[media] uvcvideo: Set error_idx properly for extended controls API failures

When one of the requested controls doesn't exist the error_idx field
must reflect that situation. For G_EXT_CTRLS and S_EXT_CTRLS, error_idx
must be set to the control count. For TRY_EXT_CTRLS, it must be set to
the index of the unexisting control.
This issue was found by the v4l2-compliance tool.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/usb/uvc/uvc_v4l2.c

@@ -591,8 +591,10 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 
 		ret = uvc_ctrl_get(chain, &xctrl);
 		uvc_ctrl_rollback(handle);
-		if (ret >= 0)
-			ctrl->value = xctrl.value;
+		if (ret < 0)
+			return ret == -ENOENT ? -EINVAL : ret;
+
+		ctrl->value = xctrl.value;
 		break;
 	}
 
@@ -612,7 +614,7 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 		ret = uvc_ctrl_set(chain, &xctrl);
 		if (ret < 0) {
 			uvc_ctrl_rollback(handle);
-			return ret;
+			return ret == -ENOENT ? -EINVAL : ret;
 		}
 		ret = uvc_ctrl_commit(handle, &xctrl, 1);
 		if (ret == 0)
@@ -637,8 +639,9 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 			ret = uvc_ctrl_get(chain, ctrl);
 			if (ret < 0) {
 				uvc_ctrl_rollback(handle);
-				ctrls->error_idx = i;
-				return ret;
+				ctrls->error_idx = ret == -ENOENT
+						 ? ctrls->count : i;
+				return ret == -ENOENT ? -EINVAL : ret;
 			}
 		}
 		ctrls->error_idx = 0;
@@ -661,8 +664,10 @@ static long uvc_v4l2_do_ioctl(struct file *file, unsigned int cmd, void *arg)
 			ret = uvc_ctrl_set(chain, ctrl);
 			if (ret < 0) {
 				uvc_ctrl_rollback(handle);
-				ctrls->error_idx = i;
-				return ret;
+				ctrls->error_idx = (ret == -ENOENT &&
+						    cmd == VIDIOC_S_EXT_CTRLS)
+						 ? ctrls->count : i;
+				return ret == -ENOENT ? -EINVAL : ret;
 			}
 		}