mask = 0;
read_subdev = comedi_get_read_subdevice(dev_file_info);
- if (read_subdev) {
+ if (read_subdev && read_subdev->async) {
poll_wait(file, &read_subdev->async->wait_head, wait);
if (!read_subdev->busy
|| comedi_buf_read_n_available(read_subdev->async) > 0
}
}
write_subdev = comedi_get_write_subdevice(dev_file_info);
- if (write_subdev) {
+ if (write_subdev && write_subdev->async) {
poll_wait(file, &write_subdev->async->wait_head, wait);
comedi_buf_write_alloc(write_subdev->async,
write_subdev->async->prealloc_bufsz);
}
s = comedi_get_write_subdevice(dev_file_info);
- if (s == NULL) {
+ if (s == NULL || s->async == NULL) {
retval = -EIO;
goto done;
}
}
s = comedi_get_read_subdevice(dev_file_info);
- if (s == NULL) {
+ if (s == NULL || s->async == NULL) {
retval = -EIO;
goto done;
}