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 <dlfcn.h>
  31 #include <fcntl.h>
  32 #include <unistd.h>
  33 #include <errno.h>
  34 #include <pthread.h>
  35 #include <semaphore.h>
  36 #include <time.h>
  37 #include <assert.h>
  38 #include <signal.h>
  39 #include <limits.h>
  40 #include <urcu/uatomic.h>
  41 #include <urcu/futex.h>
  42 #include <urcu/compiler.h>
  43
  44 #include <lttng/ust-events.h>
  45 #include <lttng/ust-abi.h>
  46 #include <lttng/ust.h>
  47 #include <lttng/ust-error.h>
  48 #include <lttng/ust-ctl.h>
  49 #include <urcu/tls-compat.h>
  50 #include <ust-comm.h>
  51 #include <ust-fd.h>
  52 #include <usterr-signal-safe.h>
  53 #include <helper.h>
  54 #include "tracepoint-internal.h"
  55 #include "lttng-tracer-core.h"
  56 #include "compat.h"
  57 #include "../libringbuffer/rb-init.h"
  58 #include "lttng-ust-statedump.h"
  59 #include "clock.h"
  60 #include "../libringbuffer/getcpu.h"
  61 #include "getenv.h"
  62
  63 /* Concatenate lttng ust shared library name with its major version number. */
  64 #define LTTNG_UST_LIB_SO_NAME "liblttng-ust.so." __ust_stringify(CONFIG_LTTNG_UST_LIBRARY_VERSION_MAJOR)
  65
  66 /*
  67  * Has lttng ust comm constructor been called ?
  68  */
  69 static int initialized;
  70
  71 /*
  72  * The ust_lock/ust_unlock lock is used as a communication thread mutex.
  73  * Held when handling a command, also held by fork() to deal with
  74  * removal of threads, and by exit path.
  75  *
  76  * The UST lock is the centralized mutex across UST tracing control and
  77  * probe registration.
  78  *
  79  * ust_exit_mutex must never nest in ust_mutex.
  80  *
  81  * ust_fork_mutex must never nest in ust_mutex.
  82  *
  83  * ust_mutex_nest is a per-thread nesting counter, allowing the perf
  84  * counter lazy initialization called by events within the statedump,
  85  * which traces while the ust_mutex is held.
  86  *
  87  * ust_lock nests within the dynamic loader lock (within glibc) because
  88  * it is taken within the library constructor.
  89  *
  90  * The ust fd tracker lock nests within the ust_mutex.
  91  */
  92 static pthread_mutex_t ust_mutex = PTHREAD_MUTEX_INITIALIZER;
  93
  94 /* Allow nesting the ust_mutex within the same thread. */
  95 static DEFINE_URCU_TLS(int, ust_mutex_nest);
  96
  97 /*
  98  * ust_exit_mutex protects thread_active variable wrt thread exit. It
  99  * cannot be done by ust_mutex because pthread_cancel(), which takes an
 100  * internal libc lock, cannot nest within ust_mutex.
 101  *
 102  * It never nests within a ust_mutex.
 103  */
 104 static pthread_mutex_t ust_exit_mutex = PTHREAD_MUTEX_INITIALIZER;
 105
 106 /*
 107  * ust_fork_mutex protects base address statedump tracing against forks. It
 108  * prevents the dynamic loader lock to be taken (by base address statedump
 109  * tracing) while a fork is happening, thus preventing deadlock issues with
 110  * the dynamic loader lock.
 111  */
 112 static pthread_mutex_t ust_fork_mutex = PTHREAD_MUTEX_INITIALIZER;
 113
 114 /* Should the ust comm thread quit ? */
 115 static int lttng_ust_comm_should_quit;
 116
 117 /*
 118  * This variable can be tested by applications to check whether
 119  * lttng-ust is loaded. They simply have to define their own
 120  * "lttng_ust_loaded" weak symbol, and test it. It is set to 1 by the
 121  * library constructor.
 122  */
 123 int lttng_ust_loaded __attribute__((weak));
 124
 125 /*
 126  * Return 0 on success, -1 if should quit.
 127  * The lock is taken in both cases.
 128  * Signal-safe.
 129  */
 130 int ust_lock(void)
 131 {
 132         sigset_t sig_all_blocked, orig_mask;
 133         int ret, oldstate;
 134
 135         ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
 136         if (ret) {
 137                 ERR("pthread_setcancelstate: %s", strerror(ret));
 138         }
 139         if (oldstate != PTHREAD_CANCEL_ENABLE) {
 140                 ERR("pthread_setcancelstate: unexpected oldstate");
 141         }
 142         sigfillset(&sig_all_blocked);
 143         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
 144         if (ret) {
 145                 ERR("pthread_sigmask: %s", strerror(ret));
 146         }
 147         if (!URCU_TLS(ust_mutex_nest)++)
 148                 pthread_mutex_lock(&ust_mutex);
 149         ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
 150         if (ret) {
 151                 ERR("pthread_sigmask: %s", strerror(ret));
 152         }
 153         if (lttng_ust_comm_should_quit) {
 154                 return -1;
 155         } else {
 156                 return 0;
 157         }
 158 }
 159
 160 /*
 161  * ust_lock_nocheck() can be used in constructors/destructors, because
 162  * they are already nested within the dynamic loader lock, and therefore
 163  * have exclusive access against execution of liblttng-ust destructor.
 164  * Signal-safe.
 165  */
 166 void ust_lock_nocheck(void)
 167 {
 168         sigset_t sig_all_blocked, orig_mask;
 169         int ret, oldstate;
 170
 171         ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &oldstate);
 172         if (ret) {
 173                 ERR("pthread_setcancelstate: %s", strerror(ret));
 174         }
 175         if (oldstate != PTHREAD_CANCEL_ENABLE) {
 176                 ERR("pthread_setcancelstate: unexpected oldstate");
 177         }
 178         sigfillset(&sig_all_blocked);
 179         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
 180         if (ret) {
 181                 ERR("pthread_sigmask: %s", strerror(ret));
 182         }
 183         if (!URCU_TLS(ust_mutex_nest)++)
 184                 pthread_mutex_lock(&ust_mutex);
 185         ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
 186         if (ret) {
 187                 ERR("pthread_sigmask: %s", strerror(ret));
 188         }
 189 }
 190
 191 /*
 192  * Signal-safe.
 193  */
 194 void ust_unlock(void)
 195 {
 196         sigset_t sig_all_blocked, orig_mask;
 197         int ret, oldstate;
 198
 199         sigfillset(&sig_all_blocked);
 200         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_mask);
 201         if (ret) {
 202                 ERR("pthread_sigmask: %s", strerror(ret));
 203         }
 204         if (!--URCU_TLS(ust_mutex_nest))
 205                 pthread_mutex_unlock(&ust_mutex);
 206         ret = pthread_sigmask(SIG_SETMASK, &orig_mask, NULL);
 207         if (ret) {
 208                 ERR("pthread_sigmask: %s", strerror(ret));
 209         }
 210         ret = pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, &oldstate);
 211         if (ret) {
 212                 ERR("pthread_setcancelstate: %s", strerror(ret));
 213         }
 214         if (oldstate != PTHREAD_CANCEL_DISABLE) {
 215                 ERR("pthread_setcancelstate: unexpected oldstate");
 216         }
 217 }
 218
 219 /*
 220  * Wait for either of these before continuing to the main
 221  * program:
 222  * - the register_done message from sessiond daemon
 223  *   (will let the sessiond daemon enable sessions before main
 224  *   starts.)
 225  * - sessiond daemon is not reachable.
 226  * - timeout (ensuring applications are resilient to session
 227  *   daemon problems).
 228  */
 229 static sem_t constructor_wait;
 230 /*
 231  * Doing this for both the global and local sessiond.
 232  */
 233 enum {
 234         sem_count_initial_value = 4,
 235 };
 236
 237 static int sem_count = sem_count_initial_value;
 238
 239 /*
 240  * Counting nesting within lttng-ust. Used to ensure that calling fork()
 241  * from liblttng-ust does not execute the pre/post fork handlers.
 242  */
 243 static DEFINE_URCU_TLS(int, lttng_ust_nest_count);
 244
 245 /*
 246  * Info about socket and associated listener thread.
