+/*
+ * Copyright (C) 2011 - David Goulet <david.goulet@polymtl.ca>
+ * Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ * 2013 - 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.
+ */
+
+#include <stddef.h>
+#include <stdlib.h>
+#include <urcu.h>
+#include <common/futex.h>
+#include <common/macros.h>
+
+#include "dispatch.h"
+#include "ust-app.h"
+#include "testpoint.h"
+#include "fd-limit.h"
+#include "health-sessiond.h"
+#include "lttng-sessiond.h"
+#include "thread.h"
+
+struct thread_notifiers {
+ struct ust_cmd_queue *ust_cmd_queue;
+ int apps_cmd_pipe_write_fd;
+ int apps_cmd_notify_pipe_write_fd;
+ int dispatch_thread_exit;
+};
+
+/*
+ * For each tracing session, update newly registered apps. The session list
+ * lock MUST be acquired before calling this.
+ */
+static void update_ust_app(int app_sock)
+{
+ struct ltt_session *sess, *stmp;
+ const struct ltt_session_list *session_list = session_get_list();
+
+ /* Consumer is in an ERROR state. Stop any application update. */
+ if (uatomic_read(&ust_consumerd_state) == CONSUMER_ERROR) {
+ /* Stop the update process since the consumer is dead. */
+ return;
+ }
+
+ /* For all tracing session(s) */
+ cds_list_for_each_entry_safe(sess, stmp, &session_list->head, list) {
+ struct ust_app *app;
+
+ if (!session_get(sess)) {
+ continue;
+ }
+ session_lock(sess);
+ if (!sess->ust_session) {
+ goto unlock_session;
+ }
+
+ rcu_read_lock();
+ assert(app_sock >= 0);
+ app = ust_app_find_by_sock(app_sock);
+ if (app == NULL) {
+ /*
+ * Application can be unregistered before so
+ * this is possible hence simply stopping the
+ * update.
+ */
+ DBG3("UST app update failed to find app sock %d",
+ app_sock);
+ goto unlock_rcu;
+ }
+ ust_app_global_update(sess->ust_session, app);
+ unlock_rcu:
+ rcu_read_unlock();
+ unlock_session:
+ session_unlock(sess);
+ session_put(sess);
+ }
+}
+
+/*
+ * Sanitize the wait queue of the dispatch registration thread meaning removing
+ * invalid nodes from it. This is to avoid memory leaks for the case the UST
+ * notify socket is never received.
+ */
+static void sanitize_wait_queue(struct ust_reg_wait_queue *wait_queue)
+{
+ int ret, nb_fd = 0, i;
+ unsigned int fd_added = 0;
+ struct lttng_poll_event events;
+ struct ust_reg_wait_node *wait_node = NULL, *tmp_wait_node;
+
+ assert(wait_queue);
+
+ lttng_poll_init(&events);
+
+ /* Just skip everything for an empty queue. */
+ if (!wait_queue->count) {
+ goto end;
+ }
+
+ ret = lttng_poll_create(&events, wait_queue->count, LTTNG_CLOEXEC);
+ if (ret < 0) {
+ goto error_create;
+ }
+
+ cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
+ &wait_queue->head, head) {
+ assert(wait_node->app);
+ ret = lttng_poll_add(&events, wait_node->app->sock,
+ LPOLLHUP | LPOLLERR);
+ if (ret < 0) {
+ goto error;
+ }
+
+ fd_added = 1;
+ }
+
+ if (!fd_added) {
+ goto end;
+ }
+
+ /*
+ * Poll but don't block so we can quickly identify the faulty events and
+ * clean them afterwards from the wait queue.
