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

/*
 * Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
 * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 * Copyright (C) 2013 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#include <stddef.h>
#include <stdlib.h>
#include <urcu.h>
#include <common/futex.h>
#include <common/macros.h>
#include <common/shm.h>
#include <common/utils.h>
#include <sys/stat.h>

#include "register.h"
#include "lttng-sessiond.h"
#include "testpoint.h"
#include "health-sessiond.h"
#include "fd-limit.h"
#include "utils.h"
#include "thread.h"

struct thread_state {
	struct lttng_pipe *quit_pipe;
	struct ust_cmd_queue *ust_cmd_queue;
	sem_t ready;
	bool running;
	int application_socket;
};

/*
 * Creates the application socket.
 */
static int create_application_socket(void)
{
	int ret = 0;
	int apps_sock;
	const mode_t old_umask = umask(0);

	/* Create the application unix socket */
	apps_sock = lttcomm_create_unix_sock(
			the_config.apps_unix_sock_path.value);
	if (apps_sock < 0) {
		ERR("Create unix sock failed: %s",
				the_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(the_config.apps_unix_sock_path.value,
			S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH |
					S_IWOTH);
	if (ret < 0) {
		PERROR("Set file permissions failed on %s",
				the_config.apps_unix_sock_path.value);
		goto error_close_socket;
	}

	DBG3("Session daemon application socket created (fd = %d) ", apps_sock);
	ret = apps_sock;
end:
	umask(old_umask);
	return ret;
error_close_socket:
	if (close(apps_sock)) {
		PERROR("Failed to close application socket in error path");
	}
	apps_sock = -1;
	ret = -1;
	goto end;
}

/*
 * Notify UST applications using the shm mmap futex.
 */
static int notify_ust_apps(int active, bool is_root)
{
	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(
			the_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;
}

static void cleanup_application_registration_thread(void *data)
{
	struct thread_state *thread_state = data;

	if (!data) {
		return;
	}

	lttng_pipe_destroy(thread_state->quit_pipe);
	free(thread_state);
}

static void set_thread_status(struct thread_state *thread_state, bool running)
{
	DBG("Marking application registration thread's state as %s", running ? "running" : "error");
	thread_state->running = running;
	sem_post(&thread_state->ready);
}

static bool wait_thread_status(struct thread_state *thread_state)
{
	DBG("Waiting for application registration thread to be ready");
	sem_wait(&thread_state->ready);
	if (thread_state->running) {
		DBG("Application registration thread is ready");
	} else {
		ERR("Initialization of application registration thread failed");
	}

	return thread_state->running;
}

static void thread_init_cleanup(void *data)
{
	struct thread_state *thread_state = data;

	set_thread_status(thread_state, false);
}

/*
 * This thread manage application registration.
 */
static void *thread_application_registration(void *data)
{
	int sock = -1, i, ret, pollfd, err = -1;
	uint32_t revents, nb_fd;
	struct lttng_poll_event events;
	/*
	 * Gets allocated in this thread, enqueued to a global queue, dequeued
	 * and freed in the manage apps thread.
	 */
	struct ust_command *ust_cmd = NULL;
	const bool is_root = (getuid() == 0);
	struct thread_state *thread_state = data;
	const int application_socket = thread_state->application_socket;
	const int quit_pipe_read_fd = lttng_pipe_get_readfd(
			thread_state->quit_pipe);

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

	pthread_cleanup_push(thread_init_cleanup, thread_state);
	health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG);

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

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

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

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

	set_thread_status(thread_state, true);
	pthread_cleanup_pop(0);

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

	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);

			/* Thread quit pipe has been closed. Killing thread. */
			if (pollfd == quit_pipe_read_fd) {
				err = 0;
				goto exit;
			} else {
				/* Event on the registration socket */
				if (revents & LPOLLIN) {
					sock = lttcomm_accept_unix_sock(application_socket);
					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 (the_config.app_socket_timeout >= 0) {
						(void) lttcomm_setsockopt_rcv_timeout(sock,
								the_config.app_socket_timeout * 1000);
						(void) lttcomm_setsockopt_snd_timeout(sock,
								the_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");
						}
						sock = -1;
						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(&thread_state->ust_cmd_queue->head,
							&thread_state->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(&thread_state->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, is_root);

	ret = close(application_socket);
	if (ret) {
		PERROR("Failed to close application registration socket");
	}
	if (sock >= 0) {
		ret = close(sock);
		if (ret) {
			PERROR("Failed to close application socket");
		}
		lttng_fd_put(LTTNG_FD_APPS, 1);
	}
	unlink(the_config.apps_unix_sock_path.value);

