X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng-sessiond%2Fmain.c;h=076d0b7b03ce24295d8d7aeb924c7cdbcb117e16;hp=a81bca69534b4baa100c898e0ab6c1f525070262;hb=db8f1377d850c1b18d33ddc2a6f2f3c91c3210bc;hpb=6cd525e813795a1d5e38feac8dedf2c73ffb1274 diff --git a/src/bin/lttng-sessiond/main.c b/src/bin/lttng-sessiond/main.c index a81bca695..076d0b7b0 100644 --- a/src/bin/lttng-sessiond/main.c +++ b/src/bin/lttng-sessiond/main.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -76,8 +77,12 @@ static int opt_daemon; static int opt_no_kernel; static int is_root; /* Set to 1 if the daemon is running as root */ static pid_t ppid; /* Parent PID for --sig-parent option */ +static pid_t child_ppid; /* Internal parent PID use with daemonize. */ static char *rundir; +/* Set to 1 when a SIGUSR1 signal is received. */ +static int recv_child_signal; + /* * Consumer daemon specific control data. Every value not initialized here is * set to 0 by the static definition. @@ -782,7 +787,6 @@ static void update_ust_app(int app_sock) static void *thread_manage_kernel(void *data) { int ret, i, pollfd, update_poll_flag = 1, err = -1; - ssize_t size_ret; uint32_t revents, nb_fd; char tmp; struct lttng_poll_event events; @@ -2935,7 +2939,7 @@ skip_domain: { ret = cmd_enable_event(cmd_ctx->session, &cmd_ctx->lsm->domain, cmd_ctx->lsm->u.enable.channel_name, - &cmd_ctx->lsm->u.enable.event, NULL, kernel_poll_pipe[1]); + &cmd_ctx->lsm->u.enable.event, NULL, NULL, kernel_poll_pipe[1]); break; } case LTTNG_ENABLE_ALL_EVENT: @@ -3296,7 +3300,7 @@ skip_domain: ret = cmd_enable_event(cmd_ctx->session, &cmd_ctx->lsm->domain, cmd_ctx->lsm->u.enable.channel_name, - &cmd_ctx->lsm->u.enable.event, bytecode, kernel_poll_pipe[1]); + &cmd_ctx->lsm->u.enable.event, bytecode, NULL, kernel_poll_pipe[1]); break; } case LTTNG_DATA_PENDING: @@ -3697,11 +3701,17 @@ static void *thread_manage_clients(void *data) /* * Notify parent pid that we are ready to accept command for client side. + * This ppid is the one from the external process that spawned us. */ if (opt_sig_parent) { kill(ppid, SIGUSR1); } + /* Notify the parent of the fork() process that we are ready. */ + if (opt_daemon) { + kill(child_ppid, SIGUSR1); + } + if (testpoint(thread_manage_clients_before_loop)) { goto error; } @@ -3922,7 +3932,7 @@ static void usage(void) fprintf(stderr, " -d, --daemonize Start as a daemon.\n"); fprintf(stderr, " -g, --group NAME Specify the tracing group name. (default: tracing)\n"); fprintf(stderr, " -V, --version Show version number.\n"); - fprintf(stderr, " -S, --sig-parent Send SIGCHLD to parent pid to notify readiness.\n"); + fprintf(stderr, " -S, --sig-parent Send SIGUSR1 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"); @@ -4343,6 +4353,9 @@ static void sighandler(int sig) DBG("SIGTERM caught"); stop_threads(); break; + case SIGUSR1: + CMM_STORE_SHARED(recv_child_signal, 1); + break; default: break; } @@ -4381,7 +4394,12 @@ static int set_signal_handler(void) return ret; } - DBG("Signal handler set for SIGTERM, SIGPIPE and SIGINT"); + if ((ret = sigaction(SIGUSR1, &sa, NULL)) < 0) { + PERROR("sigaction"); + return ret; + } + + DBG("Signal handler set for SIGTERM, SIGUSR1, SIGPIPE and SIGINT"); return ret; } @@ -4465,6 +4483,95 @@ error: return; } +/* + * Daemonize this process by forking and making the parent wait for the child + * to signal it indicating readiness. Once