 247  */
 248 struct sock_info {
 249         const char *name;
 250         pthread_t ust_listener; /* listener thread */
 251         int root_handle;
 252         int registration_done;
 253         int allowed;
 254         int global;
 255         int thread_active;
 256
 257         char sock_path[PATH_MAX];
 258         int socket;
 259         int notify_socket;
 260
 261         char wait_shm_path[PATH_MAX];
 262         char *wait_shm_mmap;
 263         /* Keep track of lazy state dump not performed yet. */
 264         int statedump_pending;
 265         int initial_statedump_done;
 266 };
 267
 268 /* Socket from app (connect) to session daemon (listen) for communication */
 269 struct sock_info global_apps = {
 270         .name = "global",
 271         .global = 1,
 272
 273         .root_handle = -1,
 274         .registration_done = 0,
 275         .allowed = 0,
 276         .thread_active = 0,
 277
 278         .sock_path = LTTNG_DEFAULT_RUNDIR "/" LTTNG_UST_SOCK_FILENAME,
 279         .socket = -1,
 280         .notify_socket = -1,
 281
 282         .wait_shm_path = "/" LTTNG_UST_WAIT_FILENAME,
 283
 284         .statedump_pending = 0,
 285         .initial_statedump_done = 0,
 286 };
 287
 288 /* TODO: allow global_apps_sock_path override */
 289
 290 struct sock_info local_apps = {
 291         .name = "local",
 292         .global = 0,
 293         .root_handle = -1,
 294         .registration_done = 0,
 295         .allowed = 0,   /* Check setuid bit first */
 296         .thread_active = 0,
 297
 298         .socket = -1,
 299         .notify_socket = -1,
 300
 301         .statedump_pending = 0,
 302         .initial_statedump_done = 0,
 303 };
 304
 305 static int wait_poll_fallback;
 306
 307 static const char *cmd_name_mapping[] = {
 308         [ LTTNG_UST_RELEASE ] = "Release",
 309         [ LTTNG_UST_SESSION ] = "Create Session",
 310         [ LTTNG_UST_TRACER_VERSION ] = "Get Tracer Version",
 311
 312         [ LTTNG_UST_TRACEPOINT_LIST ] = "Create Tracepoint List",
 313         [ LTTNG_UST_WAIT_QUIESCENT ] = "Wait for Quiescent State",
 314         [ LTTNG_UST_REGISTER_DONE ] = "Registration Done",
 315         [ LTTNG_UST_TRACEPOINT_FIELD_LIST ] = "Create Tracepoint Field List",
 316
 317         /* Session FD commands */
 318         [ LTTNG_UST_CHANNEL ] = "Create Channel",
 319         [ LTTNG_UST_SESSION_START ] = "Start Session",
 320         [ LTTNG_UST_SESSION_STOP ] = "Stop Session",
 321
 322         /* Channel FD commands */
 323         [ LTTNG_UST_STREAM ] = "Create Stream",
 324         [ LTTNG_UST_EVENT ] = "Create Event",
 325
 326         /* Event and Channel FD commands */
 327         [ LTTNG_UST_CONTEXT ] = "Create Context",
 328         [ LTTNG_UST_FLUSH_BUFFER ] = "Flush Buffer",
 329
 330         /* Event, Channel and Session commands */
 331         [ LTTNG_UST_ENABLE ] = "Enable",
 332         [ LTTNG_UST_DISABLE ] = "Disable",
 333
 334         /* Tracepoint list commands */
 335         [ LTTNG_UST_TRACEPOINT_LIST_GET ] = "List Next Tracepoint",
 336         [ LTTNG_UST_TRACEPOINT_FIELD_LIST_GET ] = "List Next Tracepoint Field",
 337
 338         /* Event FD commands */
 339         [ LTTNG_UST_FILTER ] = "Create Filter",
 340         [ LTTNG_UST_EXCLUSION ] = "Add exclusions to event",
 341 };
 342
 343 static const char *str_timeout;
 344 static int got_timeout_env;
 345
 346 extern void lttng_ring_buffer_client_overwrite_init(void);
 347 extern void lttng_ring_buffer_client_overwrite_rt_init(void);
 348 extern void lttng_ring_buffer_client_discard_init(void);
 349 extern void lttng_ring_buffer_client_discard_rt_init(void);
 350 extern void lttng_ring_buffer_metadata_client_init(void);
 351 extern void lttng_ring_buffer_client_overwrite_exit(void);
 352 extern void lttng_ring_buffer_client_overwrite_rt_exit(void);
 353 extern void lttng_ring_buffer_client_discard_exit(void);
 354 extern void lttng_ring_buffer_client_discard_rt_exit(void);
 355 extern void lttng_ring_buffer_metadata_client_exit(void);
 356
 357 static char *get_map_shm(struct sock_info *sock_info);
 358
 359 ssize_t lttng_ust_read(int fd, void *buf, size_t len)
 360 {
 361         ssize_t ret;
 362         size_t copied = 0, to_copy = len;
 363
 364         do {
 365                 ret = read(fd, buf + copied, to_copy);
 366                 if (ret > 0) {
 367                         copied += ret;
 368                         to_copy -= ret;
 369                 }
 370         } while ((ret > 0 && to_copy > 0)
 371                 || (ret < 0 && errno == EINTR));
 372         if (ret > 0) {
 373                 ret = copied;
 374         }
 375         return ret;
 376 }
 377 /*
 378  * Returns the HOME directory path. Caller MUST NOT free(3) the returned
 379  * pointer.
 380  */
 381 static
 382 const char *get_lttng_home_dir(void)
 383 {
 384        const char *val;
 385
 386        val = (const char *) lttng_getenv("LTTNG_HOME");
 387        if (val != NULL) {
 388                return val;
 389        }
 390        return (const char *) lttng_getenv("HOME");
 391 }
 392
 393 /*
 394  * Force a read (imply TLS fixup for dlopen) of TLS variables.
 395  */
 396 static
 397 void lttng_fixup_nest_count_tls(void)
 398 {
 399         asm volatile ("" : : "m" (URCU_TLS(lttng_ust_nest_count)));
 400 }
 401
 402 static
 403 void lttng_fixup_ust_mutex_nest_tls(void)
 404 {
 405         asm volatile ("" : : "m" (URCU_TLS(ust_mutex_nest)));
 406 }
 407
 408 /*
 409  * Fixup urcu bp TLS.
 410  */
 411 static
 412 void lttng_fixup_urcu_bp_tls(void)
 413 {
 414         rcu_read_lock();
 415         rcu_read_unlock();
 416 }
 417
 418 void lttng_ust_fixup_tls(void)
 419 {
 420         lttng_fixup_urcu_bp_tls();
 421         lttng_fixup_ringbuffer_tls();
 422         lttng_fixup_vtid_tls();
 423         lttng_fixup_nest_count_tls();
 424         lttng_fixup_procname_tls();
 425         lttng_fixup_ust_mutex_nest_tls();
 426         lttng_ust_fixup_fd_tracker_tls();
 427 }
 428
 429 int lttng_get_notify_socket(void *owner)
 430 {
 431         struct sock_info *info = owner;
 432
 433         return info->notify_socket;
 434 }
 435
 436 static
 437 void print_cmd(int cmd, int handle)
 438 {
 439         const char *cmd_name = "Unknown";
 440
 441         if (cmd >= 0 && cmd < LTTNG_ARRAY_SIZE(cmd_name_mapping)
 442                         && cmd_name_mapping[cmd]) {
 443                 cmd_name = cmd_name_mapping[cmd];
 444         }
 445         DBG("Message Received \"%s\" (%d), Handle \"%s\" (%d)",
 446                 cmd_name, cmd,
 447                 lttng_ust_obj_get_name(handle), handle);
 448 }
 449
 450 static
 451 int setup_global_apps(void)
 452 {
 453         int ret = 0;
 454         assert(!global_apps.wait_shm_mmap);
 455
 456         global_apps.wait_shm_mmap = get_map_shm(&global_apps);
 457         if (!global_apps.wait_shm_mmap) {
 458                 WARN("Unable to get map shm for global apps. Disabling LTTng-UST global tracing.");
 459                 global_apps.allowed = 0;
 460                 ret = -EIO;
 461                 goto error;
 462         }
 463
 464         global_apps.allowed = 1;
 465 error:
 466         return ret;
 467 }
 468 static
 469 int setup_local_apps(void)
 470 {
 471         int ret = 0;
 472         const char *home_dir;
 473         uid_t uid;
 474
 475         assert(!local_apps.wait_shm_mmap);
 476
 477         uid = getuid();
 478         /*
 479          * Disallow per-user tracing for setuid binaries.
 480          */
 481         if (uid != geteuid()) {
 482                 assert(local_apps.allowed == 0);
 483                 ret = 0;
 484                 goto end;
 485         }
 486         home_dir = get_lttng_home_dir();
 487         if (!home_dir) {
 488                 WARN("HOME environment variable not set. Disabling LTTng-UST per-user tracing.");
 489                 assert(local_apps.allowed == 0);
 490                 ret = -ENOENT;
 491                 goto end;
 492         }
 493         local_apps.allowed = 1;
 494         snprintf(local_apps.sock_path, PATH_MAX, "%s/%s/%s",
 495                 home_dir,
 496                 LTTNG_DEFAULT_HOME_RUNDIR,
 497                 LTTNG_UST_SOCK_FILENAME);
 498         snprintf(local_apps.wait_shm_path, PATH_MAX, "/%s-%u",
 499                 LTTNG_UST_WAIT_FILENAME,
 500                 uid);
 501
 502         local_apps.wait_shm_mmap = get_map_shm(&local_apps);
 503         if (!local_apps.wait_shm_mmap) {
 504                 WARN("Unable to get map shm for local apps. Disabling LTTng-UST per-user tracing.");
 505                 local_apps.allowed = 0;
 506                 ret = -EIO;
 507                 goto end;
 508         }
 509 end:
 510         return ret;
 511 }
 512
 513 /*
 514  * Get socket timeout, in ms.
 515  * -1: wait forever. 0: don't wait. >0: timeout, in ms.
 516  */
 517 static
 518 long get_timeout(void)
 519 {
 520         long constructor_delay_ms = LTTNG_UST_DEFAULT_CONSTRUCTOR_TIMEOUT_MS;
 521
 522         if (!got_timeout_env) {
 523                 str_timeout = lttng_getenv("LTTNG_UST_REGISTER_TIMEOUT");
 524                 got_timeout_env = 1;
 525         }
 526         if (str_timeout)
 527                 constructor_delay_ms = strtol(str_timeout, NULL, 10);
 528         /* All negative values are considered as "-1". */
 529         if (constructor_delay_ms < -1)
 530                 constructor_delay_ms = -1;
 531         return constructor_delay_ms;
 532 }
 533
 534 /* Timeout for notify socket send and recv. */
 535 static
 536 long get_notify_sock_timeout(void)
 537 {
 538         return get_timeout();
 539 }
 540
 541 /* Timeout for connecting to cmd and notify sockets. */
 542 static
 543 long get_connect_sock_timeout(void)
 544 {
 545         return get_timeout();
 546 }
 547
 548 /*
 549  * Return values: -1: wait forever. 0: don't wait. 1: timeout wait.
