[ltt-dev] [PATCH 2/2] Make lttctl load ltt-trace-control module automatically

[zhaolei@cn.fujitsu.com (Zhaolei)]

lttctl need to use ltt-trace-control module.
This patch make lttctl try to load ltt-trace-control module automatically when
ltt-trace-control is compiled as a module and not loaded.

Applies on ltt-control-0.63-03012009 with previous patch of:
[PATCH 1/2] Make lttctl mount debugfs automatically

Signed-off-by: Zhao lei <zhaolei at cn.fujitsu.com>
---
 liblttctl.c |   51 +++++++++++++++++++++++++++++++++++++++------------
 1 file changed, 39 insertions(+), 12 deletions(-)
diff -Nur ltt-control-0.63-03012009.org/liblttctl/liblttctl.c ltt-control-0.63-03012009.new/liblttctl/liblttctl.c
--- ltt-control-0.63-03012009.org/liblttctl/liblttctl.c	2009-01-07 15:54:45.000000000 +0800
+++ ltt-control-0.63-03012009.new/liblttctl/liblttctl.c	2009-01-07 15:54:49.000000000 +0800
@@ -42,11 +42,44 @@
 	return getdebugfsmntdir(debugfsmntdir);
 }
 
+/*
+ * This function must called posterior to initdebugfsmntdir(),
+ * because it need to use debugfsmntdir[] which is inited in initdebugfsmntdir()
+ */
+static int initmodule(void)
+{
+	char controldirname[PATH_MAX];
+	DIR *dir;
+	int tryload_done = 0;
+
+	sprintf(controldirname, "%s/ltt/control/", debugfsmntdir);
+
+check_again:
+	/*
+	 * Check ltt control's debugfs dir
+	 *
+	 * We don't check is ltt-trace-control module exist, because it maybe
+	 * compiled into kernel.
+	 */
+	dir = opendir(controldirname);
+	if (dir) {
+		closedir(dir);
+		return 0;
+	}
+
+	if (!tryload_done) {
+		system("modprobe ltt-trace-control");
+		tryload_done = 1;
+		goto check_again;
+	}
+
+	return -ENOENT;
+}
+
 int lttctl_init(void)
 {
 	int ret;
-	DIR *dir;
-	char controldirname[PATH_MAX];
+
 
 	ret = initdebugfsmntdir();
 	if (ret) {
@@ -54,18 +87,12 @@
 		return 1;
 	}
 
-	/* check ltt control's debugfs dir */
-	sprintf(controldirname, "%s/ltt/control/", debugfsmntdir);
-
-	dir = opendir(controldirname);
-	if (!dir) {
-		fprintf(stderr, "ltt-trace-control's debugfs dir not found\n");
-		closedir(dir);
-		return -errno;
+	ret = initmodule();
+	if (ret) {
+		fprintf(stderr, "Control module seems not work\n");
+		return 1;
 	}
 
-	closedir(dir);
-
 	return 0;
 }