Fix: add missing rcu read side lock
[lttng-tools.git] / src / bin / lttng-sessiond / main.c
index 8a1f753114bfe3bfaa8cd5629ea5c7e199c29aab..339b20d3ee433be2d17f33d3462b104ab6266448 100644 (file)
@@ -72,6 +72,7 @@ const char default_global_apps_pipe[] = DEFAULT_GLOBAL_APPS_PIPE;
 
 const char *progname;
 const char *opt_tracing_group;
+static const char *opt_pidfile;
 static int opt_sig_parent;
 static int opt_verbose_consumer;
 static int opt_daemon;
@@ -404,6 +405,17 @@ static void cleanup(void)
        /* First thing first, stop all threads */
        utils_close_pipe(thread_quit_pipe);
 
+       /*
+        * If opt_pidfile is undefined, the default file will be wiped when
+        * removing the rundir.
+        */
+       if (opt_pidfile) {
+               ret = remove(opt_pidfile);
+               if (ret < 0) {
+                       PERROR("remove pidfile %s", opt_pidfile);
+               }
+       }
+
        DBG("Removing %s directory", rundir);
        ret = asprintf(&cmd, "rm -rf %s", rundir);
        if (ret < 0) {
@@ -461,7 +473,7 @@ static void cleanup(void)
 static int send_unix_sock(int sock, void *buf, size_t len)
 {
        /* Check valid length */
-       if (len <= 0) {
+       if (len == 0) {
                return -1;
        }
 
@@ -626,7 +638,7 @@ static int update_kernel_stream(struct consumer_data *consumer_data, int fd)
                                        struct lttng_ht_iter iter;
                                        struct consumer_socket *socket;
 
-
+                                       rcu_read_lock();
                                        cds_lfht_for_each_entry(ksess->consumer->socks->ht,
                                                        &iter.iter, socket, node.node) {
                                                /* Code flow error */
@@ -637,9 +649,11 @@ static int update_kernel_stream(struct consumer_data *consumer_data, int fd)
                                                                channel, ksess);
                                                pthread_mutex_unlock(socket->lock);
                                                if (ret < 0) {
+                                                       rcu_read_unlock();
                                                        goto error;
                                                }
                                        }
+                                       rcu_read_unlock();
                                }
                                goto error;
                        }
@@ -689,34 +703,42 @@ static void *thread_manage_kernel(void *data)
        char tmp;
        struct lttng_poll_event events;
 
-       DBG("Thread manage kernel started");
-
-       testpoint(thread_manage_kernel);
+       DBG("[thread] Thread manage kernel started");
 
-       health_code_update(&health_thread_kernel);
-
-       testpoint(thread_manage_kernel_before_loop);
+       /*
+        * This first step of the while is to clean this structure which could free
+        * non NULL pointers so zero it before the loop.
+        */
+       memset(&events, 0, sizeof(events));
 
-       ret = create_thread_poll_set(&events, 2);
-       if (ret < 0) {
-               goto error_poll_create;
+       if (testpoint(thread_manage_kernel)) {
+               goto error_testpoint;
        }
 
-       ret = lttng_poll_add(&events, kernel_poll_pipe[0], LPOLLIN);
-       if (ret < 0) {
-               goto error;
+       health_code_update(&health_thread_kernel);
+
+       if (testpoint(thread_manage_kernel_before_loop)) {
+               goto error_testpoint;
        }
 
        while (1) {
                health_code_update(&health_thread_kernel);
 
                if (update_poll_flag == 1) {
-                       /*
-                        * Reset number of fd in the poll set. Always 2 since there is the thread
-                        * quit pipe and the kernel pipe.
-                        */
-                       events.nb_fd = 2;
+                       /* Clean events object. We are about to populate it again. */
+                       lttng_poll_clean(&events);
 
+                       ret = create_thread_poll_set(&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;
@@ -724,12 +746,7 @@ static void *thread_manage_kernel(void *data)
                        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);
+               DBG("Thread kernel polling on %d fds", LTTNG_POLL_GETNB(&events));
 
                /* Poll infinite value of time */
        restart:
@@ -751,6 +768,8 @@ static void *thread_manage_kernel(void *data)
                        continue;
                }
 
+               nb_fd = ret;
+
                for (i = 0; i < nb_fd; i++) {
                        /* Fetch once the poll data */
                        revents = LTTNG_POLL_GETEV(&events, i);
@@ -767,7 +786,13 @@ static void *thread_manage_kernel(void *data)
 