 550  */
 551 static
 552 int get_constructor_timeout(struct timespec *constructor_timeout)
 553 {
 554         long constructor_delay_ms;
 555         int ret;
 556
 557         constructor_delay_ms = get_timeout();
 558
 559         switch (constructor_delay_ms) {
 560         case -1:/* fall-through */
 561         case 0:
 562                 return constructor_delay_ms;
 563         default:
 564                 break;
 565         }
 566
 567         /*
 568          * If we are unable to find the current time, don't wait.
 569          */
 570         ret = clock_gettime(CLOCK_REALTIME, constructor_timeout);
 571         if (ret) {
 572                 /* Don't wait. */
 573                 return 0;
 574         }
 575         constructor_timeout->tv_sec += constructor_delay_ms / 1000UL;
 576         constructor_timeout->tv_nsec +=
 577                 (constructor_delay_ms % 1000UL) * 1000000UL;
 578         if (constructor_timeout->tv_nsec >= 1000000000UL) {
 579                 constructor_timeout->tv_sec++;
 580                 constructor_timeout->tv_nsec -= 1000000000UL;
 581         }
 582         /* Timeout wait (constructor_delay_ms). */
 583         return 1;
 584 }
 585
 586 static
 587 void get_allow_blocking(void)
 588 {
 589         const char *str_allow_blocking =
 590                 lttng_getenv("LTTNG_UST_ALLOW_BLOCKING");
 591
 592         if (str_allow_blocking) {
 593                 DBG("%s environment variable is set",
 594                         "LTTNG_UST_ALLOW_BLOCKING");
 595                 lttng_ust_ringbuffer_set_allow_blocking();
 596         }
 597 }
 598
 599 static
 600 int register_to_sessiond(int socket, enum ustctl_socket_type type)
 601 {
 602         return ustcomm_send_reg_msg(socket,
 603                 type,
 604                 CAA_BITS_PER_LONG,
 605                 lttng_alignof(uint8_t) * CHAR_BIT,
 606                 lttng_alignof(uint16_t) * CHAR_BIT,
 607                 lttng_alignof(uint32_t) * CHAR_BIT,
 608                 lttng_alignof(uint64_t) * CHAR_BIT,
 609                 lttng_alignof(unsigned long) * CHAR_BIT);
 610 }
 611
 612 static
 613 int send_reply(int sock, struct ustcomm_ust_reply *lur)
 614 {
 615         ssize_t len;
 616
 617         len = ustcomm_send_unix_sock(sock, lur, sizeof(*lur));
 618         switch (len) {
 619         case sizeof(*lur):
 620                 DBG("message successfully sent");
 621                 return 0;
 622         default:
 623                 if (len == -ECONNRESET) {
 624                         DBG("remote end closed connection");
 625                         return 0;
 626                 }
 627                 if (len < 0)
 628                         return len;
 629                 DBG("incorrect message size: %zd", len);
 630                 return -EINVAL;
 631         }
 632 }
 633
 634 static
 635 void decrement_sem_count(unsigned int count)
 636 {
 637         int ret;
 638
 639         assert(uatomic_read(&sem_count) >= count);
 640
 641         if (uatomic_read(&sem_count) <= 0) {
 642                 return;
 643         }
 644
 645         ret = uatomic_add_return(&sem_count, -count);
 646         if (ret == 0) {
 647                 ret = sem_post(&constructor_wait);
 648                 assert(!ret);
 649         }
 650 }
 651
 652 static
 653 int handle_register_done(struct sock_info *sock_info)
 654 {
 655         if (sock_info->registration_done)
 656                 return 0;
 657         sock_info->registration_done = 1;
 658
 659         decrement_sem_count(1);
 660         if (!sock_info->statedump_pending) {
 661                 sock_info->initial_statedump_done = 1;
 662                 decrement_sem_count(1);
 663         }
 664
 665         return 0;
 666 }
 667
 668 static
 669 int handle_register_failed(struct sock_info *sock_info)
 670 {
 671         if (sock_info->registration_done)
 672                 return 0;
 673         sock_info->registration_done = 1;
 674         sock_info->initial_statedump_done = 1;
 675
 676         decrement_sem_count(2);
 677
 678         return 0;
 679 }
 680
 681 /*
 682  * Only execute pending statedump after the constructor semaphore has
 683  * been posted by the current listener thread. This means statedump will
 684  * only be performed after the "registration done" command is received
 685  * from this thread's session daemon.
 686  *
 687  * This ensures we don't run into deadlock issues with the dynamic
 688  * loader mutex, which is held while the constructor is called and
 689  * waiting on the constructor semaphore. All operations requiring this
 690  * dynamic loader lock need to be postponed using this mechanism.
 691  *
 692  * In a scenario with two session daemons connected to the application,
 693  * it is possible that the first listener thread which receives the
 694  * registration done command issues its statedump while the dynamic
 695  * loader lock is still held by the application constructor waiting on
 696  * the semaphore. It will however be allowed to proceed when the
 697  * second session daemon sends the registration done command to the
 698  * second listener thread. This situation therefore does not produce
 699  * a deadlock.
 700  */
 701 static
 702 void handle_pending_statedump(struct sock_info *sock_info)
 703 {
 704         if (sock_info->registration_done && sock_info->statedump_pending) {
 705                 sock_info->statedump_pending = 0;
 706                 pthread_mutex_lock(&ust_fork_mutex);
 707                 lttng_handle_pending_statedump(sock_info);
 708                 pthread_mutex_unlock(&ust_fork_mutex);
 709
 710                 if (!sock_info->initial_statedump_done) {
 711                         sock_info->initial_statedump_done = 1;
 712                         decrement_sem_count(1);
 713                 }
 714         }
 715 }
 716
 717 static
 718 int handle_message(struct sock_info *sock_info,
 719                 int sock, struct ustcomm_ust_msg *lum)
 720 {
 721         int ret = 0;
 722         const struct lttng_ust_objd_ops *ops;
 723         struct ustcomm_ust_reply lur;
 724         union ust_args args;
 725         char ctxstr[LTTNG_UST_SYM_NAME_LEN];    /* App context string. */
 726         ssize_t len;
 727
 728         memset(&lur, 0, sizeof(lur));
 729
 730         if (ust_lock()) {
 731                 ret = -LTTNG_UST_ERR_EXITING;
 732                 goto error;
 733         }
 734
 735         ops = objd_ops(lum->handle);
 736         if (!ops) {
 737                 ret = -ENOENT;
 738                 goto error;
 739         }
 740
 741         switch (lum->cmd) {
 742         case LTTNG_UST_REGISTER_DONE:
 743                 if (lum->handle == LTTNG_UST_ROOT_HANDLE)
 744                         ret = handle_register_done(sock_info);
 745                 else
 746                         ret = -EINVAL;
 747                 break;
 748         case LTTNG_UST_RELEASE:
 749                 if (lum->handle == LTTNG_UST_ROOT_HANDLE)
 750                         ret = -EPERM;
 751                 else
 752                         ret = lttng_ust_objd_unref(lum->handle, 1);
 753                 break;
 754         case LTTNG_UST_FILTER:
 755         {
 756                 /* Receive filter data */
 757                 struct lttng_ust_filter_bytecode_node *bytecode;
 758
 759                 if (lum->u.filter.data_size > FILTER_BYTECODE_MAX_LEN) {
 760                         ERR("Filter data size is too large: %u bytes",
 761                                 lum->u.filter.data_size);
 762                         ret = -EINVAL;
 763                         goto error;
 764                 }
 765
 766                 if (lum->u.filter.reloc_offset > lum->u.filter.data_size) {
 767                         ERR("Filter reloc offset %u is not within data",
 768                                 lum->u.filter.reloc_offset);
 769                         ret = -EINVAL;
 770                         goto error;
 771                 }
 772
 773                 bytecode = zmalloc(sizeof(*bytecode) + lum->u.filter.data_size);
 774                 if (!bytecode) {
 775                         ret = -ENOMEM;
 776                         goto error;
 777                 }
 778                 len = ustcomm_recv_unix_sock(sock, bytecode->bc.data,
 779                                 lum->u.filter.data_size);
 780                 switch (len) {
 781                 case 0: /* orderly shutdown */
 782                         ret = 0;
 783                         free(bytecode);
 784                         goto error;
 785                 default:
 786                         if (len == lum->u.filter.data_size) {
 787                                 DBG("filter data received");
 788                                 break;
 789                         } else if (len < 0) {
 790                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 791                                 if (len == -ECONNRESET) {
 792                                         ERR("%s remote end closed connection", sock_info->name);
 793                                         ret = len;
 794                                         free(bytecode);
 795                                         goto error;
 796                                 }
 797                                 ret = len;
 798                                 free(bytecode);
 799                                 goto error;
 800                         } else {
 801                                 DBG("incorrect filter data message size: %zd", len);
 802                                 ret = -EINVAL;
 803                                 free(bytecode);
 804                                 goto error;
 805                         }
 806                 }
 807                 bytecode->bc.len = lum->u.filter.data_size;
 808                 bytecode->bc.reloc_offset = lum->u.filter.reloc_offset;
 809                 bytecode->bc.seqnum = lum->u.filter.seqnum;
 810                 if (ops->cmd) {
 811                         ret = ops->cmd(lum->handle, lum->cmd,
 812                                         (unsigned long) bytecode,
 813                                         &args, sock_info);
 814                         if (ret) {
 815                                 free(bytecode);
 816                         }
 817                         /* don't free bytecode if everything went fine. */
 818                 } else {
 819                         ret = -ENOSYS;
 820                         free(bytecode);
 821                 }
 822                 break;
 823         }
 824         case LTTNG_UST_EXCLUSION:
 825         {
 826                 /* Receive exclusion names */
 827                 struct lttng_ust_excluder_node *node;
 828                 unsigned int count;
 829
 830                 count = lum->u.exclusion.count;
 831                 if (count == 0) {
 832                         /* There are no names to read */
 833                         ret = 0;
 834                         goto error;
 835                 }
 836                 node = zmalloc(sizeof(*node) +
 837                                 count * LTTNG_UST_SYM_NAME_LEN);
