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

/*
 * Copyright (C) 2017 Julien Desfossez <jdesfossez@efficios.com>
 * Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#define _LGPL_SOURCE
#include <assert.h>
#include <inttypes.h>
#include <signal.h>

#include "timer.h"
#include "health-sessiond.h"
#include "rotation-thread.h"
#include "thread.h"

#define LTTNG_SESSIOND_SIG_QS				SIGRTMIN + 10
#define LTTNG_SESSIOND_SIG_EXIT				SIGRTMIN + 11
#define LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK	SIGRTMIN + 12
#define LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION		SIGRTMIN + 13

#define UINT_TO_PTR(value)				\
	({						\
		assert(value <= UINTPTR_MAX);		\
		(void *) (uintptr_t) value;		\
	})
#define PTR_TO_UINT(ptr) ((uintptr_t) ptr)

/*
 * Handle timer teardown race wrt memory free of private data by sessiond
 * signals are handled by a single thread, which permits a synchronization
 * point between handling of each signal. Internal lock ensures mutual
 * exclusion.
 */
static
struct timer_signal_data {
	/* Thread managing signals. */
	pthread_t tid;
	int qs_done;
	pthread_mutex_t lock;
} timer_signal = {
	.tid = 0,
	.qs_done = 0,
	.lock = PTHREAD_MUTEX_INITIALIZER,
};

/*
 * Set custom signal mask to current thread.
 */
static
void setmask(sigset_t *mask)
{
	int ret;

	ret = sigemptyset(mask);
	if (ret) {
		PERROR("sigemptyset");
	}
	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_QS);
	if (ret) {
		PERROR("sigaddset teardown");
	}
	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_EXIT);
	if (ret) {
		PERROR("sigaddset exit");
	}
	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK);
	if (ret) {
		PERROR("sigaddset pending rotation check");
	}
	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION);
	if (ret) {
		PERROR("sigaddset scheduled rotation");
	}
}

/*
 * This is the same function as timer_signal_thread_qs, when it
 * returns, it means that no timer signr is currently pending or being handled
 * by the timer thread. This cannot be called from the timer thread.
 */
static
void timer_signal_thread_qs(unsigned int signr)
{
	sigset_t pending_set;
	int ret;

	/*
	 * We need to be the only thread interacting with the thread
	 * that manages signals for teardown synchronization.
	 */
	pthread_mutex_lock(&timer_signal.lock);

	/* Ensure we don't have any signal queued for this session. */
	for (;;) {
		ret = sigemptyset(&pending_set);
		if (ret == -1) {
			PERROR("sigemptyset");
		}
		ret = sigpending(&pending_set);
		if (ret == -1) {
			PERROR("sigpending");
		}
		if (!sigismember(&pending_set, signr)) {
			break;
		}
		caa_cpu_relax();
	}

	/*
	 * From this point, no new signal handler will be fired that would try to
	 * access "session". However, we still need to wait for any currently
	 * executing handler to complete.
	 */
	cmm_smp_mb();
	CMM_STORE_SHARED(timer_signal.qs_done, 0);
	cmm_smp_mb();

	/*
	 * Kill with LTTNG_SESSIOND_SIG_QS, so signal management thread
	 * wakes up.
	 */
	kill(getpid(), LTTNG_SESSIOND_SIG_QS);

	while (!CMM_LOAD_SHARED(timer_signal.qs_done)) {
		caa_cpu_relax();
	}
	cmm_smp_mb();

	pthread_mutex_unlock(&timer_signal.lock);
}

/*
 * Start a timer on a session that will fire at a given interval
 * (timer_interval_us) and fire a given signal (signal).
 *
 * Returns a negative value on error, 0 if a timer was created, and
 * a positive value if no timer was created (not an error).
 */
static
int timer_start(timer_t *timer_id, struct ltt_session *session,
		unsigned int timer_interval_us, int signal, bool one_shot)
{
	int ret = 0, delete_ret;
	struct sigevent sev;
	struct itimerspec its;

