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SubjectRe: [PATCH v6 03/30] PCI: Export busn_resource to drivers/pci
>> -static struct resource busn_resource = {
>> +struct resource busn_resource = {
>> .name = "PCI busn",
>> .start = 0,
>> .end = 255,
>> .flags = IORESOURCE_BUS,
>> };
>> +EXPORT_SYMBOL(busn_resource);
>
> I don't think this is a good idea. We support multiple PCI domains, and
> each domain has its own 0-255 bus number range. This busn_resource is
> only for domain 0 and probably should be handled in arch code instead of
> the PCI core.
>
> Right now, I think it's possible to call pci_scan_bus_parented() or
> pci_scan_bus() several times for buses in different domains, and they would
> all share the same busn_resource, which would cause corruption.
>
> So it's already broken, but I don't want to make it harder to fix by
> exporting this stuff.

Hi Bjorn, busn_resource may would not be shared by multi domains,

We insert bus number resource like:

pci_add_resource(&resources, &busn_resource);
pci_bus_insert_busn_res(root_bus, start, bus_max); //start is the root bus number provided by arch pci host driver, bus max here == 255
get_pci_domain_busn_res(domain) //for root bus //try to get a domain specific pci_domain_busn_res, if not exist, create it.
request_resource_conflict(domain_specific_busn_res, res) //request busn res(start, bus_max) from the pci_domain_busn_res.

So every domain has its own pci_domain_busn_res , different domain would not share the same bus number resource.

Do I understand correct ?

Thanks!
Yijing.

>
>>
>> /* Ugh. Need to stop exporting this to modules. */
>> LIST_HEAD(pci_root_buses);
>> --
>> 1.7.1
>>
>
> .
>


--
Thanks!
Yijing



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