Re: [i386, x86-64] ioapic_register_intr() and assign_irq_vector() questions

Re: [i386, x86-64] ioapic_register_intr() and assign_irq_vector() questions

[Jan Beulich]

>> Looking at the call paths assign_irq_vector() can get called from, I
>> would think this function, namely as it's using static variables,
>> lacks synchronization - is there any (hidden) reason this is not
>> needed here?

>It is only called during system initialization which is single threaded. 
>If someone added ioapic hotplug they would need to do something about 
>this.

Hmm, as I looked through this I expected this to be possibly called also later, as it seems to be on paths reachable
from exported functions (which clearly can be called only after the single-threaded phase is over.

Jan

Re: [discuss] Re: [i386, x86-64] ioapic_register_intr() and assign_irq_vector() questions

[Andi Kleen]

On Friday 14 April 2006 19:16, Jan Beulich wrote:
> >> Looking at the call paths assign_irq_vector() can get called from, I
> >> would think this function, namely as it's using static variables,
> >> lacks synchronization - is there any (hidden) reason this is not
> >> needed here?
> 
> >It is only called during system initialization which is single threaded. 
> >If someone added ioapic hotplug they would need to do something about 
> >this.
> 
> Hmm, as I looked through this I expected this to be possibly called also later, as it seems to be on paths reachable
> from exported functions (which clearly can be called only after the single-threaded phase is over.

If it's not called from in tree modules we don't care. But should probably
bunk the exports if they are not needed. Which ones were it?

-Andi

Re: [discuss] Re: [i386, x86-64] ioapic_register_intr() and assign_irq_vector() questions

[Jan Beulich]

>>> Andi Kleen <ak@suse.de> 14.04.06 23:34:18 >>>
On Friday 14 April 2006 19:16, Jan Beulich wrote:
>> >> Looking at the call paths assign_irq_vector() can get called from, I
>> >> would think this function, namely as it's using static variables,
>> >> lacks synchronization - is there any (hidden) reason this is not
>> >> needed here?
>> 
>> >It is only called during system initialization which is single threaded. 
>> >If someone added ioapic hotplug they would need to do something about 
>> >this.
>> 
>> Hmm, as I looked through this I expected this to be possibly called also later, as it seems to be on paths
reachable
>> from exported functions (which clearly can be called only after the single-threaded phase is over.
>
>If it's not called from in tree modules we don't care. But should probably
>bunk the exports if they are not needed. Which ones were it?

acpi_register_gsi -> mp_register_gsi -> io_apic_set_pci_routing -> assign_irq_vector

acpi_register_gsi is being exported and called from drivers/char/8250_acpi.c.
acpi_register_gsi is also being called from acpi_pci_irq_enable, which in turn is being exported.
There appear to be more (eg through pnpacpi and hpet), but I think these are sufficient.

Jan