[PATCH v5 10/13] media: uvcvideo: Return -EACCES to inactive controls

[Ricardo Ribalda]

If a control is inactive return -EACCES to let the userspace know that
the value will not be applied automatically when the control is active
again.

Signed-off-by: Ricardo Ribalda <riba...@chromium.org>
Suggested-by: Hans Verkuil <hverk...@xs4all.nl>
---
 drivers/media/usb/uvc/uvc_ctrl.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index ba14733db757..98614e1be829 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -1578,6 +1578,18 @@ int uvc_ctrl_begin(struct uvc_video_chain *chain)
        return mutex_lock_interruptible(&chain->ctrl_mutex) ? -ERESTARTSYS : 0;
 }
 
+static bool uvc_ctrl_is_inactive(struct uvc_control *ctrl)
+{
+       struct uvc_control_mapping *map;
+
+       list_for_each_entry(map, &ctrl->info.mappings, list) {
+               if (map->master_id)
+                       return true;
+       }
+
+       return false;
+}
+
 static int uvc_ctrl_commit_entity(struct uvc_device *dev,
        struct uvc_entity *entity, int rollback)
 {
@@ -1621,8 +1633,11 @@ static int uvc_ctrl_commit_entity(struct uvc_device *dev,
 
                ctrl->dirty = 0;
 
-               if (ret < 0)
+               if (ret < 0) {
+                       if (uvc_ctrl_is_inactive(ctrl))
+                               return -EACCES;
                        return ret;
+               }
        }
 
        return 0;
-- 
2.31.0.rc2.261.g7f71774620-goog