On 31/12/05, Philippe Gerum <[EMAIL PROTECTED]> wrote:

> ...

> 2) xnintr_irq_handler() gets a cookie which is == xnshared_irq_t* (see
> xnintr_attach) that may already be invalid at that time or, and that's a
> problem, become invalid during the execution of xnintr_irq_handler().
> To prevent that, we could add a flag like IRQ_INPROGRESS but
>
> either we have to set/remove it on the adeos layer before the control is
> passed to the xnintr_irq_handler() (to be sure that cookie is not
> xnfree()'d. xnintr_detach() will do busy waiting)
>

Synchronizing the pending IRQs in ipipe_virtualize_irq() should be done
by polling the proper irq_pending count (and _not_ the hi/lo bits which
get cleared before the handler is run).

But irq_pending counter (pending_hits in the recent adeos patch) gets cleared before running the isr handler too.

In ipipe_sync_stage() :
...
            if (--cpudata->irq_pending_hits[irq] == 0) {
                 __clear_bit(rank,
                         &cpudata->irq_pending_lo[level]);
                 ipipe_mark_irq_delivery(ipd,irq,cpuid);
            }
(*)

// run the corresponding isr handler

This code drops the irq_pending_hits to 0 before running the handler.

Doesn't it make the following code wrong ?

for (_cpuid = 0; _cpuid < nr_cpus; _cpuid++)
        while (ipd->cpudata[_cpuid].irq_pending_hits[irq] > 0)
                cpu_relax();

as the handler still can be running / or even about to be run when ipd->cpudata[_cpuid].irq_pending_hits[irq] is already 0.

We can remove the (*) code at the end of ipipe_sync_stage() so that irq_pending_hits[irq] may become 0 only after the corresponding isr handler has completed.

At the same time, the irq_pending counter can't be increased anymore since we clear the IPIPE_HANDLE_FLAG before doing the busy waiting in ipipe_unregister_domain() or ipipe_virtualize_irq().
 

--

Philippe.

--
Best regards,
Dmitry Adamushko

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