-/*
- * 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_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_manage_kernel(void *data)
-{
- int ret, i, pollfd, update_poll_flag = 1, err = -1;
- uint32_t revents, nb_fd;
- char tmp;
- struct lttng_poll_event events;
-
- DBG("[thread] Thread manage kernel started");
-
- health_register(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 = sessiond_set_thread_pollset(&events, 2);
- if (ret < 0) {
- goto error_poll_create;
- }
-
- ret = lttng_poll_add(&events, kernel_poll_pipe[0], 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 (!revents) {
- /* No activity for this FD (poll implementation). */
- continue;
- }
-
- /* Thread quit pipe has been closed. Killing thread. */
- ret = sessiond_check_thread_quit_pipe(pollfd, revents);
- if (ret) {
- err = 0;
- goto exit;
- }
-
- /* Check for data on kernel pipe */
- if (revents & LPOLLIN) {
- if (pollfd == kernel_poll_pipe[0]) {
- (void) lttng_read(kernel_poll_pipe[0],
- &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:
- utils_close_pipe(kernel_poll_pipe);
- kernel_poll_pipe[0] = kernel_poll_pipe[1] = -1;
- 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(health_sessiond);
- DBG("Kernel thread dying");
- return NULL;
-}
-
projects / lttng-tools.git / blobdiff