diff mbox series

[v10,18/21] uvcvideo: improve error handling in uvc_query_ctrl()

Message ID 20210618122923.385938-19-ribalda@chromium.org
State New
Headers show
Series [v10,01/21] media: v4l2-ioctl: Fix check_ext_ctrls | expand

Commit Message

Ricardo Ribalda June 18, 2021, 12:29 p.m. UTC
From: Hans Verkuil <hverkuil-cisco@xs4all.nl>

- If __uvc_query_ctrl() failed with a non-EPIPE error, then
  report that with dev_err. If an error code is obtained, then
  report that with dev_dbg.

- For error 2 (Wrong state) return -EACCES instead of -EILSEQ.
  EACCES is a much more appropriate error code. EILSEQ will return
  "Invalid or incomplete multibyte or wide character." in strerror(),
  which is a *very* confusing message.

Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
---
 drivers/media/usb/uvc/uvc_video.c | 38 ++++++++++++++++++-------------
 1 file changed, 22 insertions(+), 16 deletions(-)

Comments

Laurent Pinchart Aug. 22, 2021, 11:52 p.m. UTC | #1
Hi Ricardo and Hans,

Thank you for the patch.

Please add a "media: " prefix to the subject line. Same for the other
patches in the series that are missing this.

On Fri, Jun 18, 2021 at 02:29:20PM +0200, Ricardo Ribalda wrote:
> From: Hans Verkuil <hverkuil-cisco@xs4all.nl>

> 

> - If __uvc_query_ctrl() failed with a non-EPIPE error, then

>   report that with dev_err. If an error code is obtained, then

>   report that with dev_dbg.

> 

> - For error 2 (Wrong state) return -EACCES instead of -EILSEQ.

>   EACCES is a much more appropriate error code. EILSEQ will return

>   "Invalid or incomplete multibyte or wide character." in strerror(),

>   which is a *very* confusing message.


I would still have split the patch in two :-)

> Reviewed-by: Ricardo Ribalda <ribalda@chromium.org>

> Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>

> ---

>  drivers/media/usb/uvc/uvc_video.c | 38 ++++++++++++++++++-------------

>  1 file changed, 22 insertions(+), 16 deletions(-)

> 

> diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c

> index daba5fe352ea..00488f15cdbf 100644

> --- a/drivers/media/usb/uvc/uvc_video.c

> +++ b/drivers/media/usb/uvc/uvc_video.c

> @@ -79,15 +79,11 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,

>  	if (likely(ret == size))

>  		return 0;

>  

> -	dev_err(&dev->udev->dev,

> -		"Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",

> -		uvc_query_name(query), cs, unit, ret, size);

> -

> -	if (ret != -EPIPE)

> -		return ret;

> +	if (ret < 0 && ret != -EPIPE)


What if ret >= 0 ? There's a change of behaviour here that isn't
documented in the commit message. It shouldn't happen, but it would be
nice to handle it correctly.

> +		goto err;

>  

> +	/* reuse data[0] to request the error code. */

>  	tmp = *(u8 *)data;

> -

>  	ret = __uvc_query_ctrl(dev, UVC_GET_CUR, 0, intfnum,

>  			       UVC_VC_REQUEST_ERROR_CODE_CONTROL, data, 1,

>  			       UVC_CTRL_CONTROL_TIMEOUT);

> @@ -95,19 +91,21 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,

>  	error = *(u8 *)data;

>  	*(u8 *)data = tmp;

>  

> -	if (ret != 1)

> -		return ret < 0 ? ret : -EPIPE;

> +	if (ret != 1) {

> +		ret = ret < 0 ? ret : -EPIPE;

> +		goto err;


This will print an error message that doesn't match the error.

> +	}

>  

> -	uvc_dbg(dev, CONTROL, "Control error %u\n", error);

> +	if (error >=1 && error <=8)


Missing space before 1 and 8.

