I wonder if we should be gating this else behind fds[i].revents != 0. It makes sense not to continue at the beginning unconditionally because we need to drop the reference if we had a device, but my concern in this branch is that we could have raced after poll(2) returned and accidentally drained something we shouldn't have.

The question I'm contemplating in particular is: if we were to avoid it here, would we observe a different state above poll(2) when we re-enter this function? e.g., a device appearing. In the worst case scenario, ignoring anything in the pipe here that wasn't at the time of the poll(2) causes a spurious wakeup and we subsequently drain it.