 838                 if (!node) {
 839                         ret = -ENOMEM;
 840                         goto error;
 841                 }
 842                 node->excluder.count = count;
 843                 len = ustcomm_recv_unix_sock(sock, node->excluder.names,
 844                                 count * LTTNG_UST_SYM_NAME_LEN);
 845                 switch (len) {
 846                 case 0: /* orderly shutdown */
 847                         ret = 0;
 848                         free(node);
 849                         goto error;
 850                 default:
 851                         if (len == count * LTTNG_UST_SYM_NAME_LEN) {
 852                                 DBG("Exclusion data received");
 853                                 break;
 854                         } else if (len < 0) {
 855                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 856                                 if (len == -ECONNRESET) {
 857                                         ERR("%s remote end closed connection", sock_info->name);
 858                                         ret = len;
 859                                         free(node);
 860                                         goto error;
 861                                 }
 862                                 ret = len;
 863                                 free(node);
 864                                 goto error;
 865                         } else {
 866                                 DBG("Incorrect exclusion data message size: %zd", len);
 867                                 ret = -EINVAL;
 868                                 free(node);
 869                                 goto error;
 870                         }
 871                 }
 872                 if (ops->cmd) {
 873                         ret = ops->cmd(lum->handle, lum->cmd,
 874                                         (unsigned long) node,
 875                                         &args, sock_info);
 876                         if (ret) {
 877                                 free(node);
 878                         }
 879                         /* Don't free exclusion data if everything went fine. */
 880                 } else {
 881                         ret = -ENOSYS;
 882                         free(node);
 883                 }
 884                 break;
 885         }
 886         case LTTNG_UST_CHANNEL:
 887         {
 888                 void *chan_data;
 889                 int wakeup_fd;
 890
 891                 len = ustcomm_recv_channel_from_sessiond(sock,
 892                                 &chan_data, lum->u.channel.len,
 893                                 &wakeup_fd);
 894                 switch (len) {
 895                 case 0: /* orderly shutdown */
 896                         ret = 0;
 897                         goto error;
 898                 default:
 899                         if (len == lum->u.channel.len) {
 900                                 DBG("channel data received");
 901                                 break;
 902                         } else if (len < 0) {
 903                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 904                                 if (len == -ECONNRESET) {
 905                                         ERR("%s remote end closed connection", sock_info->name);
 906                                         ret = len;
 907                                         goto error;
 908                                 }
 909                                 ret = len;
 910                                 goto error;
 911                         } else {
 912                                 DBG("incorrect channel data message size: %zd", len);
 913                                 ret = -EINVAL;
 914                                 goto error;
 915                         }
 916                 }
 917                 args.channel.chan_data = chan_data;
 918                 args.channel.wakeup_fd = wakeup_fd;
 919                 if (ops->cmd)
 920                         ret = ops->cmd(lum->handle, lum->cmd,
 921                                         (unsigned long) &lum->u,
 922                                         &args, sock_info);
 923                 else
 924                         ret = -ENOSYS;
 925                 break;
 926         }
 927         case LTTNG_UST_STREAM:
 928         {
 929                 /* Receive shm_fd, wakeup_fd */
 930                 ret = ustcomm_recv_stream_from_sessiond(sock,
 931                         NULL,
 932                         &args.stream.shm_fd,
 933                         &args.stream.wakeup_fd);
 934                 if (ret) {
 935                         goto error;
 936                 }
 937
 938                 if (ops->cmd)
 939                         ret = ops->cmd(lum->handle, lum->cmd,
 940                                         (unsigned long) &lum->u,
 941                                         &args, sock_info);
 942                 else
 943                         ret = -ENOSYS;
 944                 break;
 945         }
 946         case LTTNG_UST_CONTEXT:
 947                 switch (lum->u.context.ctx) {
 948                 case LTTNG_UST_CONTEXT_APP_CONTEXT:
 949                 {
 950                         char *p;
 951                         size_t ctxlen, recvlen;
 952
 953                         ctxlen = strlen("$app.") + lum->u.context.u.app_ctx.provider_name_len - 1
 954                                         + strlen(":") + lum->u.context.u.app_ctx.ctx_name_len;
 955                         if (ctxlen >= LTTNG_UST_SYM_NAME_LEN) {
 956                                 ERR("Application context string length size is too large: %zu bytes",
 957                                         ctxlen);
 958                                 ret = -EINVAL;
 959                                 goto error;
 960                         }
 961                         strcpy(ctxstr, "$app.");
 962                         p = &ctxstr[strlen("$app.")];
 963                         recvlen = ctxlen - strlen("$app.");
 964                         len = ustcomm_recv_unix_sock(sock, p, recvlen);
 965                         switch (len) {
 966                         case 0: /* orderly shutdown */
 967                                 ret = 0;
 968                                 goto error;
 969                         default:
 970                                 if (len == recvlen) {
 971                                         DBG("app context data received");
 972                                         break;
 973                                 } else if (len < 0) {
 974                                         DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
 975                                         if (len == -ECONNRESET) {
 976                                                 ERR("%s remote end closed connection", sock_info->name);
 977                                                 ret = len;
 978                                                 goto error;
 979                                         }
 980                                         ret = len;
 981                                         goto error;
 982                                 } else {
 983                                         DBG("incorrect app context data message size: %zd", len);
 984                                         ret = -EINVAL;
 985                                         goto error;
 986                                 }
 987                         }
 988                         /* Put : between provider and ctxname. */
 989                         p[lum->u.context.u.app_ctx.provider_name_len - 1] = ':';
 990                         args.app_context.ctxname = ctxstr;
 991                         break;
 992                 }
 993                 default:
 994                         break;
 995                 }
 996                 if (ops->cmd) {
 997                         ret = ops->cmd(lum->handle, lum->cmd,
 998                                         (unsigned long) &lum->u,
 999                                         &args, sock_info);
1000                 } else {
1001                         ret = -ENOSYS;
1002                 }
1003                 break;
1004         default:
1005                 if (ops->cmd)
1006                         ret = ops->cmd(lum->handle, lum->cmd,
1007                                         (unsigned long) &lum->u,
1008                                         &args, sock_info);
1009                 else
1010                         ret = -ENOSYS;
1011                 break;
1012         }
1013
1014         lur.handle = lum->handle;
1015         lur.cmd = lum->cmd;
1016         lur.ret_val = ret;
1017         if (ret >= 0) {
1018                 lur.ret_code = LTTNG_UST_OK;
1019         } else {
1020                 /*
1021                  * Use -LTTNG_UST_ERR as wildcard for UST internal
1022                  * error that are not caused by the transport, except if
1023                  * we already have a more precise error message to
1024                  * report.
1025                  */
1026                 if (ret > -LTTNG_UST_ERR) {
1027                         /* Translate code to UST error. */
1028                         switch (ret) {
1029                         case -EEXIST:
1030                                 lur.ret_code = -LTTNG_UST_ERR_EXIST;
1031                                 break;
1032                         case -EINVAL:
1033                                 lur.ret_code = -LTTNG_UST_ERR_INVAL;
1034                                 break;
1035                         case -ENOENT:
1036                                 lur.ret_code = -LTTNG_UST_ERR_NOENT;
1037                                 break;
1038                         case -EPERM:
1039                                 lur.ret_code = -LTTNG_UST_ERR_PERM;
1040                                 break;
1041                         case -ENOSYS:
1042                                 lur.ret_code = -LTTNG_UST_ERR_NOSYS;
1043                                 break;
1044                         default:
1045                                 lur.ret_code = -LTTNG_UST_ERR;
1046                                 break;
1047                         }
1048                 } else {
1049                         lur.ret_code = ret;
1050                 }
1051         }
1052         if (ret >= 0) {
1053                 switch (lum->cmd) {
1054                 case LTTNG_UST_TRACER_VERSION:
1055                         lur.u.version = lum->u.version;
1056                         break;
1057                 case LTTNG_UST_TRACEPOINT_LIST_GET:
1058                         memcpy(&lur.u.tracepoint, &lum->u.tracepoint, sizeof(lur.u.tracepoint));
1059                         break;
1060                 }
1061         }
1062         DBG("Return value: %d", lur.ret_val);
1063
1064         ust_unlock();
1065
1066         /*
1067          * Performed delayed statedump operations outside of the UST
1068          * lock. We need to take the dynamic loader lock before we take
1069          * the UST lock internally within handle_pending_statedump().
1070           */
1071         handle_pending_statedump(sock_info);
1072
1073         if (ust_lock()) {
1074                 ret = -LTTNG_UST_ERR_EXITING;
1075                 goto error;
1076         }
1077
1078         ret = send_reply(sock, &lur);
1079         if (ret < 0) {
1080                 DBG("error sending reply");
1081                 goto error;
1082         }
1083
1084         /*
1085          * LTTNG_UST_TRACEPOINT_FIELD_LIST_GET needs to send the field
1086          * after the reply.
1087          */
1088         if (lur.ret_code == LTTNG_UST_OK) {
1089                 switch (lum->cmd) {
1090                 case LTTNG_UST_TRACEPOINT_FIELD_LIST_GET:
1091                         len = ustcomm_send_unix_sock(sock,
1092                                 &args.field_list.entry,
1093                                 sizeof(args.field_list.entry));
1094                         if (len < 0) {
1095                                 ret = len;
1096                                 goto error;
1097                         }
1098                         if (len != sizeof(args.field_list.entry)) {
1099                                 ret = -EINVAL;
1100                                 goto error;
1101                         }
1102                 }
1103         }
1104
1105 error:
1106         ust_unlock();
1107
1108         return ret;
1109 }
1110
1111 static
1112 void cleanup_sock_info(struct sock_info *sock_info, int exiting)
1113 {
1114         int ret;
1115
1116         if (sock_info->root_handle != -1) {
1117                 ret = lttng_ust_objd_unref(sock_info->root_handle, 1);
1118                 if (ret) {
1119                         ERR("Error unref root handle");
1120                 }
1121                 sock_info->root_handle = -1;
1122         }
1123         sock_info->registration_done = 0;
1124         sock_info->initial_statedump_done = 0;
1125
1126         /*
1127          * wait_shm_mmap, socket and notify socket are used by listener
1128          * threads outside of the ust lock, so we cannot tear them down
1129          * ourselves, because we cannot join on these threads. Leave
1130          * responsibility of cleaning up these resources to the OS
1131          * process exit.
1132          */
1133         if (exiting)
1134                 return;
1135
1136         if (sock_info->socket != -1) {
1137                 ret = ustcomm_close_unix_sock(sock_info->socket);
1138                 if (ret) {
1139                         ERR("Error closing ust cmd socket");
1140                 }
1141                 sock_info->socket = -1;
1142         }
1143         if (sock_info->notify_socket != -1) {
1144                 ret = ustcomm_close_unix_sock(sock_info->notify_socket);
1145                 if (ret) {
1146                         ERR("Error closing ust notify socket");
1147                 }
1148                 sock_info->notify_socket = -1;
1149         }
1150         if (sock_info->wait_shm_mmap) {
1151                 long page_size;
1152
1153                 page_size = sysconf(_SC_PAGE_SIZE);
1154                 if (page_size <= 0) {
1155                         if (!page_size) {
1156                                 errno = EINVAL;
1157                         }
1158                         PERROR("Error in sysconf(_SC_PAGE_SIZE)");
1159                 } else {
1160                         ret = munmap(sock_info->wait_shm_mmap, page_size);
1161                         if (ret) {
1162                                 ERR("Error unmapping wait shm");
1163                         }
1164                 }
1165                 sock_info->wait_shm_mmap = NULL;
1166         }
1167 }
1168
1169 /*
1170  * Using fork to set umask in the child process (not multi-thread safe).
1171  * We deal with the shm_open vs ftruncate race (happening when the
1172  * sessiond owns the shm and does not let everybody modify it, to ensure
1173  * safety against shm_unlink) by simply letting the mmap fail and
1174  * retrying after a few seconds.
1175  * For global shm, everybody has rw access to it until the sessiond
1176  * starts.
1177  */
1178 static
1179 int get_wait_shm(struct sock_info *sock_info, size_t mmap_size)
1180 {
1181         int wait_shm_fd, ret;
1182         pid_t pid;
1183
1184         /*
1185          * Try to open read-only.
1186          */
1187         wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
1188         if (wait_shm_fd >= 0) {
1189                 int32_t tmp_read;
1190                 ssize_t len;
1191                 size_t bytes_read = 0;
1192
1193                 /*
1194                  * Try to read the fd. If unable to do so, try opening
1195                  * it in write mode.
1196                  */
1197                 do {
1198                         len = read(wait_shm_fd,
1199                                 &((char *) &tmp_read)[bytes_read],
1200                                 sizeof(tmp_read) - bytes_read);
1201                         if (len > 0) {
1202                                 bytes_read += len;
1203                         }
1204                 } while ((len < 0 && errno == EINTR)
1205                         || (len > 0 && bytes_read < sizeof(tmp_read)));
1206                 if (bytes_read != sizeof(tmp_read)) {
1207                         ret = close(wait_shm_fd);
1208                         if (ret) {
1209                                 ERR("close wait_shm_fd");
1210                         }
1211                         goto open_write;
1212                 }
1213                 goto end;
1214         } else if (wait_shm_fd < 0 && errno != ENOENT) {
1215                 /*
1216                  * Real-only open did not work, and it's not because the
1217                  * entry was not present. It's a failure that prohibits
1218                  * using shm.
1219                  */
1220                 ERR("Error opening shm %s", sock_info->wait_shm_path);
1221                 goto end;
1222         }
1223
1224 open_write:
1225         /*
1226          * If the open failed because the file did not exist, or because
1227          * the file was not truncated yet, try creating it ourself.
1228          */
1229         URCU_TLS(lttng_ust_nest_count)++;
1230         pid = fork();
1231         URCU_TLS(lttng_ust_nest_count)--;
1232         if (pid > 0) {
1233                 int status;
1234
1235                 /*
1236                  * Parent: wait for child to return, in which case the
1237                  * shared memory map will have been created.
1238                  */
1239                 pid = wait(&status);
1240                 if (pid < 0 || !WIFEXITED(status) || WEXITSTATUS(status) != 0) {
1241                         wait_shm_fd = -1;
1242                         goto end;
1243                 }
1244                 /*
1245                  * Try to open read-only again after creation.
1246                  */
1247                 wait_shm_fd = shm_open(sock_info->wait_shm_path, O_RDONLY, 0);
1248                 if (wait_shm_fd < 0) {
1249                         /*
1250                          * Real-only open did not work. It's a failure
1251                          * that prohibits using shm.
1252                          */
1253                         ERR("Error opening shm %s", sock_info->wait_shm_path);
1254                         goto end;
1255                 }
1256                 goto end;
1257         } else if (pid == 0) {
1258                 int create_mode;
1259
1260                 /* Child */
1261                 create_mode = S_IRUSR | S_IWUSR | S_IRGRP;
1262                 if (sock_info->global)
1263                         create_mode |= S_IROTH | S_IWGRP | S_IWOTH;
1264                 /*
1265                  * We're alone in a child process, so we can modify the
1266                  * process-wide umask.
1267                  */
1268                 umask(~create_mode);
1269                 /*
1270                  * Try creating shm (or get rw access).
1271                  * We don't do an exclusive open, because we allow other
1272                  * processes to create+ftruncate it concurrently.
1273                  */
1274                 wait_shm_fd = shm_open(sock_info->wait_shm_path,
1275                                 O_RDWR | O_CREAT, create_mode);
1276                 if (wait_shm_fd >= 0) {
1277                         ret = ftruncate(wait_shm_fd, mmap_size);
1278                         if (ret) {
1279                                 PERROR("ftruncate");
1280                                 _exit(EXIT_FAILURE);
1281                         }
1282                         _exit(EXIT_SUCCESS);
1283                 }
1284                 /*
1285                  * For local shm, we need to have rw access to accept
1286                  * opening it: this means the local sessiond will be
1287                  * able to wake us up. For global shm, we open it even
1288                  * if rw access is not granted, because the root.root
1289                  * sessiond will be able to override all rights and wake
1290                  * us up.
1291                  */
1292                 if (!sock_info->global && errno != EACCES) {
1293                         ERR("Error opening shm %s", sock_info->wait_shm_path);
1294                         _exit(EXIT_FAILURE);
1295                 }
1296                 /*
1297                  * The shm exists, but we cannot open it RW. Report
1298                  * success.
1299                  */
1300                 _exit(EXIT_SUCCESS);
1301         } else {
1302                 return -1;
1303         }
1304 end:
1305         if (wait_shm_fd >= 0 && !sock_info->global) {
1306                 struct stat statbuf;
1307
1308                 /*
1309                  * Ensure that our user is the owner of the shm file for
1310                  * local shm. If we do not own the file, it means our
1311                  * sessiond will not have access to wake us up (there is
1312                  * probably a rogue process trying to fake our
1313                  * sessiond). Fallback to polling method in this case.