+ */
+ ret = lttng_poll_wait(&events, 0);
+ if (ret < 0) {
+ goto error;
+ }
+ nb_fd = ret;
+
+ for (i = 0; i < nb_fd; i++) {
+ /* Get faulty FD. */
+ uint32_t revents = LTTNG_POLL_GETEV(&events, i);
+ int pollfd = LTTNG_POLL_GETFD(&events, i);
+
+ if (!revents) {
+ /* No activity for this FD (poll implementation). */
+ continue;
+ }
+
+ cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
+ &wait_queue->head, head) {
+ if (pollfd == wait_node->app->sock &&
+ (revents & (LPOLLHUP | LPOLLERR))) {
+ cds_list_del(&wait_node->head);
+ wait_queue->count--;
+ ust_app_destroy(wait_node->app);
+ free(wait_node);
+ /*
+ * Silence warning of use-after-free in
+ * cds_list_for_each_entry_safe which uses
+ * __typeof__(*wait_node).
+ */
+ wait_node = NULL;
+ break;
+ } else {
+ ERR("Unexpected poll events %u for sock %d", revents, pollfd);
+ goto error;
+ }
+ }
+ }
+
+ if (nb_fd > 0) {
+ DBG("Wait queue sanitized, %d node were cleaned up", nb_fd);
+ }
+
+end:
+ lttng_poll_clean(&events);
+ return;
+
+error:
+ lttng_poll_clean(&events);
+error_create:
+ ERR("Unable to sanitize wait queue");
+ return;
+}
+
+/*
+ * Send a socket to a thread This is called from the dispatch UST registration
+ * thread once all sockets are set for the application.
+ *
+ * The sock value can be invalid, we don't really care, the thread will handle
+ * it and make the necessary cleanup if so.
+ *
+ * On success, return 0 else a negative value being the errno message of the
+ * write().
+ */
+static int send_socket_to_thread(int fd, int sock)
+{
+ ssize_t ret;
+
+ /*
+ * It's possible that the FD is set as invalid with -1 concurrently just
+ * before calling this function being a shutdown state of the thread.
+ */
+ if (fd < 0) {
+ ret = -EBADF;
+ goto error;
+ }
+
+ ret = lttng_write(fd, &sock, sizeof(sock));
+ if (ret < sizeof(sock)) {
+ PERROR("write apps pipe %d", fd);
+ if (ret < 0) {
+ ret = -errno;
+ }
+ goto error;
+ }
+
+ /* All good. Don't send back the write positive ret value. */
+ ret = 0;
+error:
+ return (int) ret;
+}
+
+static void cleanup_ust_dispatch_thread(void *data)
+{
+ free(data);
+}
+
+/*
+ * Dispatch request from the registration threads to the application
+ * communication thread.
+ */
+static void *thread_dispatch_ust_registration(void *data)
+{
+ int ret, err = -1;
+ struct cds_wfcq_node *node;
+ struct ust_command *ust_cmd = NULL;
+ struct ust_reg_wait_node *wait_node = NULL, *tmp_wait_node;
+ struct ust_reg_wait_queue wait_queue = {
+ .count = 0,
+ };
+ struct thread_notifiers *notifiers = data;
+
+ rcu_register_thread();
+
+ health_register(health_sessiond, HEALTH_SESSIOND_TYPE_APP_REG_DISPATCH);
+
+ if (testpoint(sessiond_thread_app_reg_dispatch)) {
+ goto error_testpoint;
+ }
+
+ health_code_update();
+
+ CDS_INIT_LIST_HEAD(&wait_queue.head);
+
+ DBG("[thread] Dispatch UST command started");
+
+ for (;;) {
+ health_code_update();
+
+ /* Atomically prepare the queue futex */
+ futex_nto1_prepare(¬ifiers->ust_cmd_queue->futex);
+
+ if (CMM_LOAD_SHARED(notifiers->dispatch_thread_exit)) {
+ break;
+ }
+
+ do {
+ struct ust_app *app = NULL;
+ ust_cmd = NULL;
+
+ /*
+ * Make sure we don't have node(s) that have hung up before receiving
+ * the notify socket. This is to clean the list in order to avoid
+ * memory leaks from notify socket that are never seen.
