V4L/DVB (10218): cx23885: Fix Oops for mixed install of analog and digital only cards

Analog support for HVR-1250 has not been completed, but does exist for
the HVR-1800.

Since both cards use the same driver, it tries to create the analog
dev for both devices, which is not possible.

This causes a NULL error to show up in video_open and mpeg_open.

-Mark

Iterations through the cx23885_devlist must check for NULL
pointers as some supported devices only have DVB support at the moment.
Mark Jenks encoutered an Oops in a system with both an HVR-1250 and HVR-1800
installed.

-Andy
Reported-by: Mark Jenks <mjenks1968@gmail.com>
Tested-by: Mark Jenks <mjenks1968@gmail.com>
Signed-off-by: Mark Jenks <mjenks1968@gmail.com>
Signed-off-by: Andy Walls <awalls@radix.net>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/cx23885/cx23885-417.c

@@ -1586,7 +1586,8 @@ static int mpeg_open(struct file *file)
 	lock_kernel();
 	list_for_each(list, &cx23885_devlist) {
 		h = list_entry(list, struct cx23885_dev, devlist);
-		if (h->v4l_device->minor == minor) {
+		if (h->v4l_device &&
+		    h->v4l_device->minor == minor) {
 			dev = h;
 			break;
 		}

drivers/media/video/cx23885/cx23885-video.c

@@ -730,7 +730,8 @@ static int video_open(struct file *file)
 	lock_kernel();
 	list_for_each(list, &cx23885_devlist) {
 		h = list_entry(list, struct cx23885_dev, devlist);
-		if (h->video_dev->minor == minor) {
+		if (h->video_dev &&
+		    h->video_dev->minor == minor) {
 			dev  = h;
 			type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
 		}