+ * Useful for CPU hotplug feature.
+ */
+static int update_kernel_stream(int fd)
+{
+ int ret = 0;
+ struct ltt_session *session;
+ struct ltt_kernel_channel *channel;
+
+ DBG("Updating kernel streams for channel fd %d", fd);
+
+ lock_session_list();
+ cds_list_for_each_entry(session, &session_list_ptr->head, list) {
+ lock_session(session);
+ if (session->kernel_session == NULL) {
+ unlock_session(session);
+ continue;
+ }
+
+ /* This is not suppose to be 0 but this is an extra security check */
+ if (session->kernel_session->consumer_fd == 0) {
+ session->kernel_session->consumer_fd = kconsumerd_cmd_sock;
+ }
+
+ cds_list_for_each_entry(channel,
+ &session->kernel_session->channel_list.head, list) {
+ if (channel->fd == fd) {
+ DBG("Channel found, updating kernel streams");
+ ret = kernel_open_channel_stream(channel);
+ if (ret < 0) {
+ goto error;
+ }
+
+ /*
+ * 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 (session->kernel_session->kconsumer_fds_sent == 1) {
+ ret = send_kconsumerd_channel_fds(
+ session->kernel_session->consumer_fd, channel);
+ if (ret < 0) {
+ goto error;
+ }
+ }
+ goto error;
+ }
+ }
+ unlock_session(session);
+ }
+ unlock_session_list();
+ return ret;
+
+error:
+ unlock_session(session);
+ unlock_session_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;
+ uint32_t revents, nb_fd;
+ char tmp;
+ struct lttng_poll_event events;
+
+ DBG("Thread manage kernel started");
+
+ ret = create_thread_poll_set(&events, 2);
+ if (ret < 0) {
+ goto error;
+ }
+
+ ret = lttng_poll_add(&events, kernel_poll_pipe[0], LPOLLIN);
+ if (ret < 0) {
+ goto error;
+ }
+
+ while (1) {
+ if (update_poll_flag == 1) {
+ ret = update_kernel_poll(&events);
+ if (ret < 0) {
+ goto error;
+ }
+ update_poll_flag = 0;
+ }
+
+ nb_fd = LTTNG_POLL_GETNB(&events);
+
+ DBG("Thread kernel polling on %d fds", nb_fd);
+
+ /* Zeroed the poll events */
+ lttng_poll_reset(&events);
+
+ /* Poll infinite value of time */
+ ret = lttng_poll_wait(&events, -1);
+ if (ret < 0) {
+ 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;
+ }
+
+ for (i = 0; i < nb_fd; i++) {
+ /* Fetch once the poll data */
+ revents = LTTNG_POLL_GETEV(&events, i);
+ pollfd = LTTNG_POLL_GETFD(&events, i);
+
+ /* Thread quit pipe has been closed. Killing thread. */
+ ret = check_thread_quit_pipe(pollfd, revents);
+ if (ret) {
+ goto error;
+ }
+
+ /* Check for data on kernel pipe */
+ if (pollfd == kernel_poll_pipe[0] && (revents & LPOLLIN)) {
+ ret = read(kernel_poll_pipe[0], &tmp, 1);
+ update_poll_flag = 1;
+ continue;
+ } else {
+ /*
+ * New CPU detected by the kernel. Adding kernel stream to
+ * kernel session and updating the kernel consumer
+ */
+ if (revents & LPOLLIN) {
+ ret = update_kernel_stream(pollfd);
+ if (ret < 0) {
+ continue;
+ }
+ break;
+ /*
+ * TODO: We might want to handle the LPOLLERR | LPOLLHUP
+ * and unregister kernel stream at this point.
+ */
+ }
+ }
+ }
+ }
+
+error:
+ DBG("Kernel thread dying");
+ close(kernel_poll_pipe[0]);
+ close(kernel_poll_pipe[1]);
+
+ lttng_poll_clean(&events);
+
+ return NULL;
+}
+
+/*
+ * This thread manage the kconsumerd error sent back to the session daemon.
+ */
+static void *thread_manage_kconsumerd(void *data)
+{
+ int sock = 0, i, ret, pollfd;
+ uint32_t revents, nb_fd;
+ enum lttcomm_return_code code;
+ struct lttng_poll_event events;
+
+ DBG("[thread] Manage kconsumerd started");
+
+ ret = lttcomm_listen_unix_sock(kconsumerd_err_sock);
+ if (ret < 0) {
+ goto error;
+ }
+
+ /*
+ * Pass 2 as size here for the thread quit pipe and kconsumerd_err_sock.