                        /* Check for data on kernel pipe */
                        if (pollfd == kernel_poll_pipe[0] && (revents & LPOLLIN)) {
-                               ret = read(kernel_poll_pipe[0], &tmp, 1);
+                               do {
+                                       ret = read(kernel_poll_pipe[0], &tmp, 1);
+                               } while (ret < 0 && errno == EINTR);
+                               /*
+                                * Ret value is useless here, if this pipe gets any actions an
+                                * update is required anyway.
+                                */
                                update_poll_flag = 1;
                                continue;
                        } else {
@@ -794,6 +819,7 @@ 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) {
@@ -881,15 +907,15 @@ static void *thread_manage_consumer(void *data)
                goto error;
        }
 
-       nb_fd = LTTNG_POLL_GETNB(&events);
-
        health_code_update(&consumer_data->health);
 
        /* Inifinite blocking call, waiting for transmission */
 restart:
        health_poll_update(&consumer_data->health);
 
-       testpoint(thread_manage_consumer);
+       if (testpoint(thread_manage_consumer)) {
+               goto error;
+       }
 
        ret = lttng_poll_wait(&events, -1);
        health_poll_update(&consumer_data->health);
@@ -903,6 +929,8 @@ restart:
                goto error;
        }
 
+       nb_fd = ret;
+
        for (i = 0; i < nb_fd; i++) {
                /* Fetch once the poll data */
                revents = LTTNG_POLL_GETEV(&events, i);
@@ -980,9 +1008,6 @@ restart:
 
        health_code_update(&consumer_data->health);
 
-       /* Update number of fd */
-       nb_fd = LTTNG_POLL_GETNB(&events);
-
        /* Inifinite blocking call, waiting for transmission */
 restart_poll:
        health_poll_update(&consumer_data->health);
@@ -998,6 +1023,8 @@ restart_poll:
                goto error;
        }
 
+       nb_fd = ret;
+
        for (i = 0; i < nb_fd; i++) {
                /* Fetch once the poll data */
                revents = LTTNG_POLL_GETEV(&events, i);
@@ -1093,11 +1120,13 @@ static void *thread_manage_apps(void *data)
 
        DBG("[thread] Manage application started");
 
-       testpoint(thread_manage_apps);
-
        rcu_register_thread();
        rcu_thread_online();
 
+       if (testpoint(thread_manage_apps)) {
+               goto error_testpoint;
+       }
+
        health_code_update(&health_thread_app_manage);
 
        ret = create_thread_poll_set(&events, 2);
@@ -1110,17 +1139,14 @@ static void *thread_manage_apps(void *data)
                goto error;
        }
 
-       testpoint(thread_manage_apps_before_loop);
+       if (testpoint(thread_manage_apps_before_loop)) {
+               goto error;
+       }
 
        health_code_update(&health_thread_app_manage);
 
        while (1) {
-               /* Zeroed the events structure */
-               lttng_poll_reset(&events);
-
-               nb_fd = LTTNG_POLL_GETNB(&events);
-
-               DBG("Apps thread polling on %d fds", nb_fd);
+               DBG("Apps thread polling on %d fds", LTTNG_POLL_GETNB(&events));
 
                /* Inifinite blocking call, waiting for transmission */
        restart:
@@ -1137,6 +1163,8 @@ static void *thread_manage_apps(void *data)
                        goto error;
                }
 
+               nb_fd = ret;
+
                for (i = 0; i < nb_fd; i++) {
                        /* Fetch once the poll data */
                        revents = LTTNG_POLL_GETEV(&events, i);
@@ -1158,7 +1186,9 @@ static void *thread_manage_apps(void *data)
                                        goto error;
                                } else if (revents & LPOLLIN) {
                                        /* Empty pipe */
-                                       ret = read(apps_cmd_pipe[0], &ust_cmd, sizeof(ust_cmd));
+                                       do {
+                                               ret = read(apps_cmd_pipe[0], &ust_cmd, sizeof(ust_cmd));
+                                       } while (ret < 0 && errno == EINTR);
                                        if (ret < 0 || ret < sizeof(ust_cmd)) {
                                                PERROR("read apps cmd pipe");
                                                goto error;
@@ -1250,6 +1280,7 @@ exit:
 error:
        lttng_poll_clean(&events);
 error_poll_create:
+error_testpoint:
        utils_close_pipe(apps_cmd_pipe);
        apps_cmd_pipe[0] = apps_cmd_pipe[1] = -1;
 