	sev.sigev_notify = SIGEV_SIGNAL;
	sev.sigev_signo = signal;
	sev.sigev_value.sival_ptr = session;
	ret = timer_create(CLOCK_MONOTONIC, &sev, timer_id);
	if (ret == -1) {
		PERROR("timer_create");
		goto end;
	}

	its.it_value.tv_sec = timer_interval_us / 1000000;
	its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000;
	if (one_shot) {
		its.it_interval.tv_sec = 0;
		its.it_interval.tv_nsec = 0;
	} else {
		its.it_interval.tv_sec = its.it_value.tv_sec;
		its.it_interval.tv_nsec = its.it_value.tv_nsec;
	}

	ret = timer_settime(*timer_id, 0, &its, NULL);
	if (ret == -1) {
		PERROR("timer_settime");
		goto error_destroy_timer;
	}
	goto end;

error_destroy_timer:
	delete_ret = timer_delete(*timer_id);
	if (delete_ret == -1) {
		PERROR("timer_delete");
	}

end:
	return ret;
}

static
int timer_stop(timer_t *timer_id, int signal)
{
	int ret = 0;

	ret = timer_delete(*timer_id);
	if (ret == -1) {
		PERROR("timer_delete");
		goto end;
	}

	timer_signal_thread_qs(signal);
	*timer_id = 0;
end:
	return ret;
}

int timer_session_rotation_pending_check_start(struct ltt_session *session,
		unsigned int interval_us)
{
	int ret;

	if (!session_get(session)) {
		ret = -1;
		goto end;
	}
	DBG("Enabling session rotation pending check timer on session %" PRIu64,
			session->id);
	/*
	 * We arm this timer in a one-shot mode so we don't have to disable it
	 * explicitly (which could deadlock if the timer thread is blocked
	 * writing in the rotation_timer_pipe).
	 *
	 * Instead, we re-arm it if needed after the rotation_pending check as
	 * returned. Also, this timer is usually only needed once, so there is
	 * no need to go through the whole signal teardown scheme everytime.
	 */
	ret = timer_start(&session->rotation_pending_check_timer,
			session, interval_us,
			LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK,
			/* one-shot */ true);
	if (ret == 0) {
		session->rotation_pending_check_timer_enabled = true;
	}
end:
	return ret;
}

/*
 * Call with session and session_list locks held.
 */
int timer_session_rotation_pending_check_stop(struct ltt_session *session)
{
	int ret;

	assert(session);
	assert(session->rotation_pending_check_timer_enabled);

	DBG("Disabling session rotation pending check timer on session %" PRIu64,
			session->id);
	ret = timer_stop(&session->rotation_pending_check_timer,
			LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK);
	if (ret == -1) {
		ERR("Failed to stop rotate_pending_check timer");
	} else {
		session->rotation_pending_check_timer_enabled = false;
		/*
		 * The timer's reference to the session can be released safely.
		 */
		session_put(session);
	}
	return ret;
}

/*
 * Call with session and session_list locks held.
 */
int timer_session_rotation_schedule_timer_start(struct ltt_session *session,
		unsigned int interval_us)
{
	int ret;

	if (!session_get(session)) {
		ret = -1;
		goto end;
	}
	DBG("Enabling scheduled rotation timer on session \"%s\" (%ui %s)", session->name,
			interval_us, USEC_UNIT);
	ret = timer_start(&session->rotation_schedule_timer, session,
			interval_us, LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION,
			/* one-shot */ false);
	if (ret < 0) {
		goto end;
	}
	session->rotation_schedule_timer_enabled = true;
end:
	return ret;
}

