Re: Ingo's realtime_preempt patch causes kernel oops

From: Steven Rostedt
Date: Tue May 23 2006 - 13:00:27 EST

On Tue, 2006-05-23 at 18:27 +0200, Yann.LEPROVOST@xxxxxxxxxx wrote:
> I forgot to say that I let SA_SHIRQ as the IRQ line is shared...
> It seems to work correctly...

What shares it?

Reason I ask, is that this irq is now running in true interrupt context,
and that on PREEMPT_RT the spin_locks are mutexes and can schedule. So
if another device is sharing this irq, then its interrupt handler will
be running in interrupt context, and if it grabs a spin_lock than is not
a raw_spinlock_t then you will have a crash.

This won't be a problem if you only turn on Hard irqs as threads and
don't do the PREEMPT_RT.

-- Steve

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