[PATCH] v4l2-ctrls: v4l2_ctrl_request_complete() should always set ref->req

[PATCH] v4l2-ctrls: v4l2_ctrl_request_complete() should always set ref->req

[Hans Verkuil]

When the request is completed, all controls are copied to the request object.
However, when VIDIOC_G_EXT_CTRLS attempts to read control values from the
request it will read the current value instead for any control reference that
has a NULL ref->req pointer. But that's wrong: after completing the request
*all* controls should have a non-NULL ref->req pointer since they are after
all copied to the request.

So set ref->req if it wasn't set already.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reported-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
---
diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
index 2928c5e0a73d..93d33d1db4e8 100644
--- a/drivers/media/v4l2-core/v4l2-ctrls.c
+++ b/drivers/media/v4l2-core/v4l2-ctrls.c
@@ -4296,10 +4296,17 @@ void v4l2_ctrl_request_complete(struct media_request *req,
 			continue;

 		v4l2_ctrl_lock(ctrl);
-		if (ref->req)
+		if (ref->req) {
 			ptr_to_ptr(ctrl, ref->req->p_req, ref->p_req);
-		else
+		} else {
 			ptr_to_ptr(ctrl, ctrl->p_cur, ref->p_req);
+			/*
+			 * Set ref->req to ensure that when userspace wants to
+			 * obtain the controls of this request it will take
+			 * this value and not the current value of the control.
+			 */
+			ref->req = ref;
+		}
 		v4l2_ctrl_unlock(ctrl);
 	}

Re: [PATCH] v4l2-ctrls: v4l2_ctrl_request_complete() should always set ref->req

[Paul Kocialkowski]

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Hi,

On Tue 03 Mar 20, 11:34, Hans Verkuil wrote:
> When the request is completed, all controls are copied to the request object.
> However, when VIDIOC_G_EXT_CTRLS attempts to read control values from the
> request it will read the current value instead for any control reference that
> has a NULL ref->req pointer. But that's wrong: after completing the request
> *all* controls should have a non-NULL ref->req pointer since they are after
> all copied to the request.
> 
> So set ref->req if it wasn't set already.

Works fine here with this patch!

Tested-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>

Cheers,

Paul

> Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
> Reported-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
> ---
> diff --git a/drivers/media/v4l2-core/v4l2-ctrls.c b/drivers/media/v4l2-core/v4l2-ctrls.c
> index 2928c5e0a73d..93d33d1db4e8 100644
> --- a/drivers/media/v4l2-core/v4l2-ctrls.c
> +++ b/drivers/media/v4l2-core/v4l2-ctrls.c
> @@ -4296,10 +4296,17 @@ void v4l2_ctrl_request_complete(struct media_request *req,
>  			continue;
> 
>  		v4l2_ctrl_lock(ctrl);
> -		if (ref->req)
> +		if (ref->req) {
>  			ptr_to_ptr(ctrl, ref->req->p_req, ref->p_req);
> -		else
> +		} else {
>  			ptr_to_ptr(ctrl, ctrl->p_cur, ref->p_req);
> +			/*
> +			 * Set ref->req to ensure that when userspace wants to
> +			 * obtain the controls of this request it will take
> +			 * this value and not the current value of the control.
> +			 */
> +			ref->req = ref;
> +		}
>  		v4l2_ctrl_unlock(ctrl);
>  	}
> 

-- 
Paul Kocialkowski, Bootlin
Embedded Linux and kernel engineering
https://bootlin.com

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