Launch the client management thread using lttng_thread

[lttng-tools.git] / src / bin / lttng-sessiond / main.c

/*
 * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
 *                      Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 *               2013 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2 only,
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#define _LGPL_SOURCE
#include <getopt.h>
#include <grp.h>
#include <limits.h>
#include <paths.h>
#include <pthread.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <inttypes.h>
#include <sys/mman.h>
#include <sys/mount.h>
#include <sys/resource.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <urcu/uatomic.h>
#include <unistd.h>
#include <ctype.h>

#include <common/common.h>
#include <common/compat/socket.h>
#include <common/compat/getenv.h>
#include <common/defaults.h>
#include <common/kernel-consumer/kernel-consumer.h>
#include <common/futex.h>
#include <common/relayd/relayd.h>
#include <common/utils.h>
#include <common/daemonize.h>
#include <common/config/session-config.h>
#include <common/dynamic-buffer.h>
#include <lttng/event-internal.h>

#include "lttng-sessiond.h"
#include "buffer-registry.h"
#include "channel.h"
#include "cmd.h"
#include "consumer.h"
#include "context.h"
#include "event.h"
#include "kernel.h"
#include "kernel-consumer.h"
#include "modprobe.h"
#include "shm.h"
#include "ust-ctl.h"
#include "ust-consumer.h"
#include "utils.h"
#include "fd-limit.h"
#include "health-sessiond.h"
#include "testpoint.h"
#include "ust-thread.h"
#include "agent-thread.h"
#include "save.h"
#include "load-session-thread.h"
#include "notification-thread.h"
#include "notification-thread-commands.h"
#include "rotation-thread.h"
#include "lttng-syscall.h"
#include "agent.h"
#include "ht-cleanup.h"
#include "sessiond-config.h"
#include "timer.h"
#include "thread.h"
#include "client.h"

static const char *help_msg =
#ifdef LTTNG_EMBED_HELP
#include <lttng-sessiond.8.h>
#else
NULL
#endif
;

const char *progname;
static int lockfile_fd = -1;

/* Set to 1 when a SIGUSR1 signal is received. */
static int recv_child_signal;

/* Command line options */
static const struct option long_options[] = {
        { "client-sock", required_argument, 0, 'c' },
        { "apps-sock", required_argument, 0, 'a' },
        { "kconsumerd-cmd-sock", required_argument, 0, '\0' },
        { "kconsumerd-err-sock", required_argument, 0, '\0' },
        { "ustconsumerd32-cmd-sock", required_argument, 0, '\0' },
        { "ustconsumerd32-err-sock", required_argument, 0, '\0' },
        { "ustconsumerd64-cmd-sock", required_argument, 0, '\0' },
        { "ustconsumerd64-err-sock", required_argument, 0, '\0' },
        { "consumerd32-path", required_argument, 0, '\0' },
        { "consumerd32-libdir", required_argument, 0, '\0' },
        { "consumerd64-path", required_argument, 0, '\0' },
        { "consumerd64-libdir", required_argument, 0, '\0' },
        { "daemonize", no_argument, 0, 'd' },
        { "background", no_argument, 0, 'b' },
        { "sig-parent", no_argument, 0, 'S' },
        { "help", no_argument, 0, 'h' },
        { "group", required_argument, 0, 'g' },
        { "version", no_argument, 0, 'V' },
        { "quiet", no_argument, 0, 'q' },
        { "verbose", no_argument, 0, 'v' },
        { "verbose-consumer", no_argument, 0, '\0' },
        { "no-kernel", no_argument, 0, '\0' },
        { "pidfile", required_argument, 0, 'p' },
        { "agent-tcp-port", required_argument, 0, '\0' },
        { "config", required_argument, 0, 'f' },
        { "load", required_argument, 0, 'l' },
        { "kmod-probes", required_argument, 0, '\0' },
        { "extra-kmod-probes", required_argument, 0, '\0' },
        { NULL, 0, 0, 0 }
};

/* Command line options to ignore from configuration file */
static const char *config_ignore_options[] = { "help", "version", "config" };

/* Shared between threads */
static int dispatch_thread_exit;

static int apps_sock = -1;

/*
 * This pipe is used to inform the thread managing application communication
 * that a command is queued and ready to be processed.
 */
static int apps_cmd_pipe[2] = { -1, -1 };

/* Pthread, Mutexes and Semaphores */
static pthread_t apps_thread;
static pthread_t apps_notify_thread;
static pthread_t reg_apps_thread;
static pthread_t kernel_thread;
static pthread_t dispatch_thread;
static pthread_t agent_reg_thread;
static pthread_t load_session_thread;

/*
 * UST registration command queue. This queue is tied with a futex and uses a N
 * wakers / 1 waiter implemented and detailed in futex.c/.h
 *
 * The thread_registration_apps and thread_dispatch_ust_registration uses this
 * queue along with the wait/wake scheme. The thread_manage_apps receives down
 * the line new application socket and monitors it for any I/O error or clean
 * close that triggers an unregistration of the application.
 */
static struct ust_cmd_queue ust_cmd_queue;

static const char *module_proc_lttng = "/proc/lttng";

/* Load session thread information to operate. */
static struct load_session_thread_data *load_info;

/*
 * Section name to look for in the daemon configuration file.
 */
static const char * const config_section_name = "sessiond";

/* Am I root or not. Set to 1 if the daemon is running as root */
static int is_root;

/*
 * Stop all threads by closing the thread quit pipe.
 */
static void stop_threads(void)
{
        int ret;

        /* Stopping all threads */
        DBG("Terminating all threads");
        ret = sessiond_notify_quit_pipe();
        if (ret < 0) {
                ERR("write error on thread quit pipe");
        }

        /* Dispatch thread */
        CMM_STORE_SHARED(dispatch_thread_exit, 1);
        futex_nto1_wake(&ust_cmd_queue.futex);
}

/*
 * Close every consumer sockets.
 */
static void close_consumer_sockets(void)
{
        int ret;

        if (kconsumer_data.err_sock >= 0) {
                ret = close(kconsumer_data.err_sock);
                if (ret < 0) {
                        PERROR("kernel consumer err_sock close");
                }
        }
        if (ustconsumer32_data.err_sock >= 0) {
                ret = close(ustconsumer32_data.err_sock);
                if (ret < 0) {
                        PERROR("UST consumerd32 err_sock close");
                }
        }
        if (ustconsumer64_data.err_sock >= 0) {
                ret = close(ustconsumer64_data.err_sock);
                if (ret < 0) {
                        PERROR("UST consumerd64 err_sock close");
                }
        }
        if (kconsumer_data.cmd_sock >= 0) {
                ret = close(kconsumer_data.cmd_sock);
                if (ret < 0) {
                        PERROR("kernel consumer cmd_sock close");
                }
        }
        if (ustconsumer32_data.cmd_sock >= 0) {
                ret = close(ustconsumer32_data.cmd_sock);
                if (ret < 0) {
                        PERROR("UST consumerd32 cmd_sock close");
                }
        }
        if (ustconsumer64_data.cmd_sock >= 0) {
                ret = close(ustconsumer64_data.cmd_sock);
                if (ret < 0) {
                        PERROR("UST consumerd64 cmd_sock close");
                }
        }
        if (kconsumer_data.channel_monitor_pipe >= 0) {
                ret = close(kconsumer_data.channel_monitor_pipe);
                if (ret < 0) {
                        PERROR("kernel consumer channel monitor pipe close");
                }
        }
        if (ustconsumer32_data.channel_monitor_pipe >= 0) {
                ret = close(ustconsumer32_data.channel_monitor_pipe);
                if (ret < 0) {
                        PERROR("UST consumerd32 channel monitor pipe close");
                }
        }
        if (ustconsumer64_data.channel_monitor_pipe >= 0) {
                ret = close(ustconsumer64_data.channel_monitor_pipe);
                if (ret < 0) {
                        PERROR("UST consumerd64 channel monitor pipe close");
                }
        }
}

/*
 * Wait on consumer process termination.
 *
 * Need to be called with the consumer data lock held or from a context
 * ensuring no concurrent access to data (e.g: cleanup).
 */
static void wait_consumer(struct consumer_data *consumer_data)
{
        pid_t ret;
        int status;

        if (consumer_data->pid <= 0) {
                return;
        }

        DBG("Waiting for complete teardown of consumerd (PID: %d)",
                        consumer_data->pid);
        ret = waitpid(consumer_data->pid, &status, 0);
        if (ret == -1) {
                PERROR("consumerd waitpid pid: %d", consumer_data->pid)
        } else  if (!WIFEXITED(status)) {
                ERR("consumerd termination with error: %d",
                                WEXITSTATUS(ret));
        }
        consumer_data->pid = 0;
}

/*
 * Cleanup the session daemon's data structures.
 */
static void sessiond_cleanup(void)
{
        int ret;
        struct ltt_session_list *session_list = session_get_list();

        DBG("Cleanup sessiond");

        /*
         * Close the thread quit pipe. It has already done its job,
         * since we are now called.
         */
        sessiond_close_quit_pipe();

        ret = remove(config.pid_file_path.value);
        if (ret < 0) {
                PERROR("remove pidfile %s", config.pid_file_path.value);
        }

        DBG("Removing sessiond and consumerd content of directory %s",
                config.rundir.value);

        /* sessiond */
        DBG("Removing %s", config.pid_file_path.value);
        (void) unlink(config.pid_file_path.value);

        DBG("Removing %s", config.agent_port_file_path.value);
        (void) unlink(config.agent_port_file_path.value);

        /* kconsumerd */
        DBG("Removing %s", kconsumer_data.err_unix_sock_path);
        (void) unlink(kconsumer_data.err_unix_sock_path);

        DBG("Removing directory %s", config.kconsumerd_path.value);
        (void) rmdir(config.kconsumerd_path.value);

        /* ust consumerd 32 */
        DBG("Removing %s", config.consumerd32_err_unix_sock_path.value);
        (void) unlink(config.consumerd32_err_unix_sock_path.value);

        DBG("Removing directory %s", config.consumerd32_path.value);
        (void) rmdir(config.consumerd32_path.value);

        /* ust consumerd 64 */
        DBG("Removing %s", config.consumerd64_err_unix_sock_path.value);
        (void) unlink(config.consumerd64_err_unix_sock_path.value);

        DBG("Removing directory %s", config.consumerd64_path.value);
        (void) rmdir(config.consumerd64_path.value);

        pthread_mutex_destroy(&session_list->lock);

        wait_consumer(&kconsumer_data);
        wait_consumer(&ustconsumer64_data);
        wait_consumer(&ustconsumer32_data);

        DBG("Cleaning up all agent apps");
        agent_app_ht_clean();

        DBG("Closing all UST sockets");
        ust_app_clean_list();
        buffer_reg_destroy_registries();

        if (is_root && !config.no_kernel) {
                DBG2("Closing kernel fd");
                if (kernel_tracer_fd >= 0) {
                        ret = close(kernel_tracer_fd);
                        if (ret) {
                                PERROR("close");
                        }
                }
                DBG("Unloading kernel modules");
                modprobe_remove_lttng_all();
                free(syscall_table);
        }

        close_consumer_sockets();

        if (load_info) {
                load_session_destroy_data(load_info);
                free(load_info);
        }

        /*
         * We do NOT rmdir rundir because there are other processes
         * using it, for instance lttng-relayd, which can start in
         * parallel with this teardown.
         */
}

/*
 * Cleanup the daemon's option data structures.
 */
static void sessiond_cleanup_options(void)
{
        DBG("Cleaning up options");

        sessiond_config_fini(&config);

        run_as_destroy_worker();
}

/*
 * Notify UST applications using the shm mmap futex.
 */
static int notify_ust_apps(int active)
{
        char *wait_shm_mmap;

        DBG("Notifying applications of session daemon state: %d", active);

        /* See shm.c for this call implying mmap, shm and futex calls */
        wait_shm_mmap = shm_ust_get_mmap(config.wait_shm_path.value, is_root);
        if (wait_shm_mmap == NULL) {
                goto error;
        }

        /* Wake waiting process */
        futex_wait_update((int32_t *) wait_shm_mmap, active);