/*
 * Call with session and session_list locks held.
 */
int timer_session_rotation_schedule_timer_stop(struct ltt_session *session)
{
	int ret = 0;

	assert(session);

	if (!session->rotation_schedule_timer_enabled) {
		goto end;
	}

	DBG("Disabling scheduled rotation timer on session %s", session->name);
	ret = timer_stop(&session->rotation_schedule_timer,
			LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION);
	if (ret < 0) {
		ERR("Failed to stop scheduled rotation timer of session \"%s\"",
				session->name);
		goto end;
	}

	session->rotation_schedule_timer_enabled = false;
	/* The timer's reference to the session can be released safely. */
	session_put(session);
	ret = 0;
end:
	return ret;
}

/*
 * Block the RT signals for the entire process. It must be called from the
 * sessiond main before creating the threads
 */
int timer_signal_init(void)
{
	int ret;
	sigset_t mask;

	/* Block signal for entire process, so only our thread processes it. */
	setmask(&mask);
	ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
	if (ret) {
		errno = ret;
		PERROR("pthread_sigmask");
		return -1;
	}
	return 0;
}

/*
 * This thread is the sighandler for the timer signals.
 */
static
void *thread_timer(void *data)
{
	int signr;
	sigset_t mask;
	siginfo_t info;
	struct timer_thread_parameters *ctx = data;

	rcu_register_thread();
	rcu_thread_online();

	health_register(health_sessiond, HEALTH_SESSIOND_TYPE_TIMER);
	health_code_update();

	/* Only self thread will receive signal mask. */
	setmask(&mask);
	CMM_STORE_SHARED(timer_signal.tid, pthread_self());

	while (1) {
		health_code_update();

		health_poll_entry();
		signr = sigwaitinfo(&mask, &info);
		health_poll_exit();

		/*
		 * NOTE: cascading conditions are used instead of a switch case
		 * since the use of SIGRTMIN in the definition of the signals'
		 * values prevents the reduction to an integer constant.
		 */
		if (signr == -1) {
			if (errno != EINTR) {
				PERROR("sigwaitinfo");
			}
			continue;
		} else if (signr == LTTNG_SESSIOND_SIG_QS) {
			cmm_smp_mb();
			CMM_STORE_SHARED(timer_signal.qs_done, 1);
			cmm_smp_mb();
		} else if (signr == LTTNG_SESSIOND_SIG_EXIT) {
			goto end;
		} else if (signr == LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK) {
			struct ltt_session *session =
					(struct ltt_session *) info.si_value.sival_ptr;

			rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
					ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION,
					session);
		} else if (signr == LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION) {
			rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
					ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION,
					(struct ltt_session *) info.si_value.sival_ptr);
			/*
			 * The scheduled periodic rotation timer is not in
			 * "one-shot" mode. The reference to the session is not
			 * released since the timer is still enabled and can
			 * still fire.
			 */
		} else {
			ERR("Unexpected signal %d\n", info.si_signo);
		}
	}

end:
	DBG("[timer-thread] Exit");
	health_unregister(health_sessiond);
	rcu_thread_offline();
	rcu_unregister_thread();
	return NULL;
}

static
bool shutdown_timer_thread(void *data)
{
	return kill(getpid(), LTTNG_SESSIOND_SIG_EXIT) == 0;
}

bool launch_timer_thread(
		struct timer_thread_parameters *timer_thread_parameters)
{
	struct lttng_thread *thread;