received, the parent successfully + * quits. + * + * The child process undergoes the same action that daemon(3) does meaning + * setsid, chdir, and dup /dev/null into 0, 1 and 2. + * + * Return 0 on success else -1 on error. + */ +static int daemonize(void) +{ + int ret; + pid_t pid; + + /* Get parent pid of this process. */ + child_ppid = getppid(); + + pid = fork(); + if (pid < 0) { + PERROR("fork"); + goto error; + } else if (pid == 0) { + int fd; + pid_t sid; + + /* Child */ + + /* + * Get the newly created parent pid so we can signal that process when + * we are ready to operate. + */ + child_ppid = getppid(); + + sid = setsid(); + if (sid < 0) { + PERROR("setsid"); + goto error; + } + + /* Try to change directory to /. If we can't well at least notify. */ + ret = chdir("/"); + if (ret < 0) { + PERROR("chdir"); + } + + fd = open(_PATH_DEVNULL, O_RDWR, 0); + if (fd < 0) { + PERROR("open %s", _PATH_DEVNULL); + /* Let 0, 1 and 2 open since we can't bind them to /dev/null. */ + } else { + (void) dup2(fd, STDIN_FILENO); + (void) dup2(fd, STDOUT_FILENO); + (void) dup2(fd, STDERR_FILENO); + if (fd > 2) { + ret = close(fd); + if (ret < 0) { + PERROR("close"); + } + } + } + goto end; + } else { + /* Parent */ + + /* + * Waiting for child to notify this parent that it can exit. Note that + * sleep() is interrupted before the 1 second delay as soon as the + * signal is received, so it will not cause visible delay for the + * user. + */ + while (!CMM_LOAD_SHARED(recv_child_signal)) { + sleep(1); + } + + /* + * From this point on, the parent can exit and the child is now an + * operationnal session daemon ready to serve clients and applications. + */ + exit(EXIT_SUCCESS); + } + +end: + return 0; + +error: + return -1; +} + /* * main */ @@ -4478,6 +4585,10 @@ int main(int argc, char **argv) rcu_register_thread(); + if ((ret = set_signal_handler()) < 0) { + goto error; + } + setup_consumerd_path(); page_size = sysconf(_SC_PAGESIZE); @@ -4497,20 +4608,15 @@ int main(int argc, char **argv) if (opt_daemon) { int i; - /* - * fork - * child: setsid, close FD 0, 1, 2, chdir / - * parent: exit (if fork is successful) - */ - ret = daemon(0, 0); + ret = daemonize(); if (ret < 0) { - PERROR("daemon"); goto error; } + /* - * We are in the child. Make sure all other file - * descriptors are closed, in case we are called with - * more opened file descriptors than the standard ones. + * We are in the child. Make sure all other file descriptors are + * closed, in case we are called with more opened file descriptors than + * the standard ones. */ for (i = 3; i < sysconf(_SC_OPEN_MAX); i++) { (void) close(i); @@ -4703,10 +4809,6 @@ int main(int argc, char **argv) goto exit; } - if ((ret = set_signal_handler()) < 0) { - goto exit; - } - /* Setup the needed unix socket */ if ((ret = init_daemon_socket()) < 0) { goto exit; @@ -4788,7 +4890,7 @@ int main(int argc, char **argv) goto exit_health_sessiond_cleanup; } - /* Create thread to manage the client socket */ + /* Create thread to clean up RCU hash tables */ ret = pthread_create(&ht_cleanup_thread, NULL, thread_ht_cleanup, (void *) NULL); if (ret != 0) { @@ -4796,7 +4898,7 @@ int main(int argc, char **argv) goto exit_ht_cleanup; } - /* Create thread to manage the client socket */ + /* Create health-check thread */ ret = pthread_create(&health_thread, NULL, thread_manage_health, (void *) NULL); if (ret != 0) {