        /* Apps notified successfully */
        return 0;

error:
        return -1;
}

/*
 * Update the kernel poll set of all channel fd available over all tracing
 * session. Add the wakeup pipe at the end of the set.
 */
static int update_kernel_poll(struct lttng_poll_event *events)
{
        int ret;
        struct ltt_kernel_channel *channel;
        struct ltt_session *session;
        const struct ltt_session_list *session_list = session_get_list();

        DBG("Updating kernel poll set");

        session_lock_list();
        cds_list_for_each_entry(session, &session_list->head, list) {
                if (!session_get(session)) {
                        continue;
                }
                session_lock(session);
                if (session->kernel_session == NULL) {
                        session_unlock(session);
                        session_put(session);
                        continue;
                }

                cds_list_for_each_entry(channel,
                                &session->kernel_session->channel_list.head, list) {
                        /* Add channel fd to the kernel poll set */
                        ret = lttng_poll_add(events, channel->fd, LPOLLIN | LPOLLRDNORM);
                        if (ret < 0) {
                                session_unlock(session);
                                session_put(session);
                                goto error;
                        }
                        DBG("Channel fd %d added to kernel set", channel->fd);
                }
                session_unlock(session);
        }
        session_unlock_list();

        return 0;

error:
        session_unlock_list();
        return -1;
}

/*
 * Find the channel fd from 'fd' over all tracing session. When found, check
 * for new channel stream and send those stream fds to the kernel consumer.
 *
 * Useful for CPU hotplug feature.
 */
static int update_kernel_stream(int fd)
{
        int ret = 0;
        struct ltt_session *session;
        struct ltt_kernel_session *ksess;
        struct ltt_kernel_channel *channel;
        const struct ltt_session_list *session_list = session_get_list();

        DBG("Updating kernel streams for channel fd %d", fd);

        session_lock_list();
        cds_list_for_each_entry(session, &session_list->head, list) {
                if (!session_get(session)) {
                        continue;
                }
                session_lock(session);
                if (session->kernel_session == NULL) {
                        session_unlock(session);
                        session_put(session);
                        continue;
                }
                ksess = session->kernel_session;

                cds_list_for_each_entry(channel,
                                &ksess->channel_list.head, list) {
                        struct lttng_ht_iter iter;
                        struct consumer_socket *socket;

                        if (channel->fd != fd) {
                                continue;
                        }
                        DBG("Channel found, updating kernel streams");
                        ret = kernel_open_channel_stream(channel);
                        if (ret < 0) {
                                goto error;
                        }
                        /* Update the stream global counter */
                        ksess->stream_count_global += ret;

                        /*
                         * Have we already sent fds to the consumer? If yes, it
                         * means that tracing is started so it is safe to send
                         * our updated stream fds.
                         */
                        if (ksess->consumer_fds_sent != 1
                                        || ksess->consumer == NULL) {
                                ret = -1;
                                goto error;
                        }

                        rcu_read_lock();
                        cds_lfht_for_each_entry(ksess->consumer->socks->ht,
                                        &iter.iter, socket, node.node) {
                                pthread_mutex_lock(socket->lock);
                                ret = kernel_consumer_send_channel_streams(socket,
                                                channel, ksess,
                                                session->output_traces ? 1 : 0);
                                pthread_mutex_unlock(socket->lock);
                                if (ret < 0) {
                                        rcu_read_unlock();
                                        goto error;
                                }
                        }
                        rcu_read_unlock();
                }
                session_unlock(session);
                session_put(session);
        }
        session_unlock_list();
        return ret;

error:
        session_unlock(session);
        session_put(session);
        session_unlock_list();
        return ret;
}

/*
 * For each tracing session, update newly registered apps. The session list
 * lock MUST be acquired before calling this.
 */
static void update_ust_app(int app_sock)
{
        struct ltt_session *sess, *stmp;
        const struct ltt_session_list *session_list = session_get_list();

        /* Consumer is in an ERROR state. Stop any application update. */
        if (uatomic_read(&ust_consumerd_state) == CONSUMER_ERROR) {
                /* Stop the update process since the consumer is dead. */
                return;
        }

        /* For all tracing session(s) */
        cds_list_for_each_entry_safe(sess, stmp, &session_list->head, list) {
                struct ust_app *app;

                if (!session_get(sess)) {
                        continue;
                }
                session_lock(sess);
                if (!sess->ust_session) {
                        goto unlock_session;
                }

                rcu_read_lock();
                assert(app_sock >= 0);
                app = ust_app_find_by_sock(app_sock);
                if (app == NULL) {
                        /*
                         * Application can be unregistered before so
                         * this is possible hence simply stopping the
                         * update.
                         */
                        DBG3("UST app update failed to find app sock %d",
                                app_sock);
                        goto unlock_rcu;
                }
                ust_app_global_update(sess->ust_session, app);
        unlock_rcu:
                rcu_read_unlock();
        unlock_session:
                session_unlock(sess);
                session_put(sess);
        }
}

/*
 * This thread manage event coming from the kernel.
 *
 * Features supported in this thread:
 *    -) CPU Hotplug
 */
static void *thread_manage_kernel(void *data)
{
        int ret, i, pollfd, update_poll_flag = 1, err = -1;
        uint32_t revents, nb_fd;
        char tmp;
        struct lttng_poll_event events;

        DBG("[thread] Thread manage kernel started");

        health_register(health_sessiond, HEALTH_SESSIOND_TYPE_KERNEL);

        /*
         * This first step of the while is to clean this structure which could free
         * non NULL pointers so initialize it before the loop.
         */
        lttng_poll_init(&events);

        if (testpoint(sessiond_thread_manage_kernel)) {
                goto error_testpoint;
        }

        health_code_update();

        if (testpoint(sessiond_thread_manage_kernel_before_loop)) {
                goto error_testpoint;
        }

        while (1) {
                health_code_update();

                if (update_poll_flag == 1) {
                        /* Clean events object. We are about to populate it again. */
                        lttng_poll_clean(&events);

                        ret = sessiond_set_thread_pollset(&events, 2);
                        if (ret < 0) {
                                goto error_poll_create;
                        }

                        ret = lttng_poll_add(&events, kernel_poll_pipe[0], LPOLLIN);
                        if (ret < 0) {
                                goto error;
                        }

                        /* This will add the available kernel channel if any. */
                        ret = update_kernel_poll(&events);
                        if (ret < 0) {
                                goto error;
                        }
                        update_poll_flag = 0;
                }

                DBG("Thread kernel polling");

                /* Poll infinite value of time */
        restart:
                health_poll_entry();
                ret = lttng_poll_wait(&events, -1);
                DBG("Thread kernel return from poll on %d fds",
                                LTTNG_POLL_GETNB(&events));
                health_poll_exit();
                if (ret < 0) {
                        /*
                         * Restart interrupted system call.
                         */
                        if (errno == EINTR) {
                                goto restart;
                        }
                        goto error;
                } else if (ret == 0) {
                        /* Should not happen since timeout is infinite */
                        ERR("Return value of poll is 0 with an infinite timeout.\n"
                                "This should not have happened! Continuing...");
                        continue;
                }

                nb_fd = ret;

                for (i = 0; i < nb_fd; i++) {
                        /* Fetch once the poll data */
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);

                        health_code_update();

                        if (!revents) {
                                /* No activity for this FD (poll implementation). */
                                continue;
                        }

                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
                                err = 0;
                                goto exit;
                        }

                        /* Check for data on kernel pipe */
                        if (revents & LPOLLIN) {
                                if (pollfd == kernel_poll_pipe[0]) {
                                        (void) lttng_read(kernel_poll_pipe[0],
                                                &tmp, 1);
                                        /*
                                         * Ret value is useless here, if this pipe gets any actions an
                                         * update is required anyway.
                                         */
                                        update_poll_flag = 1;
                                        continue;
                                } else {
                                        /*
                                         * New CPU detected by the kernel. Adding kernel stream to
                                         * kernel session and updating the kernel consumer
                                         */
                                        ret = update_kernel_stream(pollfd);
                                        if (ret < 0) {
                                                continue;
                                        }
                                        break;
                                }
                        } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                update_poll_flag = 1;
                                continue;
                        } else {
                                ERR("Unexpected poll events %u for sock %d", revents, pollfd);
                                goto error;
                        }
                }
        }

exit:
error:
        lttng_poll_clean(&events);
error_poll_create:
error_testpoint:
        utils_close_pipe(kernel_poll_pipe);
        kernel_poll_pipe[0] = kernel_poll_pipe[1] = -1;
        if (err) {
                health_error();
                ERR("Health error occurred in %s", __func__);
                WARN("Kernel thread died unexpectedly. "
                                "Kernel tracing can continue but CPU hotplug is disabled.");
        }
        health_unregister(health_sessiond);
        DBG("Kernel thread dying");
        return NULL;
}

/*
 * Signal pthread condition of the consumer data that the thread.
 */
static void signal_consumer_condition(struct consumer_data *data, int state)
{
        pthread_mutex_lock(&data->cond_mutex);

        /*
         * The state is set before signaling. It can be any value, it's the waiter
         * job to correctly interpret this condition variable associated to the
         * consumer pthread_cond.
         *
         * A value of 0 means that the corresponding thread of the consumer data
         * was not started. 1 indicates that the thread has started and is ready
         * for action. A negative value means that there was an error during the
         * thread bootstrap.
         */
        data->consumer_thread_is_ready = state;
        (void) pthread_cond_signal(&data->cond);

        pthread_mutex_unlock(&data->cond_mutex);
}

/*
 * This thread manage the consumer error sent back to the session daemon.
 */
void *thread_manage_consumer(void *data)
{
        int sock = -1, i, ret, pollfd, err = -1, should_quit = 0;
        uint32_t revents, nb_fd;
        enum lttcomm_return_code code;
        struct lttng_poll_event events;
        struct consumer_data *consumer_data = data;
        struct consumer_socket *cmd_socket_wrapper = NULL;

        DBG("[thread] Manage consumer started");

        rcu_register_thread();
        rcu_thread_online();

        health_register(health_sessiond, HEALTH_SESSIOND_TYPE_CONSUMER);

        health_code_update();

        /*
         * Pass 3 as size here for the thread quit pipe, consumerd_err_sock and the
         * metadata_sock. Nothing more will be added to this poll set.
         */
        ret = sessiond_set_thread_pollset(&events, 3);
        if (ret < 0) {
                goto error_poll;
        }

        /*
         * The error socket here is already in a listening state which was done
         * just before spawning this thread to avoid a race between the consumer
         * daemon exec trying to connect and the listen() call.
         */
        ret = lttng_poll_add(&events, consumer_data->err_sock, LPOLLIN | LPOLLRDHUP);
        if (ret < 0) {
                goto error;
        }

        health_code_update();

        /* Infinite blocking call, waiting for transmission */
restart:
        health_poll_entry();

        if (testpoint(sessiond_thread_manage_consumer)) {
                goto error;
        }

        ret = lttng_poll_wait(&events, -1);
        health_poll_exit();
        if (ret < 0) {
                /*
                 * Restart interrupted system call.
                 */
                if (errno == EINTR) {
                        goto restart;
                }
                goto error;
        }

        nb_fd = ret;

        for (i = 0; i < nb_fd; i++) {
                /* Fetch once the poll data */
                revents = LTTNG_POLL_GETEV(&events, i);
                pollfd = LTTNG_POLL_GETFD(&events, i);

                health_code_update();

                if (!revents) {
                        /* No activity for this FD (poll implementation). */
                        continue;
                }

                /* Thread quit pipe has been closed. Killing thread. */
                ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                if (ret) {
                        err = 0;
                        goto exit;
                }

                /* Event on the registration socket */
                if (pollfd == consumer_data->err_sock) {
                        if (revents & LPOLLIN) {
                                continue;
                        } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                ERR("consumer err socket poll error");
                                goto error;
                        } else {
                                ERR("Unexpected poll events %u for sock %d", revents, pollfd);
                                goto error;
                        }
                }
        }

        sock = lttcomm_accept_unix_sock(consumer_data->err_sock);
        if (sock < 0) {
                goto error;
        }

