[PATCH v2] soc: ti: knav_qmss: remove debugfs file on teardown

[Pengpeng Hou <pengpeng@iscas.ac.cn>]

knav_queue_probe() creates the global qmss debugfs file whose show
callback reads the global knav_qdev state. knav_queue_remove() tears
down the queue manager resources but leaves the debugfs file published.

Save the debugfs dentry in struct knav_device and remove it during
teardown before the resources used by the show callback are released.
While touching the debugfs_create_file() call, spell the unchanged read-
only file mode as 0444.

Fixes: 41f93af900a2 ("soc: ti: add Keystone Navigator QMSS driver")
Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
Changes since v1:
- rebase on current linux/master
- store the debugfs dentry in struct knav_device instead of a separate
  global variable, as suggested by Nishanth
- spell the unchanged debugfs file mode as 0444 and document it
- keep the existing device_ready handling and current knav_qdev naming

 drivers/soc/ti/knav_qmss.h       | 1 +
 drivers/soc/ti/knav_qmss_queue.c | 7 +++++--
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/soc/ti/knav_qmss.h b/drivers/soc/ti/knav_qmss.h
index 037dc1b36645..8a624fbda84a 100644
--- a/drivers/soc/ti/knav_qmss.h
+++ b/drivers/soc/ti/knav_qmss.h
@@ -304,6 +304,7 @@ struct knav_device {
 	struct list_head			pools;
 	struct list_head			pdsps;
 	struct list_head			qmgrs;
+	struct dentry				*debugfs_file;
 	enum qmss_version			version;
 };
 
diff --git a/drivers/soc/ti/knav_qmss_queue.c b/drivers/soc/ti/knav_qmss_queue.c
index 7410b63af0e6..2d564c2937d4 100644
--- a/drivers/soc/ti/knav_qmss_queue.c
+++ b/drivers/soc/ti/knav_qmss_queue.c
@@ -1849,8 +1849,9 @@ static int knav_queue_probe(struct platform_device *pdev)
 		goto err;
 	}
 
-	debugfs_create_file("qmss", S_IFREG | S_IRUGO, NULL, NULL,
-			    &knav_queue_debug_fops);
+	knav_qdev->debugfs_file =
+		debugfs_create_file("qmss", 0444, NULL, NULL,
+				    &knav_queue_debug_fops);
 	device_ready = true;
 	return 0;
 
@@ -1868,6 +1869,8 @@ static void knav_queue_remove(struct platform_device *pdev)
 	struct knav_device *kdev = platform_get_drvdata(pdev);
 
 	device_ready = false;
+	debugfs_remove(kdev->debugfs_file);
+	kdev->debugfs_file = NULL;
 	knav_queue_stop_pdsps(kdev);
 	knav_queue_free_regions(kdev);
 	knav_free_queue_ranges(kdev);
-- 
2.43.0