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         if (!sock_info->statedump_pending) {
 655                 sock_info->initial_statedump_done = 1;
 656                 decrement_sem_count(1);
 657         }
 658
 659         return 0;
 660 }
 661
 662 static
 663 int handle_register_failed(struct sock_info *sock_info)
 664 {
 665         if (sock_info->registration_done)
 666                 return 0;
 667         sock_info->registration_done = 1;
 668         sock_info->initial_statedump_done = 1;
 669
 670         decrement_sem_count(2);
 671
 672         return 0;
 673 }
 674
 675 /*
 676  * Only execute pending statedump after the constructor semaphore has
 677  * been posted by the current listener thread. This means statedump will
 678  * only be performed after the "registration done" command is received
 679  * from this thread's session daemon.
 680  *
 681  * This ensures we don't run into deadlock issues with the dynamic
 682  * loader mutex, which is held while the constructor is called and
 683  * waiting on the constructor semaphore. All operations requiring this
 684  * dynamic loader lock need to be postponed using this mechanism.
 685  *
 686  * In a scenario with two session daemons connected to the application,
 687  * it is possible that the first listener thread which receives the
 688  * registration done command issues its statedump while the dynamic
 689  * loader lock is still held by the application constructor waiting on
 690  * the semaphore. It will however be allowed to proceed when the
 691  * second session daemon sends the registration done command to the
 692  * second listener thread. This situation therefore does not produce
 693  * a deadlock.
 694  */
 695 static
 696 void handle_pending_statedump(struct sock_info *sock_info)
 697 {
 698         if (sock_info->registration_done && sock_info->statedump_pending) {
 699                 sock_info->statedump_pending = 0;
 700                 pthread_mutex_lock(&ust_fork_mutex);
 701                 lttng_handle_pending_statedump(sock_info);
 702                 pthread_mutex_unlock(&ust_fork_mutex);
 703
 704                 if (!sock_info->initial_statedump_done) {
 705                         sock_info->initial_statedump_done = 1;
 706                         decrement_sem_count(1);
 707                 }
 708         }
 709 }
 710
 711 static
 712 int handle_message(struct sock_info *sock_info,
 713                 int sock, struct ustcomm_ust_msg *lum)
 714 {
 715         int ret = 0;
 716         const struct lttng_ust_objd_ops *ops;
 717         struct ustcomm_ust_reply lur;
 718         union ust_args args;
 719         char ctxstr[LTTNG_UST_SYM_NAME_LEN];    /* App context string. */
 720         ssize_t len;
 721
 722         memset(&lur, 0, sizeof(lur));
 723
 724         if (ust_lock()) {
 725                 ret = -LTTNG_UST_ERR_EXITING;
 726                 goto error;
 727         }
 728
 729         ops = objd_ops(lum->handle);
 730         if (!ops) {
 731                 ret = -ENOENT;
 732                 goto error;
 733         }
 734
 735         switch (lum->cmd) {
 736         case LTTNG_UST_REGISTER_DONE:
 737                 if (lum->handle == LTTNG_UST_ROOT_HANDLE)
 738                         ret = handle_register_done(sock_info);
 739                 else
 740                         ret = -EINVAL;
 741                 break;
 742         case LTTNG_UST_RELEASE:
 743                 if (lum->handle == LTTNG_UST_ROOT_HANDLE)
 744                         ret = -EPERM;
 745                 else
 746                         ret = lttng_ust_objd_unref(lum->handle, 1);
 747                 break;
 748         case LTTNG_UST_FILTER:
 749         {
 750                 /* Receive filter data */
 751                 struct lttng_ust_filter_bytecode_node *bytecode;
 752
 753                 if (lum->u.filter.data_size > FILTER_BYTECODE_MAX_LEN) {
 754                         ERR("Filter data size is too large: %u bytes",
 755                                 lum->u.filter.data_size);
 756                         ret = -EINVAL;
 757                         goto error;
 758                 }
 759
 760                 if (lum->u.filter.reloc_offset > lum->u.filter.data_size) {
 761                         ERR("Filter reloc offset %u is not within data",
 762                                 lum->u.filter.reloc_offset);
 763                         ret = -EINVAL;
 764                         goto error;
 765                 }
 766
 767                 bytecode = zmalloc(sizeof(*bytecode) + lum->u.filter.data_size);
 768                 if (!bytecode) {
 769                         ret = -ENOMEM;
 770                         goto error;
 771                 }
 772                 len = ustcomm_recv_unix_sock(sock, bytecode->bc.data,
 773                                 lum->u.filter.data_size);
 774                 switch (len) {
 775                 case 0: /* orderly shutdown */
 776                         ret = 0;
 777                         free(bytecode);
 778                         goto error;
 779                 default:
 780                         if (len == lum->u.filter.data_size) {
 781                                 DBG("filter data received");
 782                                 break;
 783                         } else if (len < 0) {
 784                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 785                                 if (len == -ECONNRESET) {
 786                                         ERR("%s remote end closed connection", sock_info->name);
 787                                         ret = len;
 788                                         free(bytecode);
 789                                         goto error;
 790                                 }
 791                                 ret = len;
 792                                 free(bytecode);
 793                                 goto error;
 794                         } else {
 795                                 DBG("incorrect filter data message size: %zd", len);
 796                                 ret = -EINVAL;
 797                                 free(bytecode);
 798                                 goto error;
 799                         }
 800                 }
 801                 bytecode->bc.len = lum->u.filter.data_size;
 802                 bytecode->bc.reloc_offset = lum->u.filter.reloc_offset;
 803                 bytecode->bc.seqnum = lum->u.filter.seqnum;
 804                 if (ops->cmd) {
 805                         ret = ops->cmd(lum->handle, lum->cmd,
 806                                         (unsigned long) bytecode,
 807                                         &args, sock_info);
 808                         if (ret) {
 809                                 free(bytecode);
 810                         }
 811                         /* don't free bytecode if everything went fine. */
 812                 } else {
 813                         ret = -ENOSYS;
 814                         free(bytecode);
 815                 }
 816                 break;
 817         }
 818         case LTTNG_UST_EXCLUSION:
 819         {
 820                 /* Receive exclusion names */
 821                 struct lttng_ust_excluder_node *node;
 822                 unsigned int count;
 823
 824                 count = lum->u.exclusion.count;
 825                 if (count == 0) {
 826                         /* There are no names to read */
 827                         ret = 0;
 828                         goto error;
 829                 }
 830                 node = zmalloc(sizeof(*node) +
 831                                 count * LTTNG_UST_SYM_NAME_LEN);
 832                 if (!node) {
 833                         ret = -ENOMEM;
 834                         goto error;
 835                 }
 836                 node->excluder.count = count;
 837                 len = ustcomm_recv_unix_sock(sock, node->excluder.names,
 838                                 count * LTTNG_UST_SYM_NAME_LEN);
 839                 switch (len) {
 840                 case 0: /* orderly shutdown */
 841                         ret = 0;
 842                         free(node);
 843                         goto error;
 844                 default:
 845                         if (len == count * LTTNG_UST_SYM_NAME_LEN) {
 846                                 DBG("Exclusion data received");
