[ltt-dev] [PATCH v2] lttng: remove ltt root directory if it's no needed

[Gui Jianfeng]

We have to cleanup the lttng's root directory of debugfs if 
there is nobody uses it any more.

This patch is based on 2.6.29-rc3-lttng-0.92.

Signed-off-by: Gui Jianfeng <guijianfeng at cn.fujitsu.com>
---
 include/linux/ltt-core.h  |    1 +
 ltt/ltt-core.c            |   10 ++++++++++
 ltt/ltt-trace-control.c   |    4 +++-
 ltt/ltt-userspace-event.c |    1 +
 4 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/include/linux/ltt-core.h b/include/linux/ltt-core.h
index bc244c6..28394cb 100644
--- a/include/linux/ltt-core.h
+++ b/include/linux/ltt-core.h
@@ -30,6 +30,7 @@ extern struct ltt_traces ltt_traces;
 /*
  * get dentry of ltt's root dir
  */
+void put_ltt_root(void);
 struct dentry *get_ltt_root(void);
 
 /* Keep track of trap nesting inside LTT */
diff --git a/ltt/ltt-core.c b/ltt/ltt-core.c
index 18db91d..314750b 100644
--- a/ltt/ltt-core.c
+++ b/ltt/ltt-core.c
@@ -23,6 +23,16 @@ static DEFINE_MUTEX(ltt_traces_mutex);
 
 /* dentry of ltt's root dir */
 static struct dentry *ltt_root_dentry;
+
+void put_ltt_root(void)
+{
+	if (ltt_root_dentry && list_empty(&ltt_root_dentry->d_subdirs)) {
+		debugfs_remove(ltt_root_dentry);
+		ltt_root_dentry = NULL;
+	}
+}
+EXPORT_SYMBOL_GPL(put_ltt_root);
+
 struct dentry *get_ltt_root(void)
 {
 	if (!ltt_root_dentry) {
diff --git a/ltt/ltt-trace-control.c b/ltt/ltt-trace-control.c
index 16502a2..0cdeb8a 100644
--- a/ltt/ltt-trace-control.c
+++ b/ltt/ltt-trace-control.c
@@ -740,7 +740,8 @@ err_create_destroy_trace_file:
 err_create_setup_trace_file:
 	debugfs_remove(ltt_control_dir);
 err_create_control_dir:
-err_no_root:
+	put_ltt_root();
+ err_no_root:
 	return err;
 }
 
@@ -759,6 +760,7 @@ static void __exit ltt_trace_control_exit(void)
 	debugfs_remove(ltt_setup_trace_file);
 	debugfs_remove(ltt_destroy_trace_file);
 	debugfs_remove_recursive(ltt_control_dir);
+	put_ltt_root();
 }
 
 module_init(ltt_trace_control_init);
diff --git a/ltt/ltt-userspace-event.c b/ltt/ltt-userspace-event.c
index 385bd3b..a48f336 100644
--- a/ltt/ltt-userspace-event.c
+++ b/ltt/ltt-userspace-event.c
@@ -118,6 +118,7 @@ err_no_root:
 static void __exit ltt_userspace_exit(void)
 {
 	debugfs_remove(ltt_event_file);
+	put_ltt_root();
 }
 
 module_init(ltt_userspace_init);
-- 
1.5.4.rc3