        /*
         * Set the CLOEXEC flag. Return code is useless because either way, the
         * show must go on.
         */
        (void) utils_set_fd_cloexec(sock);

        health_code_update();

        DBG2("Receiving code from consumer err_sock");

        /* Getting status code from kconsumerd */
        ret = lttcomm_recv_unix_sock(sock, &code,
                        sizeof(enum lttcomm_return_code));
        if (ret <= 0) {
                goto error;
        }

        health_code_update();
        if (code != LTTCOMM_CONSUMERD_COMMAND_SOCK_READY) {
                ERR("consumer error when waiting for SOCK_READY : %s",
                                lttcomm_get_readable_code(-code));
                goto error;
        }

        /* Connect both command and metadata sockets. */
        consumer_data->cmd_sock =
                        lttcomm_connect_unix_sock(
                                consumer_data->cmd_unix_sock_path);
        consumer_data->metadata_fd =
                        lttcomm_connect_unix_sock(
                                consumer_data->cmd_unix_sock_path);
        if (consumer_data->cmd_sock < 0 || consumer_data->metadata_fd < 0) {
                PERROR("consumer connect cmd socket");
                /* On error, signal condition and quit. */
                signal_consumer_condition(consumer_data, -1);
                goto error;
        }

        consumer_data->metadata_sock.fd_ptr = &consumer_data->metadata_fd;

        /* Create metadata socket lock. */
        consumer_data->metadata_sock.lock = zmalloc(sizeof(pthread_mutex_t));
        if (consumer_data->metadata_sock.lock == NULL) {
                PERROR("zmalloc pthread mutex");
                goto error;
        }
        pthread_mutex_init(consumer_data->metadata_sock.lock, NULL);

        DBG("Consumer command socket ready (fd: %d", consumer_data->cmd_sock);
        DBG("Consumer metadata socket ready (fd: %d)",
                        consumer_data->metadata_fd);

        /*
         * Remove the consumerd error sock since we've established a connection.
         */
        ret = lttng_poll_del(&events, consumer_data->err_sock);
        if (ret < 0) {
                goto error;
        }

        /* Add new accepted error socket. */
        ret = lttng_poll_add(&events, sock, LPOLLIN | LPOLLRDHUP);
        if (ret < 0) {
                goto error;
        }

        /* Add metadata socket that is successfully connected. */
        ret = lttng_poll_add(&events, consumer_data->metadata_fd,
                        LPOLLIN | LPOLLRDHUP);
        if (ret < 0) {
                goto error;
        }

        health_code_update();

        /*
         * Transfer the write-end of the channel monitoring and rotate pipe
         * to the consumer by issuing a SET_CHANNEL_MONITOR_PIPE command.
         */
        cmd_socket_wrapper = consumer_allocate_socket(&consumer_data->cmd_sock);
        if (!cmd_socket_wrapper) {
                goto error;
        }
        cmd_socket_wrapper->lock = &consumer_data->lock;

        ret = consumer_send_channel_monitor_pipe(cmd_socket_wrapper,
                        consumer_data->channel_monitor_pipe);
        if (ret) {
                goto error;
        }

        /* Discard the socket wrapper as it is no longer needed. */
        consumer_destroy_socket(cmd_socket_wrapper);
        cmd_socket_wrapper = NULL;

        /* The thread is completely initialized, signal that it is ready. */
        signal_consumer_condition(consumer_data, 1);

        /* Infinite blocking call, waiting for transmission */
restart_poll:
        while (1) {
                health_code_update();

                /* Exit the thread because the thread quit pipe has been triggered. */
                if (should_quit) {
                        /* Not a health error. */
                        err = 0;
                        goto exit;
                }

                health_poll_entry();
                ret = lttng_poll_wait(&events, -1);
                health_poll_exit();
                if (ret < 0) {
                        /*
                         * Restart interrupted system call.
                         */
                        if (errno == EINTR) {
                                goto restart_poll;
                        }
                        goto error;
                }

                nb_fd = ret;

                for (i = 0; i < nb_fd; i++) {
                        /* Fetch once the poll data */
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);

                        health_code_update();

                        if (!revents) {
                                /* No activity for this FD (poll implementation). */
                                continue;
                        }

                        /*
                         * Thread quit pipe has been triggered, flag that we should stop
                         * but continue the current loop to handle potential data from
                         * consumer.
                         */
                        should_quit = sessiond_check_thread_quit_pipe(pollfd, revents);

                        if (pollfd == sock) {
                                /* Event on the consumerd socket */
                                if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)
                                                && !(revents & LPOLLIN)) {
                                        ERR("consumer err socket second poll error");
                                        goto error;
                                }
                                health_code_update();
                                /* Wait for any kconsumerd error */
                                ret = lttcomm_recv_unix_sock(sock, &code,
                                                sizeof(enum lttcomm_return_code));
                                if (ret <= 0) {
                                        ERR("consumer closed the command socket");
                                        goto error;
                                }

                                ERR("consumer return code : %s",
                                                lttcomm_get_readable_code(-code));

                                goto exit;
                        } else if (pollfd == consumer_data->metadata_fd) {
                                if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)
                                                && !(revents & LPOLLIN)) {
                                        ERR("consumer err metadata socket second poll error");
                                        goto error;
                                }
                                /* UST metadata requests */
                                ret = ust_consumer_metadata_request(
                                                &consumer_data->metadata_sock);
                                if (ret < 0) {
                                        ERR("Handling metadata request");
                                        goto error;
                                }
                        }
                        /* No need for an else branch all FDs are tested prior. */
                }
                health_code_update();
        }

exit:
error:
        /*
         * We lock here because we are about to close the sockets and some other
         * thread might be using them so get exclusive access which will abort all
         * other consumer command by other threads.
         */
        pthread_mutex_lock(&consumer_data->lock);

        /* Immediately set the consumerd state to stopped */
        if (consumer_data->type == LTTNG_CONSUMER_KERNEL) {
                uatomic_set(&kernel_consumerd_state, CONSUMER_ERROR);
        } else if (consumer_data->type == LTTNG_CONSUMER64_UST ||
                        consumer_data->type == LTTNG_CONSUMER32_UST) {
                uatomic_set(&ust_consumerd_state, CONSUMER_ERROR);
        } else {
                /* Code flow error... */
                assert(0);
        }

        if (consumer_data->err_sock >= 0) {
                ret = close(consumer_data->err_sock);
                if (ret) {
                        PERROR("close");
                }
                consumer_data->err_sock = -1;
        }
        if (consumer_data->cmd_sock >= 0) {
                ret = close(consumer_data->cmd_sock);
                if (ret) {
                        PERROR("close");
                }
                consumer_data->cmd_sock = -1;
        }
        if (consumer_data->metadata_sock.fd_ptr &&
            *consumer_data->metadata_sock.fd_ptr >= 0) {
                ret = close(*consumer_data->metadata_sock.fd_ptr);
                if (ret) {
                        PERROR("close");
                }
        }
        if (sock >= 0) {
                ret = close(sock);
                if (ret) {
                        PERROR("close");
                }
        }

        unlink(consumer_data->err_unix_sock_path);
        unlink(consumer_data->cmd_unix_sock_path);
        pthread_mutex_unlock(&consumer_data->lock);

        /* Cleanup metadata socket mutex. */
        if (consumer_data->metadata_sock.lock) {
                pthread_mutex_destroy(consumer_data->metadata_sock.lock);
                free(consumer_data->metadata_sock.lock);
        }
        lttng_poll_clean(&events);

        if (cmd_socket_wrapper) {
                consumer_destroy_socket(cmd_socket_wrapper);
        }
error_poll:
        if (err) {
                health_error();
                ERR("Health error occurred in %s", __func__);
        }
        health_unregister(health_sessiond);
        DBG("consumer thread cleanup completed");

        rcu_thread_offline();
        rcu_unregister_thread();

        return NULL;
}

/*
 * This thread receives application command sockets (FDs) on the
 * apps_cmd_pipe and waits (polls) on them until they are closed
 * or an error occurs.
 *
 * At that point, it flushes the data (tracing and metadata) associated
 * with this application and tears down ust app sessions and other
 * associated data structures through ust_app_unregister().
 *
 * Note that this thread never sends commands to the applications
 * through the command sockets; it merely listens for hang-ups
 * and errors on those sockets and cleans-up as they occur.
 */
static void *thread_manage_apps(void *data)
{
        int i, ret, pollfd, err = -1;
        ssize_t size_ret;
        uint32_t revents, nb_fd;
        struct lttng_poll_event events;

        DBG("[thread] Manage application started");

        rcu_register_thread();
        rcu_thread_online();

        health_register(health_sessiond, HEALTH_SESSIOND_TYPE_APP_MANAGE);

        if (testpoint(sessiond_thread_manage_apps)) {
                goto error_testpoint;
        }

        health_code_update();

        ret = sessiond_set_thread_pollset(&events, 2);
        if (ret < 0) {
                goto error_poll_create;
        }

        ret = lttng_poll_add(&events, apps_cmd_pipe[0], LPOLLIN | LPOLLRDHUP);
        if (ret < 0) {
                goto error;
        }

        if (testpoint(sessiond_thread_manage_apps_before_loop)) {
                goto error;
        }

        health_code_update();

        while (1) {
                DBG("Apps thread polling");

                /* Inifinite blocking call, waiting for transmission */
        restart:
                health_poll_entry();
                ret = lttng_poll_wait(&events, -1);
                DBG("Apps thread return from poll on %d fds",
                                LTTNG_POLL_GETNB(&events));
                health_poll_exit();
                if (ret < 0) {
                        /*
                         * Restart interrupted system call.
                         */
                        if (errno == EINTR) {
                                goto restart;
                        }
                        goto error;
                }

                nb_fd = ret;

                for (i = 0; i < nb_fd; i++) {
                        /* Fetch once the poll data */
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);

                        health_code_update();

                        if (!revents) {
                                /* No activity for this FD (poll implementation). */
                                continue;
                        }

                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
                                err = 0;
                                goto exit;
                        }

                        /* Inspect the apps cmd pipe */
                        if (pollfd == apps_cmd_pipe[0]) {
                                if (revents & LPOLLIN) {
                                        int sock;

                                        /* Empty pipe */
                                        size_ret = lttng_read(apps_cmd_pipe[0], &sock, sizeof(sock));
                                        if (size_ret < sizeof(sock)) {
                                                PERROR("read apps cmd pipe");
                                                goto error;
                                        }

                                        health_code_update();

                                        /*
                                         * Since this is a command socket (write then read),
                                         * we only monitor the error events of the socket.
                                         */
                                        ret = lttng_poll_add(&events, sock,
                                                        LPOLLERR | LPOLLHUP | LPOLLRDHUP);
                                        if (ret < 0) {
                                                goto error;
                                        }

                                        DBG("Apps with sock %d added to poll set", sock);
                                } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                        ERR("Apps command pipe error");
                                        goto error;
                                } else {
                                        ERR("Unknown poll events %u for sock %d", revents, pollfd);
                                        goto error;
                                }
                        } else {
                                /*
                                 * At this point, we know that a registered application made
                                 * the event at poll_wait.
                                 */
                                if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                        /* Removing from the poll set */
                                        ret = lttng_poll_del(&events, pollfd);
                                        if (ret < 0) {
                                                goto error;
                                        }

                                        /* Socket closed on remote end. */
                                        ust_app_unregister(pollfd);
                                } else {
                                        ERR("Unexpected poll events %u for sock %d", revents, pollfd);
                                        goto error;
                                }
                        }

                        health_code_update();
                }
        }

exit:
error:
        lttng_poll_clean(&events);
error_poll_create:
error_testpoint:
        utils_close_pipe(apps_cmd_pipe);
        apps_cmd_pipe[0] = apps_cmd_pipe[1] = -1;

        /*
         * We don't clean the UST app hash table here since already registered
         * applications can still be controlled so let them be until the session
         * daemon dies or the applications stop.
         */

        if (err) {
                health_error();
                ERR("Health error occurred in %s", __func__);
        }
        health_unregister(health_sessiond);
        DBG("Application communication apps thread cleanup complete");
        rcu_thread_offline();
        rcu_unregister_thread();
        return NULL;
}

