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From:   Ricardo Ribalda <ribalda@chromium.org>
To:     Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Ricardo Ribalda <ribalda@chromium.org>
Subject: [PATCH v4 04/11] media: uvcvideo: set error_idx to count on EACCESS
Date:   Mon, 15 Mar 2021 18:36:02 +0100
Message-Id: <20210315173609.1547857-5-ribalda@chromium.org>
In-Reply-To: <20210315173609.1547857-1-ribalda@chromium.org>
References: <20210315173609.1547857-1-ribalda@chromium.org>
MIME-Version: 1.0
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If an error is found when validating the list of controls passed with
VIDIOC_G_EXT_CTRLS, then error_idx shall be set to ctrls->count to
indicate to userspace that no actual hardware was touched.

It would have been much nicer of course if error_idx could point to the
control index that failed the validation, but sadly that's not how the
API was designed.

Fixes v4l2-compliance:
Control ioctls (Input 0):
                fail: v4l2-test-controls.cpp(645): invalid error index write only control
        test VIDIOC_G/S/TRY_EXT_CTRLS: FAIL

Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
---
 drivers/media/usb/uvc/uvc_v4l2.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index 157310c0ca87..36eb48622d48 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -1073,7 +1073,8 @@ static int uvc_ioctl_g_ext_ctrls(struct file *file, void *fh,
 		ret = uvc_ctrl_get(chain, ctrl);
 		if (ret < 0) {
 			uvc_ctrl_rollback(handle);
-			ctrls->error_idx = i;
+			ctrls->error_idx = (ret == -EACCES) ?
+						ctrls->count : i;
 			return ret;
 		}
 	}
-- 
2.31.0.rc2.261.g7f71774620-goog