> +		uvc_dbg(dev, CONTROL,

> +			"Failed to query (%s) UVC control %u on unit %u: got error %u.\n",

> +			uvc_query_name(query), cs, unit, error);

>  

>  	switch (error) {

> -	case 0:

> -		/* Cannot happen - we received a STALL */

> -		return -EPIPE;

>  	case 1: /* Not ready */

>  		return -EBUSY;

>  	case 2: /* Wrong state */

> -		return -EILSEQ;

> +		return -EACCES;

>  	case 3: /* Power */

>  		return -EREMOTE;

>  	case 4: /* Out of range */

> @@ -123,10 +121,18 @@ int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,

>  	case 8: /* Invalid value within range */

>  		return -EINVAL;

>  	default: /* reserved or unknown */

> -		break;

> +		dev_err(&dev->udev->dev,

> +			"Failed to query (%s) UVC control %u on unit %u: got error %u.\n",

> +			uvc_query_name(query), cs, unit, error);

> +		return -EPIPE;

>  	}

>  

> -	return -EPIPE;

> +err:

> +	dev_err(&dev->udev->dev,

> +		"Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",

> +		uvc_query_name(query), cs, unit, ret, size);

> +

> +	return ret;

>  }

>  

>  static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,


-- 
Regards,

Laurent Pinchart
diff mbox series

Patch

diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index daba5fe352ea..00488f15cdbf 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -79,15 +79,11 @@  int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,
 	if (likely(ret == size))
 		return 0;
 
-	dev_err(&dev->udev->dev,
-		"Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",
-		uvc_query_name(query), cs, unit, ret, size);
-
-	if (ret != -EPIPE)
-		return ret;
+	if (ret < 0 && ret != -EPIPE)
+		goto err;
 
+	/* reuse data[0] to request the error code. */
 	tmp = *(u8 *)data;
-
 	ret = __uvc_query_ctrl(dev, UVC_GET_CUR, 0, intfnum,
 			       UVC_VC_REQUEST_ERROR_CODE_CONTROL, data, 1,
 			       UVC_CTRL_CONTROL_TIMEOUT);
@@ -95,19 +91,21 @@  int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,
 	error = *(u8 *)data;
 	*(u8 *)data = tmp;
 
-	if (ret != 1)
-		return ret < 0 ? ret : -EPIPE;
+	if (ret != 1) {
+		ret = ret < 0 ? ret : -EPIPE;
+		goto err;
+	}
 
-	uvc_dbg(dev, CONTROL, "Control error %u\n", error);
+	if (error >=1 && error <=8)
+		uvc_dbg(dev, CONTROL,
+			"Failed to query (%s) UVC control %u on unit %u: got error %u.\n",
+			uvc_query_name(query), cs, unit, error);
 
 	switch (error) {
-	case 0:
-		/* Cannot happen - we received a STALL */
-		return -EPIPE;
 	case 1: /* Not ready */
 		return -EBUSY;
 	case 2: /* Wrong state */
-		return -EILSEQ;
+		return -EACCES;
 	case 3: /* Power */
 		return -EREMOTE;
 	case 4: /* Out of range */
@@ -123,10 +121,18 @@  int uvc_query_ctrl(struct uvc_device *dev, u8 query, u8 unit,
 	case 8: /* Invalid value within range */
 		return -EINVAL;
 	default: /* reserved or unknown */
-		break;
+		dev_err(&dev->udev->dev,
+			"Failed to query (%s) UVC control %u on unit %u: got error %u.\n",
+			uvc_query_name(query), cs, unit, error);
+		return -EPIPE;
 	}
 
-	return -EPIPE;
+err:
+	dev_err(&dev->udev->dev,
+		"Failed to query (%s) UVC control %u on unit %u: %d (exp. %u).\n",
+		uvc_query_name(query), cs, unit, ret, size);
+
+	return ret;
 }
 
 static void uvc_fixup_video_ctrl(struct uvc_streaming *stream,