/*
 * Send a socket to a thread This is called from the dispatch UST registration
 * thread once all sockets are set for the application.
 *
 * The sock value can be invalid, we don't really care, the thread will handle
 * it and make the necessary cleanup if so.
 *
 * On success, return 0 else a negative value being the errno message of the
 * write().
 */
static int send_socket_to_thread(int fd, int sock)
{
        ssize_t ret;

        /*
         * It's possible that the FD is set as invalid with -1 concurrently just
         * before calling this function being a shutdown state of the thread.
         */
        if (fd < 0) {
                ret = -EBADF;
                goto error;
        }

        ret = lttng_write(fd, &sock, sizeof(sock));
        if (ret < sizeof(sock)) {
                PERROR("write apps pipe %d", fd);
                if (ret < 0) {
                        ret = -errno;
                }
                goto error;
        }

        /* All good. Don't send back the write positive ret value. */
        ret = 0;
error:
        return (int) ret;
}

/*
 * Sanitize the wait queue of the dispatch registration thread meaning removing
 * invalid nodes from it. This is to avoid memory leaks for the case the UST
 * notify socket is never received.
 */
static void sanitize_wait_queue(struct ust_reg_wait_queue *wait_queue)
{
        int ret, nb_fd = 0, i;
        unsigned int fd_added = 0;
        struct lttng_poll_event events;
        struct ust_reg_wait_node *wait_node = NULL, *tmp_wait_node;

        assert(wait_queue);

        lttng_poll_init(&events);

        /* Just skip everything for an empty queue. */
        if (!wait_queue->count) {
                goto end;
        }

        ret = lttng_poll_create(&events, wait_queue->count, LTTNG_CLOEXEC);
        if (ret < 0) {
                goto error_create;
        }

        cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
                        &wait_queue->head, head) {
                assert(wait_node->app);
                ret = lttng_poll_add(&events, wait_node->app->sock,
                                LPOLLHUP | LPOLLERR);
                if (ret < 0) {
                        goto error;
                }

                fd_added = 1;
        }

        if (!fd_added) {
                goto end;
        }

        /*
         * Poll but don't block so we can quickly identify the faulty events and
         * clean them afterwards from the wait queue.
         */
        ret = lttng_poll_wait(&events, 0);
        if (ret < 0) {
                goto error;
        }
        nb_fd = ret;

        for (i = 0; i < nb_fd; i++) {
                /* Get faulty FD. */
                uint32_t revents = LTTNG_POLL_GETEV(&events, i);
                int pollfd = LTTNG_POLL_GETFD(&events, i);

                if (!revents) {
                        /* No activity for this FD (poll implementation). */
                        continue;
                }

                cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
                                &wait_queue->head, head) {
                        if (pollfd == wait_node->app->sock &&
                                        (revents & (LPOLLHUP | LPOLLERR))) {
                                cds_list_del(&wait_node->head);
                                wait_queue->count--;
                                ust_app_destroy(wait_node->app);
                                free(wait_node);
                                /*
                                 * Silence warning of use-after-free in
                                 * cds_list_for_each_entry_safe which uses
                                 * __typeof__(*wait_node).
                                 */
                                wait_node = NULL;
                                break;
                        } else {
                                ERR("Unexpected poll events %u for sock %d", revents, pollfd);
                                goto error;
                        }
                }
        }

        if (nb_fd > 0) {
                DBG("Wait queue sanitized, %d node were cleaned up", nb_fd);
        }

end:
        lttng_poll_clean(&events);
        return;

error:
        lttng_poll_clean(&events);
error_create:
        ERR("Unable to sanitize wait queue");
        return;
}

/*
 * Dispatch request from the registration threads to the application
 * communication thread.
 */
static void *thread_dispatch_ust_registration(void *data)
{
        int ret, err = -1;
        struct cds_wfcq_node *node;
        struct ust_command *ust_cmd = NULL;
        struct ust_reg_wait_node *wait_node = NULL, *tmp_wait_node;
        struct ust_reg_wait_queue wait_queue = {
                .count = 0,
        };

        rcu_register_thread();

        health_register(health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG_DISPATCH);

        if (testpoint(sessiond_thread_app_reg_dispatch)) {
                goto error_testpoint;
        }

        health_code_update();

        CDS_INIT_LIST_HEAD(&wait_queue.head);

        DBG("[thread] Dispatch UST command started");

        for (;;) {
                health_code_update();

                /* Atomically prepare the queue futex */
                futex_nto1_prepare(&ust_cmd_queue.futex);

                if (CMM_LOAD_SHARED(dispatch_thread_exit)) {
                        break;
                }

                do {
                        struct ust_app *app = NULL;
                        ust_cmd = NULL;

                        /*
                         * Make sure we don't have node(s) that have hung up before receiving
                         * the notify socket. This is to clean the list in order to avoid
                         * memory leaks from notify socket that are never seen.
                         */
                        sanitize_wait_queue(&wait_queue);

                        health_code_update();
                        /* Dequeue command for registration */
                        node = cds_wfcq_dequeue_blocking(&ust_cmd_queue.head, &ust_cmd_queue.tail);
                        if (node == NULL) {
                                DBG("Woken up but nothing in the UST command queue");
                                /* Continue thread execution */
                                break;
                        }

                        ust_cmd = caa_container_of(node, struct ust_command, node);

                        DBG("Dispatching UST registration pid:%d ppid:%d uid:%d"
                                        " gid:%d sock:%d name:%s (version %d.%d)",
                                        ust_cmd->reg_msg.pid, ust_cmd->reg_msg.ppid,
                                        ust_cmd->reg_msg.uid, ust_cmd->reg_msg.gid,
                                        ust_cmd->sock, ust_cmd->reg_msg.name,
                                        ust_cmd->reg_msg.major, ust_cmd->reg_msg.minor);

                        if (ust_cmd->reg_msg.type == USTCTL_SOCKET_CMD) {
                                wait_node = zmalloc(sizeof(*wait_node));
                                if (!wait_node) {
                                        PERROR("zmalloc wait_node dispatch");
                                        ret = close(ust_cmd->sock);
                                        if (ret < 0) {
                                                PERROR("close ust sock dispatch %d", ust_cmd->sock);
                                        }
                                        lttng_fd_put(LTTNG_FD_APPS, 1);
                                        free(ust_cmd);
                                        goto error;
                                }
                                CDS_INIT_LIST_HEAD(&wait_node->head);

                                /* Create application object if socket is CMD. */
                                wait_node->app = ust_app_create(&ust_cmd->reg_msg,
                                                ust_cmd->sock);
                                if (!wait_node->app) {
                                        ret = close(ust_cmd->sock);
                                        if (ret < 0) {
                                                PERROR("close ust sock dispatch %d", ust_cmd->sock);
                                        }
                                        lttng_fd_put(LTTNG_FD_APPS, 1);
                                        free(wait_node);
                                        free(ust_cmd);
                                        continue;
                                }
                                /*
                                 * Add application to the wait queue so we can set the notify
                                 * socket before putting this object in the global ht.
                                 */
                                cds_list_add(&wait_node->head, &wait_queue.head);
                                wait_queue.count++;

                                free(ust_cmd);
                                /*
                                 * We have to continue here since we don't have the notify
                                 * socket and the application MUST be added to the hash table
                                 * only at that moment.
                                 */
                                continue;
                        } else {
                                /*
                                 * Look for the application in the local wait queue and set the
                                 * notify socket if found.
                                 */
                                cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
                                                &wait_queue.head, head) {
                                        health_code_update();
                                        if (wait_node->app->pid == ust_cmd->reg_msg.pid) {
                                                wait_node->app->notify_sock = ust_cmd->sock;
                                                cds_list_del(&wait_node->head);
                                                wait_queue.count--;
                                                app = wait_node->app;
                                                free(wait_node);
                                                DBG3("UST app notify socket %d is set", ust_cmd->sock);
                                                break;
                                        }
                                }

                                /*
                                 * With no application at this stage the received socket is
                                 * basically useless so close it before we free the cmd data
                                 * structure for good.
                                 */
                                if (!app) {
                                        ret = close(ust_cmd->sock);
                                        if (ret < 0) {
                                                PERROR("close ust sock dispatch %d", ust_cmd->sock);
                                        }
                                        lttng_fd_put(LTTNG_FD_APPS, 1);
                                }
                                free(ust_cmd);
                        }

                        if (app) {
                                /*
                                 * @session_lock_list
                                 *
                                 * Lock the global session list so from the register up to the
                                 * registration done message, no thread can see the application
                                 * and change its state.
                                 */
                                session_lock_list();
                                rcu_read_lock();

                                /*
                                 * Add application to the global hash table. This needs to be
                                 * done before the update to the UST registry can locate the
                                 * application.
                                 */
                                ust_app_add(app);

                                /* Set app version. This call will print an error if needed. */
                                (void) ust_app_version(app);

                                /* Send notify socket through the notify pipe. */
                                ret = send_socket_to_thread(apps_cmd_notify_pipe[1],
                                                app->notify_sock);
                                if (ret < 0) {
                                        rcu_read_unlock();
                                        session_unlock_list();
                                        /*
                                         * No notify thread, stop the UST tracing. However, this is
                                         * not an internal error of the this thread thus setting
                                         * the health error code to a normal exit.
                                         */
                                        err = 0;
                                        goto error;
                                }

                                /*
                                 * Update newly registered application with the tracing
                                 * registry info already enabled information.
                                 */
                                update_ust_app(app->sock);

                                /*
                                 * Don't care about return value. Let the manage apps threads
                                 * handle app unregistration upon socket close.
                                 */
                                (void) ust_app_register_done(app);

                                /*
                                 * Even if the application socket has been closed, send the app
                                 * to the thread and unregistration will take place at that
                                 * place.
                                 */
                                ret = send_socket_to_thread(apps_cmd_pipe[1], app->sock);
                                if (ret < 0) {
                                        rcu_read_unlock();
                                        session_unlock_list();
                                        /*
                                         * No apps. thread, stop the UST tracing. However, this is
                                         * not an internal error of the this thread thus setting
                                         * the health error code to a normal exit.
                                         */
                                        err = 0;
                                        goto error;
                                }

                                rcu_read_unlock();
                                session_unlock_list();
                        }
                } while (node != NULL);

                health_poll_entry();
                /* Futex wait on queue. Blocking call on futex() */
                futex_nto1_wait(&ust_cmd_queue.futex);
                health_poll_exit();
        }
        /* Normal exit, no error */
        err = 0;

error:
        /* Clean up wait queue. */
        cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
                        &wait_queue.head, head) {
                cds_list_del(&wait_node->head);
                wait_queue.count--;
                free(wait_node);
        }

        /* Empty command queue. */
        for (;;) {
                /* Dequeue command for registration */
                node = cds_wfcq_dequeue_blocking(&ust_cmd_queue.head, &ust_cmd_queue.tail);
                if (node == NULL) {
                        break;
                }
                ust_cmd = caa_container_of(node, struct ust_command, node);
                ret = close(ust_cmd->sock);
                if (ret < 0) {
                        PERROR("close ust sock exit dispatch %d", ust_cmd->sock);
                }
                lttng_fd_put(LTTNG_FD_APPS, 1);
                free(ust_cmd);
        }

error_testpoint:
        DBG("Dispatch thread dying");
        if (err) {
                health_error();
                ERR("Health error occurred in %s", __func__);
        }
        health_unregister(health_sessiond);
        rcu_unregister_thread();
        return NULL;
}

/*
 * This thread manage application registration.
 */
static void *thread_registration_apps(void *data)
{
        int sock = -1, i, ret, pollfd, err = -1;
        uint32_t revents, nb_fd;
        struct lttng_poll_event events;
        /*
         * Get allocated in this thread, enqueued to a global queue, dequeued and
         * freed in the manage apps thread.
         */
        struct ust_command *ust_cmd = NULL;

        DBG("[thread] Manage application registration started");

        health_register(health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG);

        if (testpoint(sessiond_thread_registration_apps)) {
                goto error_testpoint;
        }

        ret = lttcomm_listen_unix_sock(apps_sock);
        if (ret < 0) {
                goto error_listen;
        }

