Midi close race

+ if (open_devs < 2)
+ del_timer(&poll_timer);

Probably you need del_timer_sync():
Otherwise the timer could be running on another cpu.

+ open_devs--;

--
Manfred
(OT: Are there any mail archives that store the cc list? I'm not subscribed to l-k, and if I answer a mail the cc list is always lost)