--- /dev/null
+/*
+ * 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 <common/pipe.h>
+#include <common/utils.h>
+
+#include "manage-kernel.h"
+#include "testpoint.h"
+#include "health-sessiond.h"
+#include "utils.h"
+#include "thread.h"
+#include "kernel.h"
+#include "kernel-consumer.h"
+
+struct thread_notifiers {
+ struct lttng_pipe *quit_pipe;
+ int kernel_poll_pipe_read_fd;
+};
+
+/*
+ * Update the kernel poll set of all channel fd available over all tracing
+ * session. Add the wakeup pipe at the end of the set.
+ */
+static int update_kernel_poll(struct lttng_poll_event *events)
+{
+ int ret;
+ struct ltt_kernel_channel *channel;
+ struct ltt_session *session;
+ const struct ltt_session_list *session_list = session_get_list();
+
+ DBG("Updating kernel poll set");
+
+ session_lock_list();
+ cds_list_for_each_entry(session, &session_list->head, list) {
+ if (!session_get(session)) {
+ continue;
+ }
+ session_lock(session);
+ if (session->kernel_session == NULL) {
+ session_unlock(session);
+ session_put(session);
+ continue;
+ }
+
+ cds_list_for_each_entry(channel,
+ &session->kernel_session->channel_list.head, list) {
+ /* Add channel fd to the kernel poll set */
+ ret = lttng_poll_add(events, channel->fd, LPOLLIN | LPOLLRDNORM);
+ if (ret < 0) {
+ session_unlock(session);
+ session_put(session);
+ goto error;
+ }
+ DBG("Channel fd %d added to kernel set", channel->fd);
+ }
+ session_unlock(session);
+ session_put(session);
+ }
+ session_unlock_list();
+
+ return 0;
+
+error:
+ session_unlock_list();
+ return -1;
+}
+
+/*
+ * Find the channel fd from 'fd' over all tracing session. When found, check
+ * for new channel stream and send those stream fds to the kernel consumer.
+ *
+ * Useful for CPU hotplug feature.
+ */
+static int update_kernel_stream(int fd)
+{
+ int ret = 0;
+ struct ltt_session *session;
+ struct ltt_kernel_session *ksess;
+ struct ltt_kernel_channel *channel;
+ const struct ltt_session_list *session_list = session_get_list();
+
+ DBG("Updating kernel streams for channel fd %d", fd);
+
+ session_lock_list();
+ cds_list_for_each_entry(session, &session_list->head, list) {
+ if (!session_get(session)) {
+ continue;
+ }
+ session_lock(session);
+ if (session->kernel_session == NULL) {
+ session_unlock(session);
+ session_put(session);
+ continue;
+ }
+ ksess = session->kernel_session;
+
+ cds_list_for_each_entry(channel,
+ &ksess->channel_list.head, list) {
+ struct lttng_ht_iter iter;
+ struct consumer_socket *socket;
+
+ if (channel->fd != fd) {
+ continue;
+ }
+ DBG("Channel found, updating kernel streams");
+ ret = kernel_open_channel_stream(channel);
+ if (ret < 0) {
+ goto error;
+ }
+ /* Update the stream global counter */
+ ksess->stream_count_global += ret;
+
+ /*
+ * Have we already sent fds to the consumer? If yes, it
+ * means that tracing is started so it is safe to send
+ * our updated stream fds.
+ */
+ if (ksess->consumer_fds_sent != 1
+ || ksess->consumer == NULL) {
+ ret = -1;
+ goto error;
+ }
+
+ rcu_read_lock();
+ cds_lfht_for_each_entry(ksess->consumer->socks->ht,
+ &iter.iter, socket, node.node) {
+ pthread_mutex_lock(socket->lock);
+ ret = kernel_consumer_send_channel_streams(socket,
+ channel, ksess,
+ session->output_traces ? 1 : 0);
+ pthread_mutex_unlock(socket->lock);
+ if (ret < 0) {
+ rcu_read_unlock();
+ goto error;
+ }
+ }
+ rcu_read_unlock();
+ }
+ session_unlock(session);
+ session_put(session);
+ }
+ session_unlock_list();
+ return ret;
+
+error:
+ session_unlock(session);
+ session_put(session);
+ session_unlock_list();
+ return ret;
+}
+
+/*
+ * This thread manage event coming from the kernel.
+ *
+ * Features supported in this thread:
+ * -) CPU Hotplug
+ */
+static void *thread_kernel_management(void *data)
+{
+ int ret, i, pollfd, update_poll_flag = 1, err = -1;
+ uint32_t revents, nb_fd;
+ char tmp;
+ struct lttng_poll_event events;
+ struct thread_notifiers *notifiers = (thread_notifiers *) data;
+ const int quit_pipe_read_fd = lttng_pipe_get_readfd(notifiers->quit_pipe);
+
+ DBG("[thread] Thread manage kernel started");
+
+ health_register(the_health_sessiond, HEALTH_SESSIOND_TYPE_KERNEL);
+
+ /*
+ * This first step of the while is to clean this structure which could free
+ * non NULL pointers so initialize it before the loop.