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

static bool shutdown_application_registration_thread(void *data)
{
	struct thread_state *thread_state = data;
	const int write_fd = lttng_pipe_get_writefd(thread_state->quit_pipe);

	return notify_thread_pipe(write_fd) == 1;
}

struct lttng_thread *launch_application_registration_thread(
		struct ust_cmd_queue *cmd_queue)
{
	int ret;
	struct lttng_pipe *quit_pipe;
	struct thread_state *thread_state = NULL;
	struct lttng_thread *thread = NULL;
	const bool is_root = (getuid() == 0);
	int application_socket = -1;

	thread_state = zmalloc(sizeof(*thread_state));
	if (!thread_state) {
		goto error_alloc;
	}
	quit_pipe = lttng_pipe_open(FD_CLOEXEC);
	if (!quit_pipe) {
		goto error;
	}
	thread_state->quit_pipe = quit_pipe;
	thread_state->ust_cmd_queue = cmd_queue;
	application_socket = create_application_socket();
	if (application_socket < 0) {
		goto error;
	}
	thread_state->application_socket = application_socket;
	sem_init(&thread_state->ready, 0, 0);

	thread = lttng_thread_create("UST application registration",
			thread_application_registration,
			shutdown_application_registration_thread,
			cleanup_application_registration_thread,
			thread_state);
	if (!thread) {
		goto error;
	}
	/*
	 * The application registration thread now owns the application socket
	 * and the global thread state. The thread state is used to wait for
	 * the thread's status, but its ownership now belongs to the thread.
	 */
	application_socket = -1;
	if (!wait_thread_status(thread_state)) {
		thread_state = NULL;
		goto error;
	}

