debugfs: function to know if debugfs is initialized

Impact: add new debugfs API

With ftrace, some tracers are registered in early initcalls
and attempt to create files on the debugfs filesystem.
Depending on when they are activated, they can try to create their
file at any time. Some checks can be done on the tracing area
but providing a helper to know if debugfs is registered make it
really more easy.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 16 insertions, 0 deletions

diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c
index 81ae9ea3c6e1..0662ba6de85a 100644
--- a/fs/debugfs/inode.c
+++ b/fs/debugfs/inode.c
@@ -30,6 +30,7 @@
 
 static struct vfsmount *debugfs_mount;
 static int debugfs_mount_count;
+static bool debugfs_registered;
 
 static struct inode *debugfs_get_inode(struct super_block *sb, int mode, dev_t dev)
 {
@@ -496,6 +497,16 @@ exit:
 }
 EXPORT_SYMBOL_GPL(debugfs_rename);
 
+/**
+ * debugfs_initialized - Tells whether debugfs has been registered
+ */
+bool debugfs_initialized(void)
+{
+        return debugfs_registered;
+}
+EXPORT_SYMBOL_GPL(debugfs_initialized);
+
+
 static struct kobject *debug_kobj;
 
 static int __init debugfs_init(void)
@@ -509,11 +520,16 @@ static int __init debugfs_init(void)
         retval = register_filesystem(&debug_fs_type);
         if (retval)
                 kobject_put(debug_kobj);
+        else
+                debugfs_registered = true;
+
         return retval;
 }
 
 static void __exit debugfs_exit(void)
 {
+        debugfs_registered = false;
+
         simple_release_fs(&debugfs_mount, &debugfs_mount_count);
         unregister_filesystem(&debug_fs_type);
         kobject_put(debug_kobj);