From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [Adeos-main] [PATCH+HACK] optimise root stalling
From: Philippe Gerum <rpm@xenomai.org>
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Date: Thu, 28 Sep 2006 11:16:37 +0200
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To: Jan Kiszka <jan.kiszka@domain.hid>
Cc: adeos-main@gna.org

On Thu, 2006-09-28 at 11:15 +0200, Jan Kiszka wrote:
> Philippe Gerum wrote:
> > On Mon, 2006-09-25 at 09:35 +0200, Jan Kiszka wrote:
> > 
> > This one won't work. We need to forcibly re-enable the hw IRQs upon root
> > unstall requests, regardless of the fact that interrupts are pending in
> > the log; some code rely on this. E.g. Adeos/ppc over 2.4 would remain
> > stuck in the delay calibration routine, but there are other more tricky
> > places where this would bite too.
> 
> But this would be ok?
> 
> #else  /* !CONFIG_SMP */
>         __clear_bit(IPIPE_STALL_FLAG,
>                     &ipipe_root_domain->cpudata[cpuid].status);
> 
>        if (unlikely(ipipe_root_domain->cpudata[cpuid].irq_pending_hi !=
>            0)) {
>                local_irq_disable_hw();
>                __ipipe_sync_pipeline(IPIPE_IRQMASK_ANY);
>        }
>        local_irq_enable_hw();
> #endif /* CONFIG_SMP */
> 
> So we can still save one disable IRQ in the fastpath.
> 

But in such a case, you would have to use clear_bit() to keep atomicity.

> Jan
> 
-- 
Philippe.