On 03/27/2013 10:30 AM, Jan Kiszka wrote:
> On 2013-03-27 10:23, Gilles Chanteperdrix wrote:
>> On 03/27/2013 07:50 AM, Jan Kiszka wrote:
>>
>>> On 2013-03-27 00:05, Gilles Chanteperdrix wrote:
>>>>
>>>> Hi Jan,
>>>>
>>>> I seem to recall you sent patches to fix threaded irqs some time ago. I
>>>
>>> In fact, that was Wolfgang with commits fdda86bca9 and 54d161b85b for
>>> 2.6.38 back then.
>>>
>>>> am having a problem here without SMP, whereas the system works with
>>>> SMP. A fasteoi irq handler triggers repeatedly while its threaded
>>>> counterpart never gets triggered. I believe this is because
>>>> handle_fasteoi_irq unconditionally releases the irq line.
>>>
>>> You mean it doesn't respect the conditions in cond_unmask_irq?
>>>
>>>> The following
>>>> patch seems to fix the issue though I would prefer a cleaner solution.
>>>>
>>>> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
>>>> index 11e75d1..2ff8d3a 100644
>>>> --- a/kernel/irq/chip.c
>>>> +++ b/kernel/irq/chip.c
>>>> @@ -463,8 +463,11 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc
>>>> *desc)
>>>>
>>>> #ifdef CONFIG_IPIPE
>>>> /* XXX: IRQCHIP_EOI_IF_HANDLED is ignored. */
>>>> - if (desc->irq_data.chip->irq_release)
>>>> - desc->irq_data.chip->irq_release(&desc->irq_data);
>>>> + if (desc->irq_data.chip->irq_release) {
>>>> + if ((!(desc->istate & IRQS_ONESHOT) ||
>>>> + !desc->threads_oneshot))
>>>> + desc->irq_data.chip->irq_release(&desc->irq_data);
>>>> + }
>>>> out_eoi:
>>>> #else /* !CONFIG_IPIPE */
>>>> if (desc->istate & IRQS_ONESHOT)
>>>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>>>> index e49a288..485c2c4 100644
>>>> --- a/kernel/irq/manage.c
>>>> +++ b/kernel/irq/manage.c
>>>> @@ -715,9 +715,15 @@ again:
>>>>
>>>> desc->threads_oneshot &= ~action->thread_mask;
>>>>
>>>> - if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data) &&
>>>> - irqd_irq_masked(&desc->irq_data))
>>>> - unmask_irq(desc);
>>>> + if (!desc->threads_oneshot && !irqd_irq_disabled(&desc->irq_data)) {
>>>> +#ifdef CONFIG_IPIPE
>>>> + if (desc->irq_data.chip->irq_release)
>>>> + desc->irq_data.chip->irq_release(&desc->irq_data);
>>>> + else
>>>> +#endif
>>>> + if (irqd_irq_masked(&desc->irq_data))
>>>> + unmask_irq(desc);
>>>> + }
>>>>
>>>> out_unlock:
>>>> raw_spin_unlock_irq(&desc->lock);
>>>>
>>>>
>>>
>>> So this basically extends I-pipe's held phase of the IRQ to the threaded
>>> handler if we are working in oneshot mode, right?
>>>
>>> I will have to dig into this again, but without remembering all details,
>>> there are some things that do not look OK:
>>> - Shouldn't we just replace unmask_irq with irq_release for the I-pipe
>>> case? IOW: There is too much code under #ifdef CONFIG_IPIPE.
>>
>>
>> No, unmask_irq still has to use ->irq_unmask, while the masking done by
>> the I-pipe has to use ->irq_release.
>
> No, I mean that unmask should be replaced by release, but we must not
> apply different conditions on the unmask, at least the logical one. If
> Linux wants the line to remain masked, we have to respect this. That is
> currently (also) broken after the last refactoring.
Ok, how about this one:
iff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index 11e75d1..47d1d27 100644
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -256,13 +256,19 @@ void mask_irq(struct irq_desc *desc)
void unmask_irq(struct irq_desc *desc)
{
unsigned long flags;
-
+
+ flags = hard_cond_local_irq_save();
+#ifdef CONFIG_IPIPE
+ if (desc->irq_data.chip->irq_release) {
+ desc->irq_data.chip->irq_release(&desc->irq_data);
+ irq_state_clr_masked(desc);
+ } else
+#endif /* CONFIG_IPIPE */
if (desc->irq_data.chip->irq_unmask) {
- flags = hard_cond_local_irq_save();
desc->irq_data.chip->irq_unmask(&desc->irq_data);
irq_state_clr_masked(desc);
- hard_cond_local_irq_restore(flags);
}
+ hard_cond_local_irq_restore(flags);
}
/*
@@ -463,8 +469,7 @@ handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc)
#ifdef CONFIG_IPIPE
/* XXX: IRQCHIP_EOI_IF_HANDLED is ignored. */
- if (desc->irq_data.chip->irq_release)
- desc->irq_data.chip->irq_release(&desc->irq_data);
+ cond_unmask_irq(desc);
out_eoi:
#else /* !CONFIG_IPIPE */
if (desc->istate & IRQS_ONESHOT)
@@ -682,12 +687,15 @@ void __ipipe_end_level_irq(unsigned irq, struct irq_desc
*desc)
void __ipipe_ack_fasteoi_irq(unsigned irq, struct irq_desc *desc)
{
desc->irq_data.chip->irq_hold(&desc->irq_data);
+ irq_state_set_masked(desc);
}
void __ipipe_end_fasteoi_irq(unsigned irq, struct irq_desc *desc)
{
- if (desc->irq_data.chip->irq_release)
+ if (desc->irq_data.chip->irq_release) {
+ irq_state_clr_masked(desc);
desc->irq_data.chip->irq_release(&desc->irq_data);
+ }
}
void __ipipe_ack_edge_irq(unsigned irq, struct irq_desc *desc)
--
Gilles.
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