+ */
+ sanitize_wait_queue(&wait_queue);
+
+ health_code_update();
+ /* Dequeue command for registration */
+ node = cds_wfcq_dequeue_blocking(
+ ¬ifiers->ust_cmd_queue->head,
+ ¬ifiers->ust_cmd_queue->tail);
+ if (node == NULL) {
+ DBG("Woken up but nothing in the UST command queue");
+ /* Continue thread execution */
+ break;
+ }
+
+ ust_cmd = caa_container_of(node, struct ust_command, node);
+
+ DBG("Dispatching UST registration pid:%d ppid:%d uid:%d"
+ " gid:%d sock:%d name:%s (version %d.%d)",
+ ust_cmd->reg_msg.pid, ust_cmd->reg_msg.ppid,
+ ust_cmd->reg_msg.uid, ust_cmd->reg_msg.gid,
+ ust_cmd->sock, ust_cmd->reg_msg.name,
+ ust_cmd->reg_msg.major, ust_cmd->reg_msg.minor);
+
+ if (ust_cmd->reg_msg.type == USTCTL_SOCKET_CMD) {
+ wait_node = zmalloc(sizeof(*wait_node));
+ if (!wait_node) {
+ PERROR("zmalloc wait_node dispatch");
+ ret = close(ust_cmd->sock);
+ if (ret < 0) {
+ PERROR("close ust sock dispatch %d", ust_cmd->sock);
+ }
+ lttng_fd_put(LTTNG_FD_APPS, 1);
+ free(ust_cmd);
+ goto error;
+ }
+ CDS_INIT_LIST_HEAD(&wait_node->head);
+
+ /* Create application object if socket is CMD. */
+ wait_node->app = ust_app_create(&ust_cmd->reg_msg,
+ ust_cmd->sock);
+ if (!wait_node->app) {
+ ret = close(ust_cmd->sock);
+ if (ret < 0) {
+ PERROR("close ust sock dispatch %d", ust_cmd->sock);
+ }
+ lttng_fd_put(LTTNG_FD_APPS, 1);
+ free(wait_node);
+ free(ust_cmd);
+ continue;
+ }
+ /*
+ * Add application to the wait queue so we can set the notify
+ * socket before putting this object in the global ht.
+ */
+ cds_list_add(&wait_node->head, &wait_queue.head);
+ wait_queue.count++;
+
+ free(ust_cmd);
+ /*
+ * We have to continue here since we don't have the notify
+ * socket and the application MUST be added to the hash table
+ * only at that moment.
+ */
+ continue;
+ } else {
+ /*
+ * Look for the application in the local wait queue and set the
+ * notify socket if found.
+ */
+ cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
+ &wait_queue.head, head) {
+ health_code_update();
+ if (wait_node->app->pid == ust_cmd->reg_msg.pid) {
+ wait_node->app->notify_sock = ust_cmd->sock;
+ cds_list_del(&wait_node->head);
+ wait_queue.count--;
+ app = wait_node->app;
+ free(wait_node);
+ DBG3("UST app notify socket %d is set", ust_cmd->sock);
+ break;
+ }
+ }
+
+ /*
+ * With no application at this stage the received socket is
+ * basically useless so close it before we free the cmd data
+ * structure for good.
+ */
+ if (!app) {
+ ret = close(ust_cmd->sock);
+ if (ret < 0) {
+ PERROR("close ust sock dispatch %d", ust_cmd->sock);
+ }
+ lttng_fd_put(LTTNG_FD_APPS, 1);
+ }
+ free(ust_cmd);
+ }
+
+ if (app) {
+ /*
+ * @session_lock_list
+ *
+ * Lock the global session list so from the register up to the
+ * registration done message, no thread can see the application
+ * and change its state.
+ */
+ session_lock_list();
+ rcu_read_lock();
+
+ /*
+ * Add application to the global hash table. This needs to be
+ * done before the update to the UST registry can locate the
+ * application.
+ */
+ ust_app_add(app);
+
+ /* Set app version. This call will print an error if needed. */
+ (void) ust_app_version(app);
+
+ /* Send notify socket through the notify pipe. */
+ ret = send_socket_to_thread(
+ notifiers->apps_cmd_notify_pipe_write_fd,
+ app->notify_sock);
+ if (ret < 0) {
+ rcu_read_unlock();
+ session_unlock_list();
+ /*
+ * No notify thread, stop the UST tracing. However, this is
+ * not an internal error of the this thread thus setting
+ * the health error code to a normal exit.
