media: uvcvideo: Check controls flags before accessing them

media: uvcvideo: Check controls flags before accessing them

[ Upstream commit ee929d5a10ca433a1c21b9aaeb70a67c5507c101 ]

We can figure out if reading/writing a set of controls can fail without
accessing them by checking their flags.

This way we can honor the API closer:

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.

Fixes v4l2-compliance:
Control ioctls (Input 0):
		warn: v4l2-test-controls.cpp(765): g_ext_ctrls(0) invalid error_idx 0
                fail: v4l2-test-controls.cpp(645): invalid error index write only control
        test VIDIOC_G/S/TRY_EXT_CTRLS: FAIL

Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Stable-dep-of: 9f582f0418ed ("media: uvcvideo: Check for INACTIVE in uvc_ctrl_is_accessible()")
Signed-off-by: Sasha Levin <sashal@kernel.org>