	thread = lttng_thread_create("Timer",
			thread_timer,
			shutdown_timer_thread,
			NULL,
			timer_thread_parameters);
	if (!thread) {
		goto error;
	}
	lttng_thread_put(thread);
	return true;
error:
	return false;
}
Commit	Line	Data
d086f507	1	/*
ab5be9fa MJ	2	* Copyright (C) 2017 Julien Desfossez <jdesfossez@efficios.com>
ab5be9fa MJ	3	* Copyright (C) 2018 Jérémie Galarneau <jeremie.galarneau@efficios.com>
d086f507	4	*
ab5be9fa	5	* SPDX-License-Identifier: GPL-2.0-only
d086f507	6	*
d086f507 JD	7	*/
	8
	9	#define _LGPL_SOURCE
	10	#include <assert.h>
	11	#include <inttypes.h>
	12	#include <signal.h>
	13
8e319828	14	#include "timer.h"
d086f507 JD	15	#include "health-sessiond.h"
d086f507 JD	16	#include "rotation-thread.h"
bc26e826	17	#include "thread.h"
d086f507	18
92816cc3 JG	19	#define LTTNG_SESSIOND_SIG_QS SIGRTMIN + 10
	20	#define LTTNG_SESSIOND_SIG_EXIT SIGRTMIN + 11
	21	#define LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK SIGRTMIN + 12
	22	#define LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION SIGRTMIN + 13
	23
	24	#define UINT_TO_PTR(value) \
	25	({ \
	26	assert(value <= UINTPTR_MAX); \
	27	(void *) (uintptr_t) value; \
	28	})
	29	#define PTR_TO_UINT(ptr) ((uintptr_t) ptr)
	30
	31	/*
	32	* Handle timer teardown race wrt memory free of private data by sessiond
	33	* signals are handled by a single thread, which permits a synchronization
	34	* point between handling of each signal. Internal lock ensures mutual
	35	* exclusion.
	36	*/
d086f507	37	static
92816cc3 JG	38	struct timer_signal_data {
	39	/* Thread managing signals. */
	40	pthread_t tid;
	41	int qs_done;
	42	pthread_mutex_t lock;
	43	} timer_signal = {
d086f507 JD	44	.tid = 0,
	45	.qs_done = 0,
	46	.lock = PTHREAD_MUTEX_INITIALIZER,
	47	};
	48
	49	/*
	50	* Set custom signal mask to current thread.
	51	*/
	52	static
	53	void setmask(sigset_t *mask)
	54	{
	55	int ret;
	56
	57	ret = sigemptyset(mask);
	58	if (ret) {
	59	PERROR("sigemptyset");
	60	}
92816cc3	61	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_QS);
d086f507 JD	62	if (ret) {
	63	PERROR("sigaddset teardown");
	64	}
	65	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_EXIT);
	66	if (ret) {
	67	PERROR("sigaddset exit");
	68	}
92816cc3	69	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK);
d88744a4	70	if (ret) {
92816cc3	71	PERROR("sigaddset pending rotation check");
d88744a4	72	}
92816cc3	73	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION);
259c2674	74	if (ret) {
92816cc3	75	PERROR("sigaddset scheduled rotation");
259c2674	76	}
d086f507 JD	77	}
	78
	79	/*
92816cc3	80	* This is the same function as timer_signal_thread_qs, when it
d086f507 JD	81	* returns, it means that no timer signr is currently pending or being handled
	82	* by the timer thread. This cannot be called from the timer thread.
	83	*/
	84	static
92816cc3	85	void timer_signal_thread_qs(unsigned int signr)
d086f507 JD	86	{
	87	sigset_t pending_set;
	88	int ret;
	89
	90	/*
	91	* We need to be the only thread interacting with the thread
	92	* that manages signals for teardown synchronization.
	93	*/
	94	pthread_mutex_lock(&timer_signal.lock);
	95
	96	/* Ensure we don't have any signal queued for this session. */
	97	for (;;) {
	98	ret = sigemptyset(&pending_set);
	99	if (ret == -1) {
	100	PERROR("sigemptyset");
	101	}
	102	ret = sigpending(&pending_set);
	103	if (ret == -1) {
	104	PERROR("sigpending");
