i have released the -V0.7.41-00 Real-Time Preemption patch (merged to
2.6.12-rc1), which can be downloaded from the usual place:

  http://redhat.com/~mingo/realtime-preempt/

the biggest change in this patch is the merge of Paul E. McKenney's
preemptable RCU code. The new RCU code is active on PREEMPT_RT. While it
is still quite experimental at this stage, it allowed the removal of
locking cruft (mainly in the networking code), so it could solve some of
the longstanding netfilter/networking deadlocks/crashes reported by a
number of people. Be careful nevertheless.

there are a couple of minor changes relative to Paul's latest
preemptable-RCU code drop:

 - made the two variants two #ifdef blocks - this is sufficient for now
   and we'll see what the best way is in the longer run.

 - moved rcu_check_callbacks() from the timer IRQ to ksoftirqd. (the
   timer IRQ still runs in hardirq context on PREEMPT_RT.)

 - changed the irq-flags method to a preempt_disable()-based method, and
   moved the lock taking outside of the critical sections. (due to locks
   potentially sleeping on PREEMPT_RT).

to create a -V0.7.41-00 tree from scratch, the patching order is:

  http://kernel.org/pub/linux/kernel/v2.6/linux-2.6.11.tar.bz2
  http://kernel.org/pub/linux/kernel/v2.6/testing/patch-2.6.12-rc1.bz2
  http://redhat.com/~mingo/realtime-preempt/realtime-preempt-2.6.12-rc1...

        Ingo

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