 847                                 break;
 848                         } else if (len < 0) {
 849                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 850                                 if (len == -ECONNRESET) {
 851                                         ERR("%s remote end closed connection", sock_info->name);
 852                                         ret = len;
 853                                         free(node);
 854                                         goto error;
 855                                 }
 856                                 ret = len;
 857                                 free(node);
 858                                 goto error;
 859                         } else {
 860                                 DBG("Incorrect exclusion data message size: %zd", len);
 861                                 ret = -EINVAL;
 862                                 free(node);
 863                                 goto error;
 864                         }
 865                 }
 866                 if (ops->cmd) {
 867                         ret = ops->cmd(lum->handle, lum->cmd,
 868                                         (unsigned long) node,
 869                                         &args, sock_info);
 870                         if (ret) {
 871                                 free(node);
 872                         }
 873                         /* Don't free exclusion data if everything went fine. */
 874                 } else {
 875                         ret = -ENOSYS;
 876                         free(node);
 877                 }
 878                 break;
 879         }
 880         case LTTNG_UST_CHANNEL:
 881         {
 882                 void *chan_data;
 883                 int wakeup_fd;
 884
 885                 len = ustcomm_recv_channel_from_sessiond(sock,
 886                                 &chan_data, lum->u.channel.len,
 887                                 &wakeup_fd);
 888                 switch (len) {
 889                 case 0: /* orderly shutdown */
 890                         ret = 0;
 891                         goto error;
 892                 default:
 893                         if (len == lum->u.channel.len) {
 894                                 DBG("channel data received");
 895                                 break;
 896                         } else if (len < 0) {
 897                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 898                                 if (len == -ECONNRESET) {
 899                                         ERR("%s remote end closed connection", sock_info->name);
 900                                         ret = len;
 901                                         goto error;
 902                                 }
 903                                 ret = len;
 904                                 goto error;
 905                         } else {
 906                                 DBG("incorrect channel data message size: %zd", len);
 907                                 ret = -EINVAL;
 908                                 goto error;
 909                         }
 910                 }
 911                 args.channel.chan_data = chan_data;
 912                 args.channel.wakeup_fd = wakeup_fd;
 913                 if (ops->cmd)
 914                         ret = ops->cmd(lum->handle, lum->cmd,
 915                                         (unsigned long) &lum->u,
 916                                         &args, sock_info);
 917                 else
 918                         ret = -ENOSYS;
 919                 break;
 920         }
 921         case LTTNG_UST_STREAM:
 922         {
 923                 /* Receive shm_fd, wakeup_fd */
 924                 ret = ustcomm_recv_stream_from_sessiond(sock,
 925                         NULL,
 926                         &args.stream.shm_fd,
 927                         &args.stream.wakeup_fd);
 928                 if (ret) {
 929                         goto error;
 930                 }
 931
 932                 if (ops->cmd)
 933                         ret = ops->cmd(lum->handle, lum->cmd,
 934                                         (unsigned long) &lum->u,
 935                                         &args, sock_info);
 936                 else
 937                         ret = -ENOSYS;
 938                 break;
 939         }
 940         case LTTNG_UST_CONTEXT:
 941                 switch (lum->u.context.ctx) {
 942                 case LTTNG_UST_CONTEXT_APP_CONTEXT:
 943                 {
 944                         char *p;
 945                         size_t ctxlen, recvlen;
 946
 947                         ctxlen = strlen("$app.") + lum->u.context.u.app_ctx.provider_name_len - 1
 948                                         + strlen(":") + lum->u.context.u.app_ctx.ctx_name_len;
 949                         if (ctxlen >= LTTNG_UST_SYM_NAME_LEN) {
 950                                 ERR("Application context string length size is too large: %zu bytes",
 951                                         ctxlen);
 952                                 ret = -EINVAL;
 953                                 goto error;
 954                         }
 955                         strcpy(ctxstr, "$app.");
 956                         p = &ctxstr[strlen("$app.")];
 957                         recvlen = ctxlen - strlen("$app.");
 958                         len = ustcomm_recv_unix_sock(sock, p, recvlen);
 959                         switch (len) {
 960                         case 0: /* orderly shutdown */
 961                                 ret = 0;
 962                                 goto error;
 963                         default:
 964                                 if (len == recvlen) {
 965                                         DBG("app context data received");
 966                                         break;
 967                                 } else if (len < 0) {
 968                                         DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 969                                         if (len == -ECONNRESET) {
 970                                                 ERR("%s remote end closed connection", sock_info->name);
 971                                                 ret = len;
 972                                                 goto error;
 973                                         }
 974                                         ret = len;
 975                                         goto error;
 976                                 } else {
 977                                         DBG("incorrect app context data message size: %zd", len);
 978                                         ret = -EINVAL;
 979                                         goto error;
 980                                 }
 981                         }
 982                         /* Put : between provider and ctxname. */
 983                         p[lum->u.context.u.app_ctx.provider_name_len - 1] = ':';
 984                         args.app_context.ctxname = ctxstr;
 985                         break;
 986                 }
 987                 default:
 988                         break;
 989                 }
 990                 if (ops->cmd) {
 991                         ret = ops->cmd(lum->handle, lum->cmd,
 992                                         (unsigned long) &lum->u,
 993                                         &args, sock_info);
 994                 } else {
 995                         ret = -ENOSYS;
 996                 }
 997                 break;
 998         default:
 999                 if (ops->cmd)
1000                         ret = ops->cmd(lum->handle, lum->cmd,
1001                                         (unsigned long) &lum->u,
1002                                         &args, sock_info);
1003                 else
1004                         ret = -ENOSYS;
1005                 break;
1006         }
1007
1008         lur.handle = lum->handle;
1009         lur.cmd = lum->cmd;
1010         lur.ret_val = ret;
1011         if (ret >= 0) {
1012                 lur.ret_code = LTTNG_UST_OK;
1013         } else {
1014                 /*
1015                  * Use -LTTNG_UST_ERR as wildcard for UST internal
1016                  * error that are not caused by the transport, except if
1017                  * we already have a more precise error message to
1018                  * report.
1019                  */
1020                 if (ret > -LTTNG_UST_ERR) {
1021                         /* Translate code to UST error. */
1022                         switch (ret) {
1023                         case -EEXIST:
1024                                 lur.ret_code = -LTTNG_UST_ERR_EXIST;
1025                                 break;
1026                         case -EINVAL:
1027                                 lur.ret_code = -LTTNG_UST_ERR_INVAL;
1028                                 break;
1029                         case -ENOENT:
1030                                 lur.ret_code = -LTTNG_UST_ERR_NOENT;
1031                                 break;
1032                         case -EPERM:
1033                                 lur.ret_code = -LTTNG_UST_ERR_PERM;
1034                                 break;
1035                         case -ENOSYS:
1036                                 lur.ret_code = -LTTNG_UST_ERR_NOSYS;
1037                                 break;
1038                         default:
1039                                 lur.ret_code = -LTTNG_UST_ERR;
1040                                 break;
1041                         }
1042                 } else {
1043                         lur.ret_code = ret;
1044                 }
1045         }
1046         if (ret >= 0) {
1047                 switch (lum->cmd) {
1048                 case LTTNG_UST_TRACER_VERSION:
1049                         lur.u.version = lum->u.version;
1050                         break;
1051                 case LTTNG_UST_TRACEPOINT_LIST_GET:
1052                         memcpy(&lur.u.tracepoint, &lum->u.tracepoint, sizeof(lur.u.tracepoint));
1053                         break;
1054                 }
1055         }
1056         DBG("Return value: %d", lur.ret_val);
1057
1058         ust_unlock();
1059
1060         /*
1061          * Performed delayed statedump operations outside of the UST
1062          * lock. We need to take the dynamic loader lock before we take
1063          * the UST lock internally within handle_pending_statedump().
1064           */
1065         handle_pending_statedump(sock_info);
1066
1067         if (ust_lock()) {
1068                 ret = -LTTNG_UST_ERR_EXITING;
1069                 goto error;
1070         }
1071
1072         ret = send_reply(sock, &lur);
1073         if (ret < 0) {
1074                 DBG("error sending reply");
1075                 goto error;
1076         }
1077
1078         /*
1079          * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
1080          * after the reply.
1081          */
1082         if (lur.ret_code == LTTNG_UST_OK) {
1083                 switch (lum->cmd) {
1084                 case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
1085                         len = ustcomm_send_unix_sock(sock,
1086                                 &args.field_list.entry,
1087                                 sizeof(args.field_list.entry));
1088                         if (len < 0) {
1089                                 ret = len;
1090                                 goto error;
1091                         }
1092                         if (len != sizeof(args.field_list.entry)) {
1093                                 ret = -EINVAL;
1094                                 goto error;
1095                         }
1096                 }
1097         }
1098
1099 error:
1100         ust_unlock();
1101
1102         return ret;
1103 }
1104
1105 static
1106 void cleanup_sock_info(struct sock_info *sock_info, int exiting)
1107 {
1108         int ret;
1109
1110         if (sock_info->root_handle != -1) {
1111                 ret = lttng_ust_objd_unref(sock_info->root_handle, 1);
1112                 if (ret) {
1113                         ERR("Error unref root handle");
1114                 }
1115                 sock_info->root_handle = -1;
1116         }
1117         sock_info->registration_done = 0;
1118         sock_info->initial_statedump_done = 0;
1119
1120         /*
1121          * wait_shm_mmap, socket and notify socket are used by listener
1122          * threads outside of the ust lock, so we cannot tear them down
1123          * ourselves, because we cannot join on these threads. Leave
1124          * responsibility of cleaning up these resources to the OS
1125          * process exit.
1126          */
1127         if (exiting)
1128                 return;
1129
1130         if (sock_info->socket != -1) {
1131                 ret = ustcomm_close_unix_sock(sock_info->socket);
1132                 if (ret) {
1133                         ERR("Error closing ust cmd socket");
1134                 }
1135                 sock_info->socket = -1;
1136         }
1137         if (sock_info->notify_socket != -1) {
1138                 ret = ustcomm_close_unix_sock(sock_info->notify_socket);
1139                 if (ret) {
1140                         ERR("Error closing ust notify socket");
1141                 }
1142                 sock_info->notify_socket = -1;
1143         }
1144         if (sock_info->wait_shm_mmap) {
1145                 long page_size;
1146
1147                 page_size = sysconf(_SC_PAGE_SIZE);
1148                 if (page_size <= 0) {
1149                         if (!page_size) {
1150                                 errno = EINVAL;
1151                         }
1152                         PERROR("Error in sysconf(_SC_PAGE_SIZE)");
1153                 } else {
1154                         ret = munmap(sock_info->wait_shm_mmap, page_size);
1155                         if (ret) {
1156                                 ERR("Error unmapping wait shm");
1157                         }
1158                 }
1159                 sock_info->wait_shm_mmap = NULL;
1160         }
1161 }
1162
1163 /*
1164  * Using fork to set umask in the child process (not multi-thread safe).
1165  * We deal with the shm_open vs ftruncate race (happening when the
1166  * sessiond owns the shm and does not let everybody modify it, to ensure
1167  * safety against shm_unlink) by simply letting the mmap fail and
1168  * retrying after a few seconds.
1169  * For global shm, everybody has rw access to it until the sessiond
1170  * starts.
1171  */
1172 static
1173 int get_wait_shm(struct sock_info *sock_info, size_t mmap_size)
1174 {
1175         int wait_shm_fd, ret;
1176         pid_t pid;
1177
1178         /*
1179          * Try to open read-only.
1180          */
1181         wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
1182         if (wait_shm_fd >= 0) {
1183                 int32_t tmp_read;
1184                 ssize_t len;
1185                 size_t bytes_read = 0;
1186
1187                 /*
1188                  * Try to read the fd. If unable to do so, try opening
1189                  * it in write mode.
1190                  */
1191                 do {
1192                         len = read(wait_shm_fd,
1193                                 &((char *) &tmp_read)[bytes_read],
1194                                 sizeof(tmp_read) - bytes_read);
1195                         if (len > 0) {
1196                                 bytes_read += len;
1197                         }
1198                 } while ((len < 0 && errno == EINTR)
1199                         || (len > 0 && bytes_read < sizeof(tmp_read)));
1200                 if (bytes_read != sizeof(tmp_read)) {
1201                         ret = close(wait_shm_fd);
1202                         if (ret) {
1203                                 ERR("close wait_shm_fd");
1204                         }
1205                         goto open_write;
1206                 }
1207                 goto end;
1208         } else if (wait_shm_fd < 0 && errno != ENOENT) {
1209                 /*
1210                  * Real-only open did not work, and it's not because the
1211                  * entry was not present. It's a failure that prohibits
1212                  * using shm.
1213                  */
1214                 ERR("Error opening shm %s", sock_info->wait_shm_path);
1215                 goto end;
1216         }
1217
1218 open_write:
1219         /*
1220          * If the open failed because the file did not exist, or because
1221          * the file was not truncated yet, try creating it ourself.
1222          */
1223         URCU_TLS(lttng_ust_nest_count)++;
1224         pid = fork();
1225         URCU_TLS(lttng_ust_nest_count)--;
1226         if (pid > 0) {
1227                 int status;
1228
1229                 /*
1230                  * Parent: wait for child to return, in which case the
1231                  * shared memory map will have been created.
1232                  */
1233                 pid = wait(&status);
1234                 if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
1235                         wait_shm_fd = -1;
1236                         goto end;
1237                 }
1238                 /*
1239                  * Try to open read-only again after creation.
1240                  */
1241                 wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
1242                 if (wait_shm_fd < 0) {
1243                         /*
1244                          * Real-only open did not work. It's a failure
1245                          * that prohibits using shm.
1246                          */
1247                         ERR("Error opening shm %s", sock_info->wait_shm_path);
1248                         goto end;
1249                 }
1250                 goto end;
1251         } else if (pid == 0) {
1252                 int create_mode;
1253
1254                 /* Child */
1255                 create_mode = S_IRUSR | S_IWUSR | S_IRGRP;
1256                 if (sock_info->global)
1257                         create_mode |= S_IROTH | S_IWGRP | S_IWOTH;
1258                 /*
1259                  * We're alone in a child process, so we can modify the
1260                  * process-wide umask.
1261                  */
1262                 umask(~create_mode);
1263                 /*
1264                  * Try creating shm (or get rw access).
1265                  * We don't do an exclusive open, because we allow other
1266                  * processes to create+ftruncate it concurrently.
1267                  */
1268                 wait_shm_fd = shm_open(sock_info->wait_shm_path,
1269                                 O_RDWR | O_CREAT, create_mode);
1270                 if (wait_shm_fd >= 0) {
1271                         ret = ftruncate(wait_shm_fd, mmap_size);
1272                         if (ret) {
1273                                 PERROR("ftruncate");
1274                                 _exit(EXIT_FAILURE);
1275                         }
1276                         _exit(EXIT_SUCCESS);
1277                 }
1278                 /*
1279                  * For local shm, we need to have rw access to accept
1280                  * opening it: this means the local sessiond will be
1281                  * able to wake us up. For global shm, we open it even
1282                  * if rw access is not granted, because the root.root
1283                  * sessiond will be able to override all rights and wake
1284                  * us up.
1285                  */
1286                 if (!sock_info->global && errno != EACCES) {
1287                         ERR("Error opening shm %s", sock_info->wait_shm_path);
1288                         _exit(EXIT_FAILURE);
1289                 }
1290                 /*
1291                  * The shm exists, but we cannot open it RW. Report
1292                  * success.
1293                  */
1294                 _exit(EXIT_SUCCESS);
1295         } else {
1296                 return -1;
1297         }
1298 end:
1299         if (wait_shm_fd >= 0 && !sock_info->global) {
1300                 struct stat statbuf;
1301
1302                 /*
1303                  * Ensure that our user is the owner of the shm file for
1304                  * local shm. If we do not own the file, it means our
1305                  * sessiond will not have access to wake us up (there is
1306                  * probably a rogue process trying to fake our
1307                  * sessiond). Fallback to polling method in this case.
1308                  */
1309                 ret = fstat(wait_shm_fd, &statbuf);
1310                 if (ret) {
1311                         PERROR("fstat");
1312                         goto error_close;
1313                 }
1314                 if (statbuf.st_uid != getuid())
1315                         goto error_close;
1316         }
1317         return wait_shm_fd;
1318
1319 error_close:
1320         ret = close(wait_shm_fd);
1321         if (ret) {
1322                 PERROR("Error closing fd");
1323         }
1324         return -1;
1325 }
1326
1327 static
1328 char *get_map_shm(struct sock_info *sock_info)
1329 {
1330         long page_size;
1331         int wait_shm_fd, ret;
1332         char *wait_shm_mmap;
1333
1334         page_size = sysconf(_SC_PAGE_SIZE);
1335         if (page_size <= 0) {
1336                 if (!page_size) {
1337                         errno = EINVAL;
1338                 }
1339                 PERROR("Error in sysconf(_SC_PAGE_SIZE)");
1340                 goto error;
1341         }
1342
1343         lttng_ust_lock_fd_tracker();
1344         wait_shm_fd = get_wait_shm(sock_info, page_size);
1345         if (wait_shm_fd < 0) {
1346                 lttng_ust_unlock_fd_tracker();
1347                 goto error;
1348         }
1349
1350         ret = lttng_ust_add_fd_to_tracker(wait_shm_fd);
1351         if (ret < 0) {
1352                 ret = close(wait_shm_fd);
1353                 if (!ret) {
1354                         PERROR("Error closing fd");
1355                 }
1356                 lttng_ust_unlock_fd_tracker();
1357                 goto error;
1358         }
1359
1360         wait_shm_fd = ret;
1361         lttng_ust_unlock_fd_tracker();
1362
1363         wait_shm_mmap = mmap(NULL, page_size, PROT_READ,
1364                   MAP_SHARED, wait_shm_fd, 0);
1365
1366         /* close shm fd immediately after taking the mmap reference */
1367         lttng_ust_lock_fd_tracker();
1368         ret = close(wait_shm_fd);
1369         if (!ret) {
1370                 lttng_ust_delete_fd_from_tracker(wait_shm_fd);
1371         } else {
1372                 PERROR("Error closing fd");
1373         }
1374         lttng_ust_unlock_fd_tracker();
1375
1376         if (wait_shm_mmap == MAP_FAILED) {
1377                 DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
1378                 goto error;
1379         }
1380         return wait_shm_mmap;
1381
1382 error:
1383         return NULL;
1384 }
1385
1386 static
1387 void wait_for_sessiond(struct sock_info *sock_info)
1388 {
1389         /* Use ust_lock to check if we should quit. */
1390         if (ust_lock()) {
1391                 goto quit;
1392         }
1393         if (wait_poll_fallback) {
1394                 goto error;
1395         }
1396         ust_unlock();
1397
1398         assert(sock_info->wait_shm_mmap);
1399
1400         DBG("Waiting for %s apps sessiond", sock_info->name);
1401         /* Wait for futex wakeup */
1402         if (uatomic_read((int32_t *) sock_info->wait_shm_mmap))
1403                 goto end_wait;
1404
1405         while (futex_async((int32_t *) sock_info->wait_shm_mmap,
1406                         FUTEX_WAIT, 0, NULL, NULL, 0)) {
1407                 switch (errno) {
1408                 case EWOULDBLOCK:
1409                         /* Value already changed. */
1410                         goto end_wait;
1411                 case EINTR:
1412                         /* Retry if interrupted by signal. */
1413                         break;  /* Get out of switch. */
1414                 case EFAULT:
1415                         wait_poll_fallback = 1;
1416                         DBG(
1417 "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
1418 "do not support FUTEX_WAKE on read-only memory mappings correctly. "
1419 "Please upgrade your kernel "
1420 "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
1421 "mainline). LTTng-UST will use polling mode fallback.");
1422                         if (ust_debug())
1423                                 PERROR("futex");
1424                         goto end_wait;
1425                 }
1426         }
1427 end_wait:
1428         return;
1429
1430 quit:
1431         ust_unlock();
1432         return;
1433
1434 error:
1435         ust_unlock();
1436         return;
1437 }
1438
1439 /*
1440  * This thread does not allocate any resource, except within
1441  * handle_message, within mutex protection. This mutex protects against
1442  * fork and exit.
1443  * The other moment it allocates resources is at socket connection, which
1444  * is also protected by the mutex.
1445  */
1446 static
1447 void *ust_listener_thread(void *arg)
1448 {
1449         struct sock_info *sock_info = arg;
1450         int sock, ret, prev_connect_failed = 0, has_waited = 0, fd;
1451         long timeout;
1452
1453         lttng_ust_fixup_tls();
1454         /*
1455          * If available, add '-ust' to the end of this thread's
1456          * process name
1457          */
1458         ret = lttng_ust_setustprocname();
1459         if (ret) {
1460                 ERR("Unable to set UST process name");
1461         }
1462
1463         /* Restart trying to connect to the session daemon */
1464 restart:
1465         if (prev_connect_failed) {
1466                 /* Wait for sessiond availability with pipe */
1467                 wait_for_sessiond(sock_info);
1468                 if (has_waited) {
1469                         has_waited = 0;
1470                         /*
1471                          * Sleep for 5 seconds before retrying after a
1472                          * sequence of failure / wait / failure. This
1473                          * deals with a killed or broken session daemon.
1474                          */
1475                         sleep(5);
1476                 } else {
1477                         has_waited = 1;
1478                 }
1479                 prev_connect_failed = 0;
1480         }
1481
1482         if (ust_lock()) {
1483                 goto quit;
1484         }
1485
1486         if (sock_info->socket != -1) {
1487                 /* FD tracker is updated by ustcomm_close_unix_sock() */
1488                 ret = ustcomm_close_unix_sock(sock_info->socket);
1489                 if (ret) {
1490                         ERR("Error closing %s ust cmd socket",
1491                                 sock_info->name);
1492                 }
1493                 sock_info->socket = -1;
1494         }
1495         if (sock_info->notify_socket != -1) {
1496                 /* FD tracker is updated by ustcomm_close_unix_sock() */
1497                 ret = ustcomm_close_unix_sock(sock_info->notify_socket);
1498                 if (ret) {
1499                         ERR("Error closing %s ust notify socket",
1500                                 sock_info->name);
1501                 }
1502                 sock_info->notify_socket = -1;
1503         }
1504
1505
1506         /*
1507          * Register. We need to perform both connect and sending
1508          * registration message before doing the next connect otherwise
1509          * we may reach unix socket connect queue max limits and block
1510          * on the 2nd connect while the session daemon is awaiting the
1511          * first connect registration message.
1512          */
1513         /* Connect cmd socket */
1514         lttng_ust_lock_fd_tracker();
1515         ret = ustcomm_connect_unix_sock(sock_info->sock_path,
1516                 get_connect_sock_timeout());
1517         if (ret < 0) {
1518                 lttng_ust_unlock_fd_tracker();
1519                 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
1520                 prev_connect_failed = 1;
1521
1522                 /*
1523                  * If we cannot find the sessiond daemon, don't delay
1524                  * constructor execution.
1525                  */
1526                 ret = handle_register_failed(sock_info);
1527                 assert(!ret);
1528                 ust_unlock();
1529                 goto restart;
1530         }
1531         fd = ret;
1532         ret = lttng_ust_add_fd_to_tracker(fd);
1533         if (ret < 0) {
1534                 ret = close(fd);
1535                 if (ret) {
1536                         PERROR("close on sock_info->socket");
1537                 }
1538                 ret = -1;
1539                 lttng_ust_unlock_fd_tracker();
1540                 ust_unlock();
1541                 goto quit;
1542         }
1543
1544         sock_info->socket = ret;
1545         lttng_ust_unlock_fd_tracker();
1546
1547         ust_unlock();
1548         /*
1549          * Unlock/relock ust lock because connect is blocking (with
1550          * timeout). Don't delay constructors on the ust lock for too
1551          * long.
1552          */
1553         if (ust_lock()) {
1554                 goto quit;
1555         }
1556
1557         /*
1558          * Create only one root handle per listener thread for the whole
1559          * process lifetime, so we ensure we get ID which is statically
1560          * assigned to the root handle.