	105	}
	106	if (!sigismember(&pending_set, signr)) {
	107	break;
	108	}
	109	caa_cpu_relax();
	110	}
	111
	112	/*
	113	* From this point, no new signal handler will be fired that would try to
	114	* access "session". However, we still need to wait for any currently
	115	* executing handler to complete.
	116	*/
	117	cmm_smp_mb();
	118	CMM_STORE_SHARED(timer_signal.qs_done, 0);
	119	cmm_smp_mb();
	120
	121	/*
92816cc3	122	* Kill with LTTNG_SESSIOND_SIG_QS, so signal management thread
d086f507 JD	123	* wakes up.
d086f507 JD	124	*/
92816cc3	125	kill(getpid(), LTTNG_SESSIOND_SIG_QS);
d086f507 JD	126
	127	while (!CMM_LOAD_SHARED(timer_signal.qs_done)) {
	128	caa_cpu_relax();
	129	}
	130	cmm_smp_mb();
	131
	132	pthread_mutex_unlock(&timer_signal.lock);
	133	}
	134
	135	/*
	136	* Start a timer on a session that will fire at a given interval
	137	* (timer_interval_us) and fire a given signal (signal).
	138	*
	139	* Returns a negative value on error, 0 if a timer was created, and
	140	* a positive value if no timer was created (not an error).
	141	*/
	142	static
c7031a2c	143	int timer_start(timer_t timer_id, struct ltt_session session,
d086f507 JD	144	unsigned int timer_interval_us, int signal, bool one_shot)
	145	{
	146	int ret = 0, delete_ret;
	147	struct sigevent sev;
	148	struct itimerspec its;
	149
d086f507 JD	150	sev.sigev_notify = SIGEV_SIGNAL;
d086f507 JD	151	sev.sigev_signo = signal;
c7031a2c	152	sev.sigev_value.sival_ptr = session;
92816cc3	153	ret = timer_create(CLOCK_MONOTONIC, &sev, timer_id);
d086f507 JD	154	if (ret == -1) {
	155	PERROR("timer_create");
	156	goto end;
	157	}
	158
	159	its.it_value.tv_sec = timer_interval_us / 1000000;
	160	its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000;
	161	if (one_shot) {
	162	its.it_interval.tv_sec = 0;
	163	its.it_interval.tv_nsec = 0;
	164	} else {
	165	its.it_interval.tv_sec = its.it_value.tv_sec;
	166	its.it_interval.tv_nsec = its.it_value.tv_nsec;
	167	}
	168
	169	ret = timer_settime(*timer_id, 0, &its, NULL);
	170	if (ret == -1) {
	171	PERROR("timer_settime");
	172	goto error_destroy_timer;
	173	}
	174	goto end;
	175
	176	error_destroy_timer:
	177	delete_ret = timer_delete(*timer_id);
	178	if (delete_ret == -1) {
	179	PERROR("timer_delete");
	180	}
	181
	182	end:
	183	return ret;
	184	}
	185
	186	static
92816cc3	187	int timer_stop(timer_t *timer_id, int signal)
d086f507 JD	188	{
	189	int ret = 0;
	190
	191	ret = timer_delete(*timer_id);
	192	if (ret == -1) {
	193	PERROR("timer_delete");
	194	goto end;
	195	}
	196
92816cc3	197	timer_signal_thread_qs(signal);
d086f507 JD	198	*timer_id = 0;
	199	end:
	200	return ret;
	201	}
	202
92816cc3	203	int timer_session_rotation_pending_check_start(struct ltt_session *session,
d88744a4 JD	204	unsigned int interval_us)
	205	{
	206	int ret;
	207
c7031a2c JG	208	if (!session_get(session)) {
	209	ret = -1;
	210	goto end;
	211	}
92816cc3 JG	212	DBG("Enabling session rotation pending check timer on session %" PRIu64,
92816cc3 JG	213	session->id);
d88744a4 JD	214	/*
d88744a4 JD	215	* We arm this timer in a one-shot mode so we don't have to disable it
92816cc3 JG	216	* explicitly (which could deadlock if the timer thread is blocked
	217	* writing in the rotation_timer_pipe).
	218	*
d88744a4	219	* Instead, we re-arm it if needed after the rotation_pending check as
92816cc3 JG	220	* returned. Also, this timer is usually only needed once, so there is
