--- /dev/null
+/*
+ * Copyright (C) 2017 - Julien Desfossez <jdesfossez@efficios.com>
+ * Copyright (C) 2018 - 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 <assert.h>
+#include <inttypes.h>
+#include <signal.h>
+
+#include "timer.h"
+#include "health-sessiond.h"
+#include "rotation-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, uint64_t session_id,
+ 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 = UINT_TO_PTR(session_id);
+ 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;
+
+ 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->id, interval_us,
+ LTTNG_SESSIOND_SIG_PENDING_ROTATION_CHECK,
+ /* one-shot */ true);
+ if (ret == 0) {
+ session->rotation_pending_check_timer_enabled = true;
+ }
+
+ 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);
+
+ 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;
+ }
+ 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;
+
+ DBG("Enabling scheduled rotation timer on session \"%s\" (%ui µs)", session->name,
+ interval_us);
+ ret = timer_start(&session->rotation_schedule_timer, session->id,
+ 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;
+ 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.
+ */
+void *timer_thread_func(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) {
+ rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
+ ROTATION_THREAD_JOB_TYPE_CHECK_PENDING_ROTATION,
+ /* session_id */ PTR_TO_UINT(info.si_value.sival_ptr));
+ } else if (signr == LTTNG_SESSIOND_SIG_SCHEDULED_ROTATION) {
+ rotation_thread_enqueue_job(ctx->rotation_thread_job_queue,
+ ROTATION_THREAD_JOB_TYPE_SCHEDULED_ROTATION,
+ /* session_id */ PTR_TO_UINT(info.si_value.sival_ptr));
+ } 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;
+}
+
+void timer_exit(void)
+{
+ kill(getpid(), LTTNG_SESSIOND_SIG_EXIT);
+}
projects / lttng-tools.git / blobdiff