Fix comments and enforce expected return values

[lttng-tools.git] / src / bin / lttng / lttng.c

diff --git a/src/bin/lttng/lttng.c b/src/bin/lttng/lttng.c
index aeaad1469725db898871c6a644f1b2a00119d8a7..36d4c913df48ab681cbfac27e428c3f7888d339c 100644 (file)
--- a/src/bin/lttng/lttng.c
+++ b/src/bin/lttng/lttng.c
@@ -82,23 +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");
@@ -316,19 +316,20 @@ static int spawn_sessiond(char *pathname)
        } else if (pid > 0) {
                sessiond_pid = pid;
                /*
-                * 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.
+                * 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);
                }
+               /*
+                * The signal handler will nullify sessiond_pid on SIGCHLD
+                */
                if (!sessiond_pid) {
                        exit(EXIT_FAILURE);
                }