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

/*
 * 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 <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)				\
	({						\
		LTTNG_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;

	LTTNG_ASSERT(session);
	LTTNG_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;

	LTTNG_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 = (timer_thread_parameters *) data;

	rcu_register_thread();
	rcu_thread_online();

	health_register(the_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", info.si_signo);
		}
	}

end:
	DBG("Thread exit");
	health_unregister(the_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
d086f507 JD	10	#include <inttypes.h>
	11	#include <signal.h>
	12
8e319828	13	#include "timer.h"
d086f507 JD	14	#include "health-sessiond.h"
d086f507 JD	15	#include "rotation-thread.h"
bc26e826	16	#include "thread.h"
d086f507	17
92816cc3 JG	18	#define LTTNG_SESSIOND_SIG_QS SIGRTMIN + 10
	19	#define LTTNG_SESSIOND_SIG_EXIT SIGRTMIN + 11
	20	#define LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK SIGRTMIN + 12
	21	#define LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION SIGRTMIN + 13
	22
	23	#define UINT_TO_PTR(value) \
	24	({ \
a0377dfe	25	LTTNG_ASSERT(value <= UINTPTR_MAX); \
92816cc3 JG	26	(void *) (uintptr_t) value; \
	27	})
	28	#define PTR_TO_UINT(ptr) ((uintptr_t) ptr)
	29
	30	/*
	31	* Handle timer teardown race wrt memory free of private data by sessiond
	32	* signals are handled by a single thread, which permits a synchronization
	33	* point between handling of each signal. Internal lock ensures mutual
	34	* exclusion.
	35	*/
d086f507	36	static
92816cc3 JG	37	struct timer_signal_data {
	38	/* Thread managing signals. */
	39	pthread_t tid;
	40	int qs_done;
	41	pthread_mutex_t lock;
	42	} timer_signal = {
d086f507 JD	43	.tid = 0,
	44	.qs_done = 0,
	45	.lock = PTHREAD_MUTEX_INITIALIZER,
	46	};
	47
	48	/*
	49	* Set custom signal mask to current thread.
	50	*/
	51	static
	52	void setmask(sigset_t *mask)
	53	{
	54	int ret;
	55
	56	ret = sigemptyset(mask);
	57	if (ret) {
	58	PERROR("sigemptyset");
	59	}
92816cc3	60	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_QS);
d086f507 JD	61	if (ret) {
	62	PERROR("sigaddset teardown");
	63	}
	64	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_EXIT);
	65	if (ret) {
	66	PERROR("sigaddset exit");
	67	}
92816cc3	68	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK);
d88744a4	69	if (ret) {
92816cc3	70	PERROR("sigaddset pending rotation check");
d88744a4	71	}
92816cc3	72	ret = sigaddset(mask, LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION);
259c2674	73	if (ret) {
92816cc3	74	PERROR("sigaddset scheduled rotation");
259c2674	75	}
d086f507 JD	76	}
	77
	78	/*
92816cc3	79	* This is the same function as timer_signal_thread_qs, when it
d086f507 JD	80	* returns, it means that no timer signr is currently pending or being handled
	81	* by the timer thread. This cannot be called from the timer thread.
	82	*/
	83	static
92816cc3	84	void timer_signal_thread_qs(unsigned int signr)
d086f507 JD	85	{
	86	sigset_t pending_set;
	87	int ret;
	88
	89	/*
	90	* We need to be the only thread interacting with the thread
	91	* that manages signals for teardown synchronization.
	92	*/
	93	pthread_mutex_lock(&timer_signal.lock);
	94
	95	/* Ensure we don't have any signal queued for this session. */
	96	for (;;) {
	97	ret = sigemptyset(&pending_set);
	98	if (ret == -1) {
	99	PERROR("sigemptyset");
	100	}
	101	ret = sigpending(&pending_set);
	102	if (ret == -1) {
	103	PERROR("sigpending");
	104	}
	105	if (!sigismember(&pending_set, signr)) {
	106	break;
	107	}
	108	caa_cpu_relax();
	109	}
	110
	111	/*
	112	* From this point, no new signal handler will be fired that would try to
	113	* access "session". However, we still need to wait for any currently
	114	* executing handler to complete.
