* sufficient (unless there have been 2**32 detaches in the
* meantime!), but check the subdevice pointer as well just in
* case.
+ *
+ * Also check the subdevice is still in a suitable state to
+ * become non-busy in case it changed behind our back.
*/
new_s = comedi_file_read_subdevice(file);
if (dev->attached && old_detach_count == dev->detach_count &&
- s == new_s && new_s->async == async) {
- if (become_nonbusy ||
- comedi_buf_read_n_available(s) == 0)
- do_become_nonbusy(dev, s);
- }
+ s == new_s && new_s->async == async && s->busy == file &&
+ !(async->cmd.flags & CMDF_WRITE) &&
+ !comedi_is_subdevice_running(s) &&
+ comedi_buf_read_n_available(s) == 0)
+ do_become_nonbusy(dev, s);
mutex_unlock(&dev->mutex);
}
out: