[media] v4l2-fh: add v4l2_fh_is_singular
Several drivers need to do something when the first filehandle is opened
or the last filehandle is closed. Most implement some use count mechanism,
but if they use v4l2_fh, then you can also just check if this is the only
filehandle for the device node. A simple helper function can do this.
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/include/media/v4l2-fh.h b/include/media/v4l2-fh.h
index 5657881..0206aa5 100644
--- a/include/media/v4l2-fh.h
+++ b/include/media/v4l2-fh.h
@@ -77,5 +77,18 @@
* v4l2_fh struct) is NULL. This function always returns 0.
*/
int v4l2_fh_release(struct file *filp);
+/*
+ * Returns 1 if this filehandle is the only filehandle opened for the
+ * associated video_device. If fh is NULL, then it returns 0.
+ */
+int v4l2_fh_is_singular(struct v4l2_fh *fh);
+/*
+ * Helper function with struct file as argument. If filp->private_data is
+ * NULL, then it will return 0.
+ */
+static inline int v4l2_fh_is_singular_file(struct file *filp)
+{
+ return v4l2_fh_is_singular(filp->private_data);
+}
#endif /* V4L2_EVENT_H */