1561          */
1562         if (sock_info->root_handle == -1) {
1563                 ret = lttng_abi_create_root_handle();
1564                 if (ret < 0) {
1565                         ERR("Error creating root handle");
1566                         goto quit;
1567                 }
1568                 sock_info->root_handle = ret;
1569         }
1570
1571         ret = register_to_sessiond(sock_info->socket, USTCTL_SOCKET_CMD);
1572         if (ret < 0) {
1573                 ERR("Error registering to %s ust cmd socket",
1574                         sock_info->name);
1575                 prev_connect_failed = 1;
1576                 /*
1577                  * If we cannot register to the sessiond daemon, don't
1578                  * delay constructor execution.
1579                  */
1580                 ret = handle_register_failed(sock_info);
1581                 assert(!ret);
1582                 ust_unlock();
1583                 goto restart;
1584         }
1585
1586         ust_unlock();
1587         /*
1588          * Unlock/relock ust lock because connect is blocking (with
1589          * timeout). Don't delay constructors on the ust lock for too
1590          * long.
1591          */
1592         if (ust_lock()) {
1593                 goto quit;
1594         }
1595
1596         /* Connect notify socket */
1597         lttng_ust_lock_fd_tracker();
1598         ret = ustcomm_connect_unix_sock(sock_info->sock_path,
1599                 get_connect_sock_timeout());
1600         if (ret < 0) {
1601                 lttng_ust_unlock_fd_tracker();
1602                 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
1603                 prev_connect_failed = 1;
1604
1605                 /*
1606                  * If we cannot find the sessiond daemon, don't delay
1607                  * constructor execution.
1608                  */
1609                 ret = handle_register_failed(sock_info);
1610                 assert(!ret);
1611                 ust_unlock();
1612                 goto restart;
1613         }
1614
1615         fd = ret;
1616         ret = lttng_ust_add_fd_to_tracker(fd);
1617         if (ret < 0) {
1618                 ret = close(fd);
1619                 if (ret) {
1620                         PERROR("close on sock_info->notify_socket");
1621                 }
1622                 ret = -1;
1623                 lttng_ust_unlock_fd_tracker();
1624                 ust_unlock();
1625                 goto quit;
1626         }
1627
1628         sock_info->notify_socket = ret;
1629         lttng_ust_unlock_fd_tracker();
1630
1631         ust_unlock();
1632         /*
1633          * Unlock/relock ust lock because connect is blocking (with
1634          * timeout). Don't delay constructors on the ust lock for too
1635          * long.
1636          */
1637         if (ust_lock()) {
1638                 goto quit;
1639         }
1640
1641         timeout = get_notify_sock_timeout();
1642         if (timeout >= 0) {
1643                 /*
1644                  * Give at least 10ms to sessiond to reply to
1645                  * notifications.
1646                  */
1647                 if (timeout < 10)
1648                         timeout = 10;
1649                 ret = ustcomm_setsockopt_rcv_timeout(sock_info->notify_socket,
1650                                 timeout);
1651                 if (ret < 0) {
1652                         WARN("Error setting socket receive timeout");
1653                 }
1654                 ret = ustcomm_setsockopt_snd_timeout(sock_info->notify_socket,
1655                                 timeout);
1656                 if (ret < 0) {
1657                         WARN("Error setting socket send timeout");
1658                 }
1659         } else if (timeout < -1) {
1660                 WARN("Unsupported timeout value %ld", timeout);
1661         }
1662
1663         ret = register_to_sessiond(sock_info->notify_socket,
1664                         USTCTL_SOCKET_NOTIFY);
1665         if (ret < 0) {
1666                 ERR("Error registering to %s ust notify socket",
1667                         sock_info->name);
1668                 prev_connect_failed = 1;
1669                 /*
1670                  * If we cannot register to the sessiond daemon, don't
1671                  * delay constructor execution.
1672                  */
1673                 ret = handle_register_failed(sock_info);
1674                 assert(!ret);
1675                 ust_unlock();
1676                 goto restart;
1677         }
1678         sock = sock_info->socket;
1679
1680         ust_unlock();
1681
1682         for (;;) {
1683                 ssize_t len;
1684                 struct ustcomm_ust_msg lum;
1685
1686                 len = ustcomm_recv_unix_sock(sock, &lum, sizeof(lum));
1687                 switch (len) {
1688                 case 0: /* orderly shutdown */
1689                         DBG("%s lttng-sessiond has performed an orderly shutdown", sock_info->name);
1690                         if (ust_lock()) {
1691                                 goto quit;
1692                         }
1693                         /*
1694                          * Either sessiond has shutdown or refused us by closing the socket.
1695                          * In either case, we don't want to delay construction execution,
1696                          * and we need to wait before retry.
1697                          */
1698                         prev_connect_failed = 1;
1699                         /*
1700                          * If we cannot register to the sessiond daemon, don't
1701                          * delay constructor execution.
1702                          */
1703                         ret = handle_register_failed(sock_info);
1704                         assert(!ret);
1705                         ust_unlock();
1706                         goto end;
1707                 case sizeof(lum):
1708                         print_cmd(lum.cmd, lum.handle);
1709                         ret = handle_message(sock_info, sock, &lum);
1710                         if (ret) {
1711                                 ERR("Error handling message for %s socket",
1712                                         sock_info->name);
1713                                 /*
1714                                  * Close socket if protocol error is
1715                                  * detected.
1716                                  */
1717                                 goto end;
1718                         }
1719                         continue;
1720                 default:
1721                         if (len < 0) {
1722                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
1723                         } else {
1724                                 DBG("incorrect message size (%s socket): %zd", sock_info->name, len);
1725                         }
1726                         if (len == -ECONNRESET) {
1727                                 DBG("%s remote end closed connection", sock_info->name);
1728                                 goto end;
1729                         }
1730                         goto end;
1731                 }
1732
1733         }
1734 end:
1735         if (ust_lock()) {
1736                 goto quit;
1737         }
1738         /* Cleanup socket handles before trying to reconnect */
1739         lttng_ust_objd_table_owner_cleanup(sock_info);
1740         ust_unlock();
1741         goto restart;   /* try to reconnect */
1742
1743 quit:
1744         ust_unlock();
1745
1746         pthread_mutex_lock(&ust_exit_mutex);
1747         sock_info->thread_active = 0;
1748         pthread_mutex_unlock(&ust_exit_mutex);
1749         return NULL;
1750 }
1751
1752 /*
1753  * Weak symbol to call when the ust malloc wrapper is not loaded.