+ * Nothing more will be added to this poll set.
+ */
+ ret = create_thread_poll_set(&events, 2);
+ if (ret < 0) {
+ goto error;
+ }
+
+ ret = lttng_poll_add(&events, kconsumerd_err_sock, LPOLLIN | LPOLLRDHUP);
+ if (ret < 0) {
+ goto error;
+ }
+
+ nb_fd = LTTNG_POLL_GETNB(&events);
+
+ /* Inifinite blocking call, waiting for transmission */
+ ret = lttng_poll_wait(&events, -1);
+ if (ret < 0) {
+ goto error;
+ }
+
+ for (i = 0; i < nb_fd; i++) {
+ /* Fetch once the poll data */
+ revents = LTTNG_POLL_GETEV(&events, i);
+ pollfd = LTTNG_POLL_GETFD(&events, i);
+
+ /* Thread quit pipe has been closed. Killing thread. */
+ ret = check_thread_quit_pipe(pollfd, revents);
+ if (ret) {
+ goto error;
+ }
+
+ /* Event on the registration socket */
+ if (pollfd == kconsumerd_err_sock) {
+ if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
+ ERR("Kconsumerd err socket poll error");
+ goto error;
+ }
+ }
+ }
+
+ sock = lttcomm_accept_unix_sock(kconsumerd_err_sock);
+ if (sock < 0) {
+ goto error;
+ }
+
+ /* Getting status code from kconsumerd */
+ ret = lttcomm_recv_unix_sock(sock, &code, sizeof(enum lttcomm_return_code));
+ if (ret <= 0) {
+ goto error;
+ }
+
+ if (code == KCONSUMERD_COMMAND_SOCK_READY) {
+ kconsumerd_cmd_sock = lttcomm_connect_unix_sock(kconsumerd_cmd_unix_sock_path);
+ if (kconsumerd_cmd_sock < 0) {
+ sem_post(&kconsumerd_sem);
+ perror("kconsumerd connect");
+ goto error;
+ }
+ /* Signal condition to tell that the kconsumerd is ready */
+ sem_post(&kconsumerd_sem);
+ DBG("Kconsumerd command socket ready");
+ } else {
+ DBG("Kconsumerd error when waiting for SOCK_READY : %s",
+ lttcomm_get_readable_code(-code));
+ goto error;
+ }
+
+ /* Remove the kconsumerd error socket since we have established a connexion */
+ ret = lttng_poll_del(&events, kconsumerd_err_sock);
+ if (ret < 0) {
+ goto error;
+ }
+
+ ret = lttng_poll_add(&events, sock, LPOLLIN | LPOLLRDHUP);
+ if (ret < 0) {
+ goto error;
+ }
+
+ /* Update number of fd */
+ nb_fd = LTTNG_POLL_GETNB(&events);
+
+ /* Inifinite blocking call, waiting for transmission */
+ ret = lttng_poll_wait(&events, -1);
+ if (ret < 0) {
+ goto error;
+ }
+
+ for (i = 0; i < nb_fd; i++) {
+ /* Fetch once the poll data */
+ revents = LTTNG_POLL_GETEV(&events, i);
+ pollfd = LTTNG_POLL_GETFD(&events, i);
+
+ /* Thread quit pipe has been closed. Killing thread. */
+ ret = check_thread_quit_pipe(pollfd, revents);
+ if (ret) {
+ goto error;
+ }
+
+ /* Event on the kconsumerd socket */
+ if (pollfd == sock) {
+ if (revents & (LPOLLERR | LPOLLHUP | LPOLLRDHUP)) {
+ ERR("Kconsumerd err socket second poll error");
+ goto error;
+ }
+ }
+ }
+
+ /* Wait for any kconsumerd error */
+ ret = lttcomm_recv_unix_sock(sock, &code, sizeof(enum lttcomm_return_code));
+ if (ret <= 0) {
+ ERR("Kconsumerd closed the command socket");
+ goto error;
+ }
+
+ ERR("Kconsumerd return code : %s", lttcomm_get_readable_code(-code));
+
+error:
+ DBG("Kconsumerd thread dying");
+ close(kconsumerd_err_sock);
+ close(kconsumerd_cmd_sock);
+ close(sock);
+
+ unlink(kconsumerd_err_unix_sock_path);
+ unlink(kconsumerd_cmd_unix_sock_path);
+ kconsumerd_pid = 0;
+
+ lttng_poll_clean(&events);
+
+ return NULL;
+}
+
+/*
+ * This thread manage application communication.