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

	return thread;
error:
	lttng_thread_put(thread);
	cleanup_application_registration_thread(thread_state);
	if (application_socket >= 0) {
		if (close(application_socket)) {
			PERROR("Failed to close application registration socket");
		}
	}
error_alloc:
	return NULL;
}
Commit	Line	Data
	1	/*
	2	* Copyright (C) 2011 David Goulet <david.goulet@polymtl.ca>
	3	* Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
	4	* Copyright (C) 2013 Jérémie Galarneau <jeremie.galarneau@efficios.com>
	5	*
	6	* SPDX-License-Identifier: GPL-2.0-only
	7	*
	8	*/
	9
	10	#include <stddef.h>
	11	#include <stdlib.h>
	12	#include <urcu.h>
	13	#include <common/futex.h>
	14	#include <common/macros.h>
	15	#include <common/shm.h>
	16	#include <common/utils.h>
	17	#include <sys/stat.h>
	18
	19	#include "register.h"
	20	#include "lttng-sessiond.h"
	21	#include "testpoint.h"
	22	#include "health-sessiond.h"
	23	#include "fd-limit.h"
	24	#include "utils.h"
	25	#include "thread.h"
	26
	27	struct thread_state {
	28	struct lttng_pipe *quit_pipe;
	29	struct ust_cmd_queue *ust_cmd_queue;
	30	sem_t ready;
	31	bool running;
	32	int application_socket;
	33	};
	34
	35	/*
	36	* Creates the application socket.
	37	*/
	38	static int create_application_socket(void)
	39	{
	40	int ret = 0;
	41	int apps_sock;
	42	const mode_t old_umask = umask(0);
	43
	44	/* Create the application unix socket */
	45	apps_sock = lttcomm_create_unix_sock(
	46	the_config.apps_unix_sock_path.value);
	47	if (apps_sock < 0) {
	48	ERR("Create unix sock failed: %s",
	49	the_config.apps_unix_sock_path.value);
	50	ret = -1;
	51	goto end;
	52	}
	53
	54	/* Set the cloexec flag */
	55	ret = utils_set_fd_cloexec(apps_sock);
	56	if (ret < 0) {
	57	ERR("Unable to set CLOEXEC flag to the app Unix socket (fd: %d). "
	58	"Continuing but note that the consumer daemon will have a "
	59	"reference to this socket on exec()", apps_sock);
	60	}
	61
	62	/* File permission MUST be 666 */
	63	ret = chmod(the_config.apps_unix_sock_path.value,
	64	S_IRUSR \| S_IWUSR \| S_IRGRP \| S_IWGRP \| S_IROTH \|
	65	S_IWOTH);
	66	if (ret < 0) {
	67	PERROR("Set file permissions failed on %s",
	68	the_config.apps_unix_sock_path.value);
	69	goto error_close_socket;
	70	}
	71
	72	DBG3("Session daemon application socket created (fd = %d) ", apps_sock);
	73	ret = apps_sock;
	74	end:
	75	umask(old_umask);
	76	return ret;
	77	error_close_socket:
	78	if (close(apps_sock)) {
	79	PERROR("Failed to close application socket in error path");
	80	}
	81	apps_sock = -1;
	82	ret = -1;
	83	goto end;
	84	}
	85
	86	/*
	87	* Notify UST applications using the shm mmap futex.
	88	*/
	89	static int notify_ust_apps(int active, bool is_root)
	90	{
	91	char *wait_shm_mmap;
	92
	93	DBG("Notifying applications of session daemon state: %d", active);
	94
	95	/* See shm.c for this call implying mmap, shm and futex calls */
	96	wait_shm_mmap = shm_ust_get_mmap(
	97	the_config.wait_shm_path.value, is_root);
	98	if (wait_shm_mmap == NULL) {
	99	goto error;
	100	}
	101
	102	/* Wake waiting process */
	103	futex_wait_update((int32_t *) wait_shm_mmap, active);
	104
	105	/* Apps notified successfully */
	106	return 0;
	107
	108	error:
	109	return -1;
	110	}
	111
	112	static void cleanup_application_registration_thread(void *data)
	113	{
	114	struct thread_state *thread_state = data;
	115
	116	if (!data) {
	117	return;
	118	}
	119
	120	lttng_pipe_destroy(thread_state->quit_pipe);
	121	free(thread_state);
	122	}
	123
	124	static void set_thread_status(struct thread_state *thread_state, bool running)
	125	{
	126	DBG("Marking application registration thread's state as %s", running ? "running" : "error");
	127	thread_state->running = running;
	128	sem_post(&thread_state->ready);
	129	}
	130
	131	static bool wait_thread_status(struct thread_state *thread_state)
	132	{
	133	DBG("Waiting for application registration thread to be ready");
	134	sem_wait(&thread_state->ready);
	135	if (thread_state->running) {
	136	DBG("Application registration thread is ready");
	137	} else {
	138	ERR("Initialization of application registration thread failed");
	139	}
	140
	141	return thread_state->running;
	142	}
	143
	144	static void thread_init_cleanup(void *data)
	145	{
	146	struct thread_state *thread_state = data;
	147
	148	set_thread_status(thread_state, false);
