Hi,
It turns out the root cause of the problem is a race condition in the apic
code.
I attach a patch to fix this problem. It works on my machine.
Haohui
On Mon, Apr 5, 2010 at 12:15 AM, Haohui Mai <haohui....@gmail.com> wrote:
> Hello,
>
> I'm playing around with L4:Pistachio on a 8-core machine a little bit, and
> it seems that I'm having a race condition in interrupt handling.
>
> at src/api/v4/interrupt.cc, around Line 423:
>
> current->dequeue_send(handler_tcb);
> handler_tcb->set_tag(msg_tag_t::irq_tag());
> handler_tcb->set_partner(current->get_global_id());
> handler_tcb->unlock();
>
> The routine overrides the handler_tcb directly. However, the handler might
> be in the middle of IPC (where it's in locked_waiting state in my machine),
> thus the handler enters an undefined state.
>
> So what happens to my machine is that the program runs on L4:Pistachio, it
> can process the mouse interrupt for a while, then the interrupt controller
> goes into an inconsistent state:
>
>
> IRQ 12: IOAPIC 8, Line 12: vec 80, phys, high, edge, masked dest 0
> redir entries mismatch hw 0 50 != soft 0 10050
> hw: vec 80, phys, high, edge, unmasked dest 0
>
> I have no idea of how to fix it. Any suggestions are highly appreciated.
>
> Cheers,
>
> Haohui
>
Index: kernel/src/platform/generic/intctrl-apic.h
===================================================================
--- kernel/src/platform/generic/intctrl-apic.h (revision 1653)
+++ kernel/src/platform/generic/intctrl-apic.h (working copy)
@@ -79,6 +79,7 @@
ioapic_redir_t entry;
ioapic_t* ioapic;
word_t line;
+ spinlock_t lock;
bool pending;
};
Index: kernel/src/platform/generic/intctrl-apic.cc
===================================================================
--- kernel/src/platform/generic/intctrl-apic.cc (revision 1653)
+++ kernel/src/platform/generic/intctrl-apic.cc (working copy)
@@ -490,11 +490,13 @@
#endif
ASSERT(redir[irq].is_valid());
+ redir[irq].lock.lock();
if (redir[irq].entry.is_edge_triggered())
{
if (redir[irq].pending)
{
redir[irq].pending = false;
+ redir[irq].lock.unlock();
return true; // leave IRQ masked, since there was another pending
}
redir[irq].entry.unmask_irq();
@@ -504,6 +506,7 @@
redir[irq].entry.unmask_irq();
sync_redir_entry(&redir[irq], sync_low);
}
+ redir[irq].lock.unlock();
return false;
}
@@ -580,6 +583,7 @@
{
bool deliver = true;
+ redir[irq].lock.lock();
// edge triggered IRQs are marked as pending if masked
if ( redir[irq].entry.is_edge_triggered() &&
redir[irq].entry.x.mask )
@@ -587,6 +591,7 @@
redir[irq].pending = true;
deliver = false;
}
+ redir[irq].lock.unlock();
mask(irq);
local_apic.EOI();