1314                  */
1315                 ret = fstat(wait_shm_fd, &statbuf);
1316                 if (ret) {
1317                         PERROR("fstat");
1318                         goto error_close;
1319                 }
1320                 if (statbuf.st_uid != getuid())
1321                         goto error_close;
1322         }
1323         return wait_shm_fd;
1324
1325 error_close:
1326         ret = close(wait_shm_fd);
1327         if (ret) {
1328                 PERROR("Error closing fd");
1329         }
1330         return -1;
1331 }
1332
1333 static
1334 char *get_map_shm(struct sock_info *sock_info)
1335 {
1336         long page_size;
1337         int wait_shm_fd, ret;
1338         char *wait_shm_mmap;
1339
1340         page_size = sysconf(_SC_PAGE_SIZE);
1341         if (page_size <= 0) {
1342                 if (!page_size) {
1343                         errno = EINVAL;
1344                 }
1345                 PERROR("Error in sysconf(_SC_PAGE_SIZE)");
1346                 goto error;
1347         }
1348
1349         lttng_ust_lock_fd_tracker();
1350         wait_shm_fd = get_wait_shm(sock_info, page_size);
1351         if (wait_shm_fd < 0) {
1352                 lttng_ust_unlock_fd_tracker();
1353                 goto error;
1354         }
1355
1356         ret = lttng_ust_add_fd_to_tracker(wait_shm_fd);
1357         if (ret < 0) {
1358                 ret = close(wait_shm_fd);
1359                 if (!ret) {
1360                         PERROR("Error closing fd");
1361                 }
1362                 lttng_ust_unlock_fd_tracker();
1363                 goto error;
1364         }
1365
1366         wait_shm_fd = ret;
1367         lttng_ust_unlock_fd_tracker();
1368
1369         wait_shm_mmap = mmap(NULL, page_size, PROT_READ,
1370                   MAP_SHARED, wait_shm_fd, 0);
1371
1372         /* close shm fd immediately after taking the mmap reference */
1373         lttng_ust_lock_fd_tracker();
1374         ret = close(wait_shm_fd);
1375         if (!ret) {
1376                 lttng_ust_delete_fd_from_tracker(wait_shm_fd);
1377         } else {
1378                 PERROR("Error closing fd");
1379         }
1380         lttng_ust_unlock_fd_tracker();
1381
1382         if (wait_shm_mmap == MAP_FAILED) {
1383                 DBG("mmap error (can be caused by race with sessiond). Fallback to poll mode.");
1384                 goto error;
1385         }
1386         return wait_shm_mmap;
1387
1388 error:
1389         return NULL;
1390 }
1391
1392 static
1393 void wait_for_sessiond(struct sock_info *sock_info)
1394 {
1395         /* Use ust_lock to check if we should quit. */
1396         if (ust_lock()) {
1397                 goto quit;
1398         }
1399         if (wait_poll_fallback) {
1400                 goto error;
1401         }
1402         ust_unlock();
1403
1404         assert(sock_info->wait_shm_mmap);
1405
1406         DBG("Waiting for %s apps sessiond", sock_info->name);
1407         /* Wait for futex wakeup */
1408         if (uatomic_read((int32_t *) sock_info->wait_shm_mmap))
1409                 goto end_wait;
1410
1411         while (futex_async((int32_t *) sock_info->wait_shm_mmap,
1412                         FUTEX_WAIT, 0, NULL, NULL, 0)) {
1413                 switch (errno) {
1414                 case EWOULDBLOCK:
1415                         /* Value already changed. */
1416                         goto end_wait;
1417                 case EINTR:
1418                         /* Retry if interrupted by signal. */
1419                         break;  /* Get out of switch. */
1420                 case EFAULT:
1421                         wait_poll_fallback = 1;
1422                         DBG(
1423 "Linux kernels 2.6.33 to 3.0 (with the exception of stable versions) "
1424 "do not support FUTEX_WAKE on read-only memory mappings correctly. "
1425 "Please upgrade your kernel "
1426 "(fix is commit 9ea71503a8ed9184d2d0b8ccc4d269d05f7940ae in Linux kernel "
1427 "mainline). LTTng-UST will use polling mode fallback.");
1428                         if (ust_debug())
1429                                 PERROR("futex");
1430                         goto end_wait;
1431                 }
1432         }
1433 end_wait:
1434         return;
1435
1436 quit:
1437         ust_unlock();
1438         return;
1439
1440 error:
1441         ust_unlock();
1442         return;
1443 }
1444
1445 /*
1446  * This thread does not allocate any resource, except within
1447  * handle_message, within mutex protection. This mutex protects against
1448  * fork and exit.
1449  * The other moment it allocates resources is at socket connection, which
1450  * is also protected by the mutex.
1451  */
1452 static
1453 void *ust_listener_thread(void *arg)
1454 {
1455         struct sock_info *sock_info = arg;
1456         int sock, ret, prev_connect_failed = 0, has_waited = 0, fd;
1457         long timeout;
1458
1459         lttng_ust_fixup_tls();
1460         lttng_ust_fd_tracker_register_thread();
1461         /*
1462          * If available, add '-ust' to the end of this thread's
1463          * process name
1464          */
1465         ret = lttng_ust_setustprocname();
1466         if (ret) {
1467                 ERR("Unable to set UST process name");
1468         }
1469
1470         /* Restart trying to connect to the session daemon */
1471 restart:
1472         if (prev_connect_failed) {
1473                 /* Wait for sessiond availability with pipe */
1474                 wait_for_sessiond(sock_info);
1475                 if (has_waited) {
1476                         has_waited = 0;
1477                         /*
1478                          * Sleep for 5 seconds before retrying after a
1479                          * sequence of failure / wait / failure. This
1480                          * deals with a killed or broken session daemon.
1481                          */
1482                         sleep(5);
1483                 } else {
1484                         has_waited = 1;
1485                 }
1486                 prev_connect_failed = 0;
1487         }
1488
1489         if (ust_lock()) {
1490                 goto quit;
1491         }
1492
1493         if (sock_info->socket != -1) {
1494                 /* FD tracker is updated by ustcomm_close_unix_sock() */
1495                 ret = ustcomm_close_unix_sock(sock_info->socket);
1496                 if (ret) {
1497                         ERR("Error closing %s ust cmd socket",
1498                                 sock_info->name);
1499                 }
1500                 sock_info->socket = -1;
1501         }
1502         if (sock_info->notify_socket != -1) {
1503                 /* FD tracker is updated by ustcomm_close_unix_sock() */
1504                 ret = ustcomm_close_unix_sock(sock_info->notify_socket);
1505                 if (ret) {
1506                         ERR("Error closing %s ust notify socket",
1507                                 sock_info->name);
1508                 }
1509                 sock_info->notify_socket = -1;
1510         }
1511
1512
1513         /*
1514          * Register. We need to perform both connect and sending
1515          * registration message before doing the next connect otherwise
1516          * we may reach unix socket connect queue max limits and block
1517          * on the 2nd connect while the session daemon is awaiting the
1518          * first connect registration message.
1519          */
1520         /* Connect cmd socket */
1521         lttng_ust_lock_fd_tracker();
1522         ret = ustcomm_connect_unix_sock(sock_info->sock_path,
1523                 get_connect_sock_timeout());
1524         if (ret < 0) {
1525                 lttng_ust_unlock_fd_tracker();
1526                 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
1527                 prev_connect_failed = 1;
1528
1529                 /*
1530                  * If we cannot find the sessiond daemon, don't delay
1531                  * constructor execution.
1532                  */
1533                 ret = handle_register_failed(sock_info);
1534                 assert(!ret);
1535                 ust_unlock();
1536                 goto restart;
1537         }
1538         fd = ret;
1539         ret = lttng_ust_add_fd_to_tracker(fd);
1540         if (ret < 0) {
1541                 ret = close(fd);
1542                 if (ret) {
1543                         PERROR("close on sock_info->socket");
1544                 }
1545                 ret = -1;
1546                 lttng_ust_unlock_fd_tracker();
1547                 ust_unlock();
1548                 goto quit;
1549         }
1550
1551         sock_info->socket = ret;
1552         lttng_ust_unlock_fd_tracker();
1553
1554         ust_unlock();
1555         /*
1556          * Unlock/relock ust lock because connect is blocking (with
1557          * timeout). Don't delay constructors on the ust lock for too
1558          * long.
1559          */
1560         if (ust_lock()) {
1561                 goto quit;
1562         }
1563
1564         /*
1565          * Create only one root handle per listener thread for the whole
1566          * process lifetime, so we ensure we get ID which is statically
1567          * assigned to the root handle.
1568          */
1569         if (sock_info->root_handle == -1) {
1570                 ret = lttng_abi_create_root_handle();
1571                 if (ret < 0) {
1572                         ERR("Error creating root handle");
1573                         goto quit;
1574                 }
1575                 sock_info->root_handle = ret;
1576         }
1577
1578         ret = register_to_sessiond(sock_info->socket, USTCTL_SOCKET_CMD);
1579         if (ret < 0) {
1580                 ERR("Error registering to %s ust cmd socket",
1581                         sock_info->name);
1582                 prev_connect_failed = 1;
1583                 /*
1584                  * If we cannot register to the sessiond daemon, don't
1585                  * delay constructor execution.
1586                  */
1587                 ret = handle_register_failed(sock_info);
1588                 assert(!ret);
1589                 ust_unlock();
1590                 goto restart;
1591         }
1592
1593         ust_unlock();
1594         /*
1595          * Unlock/relock ust lock because connect is blocking (with
1596          * timeout). Don't delay constructors on the ust lock for too
1597          * long.
1598          */
1599         if (ust_lock()) {
1600                 goto quit;
1601         }
1602
1603         /* Connect notify socket */
1604         lttng_ust_lock_fd_tracker();
1605         ret = ustcomm_connect_unix_sock(sock_info->sock_path,
1606                 get_connect_sock_timeout());
1607         if (ret < 0) {
1608                 lttng_ust_unlock_fd_tracker();
1609                 DBG("Info: sessiond not accepting connections to %s apps socket", sock_info->name);
1610                 prev_connect_failed = 1;
1611
1612                 /*
1613                  * If we cannot find the sessiond daemon, don't delay
1614                  * constructor execution.