1754  */
1755 __attribute__((weak))
1756 void lttng_ust_malloc_wrapper_init(void)
1757 {
1758 }
1759
1760 /*
1761  * sessiond monitoring thread: monitor presence of global and per-user
1762  * sessiond by polling the application common named pipe.
1763  */
1764 void __attribute__((constructor)) lttng_ust_init(void)
1765 {
1766         struct timespec constructor_timeout;
1767         sigset_t sig_all_blocked, orig_parent_mask;
1768         pthread_attr_t thread_attr;
1769         int timeout_mode;
1770         int ret;
1771
1772         if (uatomic_xchg(&initialized, 1) == 1)
1773                 return;
1774
1775         /*
1776          * Fixup interdependency between TLS fixup mutex (which happens
1777          * to be the dynamic linker mutex) and ust_lock, taken within
1778          * the ust lock.
1779          */
1780         lttng_ust_fixup_tls();
1781
1782         lttng_ust_loaded = 1;
1783
1784         /*
1785          * We want precise control over the order in which we construct
1786          * our sub-libraries vs starting to receive commands from
1787          * sessiond (otherwise leading to errors when trying to create
1788          * sessiond before the init functions are completed).
1789          */
1790         init_usterr();
1791         lttng_ust_getenv_init();        /* Needs init_usterr() to be completed. */
1792         init_tracepoint();
1793         lttng_ust_init_fd_tracker();
1794         lttng_ust_clock_init();
1795         lttng_ust_getcpu_init();
1796         lttng_ust_statedump_init();
1797         lttng_ring_buffer_metadata_client_init();
1798         lttng_ring_buffer_client_overwrite_init();
1799         lttng_ring_buffer_client_overwrite_rt_init();
1800         lttng_ring_buffer_client_discard_init();
1801         lttng_ring_buffer_client_discard_rt_init();
1802         lttng_perf_counter_init();
1803         /*
1804          * Invoke ust malloc wrapper init before starting other threads.
1805          */
1806         lttng_ust_malloc_wrapper_init();
1807
1808         timeout_mode = get_constructor_timeout(&constructor_timeout);
1809
1810         get_allow_blocking();
1811
1812         ret = sem_init(&constructor_wait, 0, 0);
1813         if (ret) {
1814                 PERROR("sem_init");
1815         }
1816
1817         ret = setup_global_apps();
1818         if (ret) {
1819                 assert(global_apps.allowed == 0);
1820                 DBG("global apps setup returned %d", ret);
1821         }
1822
1823         ret = setup_local_apps();
1824         if (ret) {
1825                 assert(local_apps.allowed == 0);
1826                 DBG("local apps setup returned %d", ret);
1827         }
1828
1829         /* A new thread created by pthread_create inherits the signal mask
1830          * from the parent. To avoid any signal being received by the
1831          * listener thread, we block all signals temporarily in the parent,
1832          * while we create the listener thread.
1833          */
1834         sigfillset(&sig_all_blocked);
1835         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
1836         if (ret) {
1837                 ERR("pthread_sigmask: %s", strerror(ret));
1838         }
1839
1840         ret = pthread_attr_init(&thread_attr);
1841         if (ret) {
1842                 ERR("pthread_attr_init: %s", strerror(ret));
1843         }
1844         ret = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
1845         if (ret) {
1846                 ERR("pthread_attr_setdetachstate: %s", strerror(ret));
1847         }
1848
1849         if (global_apps.allowed) {
1850                 pthread_mutex_lock(&ust_exit_mutex);
1851                 ret = pthread_create(&global_apps.ust_listener, &thread_attr,
1852                                 ust_listener_thread, &global_apps);
1853                 if (ret) {
1854                         ERR("pthread_create global: %s", strerror(ret));
1855                 }
1856                 global_apps.thread_active = 1;
1857                 pthread_mutex_unlock(&ust_exit_mutex);
1858         } else {
1859                 handle_register_done(&global_apps);
1860         }
1861
1862         if (local_apps.allowed) {
1863                 pthread_mutex_lock(&ust_exit_mutex);
1864                 ret = pthread_create(&local_apps.ust_listener, &thread_attr,
1865                                 ust_listener_thread, &local_apps);
1866                 if (ret) {
1867                         ERR("pthread_create local: %s", strerror(ret));
1868                 }
1869                 local_apps.thread_active = 1;
1870                 pthread_mutex_unlock(&ust_exit_mutex);
1871         } else {
1872                 handle_register_done(&local_apps);
1873         }
1874         ret = pthread_attr_destroy(&thread_attr);
1875         if (ret) {
1876                 ERR("pthread_attr_destroy: %s", strerror(ret));
1877         }
1878
1879         /* Restore original signal mask in parent */
1880         ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
1881         if (ret) {
1882                 ERR("pthread_sigmask: %s", strerror(ret));
1883         }
1884
1885         switch (timeout_mode) {
1886         case 1: /* timeout wait */
1887                 do {
1888                         ret = sem_timedwait(&constructor_wait,
1889                                         &constructor_timeout);
1890                 } while (ret < 0 && errno == EINTR);
1891                 if (ret < 0) {
1892                         switch (errno) {
1893                         case ETIMEDOUT:
1894                                 ERR("Timed out waiting for lttng-sessiond");
1895                                 break;
1896                         case EINVAL:
1897                                 PERROR("sem_timedwait");
1898                                 break;
1899                         default:
1900                                 ERR("Unexpected error \"%s\" returned by sem_timedwait",
1901                                         strerror(errno));
1902                         }
1903                 }
1904                 break;
1905         case -1:/* wait forever */
1906                 do {
1907                         ret = sem_wait(&constructor_wait);
1908                 } while (ret < 0 && errno == EINTR);
1909                 if (ret < 0) {
1910                         switch (errno) {
1911                         case EINVAL:
1912                                 PERROR("sem_wait");
1913                                 break;
1914                         default:
1915                                 ERR("Unexpected error \"%s\" returned by sem_wait",
1916                                         strerror(errno));
1917                         }
1918                 }
1919                 break;
1920         case 0: /* no timeout */
1921                 break;
1922         }
1923 }
1924
1925 static
1926 void lttng_ust_cleanup(int exiting)
1927 {
1928         cleanup_sock_info(&global_apps, exiting);
1929         cleanup_sock_info(&local_apps, exiting);
1930         local_apps.allowed = 0;
1931         global_apps.allowed = 0;
1932         /*
1933          * The teardown in this function all affect data structures
1934          * accessed under the UST lock by the listener thread. This
1935          * lock, along with the lttng_ust_comm_should_quit flag, ensure
1936          * that none of these threads are accessing this data at this
1937          * point.
1938          */
1939         lttng_ust_abi_exit();
1940         lttng_ust_events_exit();
1941         lttng_perf_counter_exit();
1942         lttng_ring_buffer_client_discard_rt_exit();
1943         lttng_ring_buffer_client_discard_exit();
1944         lttng_ring_buffer_client_overwrite_rt_exit();
1945         lttng_ring_buffer_client_overwrite_exit();
1946         lttng_ring_buffer_metadata_client_exit();
1947         lttng_ust_statedump_destroy();
1948         exit_tracepoint();
1949         if (!exiting) {
1950                 /* Reinitialize values for fork */
1951                 sem_count = sem_count_initial_value;
1952                 lttng_ust_comm_should_quit = 0;
1953                 initialized = 0;
1954         }
1955 }
1956
1957 void __attribute__((destructor)) lttng_ust_exit(void)
1958 {
1959         int ret;
1960
1961         /*
1962          * Using pthread_cancel here because:
1963          * A) we don't want to hang application teardown.
1964          * B) the thread is not allocating any resource.
1965          */
1966
1967         /*
1968          * Require the communication thread to quit. Synchronize with
1969          * mutexes to ensure it is not in a mutex critical section when
1970          * pthread_cancel is later called.
1971          */
1972         ust_lock_nocheck();
1973         lttng_ust_comm_should_quit = 1;
1974         ust_unlock();
1975
1976         pthread_mutex_lock(&ust_exit_mutex);
1977         /* cancel threads */
1978         if (global_apps.thread_active) {
1979                 ret = pthread_cancel(global_apps.ust_listener);
1980                 if (ret) {
1981                         ERR("Error cancelling global ust listener thread: %s",
1982                                 strerror(ret));
1983                 } else {
1984                         global_apps.thread_active = 0;
1985                 }
1986         }
1987         if (local_apps.thread_active) {
1988                 ret = pthread_cancel(local_apps.ust_listener);
1989                 if (ret) {
1990                         ERR("Error cancelling local ust listener thread: %s",
1991                                 strerror(ret));
1992                 } else {
1993                         local_apps.thread_active = 0;
1994                 }
1995         }
1996         pthread_mutex_unlock(&ust_exit_mutex);
1997
1998         /*
1999          * Do NOT join threads: use of sys_futex makes it impossible to
2000          * join the threads without using async-cancel, but async-cancel
2001          * is delivered by a signal, which could hit the target thread
2002          * anywhere in its code path, including while the ust_lock() is
2003          * held, causing a deadlock for the other thread. Let the OS
2004          * cleanup the threads if there are stalled in a syscall.
2005          */
2006         lttng_ust_cleanup(1);
2007 }
2008
2009 /*
2010  * We exclude the worker threads across fork and clone (except
2011  * CLONE_VM), because these system calls only keep the forking thread
2012  * running in the child.  Therefore, we don't want to call fork or clone
2013  * in the middle of an tracepoint or ust tracing state modification.
2014  * Holding this mutex protects these structures across fork and clone.
2015  */
2016 void ust_before_fork(sigset_t *save_sigset)
2017 {
2018         /*
2019          * Disable signals. This is to avoid that the child intervenes
2020          * before it is properly setup for tracing. It is safer to
2021          * disable all signals, because then we know we are not breaking
2022          * anything by restoring the original mask.
2023          */
2024         sigset_t all_sigs;
2025         int ret;
2026
2027         /* Fixup lttng-ust TLS. */
2028         lttng_ust_fixup_tls();
2029
2030         if (URCU_TLS(lttng_ust_nest_count))
2031                 return;
2032         /* Disable signals */
2033         sigfillset(&all_sigs);
2034         ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset);
2035         if (ret == -1) {
2036                 PERROR("sigprocmask");
2037         }
2038
2039         pthread_mutex_lock(&ust_fork_mutex);
2040
2041         ust_lock_nocheck();
2042         rcu_bp_before_fork();
2043 }
2044
2045 static void ust_after_fork_common(sigset_t *restore_sigset)
2046 {
2047         int ret;
2048
2049         DBG("process %d", getpid());
2050         ust_unlock();
2051
2052         pthread_mutex_unlock(&ust_fork_mutex);
2053
2054         /* Restore signals */
2055         ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL);
2056         if (ret == -1) {
2057                 PERROR("sigprocmask");
2058         }
2059 }
2060
2061 void ust_after_fork_parent(sigset_t *restore_sigset)
2062 {
2063         if (URCU_TLS(lttng_ust_nest_count))
2064                 return;
2065         DBG("process %d", getpid());
2066         rcu_bp_after_fork_parent();
2067         /* Release mutexes and reenable signals */
2068         ust_after_fork_common(restore_sigset);
2069 }
2070
2071 /*
2072  * After fork, in the child, we need to cleanup all the leftover state,
2073  * except the worker thread which already magically disappeared thanks
2074  * to the weird Linux fork semantics. After tyding up, we call
2075  * lttng_ust_init() again to start over as a new PID.
2076  *
2077  * This is meant for forks() that have tracing in the child between the
2078  * fork and following exec call (if there is any).
2079  */
2080 void ust_after_fork_child(sigset_t *restore_sigset)
2081 {
2082         if (URCU_TLS(lttng_ust_nest_count))
2083                 return;
2084         lttng_context_vpid_reset();
2085         lttng_context_vtid_reset();
2086         lttng_context_procname_reset();
2087         DBG("process %d", getpid());
2088         /* Release urcu mutexes */
2089         rcu_bp_after_fork_child();
2090         lttng_ust_cleanup(0);
2091         /* Release mutexes and reenable signals */
2092         ust_after_fork_common(restore_sigset);
2093         lttng_ust_init();
2094 }
2095
2096 void lttng_ust_sockinfo_session_enabled(void *owner)
2097 {
2098         struct sock_info *sock_info = owner;
2099         sock_info->statedump_pending = 1;
2100 }