+ */
+ lttng_poll_init(&events);
+
+ if (testpoint(sessiond_thread_manage_kernel)) {
+ goto error_testpoint;
+ }
+
+ health_code_update();
+
+ if (testpoint(sessiond_thread_manage_kernel_before_loop)) {
+ goto error_testpoint;
+ }
+
+ while (1) {
+ health_code_update();
+
+ if (update_poll_flag == 1) {
+ /* Clean events object. We are about to populate it again. */
+ lttng_poll_clean(&events);
+
+ ret = lttng_poll_create(&events, 2, LTTNG_CLOEXEC);
+ if (ret < 0) {
+ goto error_poll_create;
+ }
+
+ ret = lttng_poll_add(&events,
+ notifiers->kernel_poll_pipe_read_fd,
+ LPOLLIN);
+ if (ret < 0) {
+ goto error;
+ }
+
+ ret = lttng_poll_add(&events,
+ quit_pipe_read_fd,
+ LPOLLIN);
+ if (ret < 0) {
+ goto error;
+ }
+
+ /* This will add the available kernel channel if any. */
+ ret = update_kernel_poll(&events);
+ if (ret < 0) {
+ goto error;
+ }
+ update_poll_flag = 0;
+ }
+
+ DBG("Thread kernel polling");
+
+ /* Poll infinite value of time */
+ restart:
+ health_poll_entry();
+ ret = lttng_poll_wait(&events, -1);
+ DBG("Thread kernel return from poll on %d fds",
+ LTTNG_POLL_GETNB(&events));
+ health_poll_exit();
+ if (ret < 0) {
+ /*
+ * Restart interrupted system call.
+ */
+ if (errno == EINTR) {
+ goto restart;
+ }
+ goto error;
+ } else if (ret == 0) {
+ /* Should not happen since timeout is infinite */
+ ERR("Return value of poll is 0 with an infinite timeout.\n"
+ "This should not have happened! Continuing...");
+ continue;
+ }
+
+ nb_fd = ret;
+
+ for (i = 0; i < nb_fd; i++) {
+ /* Fetch once the poll data */
+ revents = LTTNG_POLL_GETEV(&events, i);
+ pollfd = LTTNG_POLL_GETFD(&events, i);
+
+ health_code_update();
+
+ if (pollfd == quit_pipe_read_fd) {
+ err = 0;
+ goto exit;
+ }
+
+ /* Check for data on kernel pipe */
+ if (revents & LPOLLIN) {
+ if (pollfd == notifiers->kernel_poll_pipe_read_fd) {
+ (void) lttng_read(notifiers->kernel_poll_pipe_read_fd,
+ &tmp, 1);
+ /*
+ * Ret value is useless here, if this pipe gets any actions an
+ * update is required anyway.
+ */
+ update_poll_flag = 1;
+ continue;
+ } else {
+ /*
+ * New CPU detected by the kernel. Adding kernel stream to
+ * kernel session and updating the kernel consumer
+ */
+ ret = update_kernel_stream(pollfd);
+ if (ret < 0) {
+ continue;
+ }
+ break;
+ }
+ } else if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
+ update_poll_flag = 1;
+ continue;
+ } else {
+ ERR("Unexpected poll events %u for sock %d", revents, pollfd);
+ goto error;
+ }
+ }
+ }
+
+exit:
+error:
+ lttng_poll_clean(&events);
+error_poll_create:
+error_testpoint:
+ if (err) {
+ health_error();
+ ERR("Health error occurred in %s", __func__);
+ WARN("Kernel thread died unexpectedly. "
+ "Kernel tracing can continue but CPU hotplug is disabled.");
+ }
+ health_unregister(the_health_sessiond);
+ DBG("Kernel thread dying");
+ return NULL;
+}
+
+static bool shutdown_kernel_management_thread(void *data)
+{
+ struct thread_notifiers *notifiers = (thread_notifiers *) data;
+ const int write_fd = lttng_pipe_get_writefd(notifiers->quit_pipe);
+
+ return notify_thread_pipe(write_fd) == 1;
+}
+
+static void cleanup_kernel_management_thread(void *data)
+{
+ struct thread_notifiers *notifiers = (thread_notifiers *) data;
+
+ lttng_pipe_destroy(notifiers->quit_pipe);
+ free(notifiers);
+}
+
+bool launch_kernel_management_thread(int kernel_poll_pipe_read_fd)
+{
+ struct lttng_pipe *quit_pipe;
+ struct thread_notifiers *notifiers = NULL;
+ struct lttng_thread *thread;
+
+ notifiers = (thread_notifiers *) zmalloc(sizeof(*notifiers));
+ if (!notifiers) {
+ goto error_alloc;
+ }
+ quit_pipe = lttng_pipe_open(FD_CLOEXEC);
+ if (!quit_pipe) {
+ goto error;
+ }
+ notifiers->quit_pipe = quit_pipe;
+ notifiers->kernel_poll_pipe_read_fd = kernel_poll_pipe_read_fd;
+
+ thread = lttng_thread_create("Kernel management",
+ thread_kernel_management,
+ shutdown_kernel_management_thread,
+ cleanup_kernel_management_thread,
+ notifiers);
+ if (!thread) {
+ goto error;
+ }
+ lttng_thread_put(thread);
+ return true;
+error:
+ cleanup_kernel_management_thread(notifiers);
+error_alloc:
+ return false;
+}
projects / lttng-tools.git / blobdiff