[PATCHv2 for v5.3] v4l2-subdev: fix regression in check_pad()

[PATCHv2 for v5.3] v4l2-subdev: fix regression in check_pad()

[Hans Verkuil]

sd->entity.graph_obj.mdev can be NULL when this function is called, and
that breaks existing drivers (rcar-vin, but probably others as well).

Check if sd->entity.num_pads is non-zero instead since that doesn't depend
on mdev.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Fixes: a8fa55078a77 ("media: v4l2-subdev: Verify arguments in v4l2_subdev_call()")
Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
---
Changes in v2:

- Don't change the coding style, just fix the bug.
---
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c
index 21fb90d66bfc..25c73c13cc7e 100644
--- a/drivers/media/v4l2-core/v4l2-subdev.c
+++ b/drivers/media/v4l2-core/v4l2-subdev.c
@@ -124,7 +124,7 @@ static inline int check_which(__u32 which)
 static inline int check_pad(struct v4l2_subdev *sd, __u32 pad)
 {
 #if defined(CONFIG_MEDIA_CONTROLLER)
-	if (sd->entity.graph_obj.mdev) {
+	if (sd->entity.num_pads) {
 		if (pad >= sd->entity.num_pads)
 			return -EINVAL;
 		return 0;

Re: [PATCHv2 for v5.3] v4l2-subdev: fix regression in check_pad()

[Geert Uytterhoeven]

[-- Attachment #1: Type: text/plain, Size: 1272 bytes --]

 	Hi Hans,

On Sat, 29 Jun 2019, Hans Verkuil wrote:
> sd->entity.graph_obj.mdev can be NULL when this function is called, and
> that breaks existing drivers (rcar-vin, but probably others as well).
>
> Check if sd->entity.num_pads is non-zero instead since that doesn't depend
> on mdev.
>
> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Reported-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
> Fixes: a8fa55078a77 ("media: v4l2-subdev: Verify arguments in v4l2_subdev_call()")
> Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>

Thanks, this fixes the following boot regression on r8a7791/koelsch:

     -rcar-vin e6ef0000.video: Device registered as video27
     +rcar-vin e6ef0000.video: Unsupported media bus format for adv7612 13-004c
     +rcar-vin e6ef0000.video: Notifier registration failed
     +rcar-vin: probe of e6ef0000.video failed with error -22

Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

 						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
 							    -- Linus Torvalds