1615                  */
1616                 ret = handle_register_failed(sock_info);
1617                 assert(!ret);
1618                 ust_unlock();
1619                 goto restart;
1620         }
1621
1622         fd = ret;
1623         ret = lttng_ust_add_fd_to_tracker(fd);
1624         if (ret < 0) {
1625                 ret = close(fd);
1626                 if (ret) {
1627                         PERROR("close on sock_info->notify_socket");
1628                 }
1629                 ret = -1;
1630                 lttng_ust_unlock_fd_tracker();
1631                 ust_unlock();
1632                 goto quit;
1633         }
1634
1635         sock_info->notify_socket = ret;
1636         lttng_ust_unlock_fd_tracker();
1637
1638         ust_unlock();
1639         /*
1640          * Unlock/relock ust lock because connect is blocking (with
1641          * timeout). Don't delay constructors on the ust lock for too
1642          * long.
1643          */
1644         if (ust_lock()) {
1645                 goto quit;
1646         }
1647
1648         timeout = get_notify_sock_timeout();
1649         if (timeout >= 0) {
1650                 /*
1651                  * Give at least 10ms to sessiond to reply to
1652                  * notifications.
1653                  */
1654                 if (timeout < 10)
1655                         timeout = 10;
1656                 ret = ustcomm_setsockopt_rcv_timeout(sock_info->notify_socket,
1657                                 timeout);
1658                 if (ret < 0) {
1659                         WARN("Error setting socket receive timeout");
1660                 }
1661                 ret = ustcomm_setsockopt_snd_timeout(sock_info->notify_socket,
1662                                 timeout);
1663                 if (ret < 0) {
1664                         WARN("Error setting socket send timeout");
1665                 }
1666         } else if (timeout < -1) {
1667                 WARN("Unsupported timeout value %ld", timeout);
1668         }
1669
1670         ret = register_to_sessiond(sock_info->notify_socket,
1671                         USTCTL_SOCKET_NOTIFY);
1672         if (ret < 0) {
1673                 ERR("Error registering to %s ust notify socket",
1674                         sock_info->name);
1675                 prev_connect_failed = 1;
1676                 /*
1677                  * If we cannot register to the sessiond daemon, don't
1678                  * delay constructor execution.
1679                  */
1680                 ret = handle_register_failed(sock_info);
1681                 assert(!ret);
1682                 ust_unlock();
1683                 goto restart;
1684         }
1685         sock = sock_info->socket;
1686
1687         ust_unlock();
1688
1689         for (;;) {
1690                 ssize_t len;
1691                 struct ustcomm_ust_msg lum;
1692
1693                 len = ustcomm_recv_unix_sock(sock, &lum, sizeof(lum));
1694                 switch (len) {
1695                 case 0: /* orderly shutdown */
1696                         DBG("%s lttng-sessiond has performed an orderly shutdown", sock_info->name);
1697                         if (ust_lock()) {
1698                                 goto quit;
1699                         }
1700                         /*
1701                          * Either sessiond has shutdown or refused us by closing the socket.
1702                          * In either case, we don't want to delay construction execution,
1703                          * and we need to wait before retry.
1704                          */
1705                         prev_connect_failed = 1;
1706                         /*
1707                          * If we cannot register to the sessiond daemon, don't
1708                          * delay constructor execution.
1709                          */
1710                         ret = handle_register_failed(sock_info);
1711                         assert(!ret);
1712                         ust_unlock();
1713                         goto end;
1714                 case sizeof(lum):
1715                         print_cmd(lum.cmd, lum.handle);
1716                         ret = handle_message(sock_info, sock, &lum);
1717                         if (ret) {
1718                                 ERR("Error handling message for %s socket",
1719                                         sock_info->name);
1720                                 /*
1721                                  * Close socket if protocol error is
1722                                  * detected.
1723                                  */
1724                                 goto end;
1725                         }
1726                         continue;
1727                 default:
1728                         if (len < 0) {
1729                                 DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
1730                         } else {
1731                                 DBG("incorrect message size (%s socket): %zd", sock_info->name, len);
1732                         }
1733                         if (len == -ECONNRESET) {
1734                                 DBG("%s remote end closed connection", sock_info->name);
1735                                 goto end;
1736                         }
1737                         goto end;
1738                 }
1739
1740         }
1741 end:
1742         if (ust_lock()) {
1743                 goto quit;
1744         }
1745         /* Cleanup socket handles before trying to reconnect */
1746         lttng_ust_objd_table_owner_cleanup(sock_info);
1747         ust_unlock();
1748         goto restart;   /* try to reconnect */
1749
1750 quit:
1751         ust_unlock();
1752
1753         pthread_mutex_lock(&ust_exit_mutex);
1754         sock_info->thread_active = 0;
1755         pthread_mutex_unlock(&ust_exit_mutex);
1756         return NULL;
1757 }
1758
1759 /*
1760  * Weak symbol to call when the ust malloc wrapper is not loaded.
1761  */
1762 __attribute__((weak))
1763 void lttng_ust_malloc_wrapper_init(void)
1764 {
1765 }
1766
1767 /*
1768  * sessiond monitoring thread: monitor presence of global and per-user
1769  * sessiond by polling the application common named pipe.
1770  */
1771 void __attribute__((constructor)) lttng_ust_init(void)
1772 {
1773         struct timespec constructor_timeout;
1774         sigset_t sig_all_blocked, orig_parent_mask;
1775         pthread_attr_t thread_attr;
1776         int timeout_mode;
1777         int ret;
1778         void *handle;
1779
1780         if (uatomic_xchg(&initialized, 1) == 1)
1781                 return;
1782
1783         /*
1784          * Fixup interdependency between TLS fixup mutex (which happens
1785          * to be the dynamic linker mutex) and ust_lock, taken within
1786          * the ust lock.
1787          */
1788         lttng_ust_fixup_tls();
1789
1790         lttng_ust_loaded = 1;
1791
1792         /*
1793          * We need to ensure that the liblttng-ust library is not unloaded to avoid
1794          * the unloading of code used by the ust_listener_threads as we can not
1795          * reliably know when they exited. To do that, manually load
1796          * liblttng-ust.so to increment the dynamic loader's internal refcount for
1797          * this library so it never becomes zero, thus never gets unloaded from the
1798          * address space of the process. Since we are already running in the
1799          * constructor of the LTTNG_UST_LIB_SO_NAME library, calling dlopen will
1800          * simply increment the refcount and no additionnal work is needed by the
1801          * dynamic loader as the shared library is already loaded in the address
1802          * space. As a safe guard, we use the RTLD_NODELETE flag to prevent
1803          * unloading of the UST library if its refcount becomes zero (which should
1804          * never happen). Do the return value check but discard the handle at the
1805          * end of the function as it's not needed.
1806          */
1807         handle = dlopen(LTTNG_UST_LIB_SO_NAME, RTLD_LAZY | RTLD_NODELETE);
1808         if (!handle) {
1809                 ERR("dlopen of liblttng-ust shared library (%s).", LTTNG_UST_LIB_SO_NAME);
1810         }
1811
1812         /*
1813          * We want precise control over the order in which we construct
1814          * our sub-libraries vs starting to receive commands from
1815          * sessiond (otherwise leading to errors when trying to create
1816          * sessiond before the init functions are completed).
1817          */
1818         init_usterr();
1819         lttng_ust_getenv_init();        /* Needs init_usterr() to be completed. */
1820         init_tracepoint();
1821         lttng_ust_init_fd_tracker();
1822         lttng_ust_clock_init();
1823         lttng_ust_getcpu_init();
1824         lttng_ust_statedump_init();
1825         lttng_ring_buffer_metadata_client_init();
1826         lttng_ring_buffer_client_overwrite_init();
1827         lttng_ring_buffer_client_overwrite_rt_init();
1828         lttng_ring_buffer_client_discard_init();
1829         lttng_ring_buffer_client_discard_rt_init();
1830         lttng_perf_counter_init();
1831         /*
1832          * Invoke ust malloc wrapper init before starting other threads.
1833          */
1834         lttng_ust_malloc_wrapper_init();
1835
1836         timeout_mode = get_constructor_timeout(&constructor_timeout);
1837
1838         get_allow_blocking();
1839
1840         ret = sem_init(&constructor_wait, 0, 0);
1841         if (ret) {
1842                 PERROR("sem_init");
1843         }
1844
1845         ret = setup_global_apps();
1846         if (ret) {
1847                 assert(global_apps.allowed == 0);
1848                 DBG("global apps setup returned %d", ret);
1849         }
1850
1851         ret = setup_local_apps();
1852         if (ret) {
1853                 assert(local_apps.allowed == 0);
1854                 DBG("local apps setup returned %d", ret);
1855         }
1856
1857         /* A new thread created by pthread_create inherits the signal mask
1858          * from the parent. To avoid any signal being received by the
1859          * listener thread, we block all signals temporarily in the parent,
1860          * while we create the listener thread.