	149	}
	150
	151	/*
	152	* This thread manage application registration.
	153	*/
	154	static void thread_application_registration(void data)
	155	{
	156	int sock = -1, i, ret, pollfd, err = -1;
	157	uint32_t revents, nb_fd;
	158	struct lttng_poll_event events;
	159	/*
	160	* Gets allocated in this thread, enqueued to a global queue, dequeued
	161	* and freed in the manage apps thread.
	162	*/
	163	struct ust_command *ust_cmd = NULL;
	164	const bool is_root = (getuid() == 0);
	165	struct thread_state *thread_state = data;
	166	const int application_socket = thread_state->application_socket;
	167	const int quit_pipe_read_fd = lttng_pipe_get_readfd(
	168	thread_state->quit_pipe);
	169
	170	DBG("[thread] Manage application registration started");
	171
	172	pthread_cleanup_push(thread_init_cleanup, thread_state);
	173	health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG);
	174
	175	ret = lttcomm_listen_unix_sock(application_socket);
	176	if (ret < 0) {
	177	goto error_listen;
	178	}
	179
	180	/*
	181	* Pass 2 as size here for the thread quit pipe and apps_sock. Nothing
	182	* more will be added to this poll set.
	183	*/
	184	ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
	185	if (ret < 0) {
	186	goto error_create_poll;
	187	}
	188
	189	/* Add the application registration socket */
	190	ret = lttng_poll_add(&events, application_socket, LPOLLIN \| LPOLLRDHUP);
	191	if (ret < 0) {
	192	goto error_poll_add;
	193	}
	194
	195	/* Add the application registration socket */
	196	ret = lttng_poll_add(&events, quit_pipe_read_fd, LPOLLIN \| LPOLLRDHUP);
	197	if (ret < 0) {
	198	goto error_poll_add;
	199	}
	200
	201	set_thread_status(thread_state, true);
	202	pthread_cleanup_pop(0);
	203
	204	if (testpoint(sessiond_thread_registration_apps)) {
	205	goto error_poll_add;
	206	}
	207
	208	while (1) {
	209	DBG("Accepting application registration");
	210
	211	/* Inifinite blocking call, waiting for transmission */
	212	restart:
	213	health_poll_entry();
	214	ret = lttng_poll_wait(&events, -1);
	215	health_poll_exit();
	216	if (ret < 0) {
	217	/*
	218	* Restart interrupted system call.
	219	*/
	220	if (errno == EINTR) {
	221	goto restart;
	222	}
	223	goto error;
	224	}
	225
	226	nb_fd = ret;
	227
	228	for (i = 0; i < nb_fd; i++) {
	229	health_code_update();
	230
	231	/* Fetch once the poll data */
	232	revents = LTTNG_POLL_GETEV(&events, i);
	233	pollfd = LTTNG_POLL_GETFD(&events, i);
	234
	235	/* Thread quit pipe has been closed. Killing thread. */
	236	if (pollfd == quit_pipe_read_fd) {
	237	err = 0;
	238	goto exit;
	239	} else {
	240	/* Event on the registration socket */
	241	if (revents & LPOLLIN) {
	242	sock = lttcomm_accept_unix_sock(application_socket);
	243	if (sock < 0) {
	244	goto error;
	245	}
	246
	247	/*
	248	* Set socket timeout for both receiving and ending.
	249	* app_socket_timeout is in seconds, whereas
	250	* lttcomm_setsockopt_rcv_timeout and
	251	* lttcomm_setsockopt_snd_timeout expect msec as
	252	* parameter.
	253	*/
	254	if (the_config.app_socket_timeout >= 0) {
	255	(void) lttcomm_setsockopt_rcv_timeout(sock,
	256	the_config.app_socket_timeout * 1000);
	257	(void) lttcomm_setsockopt_snd_timeout(sock,
	258	the_config.app_socket_timeout * 1000);
	259	}
	260
	261	/*
	262	* Set the CLOEXEC flag. Return code is useless because
	263	* either way, the show must go on.
	264	*/
	265	(void) utils_set_fd_cloexec(sock);
	266
	267	/* Create UST registration command for enqueuing */
	268	ust_cmd = zmalloc(sizeof(struct ust_command));
	269	if (ust_cmd == NULL) {
	270	PERROR("ust command zmalloc");
	271	ret = close(sock);
	272	if (ret) {
	273	PERROR("close");
	274	}
	275	sock = -1;
	276	goto error;
	277	}
	278
	279	/*
	280	* Using message-based transmissions to ensure we don't
	281	* have to deal with partially received messages.
	282	*/
	283	ret = lttng_fd_get(LTTNG_FD_APPS, 1);
	284	if (ret < 0) {
	285	ERR("Exhausted file descriptors allowed for applications.");
	286	free(ust_cmd);
	287	ret = close(sock);
	288	if (ret) {
	289	PERROR("close");
	290	}
	291	sock = -1;
	292	continue;
	293	}
	294
	295	health_code_update();
	296	ret = ust_app_recv_registration(sock, &ust_cmd->reg_msg);
	297	if (ret < 0) {
	298	free(ust_cmd);
	299	/* Close socket of the application. */
	300	ret = close(sock);
	301	if (ret) {
	302	PERROR("close");
	303	}
