lttctl: wait for lttd to complete in overwrite mode

[ltt-control.git] / lttctl / lttctl.c

diff --git a/lttctl/lttctl.c b/lttctl/lttctl.c
index 7380136fc6eefcbe1e0c4bb3da3e81e80815a438..afa55b67cc85bede5a51b44692d32a05c542d78c 100644 (file)
--- a/lttctl/lttctl.c
+++ b/lttctl/lttctl.c
@@ -2,14 +2,26 @@
  *
  * Linux Trace Toolkit Control
  *
- * Small program that controls LTT through libltt.
- *
- * Copyright 2005 -
- *     Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
+ * Small program that controls LTTng through liblttctl.
  *
  * Copyright 2008 FUJITSU
  *     Zhao Lei <zhaolei@cn.fujitsu.com>
  *     Gui Jianfeng <guijianfeng@cn.fujitsu.com>
+ * Copyright 2009-2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
  */
 
 #ifdef HAVE_CONFIG_H
@@ -144,6 +156,11 @@ static void show_arguments(void)
        printf("        Set channels root path, For -w option."
                " (ex. /mnt/debugfs/ltt)\n");
        printf("\n");
+       printf(" Environment variables:\n");
+       printf("  LTT_DAEMON\n");
+       printf("       Complete path to the lttd binary (needs to be\n");
+       printf("       specified if different than package build prefix).\n");
+       printf("\n");
 }
 
 /*
@@ -679,10 +696,13 @@ setup_trace_fail:
 }
 
 /*
- * Start a lttd daemon to write trace datas
+ * Start a lttd daemon to write trace data
  * Dump overwrite channels on overwrite!=0
  * Dump normal(non-overwrite) channels on overwrite=0
  *
+ * When called for overwrite mode, wait for lttd to return, so we are sure that
+ * trace session teardown is not executed before lttd can grab the buffer data.
+ *
  * ret: 0 on success
  *      !0 on fail
  */
@@ -743,8 +763,10 @@ static int lttctl_daemon(int overwrite)
                }
 
                /* -d option */
-               argv[argc] = "-d";
-               argc++;
+               if (!overwrite) {
+                       argv[argc] = "-d";
+                       argc++;
+               }
 
                /* overwrite option */
                if (overwrite) {