        /*
         * Pass 2 as size here for the thread quit pipe and apps socket. Nothing
         * more will be added to this poll set.
         */
        ret = sessiond_set_thread_pollset(&events, 2);
        if (ret < 0) {
                goto error_create_poll;
        }

        /* Add the application registration socket */
        ret = lttng_poll_add(&events, apps_sock, LPOLLIN | LPOLLRDHUP);
        if (ret < 0) {
                goto error_poll_add;
        }

        /* Notify all applications to register */
        ret = notify_ust_apps(1);
        if (ret < 0) {
                ERR("Failed to notify applications or create the wait shared memory.\n"
                        "Execution continues but there might be problem for already\n"
                        "running applications that wishes to register.");
        }

        while (1) {
                DBG("Accepting application registration");

                /* Inifinite blocking call, waiting for transmission */
        restart:
                health_poll_entry();
                ret = lttng_poll_wait(&events, -1);
                health_poll_exit();
                if (ret < 0) {
                        /*
                         * Restart interrupted system call.
                         */
                        if (errno == EINTR) {
                                goto restart;
                        }
                        goto error;
                }

                nb_fd = ret;

                for (i = 0; i < nb_fd; i++) {
                        health_code_update();

                        /* Fetch once the poll data */
                        revents = LTTNG_POLL_GETEV(&events, i);
                        pollfd = LTTNG_POLL_GETFD(&events, i);

                        if (!revents) {
                                /* No activity for this FD (poll implementation). */
                                continue;
                        }

                        /* Thread quit pipe has been closed. Killing thread. */
                        ret = sessiond_check_thread_quit_pipe(pollfd, revents);
                        if (ret) {
                                err = 0;
                                goto exit;
                        }

                        /* Event on the registration socket */
                        if (pollfd == apps_sock) {
                                if (revents & LPOLLIN) {
                                        sock = lttcomm_accept_unix_sock(apps_sock);
                                        if (sock < 0) {
                                                goto error;
                                        }

                                        /*
                                         * Set socket timeout for both receiving and ending.
                                         * app_socket_timeout is in seconds, whereas
                                         * lttcomm_setsockopt_rcv_timeout and
                                         * lttcomm_setsockopt_snd_timeout expect msec as
                                         * parameter.
                                         */
                                        if (config.app_socket_timeout >= 0) {
                                                (void) lttcomm_setsockopt_rcv_timeout(sock,
                                                                config.app_socket_timeout * 1000);
                                                (void) lttcomm_setsockopt_snd_timeout(sock,
                                                                config.app_socket_timeout * 1000);
                                        }

                                        /*
                                         * Set the CLOEXEC flag. Return code is useless because
                                         * either way, the show must go on.
                                         */
                                        (void) utils_set_fd_cloexec(sock);

                                        /* Create UST registration command for enqueuing */
                                        ust_cmd = zmalloc(sizeof(struct ust_command));
                                        if (ust_cmd == NULL) {
                                                PERROR("ust command zmalloc");
                                                ret = close(sock);
                                                if (ret) {
                                                        PERROR("close");
                                                }
                                                goto error;
                                        }

                                        /*
                                         * Using message-based transmissions to ensure we don't
                                         * have to deal with partially received messages.
                                         */
                                        ret = lttng_fd_get(LTTNG_FD_APPS, 1);
                                        if (ret < 0) {
                                                ERR("Exhausted file descriptors allowed for applications.");
                                                free(ust_cmd);
                                                ret = close(sock);
                                                if (ret) {
                                                        PERROR("close");
                                                }
                                                sock = -1;
                                                continue;
                                        }

                                        health_code_update();
                                        ret = ust_app_recv_registration(sock, &ust_cmd->reg_msg);
                                        if (ret < 0) {
                                                free(ust_cmd);
                                                /* Close socket of the application. */
                                                ret = close(sock);
                                                if (ret) {
                                                        PERROR("close");
                                                }
                                                lttng_fd_put(LTTNG_FD_APPS, 1);
                                                sock = -1;
                                                continue;
                                        }
                                        health_code_update();

                                        ust_cmd->sock = sock;
                                        sock = -1;

                                        DBG("UST registration received with pid:%d ppid:%d uid:%d"
                                                        " gid:%d sock:%d name:%s (version %d.%d)",
                                                        ust_cmd->reg_msg.pid, ust_cmd->reg_msg.ppid,
                                                        ust_cmd->reg_msg.uid, ust_cmd->reg_msg.gid,
                                                        ust_cmd->sock, ust_cmd->reg_msg.name,
                                                        ust_cmd->reg_msg.major, ust_cmd->reg_msg.minor);

                                        /*
                                         * Lock free enqueue the registration request. The red pill
                                         * has been taken! This apps will be part of the *system*.
                                         */
                                        cds_wfcq_enqueue(&ust_cmd_queue.head, &ust_cmd_queue.tail, &ust_cmd->node);

                                        /*
                                         * Wake the registration queue futex. Implicit memory
                                         * barrier with the exchange in cds_wfcq_enqueue.
                                         */
                                        futex_nto1_wake(&ust_cmd_queue.futex);
                                } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
                                        ERR("Register apps socket poll error");
                                        goto error;
                                } else {
                                        ERR("Unexpected poll events %u for sock %d", revents, pollfd);
                                        goto error;
                                }
                        }
                }
        }

exit:
error:
        /* Notify that the registration thread is gone */
        notify_ust_apps(0);

        if (apps_sock >= 0) {
                ret = close(apps_sock);
                if (ret) {
                        PERROR("close");
                }
        }
        if (sock >= 0) {
                ret = close(sock);
                if (ret) {
                        PERROR("close");
                }
                lttng_fd_put(LTTNG_FD_APPS, 1);
        }
        unlink(config.apps_unix_sock_path.value);

error_poll_add:
        lttng_poll_clean(&events);
error_listen:
error_create_poll:
error_testpoint:
        DBG("UST Registration thread cleanup complete");
        if (err) {
                health_error();
                ERR("Health error occurred in %s", __func__);
        }
        health_unregister(health_sessiond);

        return NULL;
}

/*
 * Setup necessary data for kernel tracer action.
 */
static int init_kernel_tracer(void)
{
        int ret;

        /* Modprobe lttng kernel modules */
        ret = modprobe_lttng_control();
        if (ret < 0) {
                goto error;
        }

        /* Open debugfs lttng */
        kernel_tracer_fd = open(module_proc_lttng, O_RDWR);
        if (kernel_tracer_fd < 0) {
                DBG("Failed to open %s", module_proc_lttng);
                goto error_open;
        }

        /* Validate kernel version */
        ret = kernel_validate_version(kernel_tracer_fd, &kernel_tracer_version,
                        &kernel_tracer_abi_version);
        if (ret < 0) {
                goto error_version;
        }

        ret = modprobe_lttng_data();
        if (ret < 0) {
                goto error_modules;
        }

        ret = kernel_supports_ring_buffer_snapshot_sample_positions(
                        kernel_tracer_fd);
        if (ret < 0) {
                goto error_modules;
        }

        if (ret < 1) {
                WARN("Kernel tracer does not support buffer monitoring. "
                        "The monitoring timer of channels in the kernel domain "
                        "will be set to 0 (disabled).");
        }

        DBG("Kernel tracer fd %d", kernel_tracer_fd);
        return 0;

error_version:
        modprobe_remove_lttng_control();
        ret = close(kernel_tracer_fd);
        if (ret) {
                PERROR("close");
        }
        kernel_tracer_fd = -1;
        return LTTNG_ERR_KERN_VERSION;

error_modules:
        ret = close(kernel_tracer_fd);
        if (ret) {
                PERROR("close");
        }

error_open:
        modprobe_remove_lttng_control();

error:
        WARN("No kernel tracer available");
        kernel_tracer_fd = -1;
        if (!is_root) {
                return LTTNG_ERR_NEED_ROOT_SESSIOND;
        } else {
                return LTTNG_ERR_KERN_NA;
        }
}

static int string_match(const char *str1, const char *str2)
{
        return (str1 && str2) && !strcmp(str1, str2);
}

/*
 * Take an option from the getopt output and set it in the right variable to be
 * used later.
 *
 * Return 0 on success else a negative value.
 */
static int set_option(int opt, const char *arg, const char *optname)
{
        int ret = 0;

        if (string_match(optname, "client-sock") || opt == 'c') {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-c, --client-sock");
                } else {
                        config_string_set(&config.client_unix_sock_path,
                                        strdup(arg));
                        if (!config.client_unix_sock_path.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "apps-sock") || opt == 'a') {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-a, --apps-sock");
                } else {
                        config_string_set(&config.apps_unix_sock_path,
                                        strdup(arg));
                        if (!config.apps_unix_sock_path.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "daemonize") || opt == 'd') {
                config.daemonize = true;
        } else if (string_match(optname, "background") || opt == 'b') {
                config.background = true;
        } else if (string_match(optname, "group") || opt == 'g') {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-g, --group");
                } else {
                        config_string_set(&config.tracing_group_name,
                                        strdup(arg));
                        if (!config.tracing_group_name.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "help") || opt == 'h') {
                ret = utils_show_help(8, "lttng-sessiond", help_msg);
                if (ret) {
                        ERR("Cannot show --help for `lttng-sessiond`");
                        perror("exec");
                }
                exit(ret ? EXIT_FAILURE : EXIT_SUCCESS);
        } else if (string_match(optname, "version") || opt == 'V') {
                fprintf(stdout, "%s\n", VERSION);
                exit(EXIT_SUCCESS);
        } else if (string_match(optname, "sig-parent") || opt == 'S') {
                config.sig_parent = true;
        } else if (string_match(optname, "kconsumerd-err-sock")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--kconsumerd-err-sock");
                } else {
                        config_string_set(&config.kconsumerd_err_unix_sock_path,
                                        strdup(arg));
                        if (!config.kconsumerd_err_unix_sock_path.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "kconsumerd-cmd-sock")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--kconsumerd-cmd-sock");
                } else {
                        config_string_set(&config.kconsumerd_cmd_unix_sock_path,
                                        strdup(arg));
                        if (!config.kconsumerd_cmd_unix_sock_path.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "ustconsumerd64-err-sock")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--ustconsumerd64-err-sock");
                } else {
                        config_string_set(&config.consumerd64_err_unix_sock_path,
                                        strdup(arg));
                        if (!config.consumerd64_err_unix_sock_path.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "ustconsumerd64-cmd-sock")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--ustconsumerd64-cmd-sock");
                } else {
                        config_string_set(&config.consumerd64_cmd_unix_sock_path,
                                        strdup(arg));
                        if (!config.consumerd64_cmd_unix_sock_path.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "ustconsumerd32-err-sock")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--ustconsumerd32-err-sock");
                } else {
                        config_string_set(&config.consumerd32_err_unix_sock_path,
                                        strdup(arg));
                        if (!config.consumerd32_err_unix_sock_path.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "ustconsumerd32-cmd-sock")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--ustconsumerd32-cmd-sock");
                } else {
                        config_string_set(&config.consumerd32_cmd_unix_sock_path,
                                        strdup(arg));
                        if (!config.consumerd32_cmd_unix_sock_path.value) {
                                ret = -ENOMEM;
                                PERROR("strdup");
                        }
                }
        } else if (string_match(optname, "no-kernel")) {
                config.no_kernel = true;
        } else if (string_match(optname, "quiet") || opt == 'q') {
                config.quiet = true;
        } else if (string_match(optname, "verbose") || opt == 'v') {
                /* Verbose level can increase using multiple -v */
                if (arg) {
                        /* Value obtained from config file */
                        config.verbose = config_parse_value(arg);
                } else {
                        /* -v used on command line */
                        config.verbose++;
                }
                /* Clamp value to [0, 3] */
                config.verbose = config.verbose < 0 ? 0 :
                        (config.verbose <= 3 ? config.verbose : 3);
        } else if (string_match(optname, "verbose-consumer")) {
                if (arg) {
                        config.verbose_consumer = config_parse_value(arg);
                } else {
                        config.verbose_consumer++;
                }
        } else if (string_match(optname, "consumerd32-path")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--consumerd32-path");
                } else {
                        config_string_set(&config.consumerd32_bin_path,
                                        strdup(arg));
                        if (!config.consumerd32_bin_path.value) {
                                PERROR("strdup");
                                ret = -ENOMEM;
                        }
                }
        } else if (string_match(optname, "consumerd32-libdir")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--consumerd32-libdir");
                } else {
                        config_string_set(&config.consumerd32_lib_dir,
                                        strdup(arg));
                        if (!config.consumerd32_lib_dir.value) {
                                PERROR("strdup");
                                ret = -ENOMEM;
                        }
                }
        } else if (string_match(optname, "consumerd64-path")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--consumerd64-path");
                } else {
                        config_string_set(&config.consumerd64_bin_path,
                                        strdup(arg));
                        if (!config.consumerd64_bin_path.value) {
                                PERROR("strdup");
                                ret = -ENOMEM;
                        }
                }
        } else if (string_match(optname, "consumerd64-libdir")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--consumerd64-libdir");
                } else {
                        config_string_set(&config.consumerd64_lib_dir,
                                        strdup(arg));
                        if (!config.consumerd64_lib_dir.value) {
                                PERROR("strdup");
                                ret = -ENOMEM;
                        }
                }
        } else if (string_match(optname, "pidfile") || opt == 'p') {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-p, --pidfile");
                } else {
                        config_string_set(&config.pid_file_path, strdup(arg));
                        if (!config.pid_file_path.value) {
                                PERROR("strdup");
                                ret = -ENOMEM;
                        }
                }
        } else if (string_match(optname, "agent-tcp-port")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--agent-tcp-port");
                } else {
                        unsigned long v;

