V4L/DVB (4316): Check __must_check warnings


Check __must_check warnings for class_device_register and class_device_create_file

video_device_create_file was declared as a void, but instead should
return the int value of class_device_create_file.

Move the check from bttv-driver.c into v4l2-dev.h, because all other
callers of video_device_create_file must also be checked.

Replace the call to class_device_create_file in videodev.c with
video_device_create_file, as defined in v4l2-dev.h, so that the
return value of class_device_create_file will be checked.

Check the return value of class_device_register in videodev.c and
pvrusb2-sysfs.c

Signed-off-by: Michael Krufky <mkrufky@linuxtv.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>
diff --git a/include/media/v4l2-dev.h b/include/media/v4l2-dev.h
index 62dae1a..f866532 100644
--- a/include/media/v4l2-dev.h
+++ b/include/media/v4l2-dev.h
@@ -341,11 +341,14 @@
 extern struct video_device* video_devdata(struct file*);
 
 #define to_video_device(cd) container_of(cd, struct video_device, class_dev)
-static inline void
+static inline int
 video_device_create_file(struct video_device *vfd,
 			 struct class_device_attribute *attr)
 {
-	class_device_create_file(&vfd->class_dev, attr);
+	int ret = class_device_create_file(&vfd->class_dev, attr);
+	if (ret < 0)
+		printk(KERN_WARNING "%s error: %d\n", __FUNCTION__, ret);
+	return ret;
 }
 static inline void
 video_device_remove_file(struct video_device *vfd,