Re: rt20 patch question

[Steven Rostedt]

On Fri, 12 May 2006, Ingo Molnar wrote:

>
> > 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.

It gets even worse, with your new fix, the softirq will schedule with
interrutps disabled, which would definitely BUG.

>
> 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.

I prefer the above. Maybe even add a WARN_ON(in_softirq()) in disable_irq.

But I must admit, I wouldn't know how to make that change without spending
more time on it then I have for this.

>
> 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.

scary.

-- Steve

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