X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=blobdiff_plain;f=src%2Fbin%2Flttng%2Flttng.c;h=e60b694e43729ab1c7ced011e11c2cae3a5e5433;hp=6e16995a9d71a88e332e8f616e8971acb7628a75;hb=852fdd0c1f836d379f8985b8df3186dc6b7daa44;hpb=4666e71c222a7348dd8134e2533027edff16d6a0

diff --git a/src/bin/lttng/lttng.c b/src/bin/lttng/lttng.c
index 6e16995a9..e60b694e4 100644
--- a/src/bin/lttng/lttng.c
+++ b/src/bin/lttng/lttng.c
@@ -40,6 +40,7 @@ int opt_verbose;
 static int opt_no_sessiond;
 static char *opt_sessiond_path;
 static pid_t sessiond_pid;
+static volatile int recv_child_signal;
 
 enum {
 	OPT_SESSION_PATH,
@@ -81,23 +82,23 @@ static struct cmd_struct commands[] =  {
 static void usage(FILE *ofp)
 {
 	fprintf(ofp, "LTTng Trace Control " VERSION"\n\n");
-	fprintf(ofp, "usage: lttng [options] <command>\n");
+	fprintf(ofp, "usage: lttng [OPTIONS] <COMMAND>\n");
 	fprintf(ofp, "\n");
 	fprintf(ofp, "Options:\n");
 	fprintf(ofp, "  -h, --help             Show this help\n");
-	fprintf(ofp, "  -g, --group NAME       Unix tracing group name. (default: tracing)\n");
-	fprintf(ofp, "  -v, --verbose          Verbose mode\n");
+	fprintf(ofp, "      --list-options     Simple listing of lttng options\n");
+	fprintf(ofp, "      --list-commands    Simple listing of lttng commands\n");
+	fprintf(ofp, "  -v, --verbose          Increase verbosity\n");
 	fprintf(ofp, "  -q, --quiet            Quiet mode\n");
+	fprintf(ofp, "  -g, --group NAME       Unix tracing group name. (default: tracing)\n");
 	fprintf(ofp, "  -n, --no-sessiond      Don't spawn a session daemon\n");
 	fprintf(ofp, "      --sessiond-path    Session daemon full path\n");
-	fprintf(ofp, "      --list-options     Simple listing of lttng options\n");
-	fprintf(ofp, "      --list-commands    Simple listing of lttng commands\n");
 	fprintf(ofp, "\n");
 	fprintf(ofp, "Commands:\n");
-	fprintf(ofp, "    add-context     Add context to event or/and channel\n");
+	fprintf(ofp, "    add-context     Add context to event and/or channel\n");
 	fprintf(ofp, "    calibrate       Quantify LTTng overhead\n");
 	fprintf(ofp, "    create          Create tracing session\n");
-	fprintf(ofp, "    destroy         Teardown tracing session\n");
+	fprintf(ofp, "    destroy         Tear down tracing session\n");
 	fprintf(ofp, "    enable-channel  Enable tracing channel\n");
 	fprintf(ofp, "    enable-event    Enable tracing event\n");
 	fprintf(ofp, "    disable-channel Disable tracing channel\n");
@@ -181,12 +182,14 @@ static void sighandler(int sig)
 		case SIGCHLD:
 			DBG("SIGCHLD caugth");
 			waitpid(sessiond_pid, &status, 0);
+			recv_child_signal = 1;
 			/* Indicate that the session daemon died */
 			sessiond_pid = 0;
 			ERR("Session daemon died (exit status %d)", WEXITSTATUS(status));
 			break;
 		case SIGUSR1:
 			/* Notify is done */
+			recv_child_signal = 1;
 			DBG("SIGUSR1 caugth");
 			break;
 		default:
@@ -294,6 +297,7 @@ static int spawn_sessiond(char *pathname)
 	pid_t pid;
 
 	MSG("Spawning a session daemon");
+	recv_child_signal = 0;
 	pid = fork();
 	if (pid == 0) {
 		/*
@@ -307,12 +311,24 @@ static int spawn_sessiond(char *pathname)
 		} else {
 			perror("execlp");
 		}
-		kill(getppid(), SIGTERM);	/* unpause parent */
+		kill(getppid(), SIGTERM);	/* wake parent */
 		exit(EXIT_FAILURE);
 	} else if (pid > 0) {
 		sessiond_pid = pid;
-		/* Wait for lttng-sessiond to start */
-		pause();
+		/*
+		 * Wait for lttng-sessiond to start. We need to use a
+		 * flag to check if the signal has been sent to us,
+		 * because the child can be scheduled before the parent,
+		 * and thus send the signal before this check. In the
+		 * signal handler, we set the recv_child_signal flag, so
+		 * anytime we check it after the fork is fine. 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 (!recv_child_signal) {
+			sleep(1);
+		}
 		if (!sessiond_pid) {
 			exit(EXIT_FAILURE);
 		}
@@ -351,7 +367,7 @@ static int check_sessiond(void)
 			pathname = opt_sessiond_path;
 		} else {
 			/* Try LTTNG_SESSIOND_PATH env variable */
-			pathname = getenv(LTTNG_SESSIOND_PATH_ENV);
+			pathname = getenv(DEFAULT_SESSIOND_PATH_ENV);
 		}
 
 		/* Let's rock and roll */
@@ -387,9 +403,9 @@ static int check_args_no_sessiond(int argc, char **argv)
 	int i;
 
 	for (i = 0; i < argc; i++) {
-		if ((strncmp(argv[i], "-h", 2) == 0) ||
-				strncmp(argv[i], "--h", 3) == 0 ||
-				strncmp(argv[i], "--list-options", 14)) {
+		if ((strncmp(argv[i], "-h", sizeof("-h")) == 0) ||
+				strncmp(argv[i], "--h", sizeof("--h")) == 0 ||
+				strncmp(argv[i], "--list-options", sizeof("--list-options")) == 0) {
 			return 1;
 		}
 	}