92816cc3 JG	221	* no need to go through the whole signal teardown scheme everytime.
d88744a4	222	*/
92816cc3	223	ret = timer_start(&session->rotation_pending_check_timer,
c7031a2c	224	session, interval_us,
92816cc3	225	LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK,
d88744a4 JD	226	/* one-shot */ true);
d88744a4 JD	227	if (ret == 0) {
92816cc3	228	session->rotation_pending_check_timer_enabled = true;
d88744a4	229	}
c7031a2c	230	end:
d88744a4 JD	231	return ret;
	232	}
	233
	234	/*
92816cc3	235	* Call with session and session_list locks held.
d88744a4	236	*/
92816cc3	237	int timer_session_rotation_pending_check_stop(struct ltt_session *session)
d88744a4 JD	238	{
	239	int ret;
	240
	241	assert(session);
3cf0ebee	242	assert(session->rotation_pending_check_timer_enabled);
d88744a4	243
92816cc3 JG	244	DBG("Disabling session rotation pending check timer on session %" PRIu64,
	245	session->id);
	246	ret = timer_stop(&session->rotation_pending_check_timer,
	247	LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK);
d88744a4	248	if (ret == -1) {
92816cc3	249	ERR("Failed to stop rotate_pending_check timer");
259c2674	250	} else {
92816cc3	251	session->rotation_pending_check_timer_enabled = false;
c7031a2c JG	252	/*
	253	* The timer's reference to the session can be released safely.
	254	*/
	255	session_put(session);
259c2674 JD	256	}
	257	return ret;
	258	}
	259
92816cc3 JG	260	/*
	261	* Call with session and session_list locks held.
	262	*/
	263	int timer_session_rotation_schedule_timer_start(struct ltt_session *session,
259c2674 JD	264	unsigned int interval_us)
	265	{
	266	int ret;
	267
c7031a2c JG	268	if (!session_get(session)) {
	269	ret = -1;
	270	goto end;
	271	}
2a1135fa JG	272	DBG("Enabling scheduled rotation timer on session \"%s\" (%ui %s)", session->name,
2a1135fa JG	273	interval_us, USEC_UNIT);
c7031a2c	274	ret = timer_start(&session->rotation_schedule_timer, session,
92816cc3 JG	275	interval_us, LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION,
92816cc3 JG	276	/* one-shot */ false);
259c2674 JD	277	if (ret < 0) {
	278	goto end;
	279	}
92816cc3	280	session->rotation_schedule_timer_enabled = true;
259c2674 JD	281	end:
	282	return ret;
	283	}
	284
	285	/*
92816cc3	286	* Call with session and session_list locks held.
259c2674	287	*/
92816cc3	288	int timer_session_rotation_schedule_timer_stop(struct ltt_session *session)
259c2674 JD	289	{
	290	int ret = 0;
	291
	292	assert(session);
	293
92816cc3	294	if (!session->rotation_schedule_timer_enabled) {
259c2674 JD	295	goto end;
	296	}
	297
92816cc3 JG	298	DBG("Disabling scheduled rotation timer on session %s", session->name);
	299	ret = timer_stop(&session->rotation_schedule_timer,
	300	LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION);
259c2674	301	if (ret < 0) {
92816cc3	302	ERR("Failed to stop scheduled rotation timer of session \"%s\"",
259c2674 JD	303	session->name);
259c2674 JD	304	goto end;
d88744a4 JD	305	}
d88744a4 JD	306
92816cc3	307	session->rotation_schedule_timer_enabled = false;
c7031a2c JG	308	/* The timer's reference to the session can be released safely. */
c7031a2c JG	309	session_put(session);
259c2674 JD	310	ret = 0;
	311	end:
	312	return ret;
d88744a4 JD	313	}
d88744a4 JD	314
d086f507 JD	315	/*
	316	* Block the RT signals for the entire process. It must be called from the
	317	* sessiond main before creating the threads
