linux-kernel - [PATCH v6 03/17] media: v4l2-ioctl: check_ext_ctrls: Return the right error

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Date:   Wed, 17 Mar 2021 17:44:57 +0100
From:   Ricardo Ribalda <ribalda@...omium.org>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        tfiga@...omium.org
Cc:     Ricardo Ribalda <ribalda@...omium.org>, stable@...r.kernel.org
Subject: [PATCH v6 03/17] media: v4l2-ioctl: check_ext_ctrls: Return the right error_idx

Drivers that do not use the ctrl-framework use this function instead.

- Return the right error_idx

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):
        warn: v4l2-test-controls.cpp(834): error_idx should be equal to count
        warn: v4l2-test-controls.cpp(855): error_idx should be equal to count

Cc: stable@...r.kernel.org
Fixes: 6fa6f831f095 ("media: v4l2-ctrls: add core request support")
Signed-off-by: Ricardo Ribalda <ribalda@...omium.org>
---
 drivers/media/v4l2-core/v4l2-ioctl.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
index 76e2e595d88d..528eb5f420f6 100644
--- a/drivers/media/v4l2-core/v4l2-ioctl.c
+++ b/drivers/media/v4l2-core/v4l2-ioctl.c
@@ -932,13 +932,14 @@ static bool check_ext_ctrls(struct v4l2_ext_controls *c, unsigned long ioctl)
 	case V4L2_CTRL_WHICH_CUR_VAL:
 		return true;
 	case V4L2_CTRL_WHICH_REQUEST_VAL:
+		c->error_idx = c->count;
 		return false;
 	}
 
 	/* Check that all controls are from the same control class. */
 	for (i = 0; i < c->count; i++) {
 		if (V4L2_CTRL_ID2WHICH(c->controls[i].id) != c->which) {
-			c->error_idx = i;
+			c->error_idx = ioctl == VIDIOC_TRY_EXT_CTRLS ? i : c->count;
 			return false;
 		}
 	}
-- 
2.31.0.rc2.261.g7f71774620-goog