Jeremy Fitzhardinge wrote:
> On 10/23/09 04:39, Han, Weidong wrote:
>> From 9c91f23076c555690488cbd81f889f279d4cf2fa Mon Sep 17 00:00:00
>> 2001
>> From: Weidong Han <weidong.han@xxxxxxxxx>
>> Date: Sat, 24 Oct 2009 03:18:30 +0800
>> Subject: [PATCH] pv-ops: fix shared irq device passthrough
>>
>> In driver/xen/events.c, whether bind_pirq is shareable or not is
>> determined by desc->action is NULL or not. But in __setup_irq,
>> startup(irq) is invoked before desc->action is assigned with
>> new action. So desc->action in startup_irq is alwasy NULL, and
>> bind_pirq is always not shareable. This results in pt_irq_create_bind
>> failure when passthrough a device which shares irq to other devices.
>>
>> This patch move desc->action before startup(irq), therefore fix
>> the problem.
>>
>
> Hm, not sure about this. The logic in __setup_irq already looks
> pretty tortured, and I'd like to avoid touching it unless there's
> definitively a bug in there.
>
> I think the right question is whether probe_irq() is really doing the
> right test, and whether it could do something else instead?
Totally agree. The better way is to change probe_irq, therefore needn't touch
kernel irq stuffs. probe_irq is just check if desc->action == NULL or not. The
code is there for a long long time (from c/s 26 in linux-2.6.18-xen.hg). I
don't know whether it can be replaced.
Regards,
Weidong
>
> J
>
>> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
>> ---
>> kernel/irq/manage.c | 14 ++++++++++----
>> 1 files changed, 10 insertions(+), 4 deletions(-)
>>
>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>> index 07a11dc..3b85b72 100644
>> --- a/kernel/irq/manage.c
>> +++ b/kernel/irq/manage.c
>> @@ -565,6 +565,7 @@ __setup_irq(unsigned int irq, struct irq_desc
>> *desc, struct irqaction *new) { struct irqaction *old, **old_ptr;
>> const char *old_name = NULL;
>> + int old_irq;
>> unsigned long flags;
>> int shared = 0;
>> int ret;
>> @@ -644,6 +645,11 @@ __setup_irq(unsigned int irq, struct irq_desc
>> *desc, struct irqaction *new) shared = 1; }
>>
>> + old = *old_ptr;
>> + old_irq = new->irq;
>> + new->irq = irq;
>> + *old_ptr = new;
>> +
>> if (!shared) {
>> irq_chip_set_defaults(desc->chip);
>>
>> @@ -654,8 +660,11 @@ __setup_irq(unsigned int irq, struct irq_desc
>> *desc, struct irqaction *new) ret =
>> __irq_set_trigger(desc, irq,
>> new->flags & IRQF_TRIGGER_MASK);
>>
>> - if (ret)
>> + if (ret) {
>> + new->irq = old_irq;
>> + *old_ptr = old;
>> goto out_thread;
>> + }
>> } else
>> compat_irq_chip_set_default_handler(desc);
>> #if defined(CONFIG_IRQ_PER_CPU)
>> @@ -690,9 +699,6 @@ __setup_irq(unsigned int irq, struct irq_desc
>> *desc, struct irqaction *new) (int)(new->flags &
>> IRQF_TRIGGER_MASK)); }
>>
>> - new->irq = irq;
>> - *old_ptr = new;
>> -
>> /* Reset broken irq detection when installing new handler */
>> desc->irq_count = 0; desc->irqs_unhandled = 0;
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