                        errno = 0;
                        v = strtoul(arg, NULL, 0);
                        if (errno != 0 || !isdigit(arg[0])) {
                                ERR("Wrong value in --agent-tcp-port parameter: %s", arg);
                                return -1;
                        }
                        if (v == 0 || v >= 65535) {
                                ERR("Port overflow in --agent-tcp-port parameter: %s", arg);
                                return -1;
                        }
                        config.agent_tcp_port.begin = config.agent_tcp_port.end = (int) v;
                        DBG3("Agent TCP port set to non default: %i", (int) v);
                }
        } else if (string_match(optname, "load") || opt == 'l') {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-l, --load");
                } else {
                        config_string_set(&config.load_session_path, strdup(arg));
                        if (!config.load_session_path.value) {
                                PERROR("strdup");
                                ret = -ENOMEM;
                        }
                }
        } else if (string_match(optname, "kmod-probes")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--kmod-probes");
                } else {
                        config_string_set(&config.kmod_probes_list, strdup(arg));
                        if (!config.kmod_probes_list.value) {
                                PERROR("strdup");
                                ret = -ENOMEM;
                        }
                }
        } else if (string_match(optname, "extra-kmod-probes")) {
                if (!arg || *arg == '\0') {
                        ret = -EINVAL;
                        goto end;
                }
                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "--extra-kmod-probes");
                } else {
                        config_string_set(&config.kmod_extra_probes_list,
                                        strdup(arg));
                        if (!config.kmod_extra_probes_list.value) {
                                PERROR("strdup");
                                ret = -ENOMEM;
                        }
                }
        } else if (string_match(optname, "config") || opt == 'f') {
                /* This is handled in set_options() thus silent skip. */
                goto end;
        } else {
                /* Unknown option or other error.
                 * Error is printed by getopt, just return */
                ret = -1;
        }

end:
        if (ret == -EINVAL) {
                const char *opt_name = "unknown";
                int i;

                for (i = 0; i < sizeof(long_options) / sizeof(struct option);
                        i++) {
                        if (opt == long_options[i].val) {
                                opt_name = long_options[i].name;
                                break;
                        }
                }

                WARN("Invalid argument provided for option \"%s\", using default value.",
                        opt_name);
        }

        return ret;
}

/*
 * config_entry_handler_cb used to handle options read from a config file.
 * See config_entry_handler_cb comment in common/config/session-config.h for the
 * return value conventions.
 */
static int config_entry_handler(const struct config_entry *entry, void *unused)
{
        int ret = 0, i;

        if (!entry || !entry->name || !entry->value) {
                ret = -EINVAL;
                goto end;
        }

        /* Check if the option is to be ignored */
        for (i = 0; i < sizeof(config_ignore_options) / sizeof(char *); i++) {
                if (!strcmp(entry->name, config_ignore_options[i])) {
                        goto end;
                }
        }

        for (i = 0; i < (sizeof(long_options) / sizeof(struct option)) - 1;
                i++) {

                /* Ignore if not fully matched. */
                if (strcmp(entry->name, long_options[i].name)) {
                        continue;
                }

                /*
                 * If the option takes no argument on the command line, we have to
                 * check if the value is "true". We support non-zero numeric values,
                 * true, on and yes.
                 */
                if (!long_options[i].has_arg) {
                        ret = config_parse_value(entry->value);
                        if (ret <= 0) {
                                if (ret) {
                                        WARN("Invalid configuration value \"%s\" for option %s",
                                                        entry->value, entry->name);
                                }
                                /* False, skip boolean config option. */
                                goto end;
                        }
                }

                ret = set_option(long_options[i].val, entry->value, entry->name);
                goto end;
        }

        WARN("Unrecognized option \"%s\" in daemon configuration file.", entry->name);

end:
        return ret;
}

/*
 * daemon configuration loading and argument parsing
 */
static int set_options(int argc, char **argv)
{
        int ret = 0, c = 0, option_index = 0;
        int orig_optopt = optopt, orig_optind = optind;
        char *optstring;
        const char *config_path = NULL;

        optstring = utils_generate_optstring(long_options,
                        sizeof(long_options) / sizeof(struct option));
        if (!optstring) {
                ret = -ENOMEM;
                goto end;
        }

        /* Check for the --config option */
        while ((c = getopt_long(argc, argv, optstring, long_options,
                                        &option_index)) != -1) {
                if (c == '?') {
                        ret = -EINVAL;
                        goto end;
                } else if (c != 'f') {
                        /* if not equal to --config option. */
                        continue;
                }

                if (lttng_is_setuid_setgid()) {
                        WARN("Getting '%s' argument from setuid/setgid binary refused for security reasons.",
                                "-f, --config");
                } else {
                        config_path = utils_expand_path(optarg);
                        if (!config_path) {
                                ERR("Failed to resolve path: %s", optarg);
                        }
                }
        }

        ret = config_get_section_entries(config_path, config_section_name,
                        config_entry_handler, NULL);
        if (ret) {
                if (ret > 0) {
                        ERR("Invalid configuration option at line %i", ret);
                        ret = -1;
                }
                goto end;
        }

        /* Reset getopt's global state */
        optopt = orig_optopt;
        optind = orig_optind;
        while (1) {
                option_index = -1;
                /*
                 * getopt_long() will not set option_index if it encounters a
                 * short option.
                 */
                c = getopt_long(argc, argv, optstring, long_options,
                                &option_index);
                if (c == -1) {
                        break;
                }

                /*
                 * Pass NULL as the long option name if popt left the index
                 * unset.
                 */
                ret = set_option(c, optarg,
                                option_index < 0 ? NULL :
                                long_options[option_index].name);
                if (ret < 0) {
                        break;
                }
        }

end:
        free(optstring);
        return ret;
}

/*
 * Creates the application socket.
 */
static int init_daemon_socket(void)
{
        int ret = 0;
        mode_t old_umask;

        old_umask = umask(0);

        /* Create the application unix socket */
        apps_sock = lttcomm_create_unix_sock(config.apps_unix_sock_path.value);
        if (apps_sock < 0) {
                ERR("Create unix sock failed: %s", config.apps_unix_sock_path.value);
                ret = -1;
                goto end;
        }

        /* Set the cloexec flag */
        ret = utils_set_fd_cloexec(apps_sock);
        if (ret < 0) {
                ERR("Unable to set CLOEXEC flag to the app Unix socket (fd: %d). "
                                "Continuing but note that the consumer daemon will have a "
                                "reference to this socket on exec()", apps_sock);
        }

        /* File permission MUST be 666 */
        ret = chmod(config.apps_unix_sock_path.value,
                        S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH | S_IWOTH);
        if (ret < 0) {
                ERR("Set file permissions failed: %s", config.apps_unix_sock_path.value);
                PERROR("chmod");
                goto end;
        }

        DBG3("Session daemon application socket %d created",
                        apps_sock);

end:
        umask(old_umask);
        return ret;
}

/*
 * Create lockfile using the rundir and return its fd.
 */
static int create_lockfile(void)
{
        return utils_create_lock_file(config.lock_file_path.value);
}

/*
 * Check if the global socket is available, and if a daemon is answering at the
 * other side. If yes, error is returned.
 *
 * Also attempts to create and hold the lock file.
 */
static int check_existing_daemon(void)
{
        int ret = 0;

        /* Is there anybody out there ? */
        if (lttng_session_daemon_alive()) {
                ret = -EEXIST;
                goto end;
        }

        lockfile_fd = create_lockfile();
        if (lockfile_fd < 0) {
                ret = -EEXIST;
                goto end;
        }
end:
        return ret;
}

static void sessiond_cleanup_lock_file(void)
{
        int ret;

        /*
         * Cleanup lock file by deleting it and finaly closing it which will
         * release the file system lock.
         */
        if (lockfile_fd >= 0) {
                ret = remove(config.lock_file_path.value);
                if (ret < 0) {
                        PERROR("remove lock file");
                }
                ret = close(lockfile_fd);
                if (ret < 0) {
                        PERROR("close lock file");
                }
        }
}

/*
 * Set the tracing group gid onto the client socket.
 *
 * Race window between mkdir and chown is OK because we are going from more
 * permissive (root.root) to less permissive (root.tracing).
 */
static int set_permissions(char *rundir)
{
        int ret;
        gid_t gid;

        gid = utils_get_group_id(config.tracing_group_name.value);

        /* Set lttng run dir */
        ret = chown(rundir, 0, gid);
        if (ret < 0) {
                ERR("Unable to set group on %s", rundir);
                PERROR("chown");
        }

        /*
         * Ensure all applications and tracing group can search the run
         * dir. Allow everyone to read the directory, since it does not
         * buy us anything to hide its content.
         */
        ret = chmod(rundir, S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH);
        if (ret < 0) {
                ERR("Unable to set permissions on %s", rundir);
                PERROR("chmod");
        }

        /* lttng client socket path */
        ret = chown(config.client_unix_sock_path.value, 0, gid);
        if (ret < 0) {
                ERR("Unable to set group on %s", config.client_unix_sock_path.value);
                PERROR("chown");
        }

        /* kconsumer error socket path */
        ret = chown(kconsumer_data.err_unix_sock_path, 0, 0);
        if (ret < 0) {
                ERR("Unable to set group on %s", kconsumer_data.err_unix_sock_path);
                PERROR("chown");
        }

        /* 64-bit ustconsumer error socket path */
        ret = chown(ustconsumer64_data.err_unix_sock_path, 0, 0);
        if (ret < 0) {
                ERR("Unable to set group on %s", ustconsumer64_data.err_unix_sock_path);
                PERROR("chown");
        }

        /* 32-bit ustconsumer compat32 error socket path */
        ret = chown(ustconsumer32_data.err_unix_sock_path, 0, 0);
        if (ret < 0) {
                ERR("Unable to set group on %s", ustconsumer32_data.err_unix_sock_path);
                PERROR("chown");
        }

        DBG("All permissions are set");

        return ret;
}

/*
 * Create the lttng run directory needed for all global sockets and pipe.
 */
static int create_lttng_rundir(void)
{
        int ret;

        DBG3("Creating LTTng run directory: %s", config.rundir.value);

        ret = mkdir(config.rundir.value, S_IRWXU);
        if (ret < 0) {
                if (errno != EEXIST) {
                        ERR("Unable to create %s", config.rundir.value);
                        goto error;
                } else {
                        ret = 0;
                }
        }

error:
        return ret;
}

/*
 * Setup sockets and directory needed by the consumerds' communication with the
 * session daemon.
 */
static int set_consumer_sockets(struct consumer_data *consumer_data)
{
        int ret;
        char *path = NULL;

        switch (consumer_data->type) {
        case LTTNG_CONSUMER_KERNEL:
                path = config.kconsumerd_path.value;
                break;
        case LTTNG_CONSUMER64_UST:
                path = config.consumerd64_path.value;
                break;
        case LTTNG_CONSUMER32_UST:
                path = config.consumerd32_path.value;
                break;
        default:
                ERR("Consumer type unknown");
                ret = -EINVAL;
                goto error;
        }
        assert(path);