	115	*/
	116	cmm_smp_mb();
	117	CMM_STORE_SHARED(timer_signal.qs_done, 0);
	118	cmm_smp_mb();
	119
	120	/*
92816cc3	121	* Kill with LTTNG_SESSIOND_SIG_QS, so signal management thread
d086f507 JD	122	* wakes up.
d086f507 JD	123	*/
92816cc3	124	kill(getpid(), LTTNG_SESSIOND_SIG_QS);
d086f507 JD	125
	126	while (!CMM_LOAD_SHARED(timer_signal.qs_done)) {
	127	caa_cpu_relax();
	128	}
	129	cmm_smp_mb();
	130
	131	pthread_mutex_unlock(&timer_signal.lock);
	132	}
	133
	134	/*
	135	* Start a timer on a session that will fire at a given interval
	136	* (timer_interval_us) and fire a given signal (signal).
	137	*
	138	* Returns a negative value on error, 0 if a timer was created, and
	139	* a positive value if no timer was created (not an error).
	140	*/
	141	static
c7031a2c	142	int timer_start(timer_t timer_id, struct ltt_session session,
d086f507 JD	143	unsigned int timer_interval_us, int signal, bool one_shot)
	144	{
	145	int ret = 0, delete_ret;
f79ead11	146	struct sigevent sev = {};
d086f507 JD	147	struct itimerspec its;
d086f507 JD	148
d086f507 JD	149	sev.sigev_notify = SIGEV_SIGNAL;
d086f507 JD	150	sev.sigev_signo = signal;
c7031a2c	151	sev.sigev_value.sival_ptr = session;
92816cc3	152	ret = timer_create(CLOCK_MONOTONIC, &sev, timer_id);
d086f507 JD	153	if (ret == -1) {
	154	PERROR("timer_create");
	155	goto end;
	156	}
	157
	158	its.it_value.tv_sec = timer_interval_us / 1000000;
	159	its.it_value.tv_nsec = (timer_interval_us % 1000000) * 1000;
	160	if (one_shot) {
	161	its.it_interval.tv_sec = 0;
	162	its.it_interval.tv_nsec = 0;
	163	} else {
	164	its.it_interval.tv_sec = its.it_value.tv_sec;
	165	its.it_interval.tv_nsec = its.it_value.tv_nsec;
	166	}
	167
	168	ret = timer_settime(*timer_id, 0, &its, NULL);
	169	if (ret == -1) {
	170	PERROR("timer_settime");
	171	goto error_destroy_timer;
	172	}
	173	goto end;
	174
	175	error_destroy_timer:
	176	delete_ret = timer_delete(*timer_id);
	177	if (delete_ret == -1) {
	178	PERROR("timer_delete");
	179	}
	180
	181	end:
	182	return ret;
	183	}
	184
	185	static
92816cc3	186	int timer_stop(timer_t *timer_id, int signal)
d086f507 JD	187	{
	188	int ret = 0;
	189
	190	ret = timer_delete(*timer_id);
	191	if (ret == -1) {
	192	PERROR("timer_delete");
	193	goto end;
	194	}
	195
92816cc3	196	timer_signal_thread_qs(signal);
d086f507 JD	197	*timer_id = 0;
	198	end:
	199	return ret;
	200	}
	201
92816cc3	202	int timer_session_rotation_pending_check_start(struct ltt_session *session,
d88744a4 JD	203	unsigned int interval_us)
	204	{
	205	int ret;
	206
c7031a2c JG	207	if (!session_get(session)) {
	208	ret = -1;
	209	goto end;
	210	}
92816cc3 JG	211	DBG("Enabling session rotation pending check timer on session %" PRIu64,
92816cc3 JG	212	session->id);
d88744a4 JD	213	/*
d88744a4 JD	214	* We arm this timer in a one-shot mode so we don't have to disable it
92816cc3 JG	215	* explicitly (which could deadlock if the timer thread is blocked
	216	* writing in the rotation_timer_pipe).
