Therefor the the tty_scedule_flip() function and replaced it
everywhere with the tty_flip_buffer_push() beause that function is
used the most by serial drivers and implements the work queue bypass
mechanism.

So now when the user sets tty->low_latency on these devices the machine
crashes ?

This is the wrong direction - in fact we have a pile we need to move
the other way !

If they resolve to the same thing in hard RT patches fine, that's a
different question.

Alan