* Steven Rostedt <[email protected]> wrote:
> Ingo,
>
> I traced this down. It is caused by the disable_irq in vortex_timer
> that is called via run_timer_softirq.
>
> disable_irq can call synchronize_irq which can schedule.
>
> And thus you get this bug since we are in a softirq.
hm. When there are threaded interrupts, we quite naturally have to
synchronize via scheduling, in synchronize_irq() - the interrupt we are
waiting on might be scheduled away!
> So I guess we have a case that we can schedule, but while atomic and
> BUG when it's really not bad. Should we add something like this:
that's not good enough, we must not schedule with the preempt_count()
set.
one solution would be to forbid disable_irq() from softirq contexts, and
to convert the vortex timeout function to a workqueue and use the
*_delayed_work() APIs to drive it - and cross fingers there's not many
places to fix.
another solution would be to make softirqs preemptible if they are
threaded. I'm a bit uneasy about that though. In that case we'd also
have to make HARDIRQ threading dependent on softirq threading, in the
Kconfig.
Ingo
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