@@ -1309,9 +1340,11 @@ static void *thread_dispatch_ust_registration(void *data)
                         * at some point in time or wait to the end of the world :)
                         */
                        if (apps_cmd_pipe[1] >= 0) {
-                               ret = write(apps_cmd_pipe[1], ust_cmd,
-                                               sizeof(struct ust_command));
-                               if (ret < 0) {
+                               do {
+                                       ret = write(apps_cmd_pipe[1], ust_cmd,
+                                                       sizeof(struct ust_command));
+                               } while (ret < 0 && errno == EINTR);
+                               if (ret < 0 || ret != sizeof(struct ust_command)) {
                                        PERROR("write apps cmd pipe");
                                        if (errno == EBADF) {
                                                /*
@@ -1358,7 +1391,9 @@ static void *thread_registration_apps(void *data)
 
        DBG("[thread] Manage application registration started");
 
-       testpoint(thread_registration_apps);
+       if (testpoint(thread_registration_apps)) {
+               goto error_testpoint;
+       }
 
        ret = lttcomm_listen_unix_sock(apps_sock);
        if (ret < 0) {
@@ -1391,8 +1426,6 @@ static void *thread_registration_apps(void *data)
        while (1) {
                DBG("Accepting application registration");
 
-               nb_fd = LTTNG_POLL_GETNB(&events);
-
                /* Inifinite blocking call, waiting for transmission */
        restart:
                health_poll_update(&health_thread_app_reg);
@@ -1408,6 +1441,8 @@ static void *thread_registration_apps(void *data)
                        goto error;
                }
 
+               nb_fd = ret;
+
                for (i = 0; i < nb_fd; i++) {
                        health_code_update(&health_thread_app_reg);
 
@@ -1513,7 +1548,6 @@ error:
                health_error(&health_thread_app_reg);
                ERR("Health error occurred in %s", __func__);
        }
-       health_exit(&health_thread_app_reg);
 
        /* Notify that the registration thread is gone */
        notify_ust_apps(0);
@@ -1537,7 +1571,9 @@ error_poll_add:
        lttng_poll_clean(&events);
 error_listen:
 error_create_poll:
+error_testpoint:
        DBG("UST Registration thread cleanup complete");
+       health_exit(&health_thread_app_reg);
 
        return NULL;
 }
@@ -1669,10 +1705,10 @@ error:
 static int join_consumer_thread(struct consumer_data *consumer_data)
 {
        void *status;
-       int ret;
 
        /* Consumer pid must be a real one. */
        if (consumer_data->pid > 0) {
+               int ret;
                ret = kill(consumer_data->pid, SIGTERM);
                if (ret) {
                        ERR("Error killing consumer daemon");
@@ -1851,7 +1887,7 @@ error:
  */
 static int start_consumerd(struct consumer_data *consumer_data)
 {
-       int ret, err;
+       int ret;
 
        /*
         * Set the listen() state on the socket since there is a possible race
@@ -1894,6 +1930,8 @@ end:
 error:
        /* Cleanup already created socket on error. */
        if (consumer_data->err_sock >= 0) {
+               int err;
+
                err = close(consumer_data->err_sock);
                if (err < 0) {
                        PERROR("close consumer data error socket");
@@ -2967,8 +3005,6 @@ static void *thread_manage_health(void *data)
        while (1) {
                DBG("Health check ready");
 
-               nb_fd = LTTNG_POLL_GETNB(&events);
-
                /* Inifinite blocking call, waiting for transmission */
 restart:
                ret = lttng_poll_wait(&events, -1);
@@ -2982,6 +3018,8 @@ restart:
                        goto error;
                }
 
+               nb_fd = ret;
+
                for (i = 0; i < nb_fd; i++) {
                        /* Fetch once the poll data */
                        revents = LTTNG_POLL_GETEV(&events, i);
@@ -3122,10 +3160,12 @@ static void *thread_manage_clients(void *data)
 
        DBG("[thread] Manage client started");
 
-       testpoint(thread_manage_clients);
-
        rcu_register_thread();
 
+       if (testpoint(thread_manage_clients)) {
+               goto error_testpoint;
+       }
+
        health_code_update(&health_thread_cmd);
 
        ret = lttcomm_listen_unix_sock(client_sock);
@@ -3155,15 +3195,15 @@ static void *thread_manage_clients(void *data)
                kill(ppid, SIGUSR1);
        }
 
