Hi, We are experiencing 'soft' deadlocks when running our code (Freebob, i.e. userspace lib for firewire audio) on RT kernels. After a few seconds, I get a kernel panic message that signals a soft lockup. The problems occur when an ISO stream (receive and/or transmit) is shut down in a SCHED_FIFO thread. More precisely when running the freebob jackd backend in real-time mode. And even more precise: they only seem to occur when jackd is shut down. There are no problems when jackd is run without RT scheduling. I havent been able to reproduce this with other test programs that are shutting down streams in a SCHED_FIFO thread. printk() debugging point to the tasklet_kill() call in ohci1349_unregister_iso_tasklet (drivers/ieee1394/ohci1394.c), that doesn't seem to return. For experiment, i've put a tasklet_disable before the tasklet_kill, and that causes the soft lockup to be due to the tasklet_disable. I would like to ask if anyone has a clue why this is happening. The only thing I can come up with is that jackd is stopped by a CTRL-C, and that the stream shutdown happens in signal handler context, which somehow interacts with the tasklet_kill. But I don't have the time now to dig into this, so for a change I ask for advice early instead of first banging my head against the wall for some days :). Thx, Pieter Palmers