1861          */
1862         sigfillset(&sig_all_blocked);
1863         ret = pthread_sigmask(SIG_SETMASK, &sig_all_blocked, &orig_parent_mask);
1864         if (ret) {
1865                 ERR("pthread_sigmask: %s", strerror(ret));
1866         }
1867
1868         ret = pthread_attr_init(&thread_attr);
1869         if (ret) {
1870                 ERR("pthread_attr_init: %s", strerror(ret));
1871         }
1872         ret = pthread_attr_setdetachstate(&thread_attr, PTHREAD_CREATE_DETACHED);
1873         if (ret) {
1874                 ERR("pthread_attr_setdetachstate: %s", strerror(ret));
1875         }
1876
1877         if (global_apps.allowed) {
1878                 pthread_mutex_lock(&ust_exit_mutex);
1879                 ret = pthread_create(&global_apps.ust_listener, &thread_attr,
1880                                 ust_listener_thread, &global_apps);
1881                 if (ret) {
1882                         ERR("pthread_create global: %s", strerror(ret));
1883                 }
1884                 global_apps.thread_active = 1;
1885                 pthread_mutex_unlock(&ust_exit_mutex);
1886         } else {
1887                 handle_register_done(&global_apps);
1888         }
1889
1890         if (local_apps.allowed) {
1891                 pthread_mutex_lock(&ust_exit_mutex);
1892                 ret = pthread_create(&local_apps.ust_listener, &thread_attr,
1893                                 ust_listener_thread, &local_apps);
1894                 if (ret) {
1895                         ERR("pthread_create local: %s", strerror(ret));
1896                 }
1897                 local_apps.thread_active = 1;
1898                 pthread_mutex_unlock(&ust_exit_mutex);
1899         } else {
1900                 handle_register_done(&local_apps);
1901         }
1902         ret = pthread_attr_destroy(&thread_attr);
1903         if (ret) {
1904                 ERR("pthread_attr_destroy: %s", strerror(ret));
1905         }
1906
1907         /* Restore original signal mask in parent */
1908         ret = pthread_sigmask(SIG_SETMASK, &orig_parent_mask, NULL);
1909         if (ret) {
1910                 ERR("pthread_sigmask: %s", strerror(ret));
1911         }
1912
1913         switch (timeout_mode) {
1914         case 1: /* timeout wait */
1915                 do {
1916                         ret = sem_timedwait(&constructor_wait,
1917                                         &constructor_timeout);
1918                 } while (ret < 0 && errno == EINTR);
1919                 if (ret < 0) {
1920                         switch (errno) {
1921                         case ETIMEDOUT:
1922                                 ERR("Timed out waiting for lttng-sessiond");
1923                                 break;
1924                         case EINVAL:
1925                                 PERROR("sem_timedwait");
1926                                 break;
1927                         default:
1928                                 ERR("Unexpected error \"%s\" returned by sem_timedwait",
1929                                         strerror(errno));
1930                         }
1931                 }
1932                 break;
1933         case -1:/* wait forever */
1934                 do {
1935                         ret = sem_wait(&constructor_wait);
1936                 } while (ret < 0 && errno == EINTR);
1937                 if (ret < 0) {
1938                         switch (errno) {
1939                         case EINVAL:
1940                                 PERROR("sem_wait");
1941                                 break;
1942                         default:
1943                                 ERR("Unexpected error \"%s\" returned by sem_wait",
1944                                         strerror(errno));
1945                         }
1946                 }
1947                 break;
1948         case 0: /* no timeout */
1949                 break;
1950         }
1951 }
1952
1953 static
1954 void lttng_ust_cleanup(int exiting)
1955 {
1956         cleanup_sock_info(&global_apps, exiting);
1957         cleanup_sock_info(&local_apps, exiting);
1958         local_apps.allowed = 0;
1959         global_apps.allowed = 0;
1960         /*
1961          * The teardown in this function all affect data structures
1962          * accessed under the UST lock by the listener thread. This
1963          * lock, along with the lttng_ust_comm_should_quit flag, ensure
1964          * that none of these threads are accessing this data at this
1965          * point.
1966          */
1967         lttng_ust_abi_exit();
1968         lttng_ust_events_exit();
1969         lttng_perf_counter_exit();
1970         lttng_ring_buffer_client_discard_rt_exit();
1971         lttng_ring_buffer_client_discard_exit();
1972         lttng_ring_buffer_client_overwrite_rt_exit();
1973         lttng_ring_buffer_client_overwrite_exit();
1974         lttng_ring_buffer_metadata_client_exit();
1975         lttng_ust_statedump_destroy();
1976         exit_tracepoint();
1977         if (!exiting) {
1978                 /* Reinitialize values for fork */
1979                 sem_count = sem_count_initial_value;
1980                 lttng_ust_comm_should_quit = 0;
1981                 initialized = 0;
1982         }
1983 }
1984
1985 void __attribute__((destructor)) lttng_ust_exit(void)
1986 {
1987         int ret;
1988
1989         /*
1990          * Using pthread_cancel here because:
1991          * A) we don't want to hang application teardown.
1992          * B) the thread is not allocating any resource.
1993          */
1994
1995         /*
1996          * Require the communication thread to quit. Synchronize with
1997          * mutexes to ensure it is not in a mutex critical section when
1998          * pthread_cancel is later called.
1999          */
2000         ust_lock_nocheck();
2001         lttng_ust_comm_should_quit = 1;
2002         ust_unlock();
2003
2004         pthread_mutex_lock(&ust_exit_mutex);
2005         /* cancel threads */
2006         if (global_apps.thread_active) {
2007                 ret = pthread_cancel(global_apps.ust_listener);
2008                 if (ret) {
2009                         ERR("Error cancelling global ust listener thread: %s",
2010                                 strerror(ret));
2011                 } else {
2012                         global_apps.thread_active = 0;
2013                 }
2014         }
2015         if (local_apps.thread_active) {
2016                 ret = pthread_cancel(local_apps.ust_listener);
2017                 if (ret) {
2018                         ERR("Error cancelling local ust listener thread: %s",
2019                                 strerror(ret));
2020                 } else {
2021                         local_apps.thread_active = 0;
2022                 }
2023         }
2024         pthread_mutex_unlock(&ust_exit_mutex);
2025
2026         /*
2027          * Do NOT join threads: use of sys_futex makes it impossible to
2028          * join the threads without using async-cancel, but async-cancel
2029          * is delivered by a signal, which could hit the target thread
2030          * anywhere in its code path, including while the ust_lock() is
2031          * held, causing a deadlock for the other thread. Let the OS
2032          * cleanup the threads if there are stalled in a syscall.
2033          */
2034         lttng_ust_cleanup(1);
2035 }
2036
2037 /*
2038  * We exclude the worker threads across fork and clone (except
2039  * CLONE_VM), because these system calls only keep the forking thread
2040  * running in the child.  Therefore, we don't want to call fork or clone
2041  * in the middle of an tracepoint or ust tracing state modification.
2042  * Holding this mutex protects these structures across fork and clone.
2043  */
2044 void ust_before_fork(sigset_t *save_sigset)
2045 {
2046         /*
2047          * Disable signals. This is to avoid that the child intervenes
2048          * before it is properly setup for tracing. It is safer to
2049          * disable all signals, because then we know we are not breaking
2050          * anything by restoring the original mask.
2051          */
2052         sigset_t all_sigs;
2053         int ret;
2054
2055         /* Fixup lttng-ust TLS. */
2056         lttng_ust_fixup_tls();
2057
2058         if (URCU_TLS(lttng_ust_nest_count))
2059                 return;
2060         /* Disable signals */
2061         sigfillset(&all_sigs);
2062         ret = sigprocmask(SIG_BLOCK, &all_sigs, save_sigset);
2063         if (ret == -1) {
2064                 PERROR("sigprocmask");
2065         }
2066
2067         pthread_mutex_lock(&ust_fork_mutex);
2068
2069         ust_lock_nocheck();
2070         urcu_bp_before_fork();
2071         lttng_ust_lock_fd_tracker();
2072 }
2073
2074 static void ust_after_fork_common(sigset_t *restore_sigset)
2075 {
2076         int ret;
2077
2078         DBG("process %d", getpid());
2079         lttng_ust_unlock_fd_tracker();
2080         ust_unlock();
2081
2082         pthread_mutex_unlock(&ust_fork_mutex);
2083
2084         /* Restore signals */
2085         ret = sigprocmask(SIG_SETMASK, restore_sigset, NULL);
2086         if (ret == -1) {
2087                 PERROR("sigprocmask");
2088         }
2089 }
2090
2091 void ust_after_fork_parent(sigset_t *restore_sigset)
2092 {
2093         if (URCU_TLS(lttng_ust_nest_count))
2094                 return;
2095         DBG("process %d", getpid());
2096         urcu_bp_after_fork_parent();
2097         /* Release mutexes and reenable signals */
2098         ust_after_fork_common(restore_sigset);
2099 }
2100
2101 /*
2102  * After fork, in the child, we need to cleanup all the leftover state,
2103  * except the worker thread which already magically disappeared thanks
2104  * to the weird Linux fork semantics. After tyding up, we call
2105  * lttng_ust_init() again to start over as a new PID.
2106  *
2107  * This is meant for forks() that have tracing in the child between the
2108  * fork and following exec call (if there is any).
2109  */
2110 void ust_after_fork_child(sigset_t *restore_sigset)
2111 {
2112         if (URCU_TLS(lttng_ust_nest_count))
2113                 return;
2114         lttng_context_vpid_reset();
2115         lttng_context_vtid_reset();
2116         lttng_context_procname_reset();
2117         DBG("process %d", getpid());
2118         /* Release urcu mutexes */
2119         urcu_bp_after_fork_child();
2120         lttng_ust_cleanup(0);
2121         /* Release mutexes and reenable signals */
2122         ust_after_fork_common(restore_sigset);
2123         lttng_ust_init();
2124 }
2125
2126 void lttng_ust_sockinfo_session_enabled(void *owner)
2127 {
2128         struct sock_info *sock_info = owner;
2129         sock_info->statedump_pending = 1;
2130 }