	318	*/
92816cc3	319	int timer_signal_init(void)
d086f507 JD	320	{
	321	int ret;
	322	sigset_t mask;
	323
	324	/* Block signal for entire process, so only our thread processes it. */
	325	setmask(&mask);
	326	ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
	327	if (ret) {
	328	errno = ret;
	329	PERROR("pthread_sigmask");
	330	return -1;
	331	}
	332	return 0;
	333	}
	334
	335	/*
	336	* This thread is the sighandler for the timer signals.
	337	*/
bc26e826 JG	338	static
bc26e826 JG	339	void thread_timer(void data)
d086f507 JD	340	{
	341	int signr;
	342	sigset_t mask;
	343	siginfo_t info;
	344	struct timer_thread_parameters *ctx = data;
	345
	346	rcu_register_thread();
	347	rcu_thread_online();
	348
	349	health_register(health_sessiond, HEALTH_SESSIOND_TYPE_TIMER);
d086f507 JD	350	health_code_update();
	351
	352	/* Only self thread will receive signal mask. */
	353	setmask(&mask);
	354	CMM_STORE_SHARED(timer_signal.tid, pthread_self());
	355
	356	while (1) {
	357	health_code_update();
	358
	359	health_poll_entry();
	360	signr = sigwaitinfo(&mask, &info);
	361	health_poll_exit();
	362
	363	/*
	364	* NOTE: cascading conditions are used instead of a switch case
	365	* since the use of SIGRTMIN in the definition of the signals'
	366	* values prevents the reduction to an integer constant.
	367	*/
	368	if (signr == -1) {
	369	if (errno != EINTR) {
	370	PERROR("sigwaitinfo");
	371	}
	372	continue;
92816cc3	373	} else if (signr == LTTNG_SESSIOND_SIG_QS) {
d086f507 JD	374	cmm_smp_mb();
	375	CMM_STORE_SHARED(timer_signal.qs_done, 1);
	376	cmm_smp_mb();
d086f507 JD	377	} else if (signr == LTTNG_SESSIOND_SIG_EXIT) {
d086f507 JD	378	goto end;
92816cc3	379	} else if (signr == LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK) {
c7031a2c JG	380	struct ltt_session *session =
	381	(struct ltt_session *) info.si_value.sival_ptr;
	382
92816cc3 JG	383	rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
92816cc3 JG	384	ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION,
c7031a2c	385	session);
92816cc3 JG	386	} else if (signr == LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION) {
	387	rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
	388	ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION,
c7031a2c JG	389	(struct ltt_session *) info.si_value.sival_ptr);
	390	/*
	391	* The scheduled periodic rotation timer is not in
	392	* "one-shot" mode. The reference to the session is not
	393	* released since the timer is still enabled and can
	394	* still fire.
	395	*/
d086f507 JD	396	} else {
	397	ERR("Unexpected signal %d\n", info.si_signo);
	398	}
	399	}
	400
	401	end:
	402	DBG("[timer-thread] Exit");
	403	health_unregister(health_sessiond);
	404	rcu_thread_offline();
	405	rcu_unregister_thread();
	406	return NULL;
	407	}
92816cc3	408
bc26e826 JG	409	static
	410	bool shutdown_timer_thread(void *data)
	411	{
	412	return kill(getpid(), LTTNG_SESSIOND_SIG_EXIT) == 0;
	413	}
	414
	415	bool launch_timer_thread(
	416	struct timer_thread_parameters *timer_thread_parameters)
92816cc3	417	{
bc26e826 JG	418	struct lttng_thread *thread;
	419
	420	thread = lttng_thread_create("Timer",
	421	thread_timer,
	422	shutdown_timer_thread,
	423	NULL,
	424	timer_thread_parameters);
	425	if (!thread) {
	426	goto error;
	427	}
	428	lttng_thread_put(thread);
	429	return true;
	430	error:
	431	return false;
92816cc3	432	}