	304	lttng_fd_put(LTTNG_FD_APPS, 1);
	305	sock = -1;
	306	continue;
	307	}
	308	health_code_update();
	309
	310	ust_cmd->sock = sock;
	311	sock = -1;
	312
	313	DBG("UST registration received with pid:%d ppid:%d uid:%d"
	314	" gid:%d sock:%d name:%s (version %d.%d)",
	315	ust_cmd->reg_msg.pid, ust_cmd->reg_msg.ppid,
	316	ust_cmd->reg_msg.uid, ust_cmd->reg_msg.gid,
	317	ust_cmd->sock, ust_cmd->reg_msg.name,
	318	ust_cmd->reg_msg.major, ust_cmd->reg_msg.minor);
	319
	320	/*
	321	* Lock free enqueue the registration request. The red pill
	322	* has been taken! This apps will be part of the system.
	323	*/
	324	cds_wfcq_enqueue(&thread_state->ust_cmd_queue->head,
	325	&thread_state->ust_cmd_queue->tail,
	326	&ust_cmd->node);
	327
	328	/*
	329	* Wake the registration queue futex. Implicit memory
	330	* barrier with the exchange in cds_wfcq_enqueue.
	331	*/
	332	futex_nto1_wake(&thread_state->ust_cmd_queue->futex);
	333	} else if (revents & (LPOLLERR \| LPOLLHUP \| LPOLLRDHUP)) {
	334	ERR("Register apps socket poll error");
	335	goto error;
	336	} else {
	337	ERR("Unexpected poll events %u for sock %d", revents, pollfd);
	338	goto error;
	339	}
	340	}
	341	}
	342	}
	343
	344	exit:
	345	error:
	346	/* Notify that the registration thread is gone */
	347	notify_ust_apps(0, is_root);
	348
	349	ret = close(application_socket);
	350	if (ret) {
	351	PERROR("Failed to close application registration socket");
	352	}
	353	if (sock >= 0) {
	354	ret = close(sock);
	355	if (ret) {
	356	PERROR("Failed to close application socket");
	357	}
	358	lttng_fd_put(LTTNG_FD_APPS, 1);
	359	}
	360	unlink(the_config.apps_unix_sock_path.value);
	361
	362	error_poll_add:
	363	lttng_poll_clean(&events);
	364	error_listen:
	365	error_create_poll:
	366	DBG("UST Registration thread cleanup complete");
	367	if (err) {
	368	health_error();
	369	ERR("Health error occurred in %s", __func__);
	370	}
	371	health_unregister(the_health_sessiond);
	372	return NULL;
	373	}
	374
	375	static bool shutdown_application_registration_thread(void *data)
	376	{
	377	struct thread_state *thread_state = data;
	378	const int write_fd = lttng_pipe_get_writefd(thread_state->quit_pipe);
	379
	380	return notify_thread_pipe(write_fd) == 1;
	381	}
	382
	383	struct lttng_thread *launch_application_registration_thread(
	384	struct ust_cmd_queue *cmd_queue)
	385	{
	386	int ret;
	387	struct lttng_pipe *quit_pipe;
	388	struct thread_state *thread_state = NULL;
	389	struct lttng_thread *thread = NULL;
	390	const bool is_root = (getuid() == 0);
	391	int application_socket = -1;
	392
	393	thread_state = zmalloc(sizeof(*thread_state));
	394	if (!thread_state) {
	395	goto error_alloc;
	396	}
	397	quit_pipe = lttng_pipe_open(FD_CLOEXEC);
	398	if (!quit_pipe) {
	399	goto error;
	400	}
	401	thread_state->quit_pipe = quit_pipe;
	402	thread_state->ust_cmd_queue = cmd_queue;
	403	application_socket = create_application_socket();
	404	if (application_socket < 0) {
	405	goto error;
	406	}
	407	thread_state->application_socket = application_socket;
	408	sem_init(&thread_state->ready, 0, 0);
	409
	410	thread = lttng_thread_create("UST application registration",
	411	thread_application_registration,
	412	shutdown_application_registration_thread,
	413	cleanup_application_registration_thread,
	414	thread_state);
	415	if (!thread) {
	416	goto error;
	417	}
	418	/*
	419	* The application registration thread now owns the application socket
	420	* and the global thread state. The thread state is used to wait for
	421	* the thread's status, but its ownership now belongs to the thread.
	422	*/
	423	application_socket = -1;
	424	if (!wait_thread_status(thread_state)) {
	425	thread_state = NULL;
	426	goto error;
	427	}
	428
	429	/* Notify all applications to register. */
	430	ret = notify_ust_apps(1, is_root);
	431	if (ret < 0) {
	432	ERR("Failed to notify applications or create the wait shared memory.\n"
	433	"Execution continues but there might be problems for already\n"
	434	"running applications that wishes to register.");
	435	}
	436
	437	return thread;
	438	error:
	439	lttng_thread_put(thread);
	440	cleanup_application_registration_thread(thread_state);
	441	if (application_socket >= 0) {
	442	if (close(application_socket)) {
	443	PERROR("Failed to close application registration socket");
	444	}
	445	}
	446	error_alloc:
	447	return NULL;
	448	}