        DBG2("Creating consumer directory: %s", path);

        ret = mkdir(path, S_IRWXU | S_IRGRP | S_IXGRP);
        if (ret < 0 && errno != EEXIST) {
                PERROR("mkdir");
                ERR("Failed to create %s", path);
                goto error;
        }
        if (is_root) {
                ret = chown(path, 0, utils_get_group_id(config.tracing_group_name.value));
                if (ret < 0) {
                        ERR("Unable to set group on %s", path);
                        PERROR("chown");
                        goto error;
                }
        }

        /* Create the consumerd error unix socket */
        consumer_data->err_sock =
                lttcomm_create_unix_sock(consumer_data->err_unix_sock_path);
        if (consumer_data->err_sock < 0) {
                ERR("Create unix sock failed: %s", consumer_data->err_unix_sock_path);
                ret = -1;
                goto error;
        }

        /*
         * Set the CLOEXEC flag. Return code is useless because either way, the
         * show must go on.
         */
        ret = utils_set_fd_cloexec(consumer_data->err_sock);
        if (ret < 0) {
                PERROR("utils_set_fd_cloexec");
                /* continue anyway */
        }

        /* File permission MUST be 660 */
        ret = chmod(consumer_data->err_unix_sock_path,
                        S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP);
        if (ret < 0) {
                ERR("Set file permissions failed: %s", consumer_data->err_unix_sock_path);
                PERROR("chmod");
                goto error;
        }

error:
        return ret;
}

/*
 * Signal handler for the daemon
 *
 * Simply stop all worker threads, leaving main() return gracefully after
 * joining all threads and calling cleanup().
 */
static void sighandler(int sig)
{
        switch (sig) {
        case SIGINT:
                DBG("SIGINT caught");
                stop_threads();
                break;
        case SIGTERM:
                DBG("SIGTERM caught");
                stop_threads();
                break;
        case SIGUSR1:
                CMM_STORE_SHARED(recv_child_signal, 1);
                break;
        default:
                break;
        }
}

/*
 * Setup signal handler for :
 *              SIGINT, SIGTERM, SIGPIPE
 */
static int set_signal_handler(void)
{
        int ret = 0;
        struct sigaction sa;
        sigset_t sigset;

        if ((ret = sigemptyset(&sigset)) < 0) {
                PERROR("sigemptyset");
                return ret;
        }

        sa.sa_mask = sigset;
        sa.sa_flags = 0;

        sa.sa_handler = sighandler;
        if ((ret = sigaction(SIGTERM, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
        }

        if ((ret = sigaction(SIGINT, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
        }

        if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
        }

        sa.sa_handler = SIG_IGN;
        if ((ret = sigaction(SIGPIPE, &sa, NULL)) < 0) {
                PERROR("sigaction");
                return ret;
        }

        DBG("Signal handler set for SIGTERM, SIGUSR1, SIGPIPE and SIGINT");

        return ret;
}

/*
 * Set open files limit to unlimited. This daemon can open a large number of
 * file descriptors in order to consume multiple kernel traces.
 */
static void set_ulimit(void)
{
        int ret;
        struct rlimit lim;

        /* The kernel does not allow an infinite limit for open files */
        lim.rlim_cur = 65535;
        lim.rlim_max = 65535;

        ret = setrlimit(RLIMIT_NOFILE, &lim);
        if (ret < 0) {
                PERROR("failed to set open files limit");
        }
}

static int write_pidfile(void)
{
        return utils_create_pid_file(getpid(), config.pid_file_path.value);
}

static int set_clock_plugin_env(void)
{
        int ret = 0;
        char *env_value = NULL;

        if (!config.lttng_ust_clock_plugin.value) {
                goto end;
        }

        ret = asprintf(&env_value, "LTTNG_UST_CLOCK_PLUGIN=%s",
                        config.lttng_ust_clock_plugin.value);
        if (ret < 0) {
                PERROR("asprintf");
                goto end;
        }

        ret = putenv(env_value);
        if (ret) {
                free(env_value);
                PERROR("putenv of LTTNG_UST_CLOCK_PLUGIN");
                goto end;
        }

        DBG("Updated LTTNG_UST_CLOCK_PLUGIN environment variable to \"%s\"",
                        config.lttng_ust_clock_plugin.value);
end:
        return ret;
}

static void destroy_all_sessions_and_wait(void)
{
        struct ltt_session *session, *tmp;
        struct ltt_session_list *session_list;

        session_list = session_get_list();
        DBG("Initiating destruction of all sessions");

        if (!session_list) {
                return;
        }

        session_lock_list();
        /* Initiate the destruction of all sessions. */
        cds_list_for_each_entry_safe(session, tmp,
                        &session_list->head, list) {
                if (!session_get(session)) {
                        continue;
                }

                session_lock(session);
                if (session->destroyed) {
                        goto unlock_session;
                }
                (void) cmd_destroy_session(session,
                                notification_thread_handle);
        unlock_session:
                session_unlock(session);
                session_put(session);
        }
        session_unlock_list();

        /* Wait for the destruction of all sessions to complete. */
        DBG("Waiting for the destruction of all sessions to complete");
        session_list_wait_empty();
        DBG("Destruction of all sessions completed");
}

/*
 * main
 */
int main(int argc, char **argv)
{
        int ret = 0, retval = 0;
        void *status;
        const char *env_app_timeout;
        struct lttng_pipe *ust32_channel_monitor_pipe = NULL,
                        *ust64_channel_monitor_pipe = NULL,
                        *kernel_channel_monitor_pipe = NULL;
        struct lttng_thread *ht_cleanup_thread = NULL;
        struct timer_thread_parameters timer_thread_parameters;
        /* Rotation thread handle. */
        struct rotation_thread_handle *rotation_thread_handle = NULL;
        /* Queue of rotation jobs populated by the sessiond-timer. */
        struct rotation_thread_timer_queue *rotation_timer_queue = NULL;
        struct lttng_thread *client_thread = NULL;

        init_kernel_workarounds();

        rcu_register_thread();

        if (set_signal_handler()) {
                retval = -1;
                goto exit_set_signal_handler;
        }

        if (timer_signal_init()) {
                retval = -1;
                goto exit_set_signal_handler;
        }

        page_size = sysconf(_SC_PAGESIZE);
        if (page_size < 0) {
                PERROR("sysconf _SC_PAGESIZE");
                page_size = LONG_MAX;
                WARN("Fallback page size to %ld", page_size);
        }

        ret = sessiond_config_init(&config);
        if (ret) {
                retval = -1;
                goto exit_set_signal_handler;
        }

        /*
         * Init config from environment variables.
         * Command line option override env configuration per-doc. Do env first.
         */
        sessiond_config_apply_env_config(&config);

        /*
         * Parse arguments and load the daemon configuration file.
         *
         * We have an exit_options exit path to free memory reserved by
         * set_options. This is needed because the rest of sessiond_cleanup()
         * depends on ht_cleanup_thread, which depends on lttng_daemonize, which
         * depends on set_options.
         */
        progname = argv[0];
        if (set_options(argc, argv)) {
                retval = -1;
                goto exit_options;
        }

        /*
         * Resolve all paths received as arguments, configuration option, or
         * through environment variable as absolute paths. This is necessary
         * since daemonizing causes the sessiond's current working directory
         * to '/'.
         */
        ret = sessiond_config_resolve_paths(&config);
        if (ret) {
                goto exit_options;
        }

        /* Apply config. */
        lttng_opt_verbose = config.verbose;
        lttng_opt_quiet = config.quiet;
        kconsumer_data.err_unix_sock_path =
                        config.kconsumerd_err_unix_sock_path.value;
        kconsumer_data.cmd_unix_sock_path =
                        config.kconsumerd_cmd_unix_sock_path.value;
        ustconsumer32_data.err_unix_sock_path =
                        config.consumerd32_err_unix_sock_path.value;
        ustconsumer32_data.cmd_unix_sock_path =
                        config.consumerd32_cmd_unix_sock_path.value;
        ustconsumer64_data.err_unix_sock_path =
                        config.consumerd64_err_unix_sock_path.value;
        ustconsumer64_data.cmd_unix_sock_path =
                        config.consumerd64_cmd_unix_sock_path.value;
        set_clock_plugin_env();

        sessiond_config_log(&config);

        if (create_lttng_rundir()) {
                retval = -1;
                goto exit_options;
        }

        /* Abort launch if a session daemon is already running. */
        if (check_existing_daemon()) {
                ERR("A session daemon is already running.");
                retval = -1;
                goto exit_options;
        }

        /* Daemonize */
        if (config.daemonize || config.background) {
                int i;

                ret = lttng_daemonize(&child_ppid, &recv_child_signal,
                        !config.background);
                if (ret < 0) {
                        retval = -1;
                        goto exit_options;
                }

                /*
                 * We are in the child. Make sure all other file descriptors are
                 * closed, in case we are called with more opened file
                 * descriptors than the standard ones and the lock file.
                 */
                for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) {
                        if (i == lockfile_fd) {
                                continue;
                        }
                        (void) close(i);
                }
        }

        if (run_as_create_worker(argv[0]) < 0) {
                goto exit_create_run_as_worker_cleanup;
        }

        /*
         * Starting from here, we can create threads. This needs to be after
         * lttng_daemonize due to RCU.
         */

        /*
         * Initialize the health check subsystem. This call should set the
         * appropriate time values.
         */
        health_sessiond = health_app_create(NR_HEALTH_SESSIOND_TYPES);
        if (!health_sessiond) {
                PERROR("health_app_create error");
                retval = -1;
                goto exit_health_sessiond_cleanup;
        }

        /* Create thread to clean up RCU hash tables */
        ht_cleanup_thread = launch_ht_cleanup_thread();
        if (!ht_cleanup_thread) {
                retval = -1;
                goto exit_ht_cleanup;
        }

        /* Create thread quit pipe */
        if (sessiond_init_thread_quit_pipe()) {
                retval = -1;
                goto exit_init_data;
        }

        /* Check if daemon is UID = 0 */
        is_root = !getuid();
        if (is_root) {
                /* Create global run dir with root access */

                kernel_channel_monitor_pipe = lttng_pipe_open(0);
                if (!kernel_channel_monitor_pipe) {
                        ERR("Failed to create kernel consumer channel monitor pipe");
                        retval = -1;
                        goto exit_init_data;
                }
                kconsumer_data.channel_monitor_pipe =
                                lttng_pipe_release_writefd(
                                        kernel_channel_monitor_pipe);
                if (kconsumer_data.channel_monitor_pipe < 0) {
                        retval = -1;
                        goto exit_init_data;
                }
        }

        /* Set consumer initial state */
        kernel_consumerd_state = CONSUMER_STOPPED;
        ust_consumerd_state = CONSUMER_STOPPED;

        ust32_channel_monitor_pipe = lttng_pipe_open(0);
        if (!ust32_channel_monitor_pipe) {
                ERR("Failed to create 32-bit user space consumer channel monitor pipe");
                retval = -1;
                goto exit_init_data;
        }
        ustconsumer32_data.channel_monitor_pipe = lttng_pipe_release_writefd(
                        ust32_channel_monitor_pipe);
        if (ustconsumer32_data.channel_monitor_pipe < 0) {
                retval = -1;
                goto exit_init_data;
        }

        /*
         * The rotation_thread_timer_queue structure is shared between the
         * sessiond timer thread and the rotation thread. The main thread keeps
         * its ownership and destroys it when both threads have been joined.
         */
        rotation_timer_queue = rotation_thread_timer_queue_create();
        if (!rotation_timer_queue) {
                retval = -1;
                goto exit_init_data;
        }
        timer_thread_parameters.rotation_thread_job_queue =
                        rotation_timer_queue;

        ust64_channel_monitor_pipe = lttng_pipe_open(0);
        if (!ust64_channel_monitor_pipe) {
                ERR("Failed to create 64-bit user space consumer channel monitor pipe");
                retval = -1;
                goto exit_init_data;
        }
        ustconsumer64_data.channel_monitor_pipe = lttng_pipe_release_writefd(
                        ust64_channel_monitor_pipe);
        if (ustconsumer64_data.channel_monitor_pipe < 0) {
                retval = -1;
                goto exit_init_data;
        }