	217	*
d88744a4	218	* Instead, we re-arm it if needed after the rotation_pending check as
92816cc3 JG	219	* returned. Also, this timer is usually only needed once, so there is
92816cc3 JG	220	* no need to go through the whole signal teardown scheme everytime.
d88744a4	221	*/
92816cc3	222	ret = timer_start(&session->rotation_pending_check_timer,
c7031a2c	223	session, interval_us,
92816cc3	224	LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK,
d88744a4 JD	225	/* one-shot */ true);
d88744a4 JD	226	if (ret == 0) {
92816cc3	227	session->rotation_pending_check_timer_enabled = true;
d88744a4	228	}
c7031a2c	229	end:
d88744a4 JD	230	return ret;
	231	}
	232
	233	/*
92816cc3	234	* Call with session and session_list locks held.
d88744a4	235	*/
92816cc3	236	int timer_session_rotation_pending_check_stop(struct ltt_session *session)
d88744a4 JD	237	{
	238	int ret;
	239
a0377dfe FD	240	LTTNG_ASSERT(session);
a0377dfe FD	241	LTTNG_ASSERT(session->rotation_pending_check_timer_enabled);
d88744a4	242
92816cc3 JG	243	DBG("Disabling session rotation pending check timer on session %" PRIu64,
	244	session->id);
	245	ret = timer_stop(&session->rotation_pending_check_timer,
	246	LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK);
d88744a4	247	if (ret == -1) {
92816cc3	248	ERR("Failed to stop rotate_pending_check timer");
259c2674	249	} else {
92816cc3	250	session->rotation_pending_check_timer_enabled = false;
c7031a2c JG	251	/*
	252	* The timer's reference to the session can be released safely.
	253	*/
	254	session_put(session);
259c2674 JD	255	}
	256	return ret;
	257	}
	258
92816cc3 JG	259	/*
	260	* Call with session and session_list locks held.
	261	*/
	262	int timer_session_rotation_schedule_timer_start(struct ltt_session *session,
259c2674 JD	263	unsigned int interval_us)
	264	{
	265	int ret;
	266
c7031a2c JG	267	if (!session_get(session)) {
	268	ret = -1;
	269	goto end;
	270	}
2a1135fa JG	271	DBG("Enabling scheduled rotation timer on session \"%s\" (%ui %s)", session->name,
2a1135fa JG	272	interval_us, USEC_UNIT);
c7031a2c	273	ret = timer_start(&session->rotation_schedule_timer, session,
92816cc3 JG	274	interval_us, LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION,
92816cc3 JG	275	/* one-shot */ false);
259c2674 JD	276	if (ret < 0) {
	277	goto end;
	278	}
92816cc3	279	session->rotation_schedule_timer_enabled = true;
259c2674 JD	280	end:
	281	return ret;
	282	}
	283
	284	/*
92816cc3	285	* Call with session and session_list locks held.
259c2674	286	*/
92816cc3	287	int timer_session_rotation_schedule_timer_stop(struct ltt_session *session)
259c2674 JD	288	{
	289	int ret = 0;
	290
a0377dfe	291	LTTNG_ASSERT(session);
259c2674	292
92816cc3	293	if (!session->rotation_schedule_timer_enabled) {
259c2674 JD	294	goto end;
	295	}
	296
92816cc3 JG	297	DBG("Disabling scheduled rotation timer on session %s", session->name);
	298	ret = timer_stop(&session->rotation_schedule_timer,
	299	LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION);
259c2674	300	if (ret < 0) {
92816cc3	301	ERR("Failed to stop scheduled rotation timer of session \"%s\"",
259c2674 JD	302	session->name);
259c2674 JD	303	goto end;
d88744a4 JD	304	}
d88744a4 JD	305
92816cc3	306	session->rotation_schedule_timer_enabled = false;
c7031a2c JG	307	/* The timer's reference to the session can be released safely. */
c7031a2c JG	308	session_put(session);
259c2674 JD	309	ret = 0;
	310	end:
	311	return ret;
d88744a4 JD	312	}
d88744a4 JD	313
d086f507 JD	314	/*
	315	* Block the RT signals for the entire process. It must be called from the
	316	* sessiond main before creating the threads
	317	*/
92816cc3	318	int timer_signal_init(void)
d086f507 JD	319	{
	320	int ret;
	321	sigset_t mask;
	322
	323	/* Block signal for entire process, so only our thread processes it. */
	324	setmask(&mask);
	325	ret = pthread_sigmask(SIG_BLOCK, &mask, NULL);
	326	if (ret) {
	327	errno = ret;
	328	PERROR("pthread_sigmask");
	329	return -1;
	330	}
	331	return 0;
	332	}
	333
	334	/*
	335	* This thread is the sighandler for the timer signals.
