+++ /dev/null
-/*
- * 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 = 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;
-}
projects / lttng-tools.git / blobdiff