Re: Threaded interrupt handlers broken?

Thomas Gleixner
2009-08-17T11:12:13Z

On Mon, 17 Aug 2009, Thomas Gleixner wrote:
> On Mon, 17 Aug 2009, Thomas Gleixner wrote:
>
> > On Mon, 17 Aug 2009, Michael Buesch wrote:
> > > Ok, I added some more debugging code:
> > > http://bu3sch.de/patches/wireless-testing/20090817-1219/patches/001-hack-threaded-irqs.patch
> > >
> > > Here's the result:
> > > http://bu3sch.de/misc/dmesg2
> > >
> > > Is it possible that the irq_to_desc() in irq_thread() fails and the
> > > resulting desc pointer points to something random? That could
> > > probably explain why the bit is set and why the spinlock is
> > > uninitialized. But it would not explain why desc->lock would still
> > > work... Maybe irq_to_desc() returns a descriptor to another irq (!=
> > > 52)?
> >
> > That would cause the whole irq code to fail. Can you send/upload your
> > .config please ?
>
> Also just add printk("desc: %p \n", desc); to the various places to
> make sure that your pointers are correct.

Gah. I think I found it.

I wonder why nobody else ever tripped over this.

Thanks,

tglx
---
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index d222515..223b062 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -607,7 +607,6 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
*/
get_task_struct(t);
new->thread = t;
- wake_up_process(t);
}

/*
@@ -712,6 +711,9 @@ __setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
new->dir = NULL;
register_handler_proc(irq, new);

+ if (new->thread)
+ wake_up_process(new->thread);
+
return 0;