-       testpoint(thread_manage_clients_before_loop);
+       if (testpoint(thread_manage_clients_before_loop)) {
+               goto error;
+       }
 
        health_code_update(&health_thread_cmd);
 
        while (1) {
                DBG("Accepting client command ...");
 
-               nb_fd = LTTNG_POLL_GETNB(&events);
-
                /* Inifinite blocking call, waiting for transmission */
        restart:
                health_poll_update(&health_thread_cmd);
@@ -3179,6 +3219,8 @@ static void *thread_manage_clients(void *data)
                        goto error;
                }
 
+               nb_fd = ret;
+
                for (i = 0; i < nb_fd; i++) {
                        /* Fetch once the poll data */
                        revents = LTTNG_POLL_GETEV(&events, i);
@@ -3330,6 +3372,7 @@ error:
 
 error_listen:
 error_create_poll:
+error_testpoint:
        unlink(client_unix_sock_path);
        if (client_sock >= 0) {
                ret = close(client_sock);
@@ -3377,6 +3420,7 @@ static void usage(void)
        fprintf(stderr, "  -S, --sig-parent                   Send SIGCHLD to parent pid to notify readiness.\n");
        fprintf(stderr, "  -q, --quiet                        No output at all.\n");
        fprintf(stderr, "  -v, --verbose                      Verbose mode. Activate DBG() macro.\n");
+       fprintf(stderr, "  -p, --pidfile FILE                 Write a pid to FILE name overriding the default value.\n");
        fprintf(stderr, "      --verbose-consumer             Verbose mode for consumer. Activate DBG() macro.\n");
        fprintf(stderr, "      --no-kernel                    Disable kernel tracer\n");
 }
@@ -3410,12 +3454,13 @@ static int parse_args(int argc, char **argv)
                { "verbose", 0, 0, 'v' },
                { "verbose-consumer", 0, 0, 'Z' },
                { "no-kernel", 0, 0, 'N' },
+               { "pidfile", 1, 0, 'p' },
                { NULL, 0, 0, 0 }
        };
 
        while (1) {
                int option_index = 0;
-               c = getopt_long(argc, argv, "dhqvVSN" "a:c:g:s:C:E:D:F:Z:u:t",
+               c = getopt_long(argc, argv, "dhqvVSN" "a:c:g:s:C:E:D:F:Z:u:t:p:",
                                long_options, &option_index);
                if (c == -1) {
                        break;
@@ -3492,6 +3537,9 @@ static int parse_args(int argc, char **argv)
                case 'T':
                        consumerd64_libdir = optarg;
                        break;
+               case 'p':
+                       opt_pidfile = optarg;
+                       break;
                default:
                        /* Unknown option or other error.
                         * Error is printed by getopt, just return */
@@ -3818,6 +3866,38 @@ static void set_ulimit(void)
        }
 }
 
+/*
+ * Write pidfile using the rundir and opt_pidfile.
+ */
+static void write_pidfile(void)
+{
+       int ret;
+       char pidfile_path[PATH_MAX];
+
+       assert(rundir);
+
+       if (opt_pidfile) {
+               strncpy(pidfile_path, opt_pidfile, sizeof(pidfile_path));
+       } else {
+               /* Build pidfile path from rundir and opt_pidfile. */
+               ret = snprintf(pidfile_path, sizeof(pidfile_path), "%s/"
+                               DEFAULT_LTTNG_SESSIOND_PIDFILE, rundir);
+               if (ret < 0) {
+                       PERROR("snprintf pidfile path");
+                       goto error;
+               }
+       }
+
+       /*
+        * Create pid file in rundir. Return value is of no importance. The
+        * execution will continue even though we are not able to write the file.
+        */
+       (void) utils_create_pid_file(getpid(), pidfile_path);
+
+error:
+       return;
+}
+
 /*
  * main
  */
@@ -3835,7 +3915,7 @@ int main(int argc, char **argv)
 
        /* Parse arguments */
        progname = argv[0];
-       if ((ret = parse_args(argc, argv) < 0)) {
+       if ((ret = parse_args(argc, argv)) < 0) {
                goto error;
        }
 
@@ -4115,6 +4195,8 @@ int main(int argc, char **argv)
                app_socket_timeout = DEFAULT_APP_SOCKET_RW_TIMEOUT;
        }
 
+       write_pidfile();
+
        /* Create thread to manage the client socket */
        ret = pthread_create(&health_thread, NULL,
                        thread_manage_health, (void *) NULL);
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