time/debug: Remove dentry pointer for debugfs

There is no need to keep the dentry pointer around for the created
debugfs file, as it is only needed when removing it from the system.
When it is to be removed, ask debugfs itself for the pointer, to save on
storage and make things a bit simpler.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20210216155020.1012407-1-gregkh@linuxfoundation.org

kernel/time/test_udelay.c

@@ -21,7 +21,6 @@
 #define DEBUGFS_FILENAME "udelay_test"
 
 static DEFINE_MUTEX(udelay_test_lock);
-static struct dentry *udelay_test_debugfs_file;
 static int udelay_test_usecs;
 static int udelay_test_iterations = DEFAULT_ITERATIONS;
 
@@ -138,8 +137,8 @@ static const struct file_operations udelay_test_debugfs_ops = {
 static int __init udelay_test_init(void)
 {
 	mutex_lock(&udelay_test_lock);
-	udelay_test_debugfs_file = debugfs_create_file(DEBUGFS_FILENAME,
-			S_IRUSR, NULL, NULL, &udelay_test_debugfs_ops);
+	debugfs_create_file(DEBUGFS_FILENAME, S_IRUSR, NULL, NULL,
+			    &udelay_test_debugfs_ops);
 	mutex_unlock(&udelay_test_lock);
 
 	return 0;
@@ -150,7 +149,7 @@ module_init(udelay_test_init);
 static void __exit udelay_test_exit(void)
 {
 	mutex_lock(&udelay_test_lock);
-	debugfs_remove(udelay_test_debugfs_file);
+	debugfs_remove(debugfs_lookup(DEBUGFS_FILENAME, NULL));
 	mutex_unlock(&udelay_test_lock);
 }