On Fri, 2 Sep 2011, Geert Uytterhoeven wrote:
On Fri, Sep 2, 2011 at 14:14, Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> wrote:
On Sun, 28 Aug 2011, I wrote:
However, I found another problem. pmac_zilog oopses when its TTY is closed
(see below). And macsonic does the same when the NIC is closed. The trace
says that irq_shutdown() died trying to call the chip irq_mask routine,
when desc->irq_data.chip (in a0) was NULL. Any ideas?
Unable to handle kernel NULL pointer dereference at virtual address (null)
Oops: 00000000
Modules linked in:
PC: [<00000000>] (null)
No, it calls a function pointer that's NULL.
void irq_shutdown(struct irq_desc *desc)
{
irq_state_set_disabled(desc);
desc->depth = 1;
if (desc->irq_data.chip->irq_shutdown)
desc->irq_data.chip->irq_shutdown(&desc->irq_data);
if (desc->irq_data.chip->irq_disable)
desc->irq_data.chip->irq_disable(&desc->irq_data);
else
desc->irq_data.chip->irq_mask(&desc->irq_data);
irq_state_set_masked(desc);
}
Oops, seems I misread the code and assumed the second "if" was an "else if",
I think that was supposed to be an "else if". Lemme look at the code
before the overhaul to be sure.
as I wrote down in my notes that it calls only one of the 3 functions :-(
But it does need either .irq_disable() or .irq_mask().
The following irq_chip structs have both .irq_disable() and .irq_mask() NULL:
- arch/m68k/apollo/dn_ints.c:apollo_irq_chip
- arch/m68k/kernel/ints.c:auto_irq_chip
- arch/m68k/kernel/ints.c:user_irq_chip
Since this is on Mac and mac_irq_chip is OK, I guess this is a non-PSC Mac,
i.e. the IRQ number is IRQ_MAC_SCC == IRQ_AUTO_4?
Thomas: As we cannot disable or mask autovector interrupts at the
autovector level,
IMHO it doesn't make much sense do add a dummy .irq_mask() function.
Can we add an extra check in irq_shutdown() to not call .irq_mask() if
it's NULL?
Yes.
Thanks,
tglx