+ */
+ err = 0;
+ goto error;
+ }
+
+ /*
+ * Update newly registered application with the tracing
+ * registry info already enabled information.
+ */
+ update_ust_app(app->sock);
+
+ /*
+ * Don't care about return value. Let the manage apps threads
+ * handle app unregistration upon socket close.
+ */
+ (void) ust_app_register_done(app);
+
+ /*
+ * Even if the application socket has been closed, send the app
+ * to the thread and unregistration will take place at that
+ * place.
+ */
+ ret = send_socket_to_thread(
+ notifiers->apps_cmd_pipe_write_fd,
+ app->sock);
+ if (ret < 0) {
+ rcu_read_unlock();
+ session_unlock_list();
+ /*
+ * No apps. thread, stop the UST tracing. However, this is
+ * not an internal error of the this thread thus setting
+ * the health error code to a normal exit.
+ */
+ err = 0;
+ goto error;
+ }
+
+ rcu_read_unlock();
+ session_unlock_list();
+ }
+ } while (node != NULL);
+
+ health_poll_entry();
+ /* Futex wait on queue. Blocking call on futex() */
+ futex_nto1_wait(¬ifiers->ust_cmd_queue->futex);
+ health_poll_exit();
+ }
+ /* Normal exit, no error */
+ err = 0;
+
+error:
+ /* Clean up wait queue. */
+ cds_list_for_each_entry_safe(wait_node, tmp_wait_node,
+ &wait_queue.head, head) {
+ cds_list_del(&wait_node->head);
+ wait_queue.count--;
+ free(wait_node);
+ }
+
+ /* Empty command queue. */
+ for (;;) {
+ /* Dequeue command for registration */
+ node = cds_wfcq_dequeue_blocking(
+ ¬ifiers->ust_cmd_queue->head,
+ ¬ifiers->ust_cmd_queue->tail);
+ if (node == NULL) {
+ break;
+ }
+ ust_cmd = caa_container_of(node, struct ust_command, node);
+ ret = close(ust_cmd->sock);
+ if (ret < 0) {
+ PERROR("close ust sock exit dispatch %d", ust_cmd->sock);
+ }
+ lttng_fd_put(LTTNG_FD_APPS, 1);
+ free(ust_cmd);
+ }
+
+error_testpoint:
+ DBG("Dispatch thread dying");
+ if (err) {
+ health_error();
+ ERR("Health error occurred in %s", __func__);
+ }
+ health_unregister(health_sessiond);
+ rcu_unregister_thread();
+ return NULL;
+}
+
+static bool shutdown_ust_dispatch_thread(void *data)
+{
+ struct thread_notifiers *notifiers = data;
+
+ CMM_STORE_SHARED(notifiers->dispatch_thread_exit, 1);
+ futex_nto1_wake(¬ifiers->ust_cmd_queue->futex);
+ return true;
+}
+
+bool launch_ust_dispatch_thread(struct ust_cmd_queue *cmd_queue,
+ int apps_cmd_pipe_write_fd,
+ int apps_cmd_notify_pipe_write_fd)
+{
+ struct lttng_thread *thread;
+ struct thread_notifiers *notifiers;
+
+ notifiers = zmalloc(sizeof(*notifiers));
+ if (!notifiers) {
+ goto error;
+ }
+ notifiers->ust_cmd_queue = cmd_queue;
+ notifiers->apps_cmd_pipe_write_fd = apps_cmd_pipe_write_fd;
+ notifiers->apps_cmd_notify_pipe_write_fd = apps_cmd_notify_pipe_write_fd;
+
+ thread = lttng_thread_create("UST registration dispatch",
+ thread_dispatch_ust_registration,
+ shutdown_ust_dispatch_thread,
+ cleanup_ust_dispatch_thread,
+ notifiers);
+ if (!thread) {
+ goto error;
+ }
+ lttng_thread_put(thread);
+ return true;
+error:
+ free(notifiers);
+ return false;
+}
projects / lttng-tools.git / commitdiff