        /*
         * Init UST app hash table. Alloc hash table before this point since
         * cleanup() can get called after that point.
         */
        if (ust_app_ht_alloc()) {
                ERR("Failed to allocate UST app hash table");
                retval = -1;
                goto exit_init_data;
        }

        /*
         * Initialize agent app hash table. We allocate the hash table here
         * since cleanup() can get called after this point.
         */
        if (agent_app_ht_alloc()) {
                ERR("Failed to allocate Agent app hash table");
                retval = -1;
                goto exit_init_data;
        }

        /*
         * These actions must be executed as root. We do that *after* setting up
         * the sockets path because we MUST make the check for another daemon using
         * those paths *before* trying to set the kernel consumer sockets and init
         * kernel tracer.
         */
        if (is_root) {
                if (set_consumer_sockets(&kconsumer_data)) {
                        retval = -1;
                        goto exit_init_data;
                }

                /* Setup kernel tracer */
                if (!config.no_kernel) {
                        init_kernel_tracer();
                        if (kernel_tracer_fd >= 0) {
                                ret = syscall_init_table();
                                if (ret < 0) {
                                        ERR("Unable to populate syscall table. "
                                                "Syscall tracing won't work "
                                                "for this session daemon.");
                                }
                        }
                }

                /* Set ulimit for open files */
                set_ulimit();
        }
        /* init lttng_fd tracking must be done after set_ulimit. */
        lttng_fd_init();

        if (set_consumer_sockets(&ustconsumer64_data)) {
                retval = -1;
                goto exit_init_data;
        }

        if (set_consumer_sockets(&ustconsumer32_data)) {
                retval = -1;
                goto exit_init_data;
        }

        /* Setup the needed unix socket */
        if (init_daemon_socket()) {
                retval = -1;
                goto exit_init_data;
        }

        /* Set credentials to socket */
        if (is_root && set_permissions(config.rundir.value)) {
                retval = -1;
                goto exit_init_data;
        }

        /* Get parent pid if -S, --sig-parent is specified. */
        if (config.sig_parent) {
                ppid = getppid();
        }

        /* Setup the kernel pipe for waking up the kernel thread */
        if (is_root && !config.no_kernel) {
                if (utils_create_pipe_cloexec(kernel_poll_pipe)) {
                        retval = -1;
                        goto exit_init_data;
                }
        }

        /* Setup the thread apps communication pipe. */
        if (utils_create_pipe_cloexec(apps_cmd_pipe)) {
                retval = -1;
                goto exit_init_data;
        }

        /* Setup the thread apps notify communication pipe. */
        if (utils_create_pipe_cloexec(apps_cmd_notify_pipe)) {
                retval = -1;
                goto exit_init_data;
        }

        /* Initialize global buffer per UID and PID registry. */
        buffer_reg_init_uid_registry();
        buffer_reg_init_pid_registry();

        /* Init UST command queue. */
        cds_wfcq_init(&ust_cmd_queue.head, &ust_cmd_queue.tail);

        cmd_init();

        /* Check for the application socket timeout env variable. */
        env_app_timeout = getenv(DEFAULT_APP_SOCKET_TIMEOUT_ENV);
        if (env_app_timeout) {
                config.app_socket_timeout = atoi(env_app_timeout);
        } else {
                config.app_socket_timeout = DEFAULT_APP_SOCKET_RW_TIMEOUT;
        }

        ret = write_pidfile();
        if (ret) {
                ERR("Error in write_pidfile");
                retval = -1;
                goto exit_init_data;
        }

        /* Initialize communication library */
        lttcomm_init();
        /* Initialize TCP timeout values */
        lttcomm_inet_init();

        if (load_session_init_data(&load_info) < 0) {
                retval = -1;
                goto exit_init_data;
        }
        load_info->path = config.load_session_path.value;

        /* Create health-check thread. */
        if (!launch_health_management_thread()) {
                retval = -1;
                goto exit_health;
        }

        /* notification_thread_data acquires the pipes' read side. */
        notification_thread_handle = notification_thread_handle_create(
                        ust32_channel_monitor_pipe,
                        ust64_channel_monitor_pipe,
                        kernel_channel_monitor_pipe);
        if (!notification_thread_handle) {
                retval = -1;
                ERR("Failed to create notification thread shared data");
                goto exit_notification;
        }

        /* Create notification thread. */
        if (!launch_notification_thread(notification_thread_handle)) {
                retval = -1;
                goto exit_notification;
        }

        /* Create timer thread. */
        if (!launch_timer_thread(&timer_thread_parameters)) {
                retval = -1;
                goto exit_notification;
        }

        /* rotation_thread_data acquires the pipes' read side. */
        rotation_thread_handle = rotation_thread_handle_create(
                        rotation_timer_queue,
                        notification_thread_handle);
        if (!rotation_thread_handle) {
                retval = -1;
                ERR("Failed to create rotation thread shared data");
                stop_threads();
                goto exit_rotation;
        }

        /* Create rotation thread. */
        if (!launch_rotation_thread(rotation_thread_handle)) {
                retval = -1;
                goto exit_rotation;
        }

        /* Create thread to manage the client socket */
        client_thread = launch_client_thread();
        if (!client_thread) {
                retval = -1;
                goto exit_client;
        }

        /* Create thread to dispatch registration */
        ret = pthread_create(&dispatch_thread, default_pthread_attr(),
                        thread_dispatch_ust_registration, (void *) NULL);
        if (ret) {
                errno = ret;
                PERROR("pthread_create dispatch");
                retval = -1;
                stop_threads();
                goto exit_dispatch;
        }

        /* Create thread to manage application registration. */
        ret = pthread_create(&reg_apps_thread, default_pthread_attr(),
                        thread_registration_apps, (void *) NULL);
        if (ret) {
                errno = ret;
                PERROR("pthread_create registration");
                retval = -1;
                stop_threads();
                goto exit_reg_apps;
        }

        /* Create thread to manage application socket */
        ret = pthread_create(&apps_thread, default_pthread_attr(),
                        thread_manage_apps, (void *) NULL);
        if (ret) {
                errno = ret;
                PERROR("pthread_create apps");
                retval = -1;
                stop_threads();
                goto exit_apps;
        }

        /* Create thread to manage application notify socket */
        ret = pthread_create(&apps_notify_thread, default_pthread_attr(),
                        ust_thread_manage_notify, (void *) NULL);
        if (ret) {
                errno = ret;
                PERROR("pthread_create notify");
                retval = -1;
                stop_threads();
                goto exit_apps_notify;
        }

        /* Create agent registration thread. */
        ret = pthread_create(&agent_reg_thread, default_pthread_attr(),
                        agent_thread_manage_registration, (void *) NULL);
        if (ret) {
                errno = ret;
                PERROR("pthread_create agent");
                retval = -1;
                stop_threads();
                goto exit_agent_reg;
        }

        /* Don't start this thread if kernel tracing is not requested nor root */
        if (is_root && !config.no_kernel) {
                /* Create kernel thread to manage kernel event */
                ret = pthread_create(&kernel_thread, default_pthread_attr(),
                                thread_manage_kernel, (void *) NULL);
                if (ret) {
                        errno = ret;
                        PERROR("pthread_create kernel");
                        retval = -1;
                        stop_threads();
                        goto exit_kernel;
                }
        }

        /* Create session loading thread. */
        ret = pthread_create(&load_session_thread, default_pthread_attr(),
                        thread_load_session, load_info);
        if (ret) {
                errno = ret;
                PERROR("pthread_create load_session_thread");
                retval = -1;
                stop_threads();
                goto exit_load_session;
        }

        /*
         * This is where we start awaiting program completion (e.g. through
         * signal that asks threads to teardown).
         */

        ret = pthread_join(load_session_thread, &status);
        if (ret) {
                errno = ret;
                PERROR("pthread_join load_session_thread");
                retval = -1;
        }

        /* Initiate teardown once activity occurs on the quit pipe. */
        sessiond_wait_for_quit_pipe(-1U);

        /*
         * Ensure that the client thread is no longer accepting new commands,
         * which could cause new sessions to be created.
         */
        if (!lttng_thread_shutdown(client_thread)) {
                ERR("Failed to shutdown the client thread, continuing teardown");
                lttng_thread_put(client_thread);
                client_thread = NULL;
        }

        destroy_all_sessions_and_wait();
exit_load_session:

        if (is_root && !config.no_kernel) {
                ret = pthread_join(kernel_thread, &status);
                if (ret) {
                        errno = ret;
                        PERROR("pthread_join");
                        retval = -1;
                }
        }
exit_kernel:

        ret = pthread_join(agent_reg_thread, &status);
        if (ret) {
                errno = ret;
                PERROR("pthread_join agent");
                retval = -1;
        }
exit_agent_reg:

        ret = pthread_join(apps_notify_thread, &status);
        if (ret) {
                errno = ret;
                PERROR("pthread_join apps notify");
                retval = -1;
        }
exit_apps_notify:

        ret = pthread_join(apps_thread, &status);
        if (ret) {
                errno = ret;
                PERROR("pthread_join apps");
                retval = -1;
        }
exit_apps:

        ret = pthread_join(reg_apps_thread, &status);
        if (ret) {
                errno = ret;
                PERROR("pthread_join");
                retval = -1;
        }
exit_reg_apps:

        /*
         * Join dispatch thread after joining reg_apps_thread to ensure
         * we don't leak applications in the queue.
         */
        ret = pthread_join(dispatch_thread, &status);
        if (ret) {
                errno = ret;
                PERROR("pthread_join");
                retval = -1;
        }
exit_dispatch:
exit_client:
exit_rotation:
exit_notification:
        lttng_thread_list_shutdown_orphans();
exit_health:
exit_init_data:
        if (client_thread) {
                lttng_thread_put(client_thread);
        }

        /*
         * Wait for all pending call_rcu work to complete before tearing
         * down data structures. call_rcu worker may be trying to
         * perform lookups in those structures.
         */
        rcu_barrier();
        /*
         * sessiond_cleanup() is called when no other thread is running, except
         * the ht_cleanup thread, which is needed to destroy the hash tables.
         */
        rcu_thread_online();
        sessiond_cleanup();

        /*
         * Ensure all prior call_rcu are done. call_rcu callbacks may push
         * hash tables to the ht_cleanup thread. Therefore, we ensure that
         * the queue is empty before shutting down the clean-up thread.
         */
        rcu_barrier();

        if (ht_cleanup_thread) {
                lttng_thread_shutdown(ht_cleanup_thread);
                lttng_thread_put(ht_cleanup_thread);
        }

        rcu_thread_offline();
        rcu_unregister_thread();

        if (rotation_thread_handle) {
                rotation_thread_handle_destroy(rotation_thread_handle);
        }

        /*
         * After the rotation and timer thread have quit, we can safely destroy
         * the rotation_timer_queue.
         */
        rotation_thread_timer_queue_destroy(rotation_timer_queue);
        /*
         * The teardown of the notification system is performed after the
         * session daemon's teardown in order to allow it to be notified
         * of the active session and channels at the moment of the teardown.
         */
        if (notification_thread_handle) {
                notification_thread_handle_destroy(notification_thread_handle);
        }
        lttng_pipe_destroy(ust32_channel_monitor_pipe);
        lttng_pipe_destroy(ust64_channel_monitor_pipe);
        lttng_pipe_destroy(kernel_channel_monitor_pipe);
exit_ht_cleanup:

        health_app_destroy(health_sessiond);
exit_health_sessiond_cleanup:
exit_create_run_as_worker_cleanup:

exit_options:
        sessiond_cleanup_lock_file();
        sessiond_cleanup_options();

exit_set_signal_handler:
        if (!retval) {
                exit(EXIT_SUCCESS);
        } else {
                exit(EXIT_FAILURE);
        }
}