setup for tracing. It is safer to
2017          * disable all signals, because then we know we are not breaking
2018          * anything by restoring the original mask.
2019          */
2020         sigset_t all_sigs;
2021         int ret;
2022
2023         /* Fixup lttng-ust TLS. */
2024         lttng_ust_fixup_tls();
2025
2026         if (URCU_TLS(lttng_ust_nest_count))
2027                 return;
2028         /* Disable signals */
2029         sigfillset(&all_sigs);
2030         ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset);
2031         if (ret == -1) {
2032                 PERROR("sigprocmask");
2033         }
2034
2035         pthread_mutex_lock(&ust_fork_mutex);
2036
2037         ust_lock_nocheck();
2038         rcu_bp_before_fork();
2039 }
2040
2041 static void ust_after_fork_common(sigset_t *restore_sigset)
2042 {
2043         int ret;
2044
2045         DBG("process %d", getpid());
2046         ust_unlock();
2047
2048         pthread_mutex_unlock(&ust_fork_mutex);
2049
2050         /* Restore signals */
2051         ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL);
2052         if (ret == -1) {
2053                 PERROR("sigprocmask");
2054         }
2055 }
2056
2057 void ust_after_fork_parent(sigset_t *restore_sigset)
2058 {
2059         if (URCU_TLS(lttng_ust_nest_count))
2060                 return;
2061         DBG("process %d", getpid());
2062         rcu_bp_after_fork_parent();
2063         /* Release mutexes and reenable signals */
2064         ust_after_fork_common(restore_sigset);
2065 }
2066
2067 /*
2068  * After fork, in the child, we need to cleanup all the leftover state,
2069  * except the worker thread which already magically disappeared thanks
2070  * to the weird Linux fork semantics. After tyding up, we call
2071  * lttng_ust_init() again to start over as a new PID.
2072  *
2073  * This is meant for forks() that have tracing in the child between the
2074  * fork and following exec call (if there is any).
2075  */
2076 void ust_after_fork_child(sigset_t *restore_sigset)
2077 {
2078         if (URCU_TLS(lttng_ust_nest_count))
2079                 return;
2080         lttng_context_vpid_reset();
2081         lttng_context_vtid_reset();
2082         lttng_context_procname_reset();
2083         DBG("process %d", getpid());
2084         /* Release urcu mutexes */
2085         rcu_bp_after_fork_child();
2086         lttng_ust_cleanup(0);
2087         /* Release mutexes and reenable signals */
2088         ust_after_fork_common(restore_sigset);
2089         lttng_ust_init();
2090 }
2091
2092 void lttng_ust_sockinfo_session_enabled(void *owner)
2093 {
2094         struct sock_info *sock_info = owner;
2095         sock_info->statedump_pending = 1;
2096 }