	336	*/
bc26e826 JG	337	static
bc26e826 JG	338	void thread_timer(void data)
d086f507 JD	339	{
	340	int signr;
	341	sigset_t mask;
	342	siginfo_t info;
7966af57	343	struct timer_thread_parameters ctx = (timer_thread_parameters ) data;
d086f507 JD	344
	345	rcu_register_thread();
	346	rcu_thread_online();
	347
412d7227	348	health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_TIMER);
d086f507 JD	349	health_code_update();
	350
	351	/* Only self thread will receive signal mask. */
	352	setmask(&mask);
	353	CMM_STORE_SHARED(timer_signal.tid, pthread_self());
	354
	355	while (1) {
	356	health_code_update();
	357
	358	health_poll_entry();
	359	signr = sigwaitinfo(&mask, &info);
	360	health_poll_exit();
	361
	362	/*
	363	* NOTE: cascading conditions are used instead of a switch case
	364	* since the use of SIGRTMIN in the definition of the signals'
	365	* values prevents the reduction to an integer constant.
	366	*/
	367	if (signr == -1) {
	368	if (errno != EINTR) {
	369	PERROR("sigwaitinfo");
	370	}
	371	continue;
92816cc3	372	} else if (signr == LTTNG_SESSIOND_SIG_QS) {
d086f507 JD	373	cmm_smp_mb();
	374	CMM_STORE_SHARED(timer_signal.qs_done, 1);
	375	cmm_smp_mb();
d086f507 JD	376	} else if (signr == LTTNG_SESSIOND_SIG_EXIT) {
d086f507 JD	377	goto end;
92816cc3	378	} else if (signr == LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK) {
c7031a2c JG	379	struct ltt_session *session =
	380	(struct ltt_session *) info.si_value.sival_ptr;
	381
92816cc3 JG	382	rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
92816cc3 JG	383	ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION,
c7031a2c	384	session);
92816cc3 JG	385	} else if (signr == LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION) {
	386	rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
	387	ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION,
c7031a2c JG	388	(struct ltt_session *) info.si_value.sival_ptr);
	389	/*
	390	* The scheduled periodic rotation timer is not in
	391	* "one-shot" mode. The reference to the session is not
	392	* released since the timer is still enabled and can
	393	* still fire.
	394	*/
d086f507	395	} else {
bd0514a5	396	ERR("Unexpected signal %d", info.si_signo);
d086f507 JD	397	}
	398	}
	399
	400	end:
bd0514a5	401	DBG("Thread exit");
412d7227	402	health_unregister(the_health_sessiond);
d086f507 JD	403	rcu_thread_offline();
	404	rcu_unregister_thread();
	405	return NULL;
	406	}
92816cc3	407
bc26e826 JG	408	static
	409	bool shutdown_timer_thread(void *data)
	410	{
	411	return kill(getpid(), LTTNG_SESSIOND_SIG_EXIT) == 0;
	412	}
	413
	414	bool launch_timer_thread(
	415	struct timer_thread_parameters *timer_thread_parameters)
92816cc3	416	{
bc26e826 JG	417	struct lttng_thread *thread;
	418
	419	thread = lttng_thread_create("Timer",
	420	thread_timer,
	421	shutdown_timer_thread,
	422	NULL,
	423	timer_thread_parameters);
	424	if (!thread) {
	425	goto error;
	426	}
	427	lttng_thread_put(thread);
	428	return true;
	429	error:
	430	return false;
92816cc3	431	}