On Mon, Feb 6, 2012 at 10:59 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote:
> On Sat, Feb 4, 2012 at 10:57 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
>> will use them insert/update busn res in pci_bus
>>
>> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
>> ---
>> drivers/pci/probe.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>> include/linux/pci.h | 3 +++
>> 2 files changed, 45 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
>> index a114173..8d4de5e 100644
>> --- a/drivers/pci/probe.c
>> +++ b/drivers/pci/probe.c
>> @@ -1622,6 +1622,48 @@ err_out:
>> return NULL;
>> }
>>
>> +void pci_bus_insert_busn_res(struct pci_bus *b, int bus, int bus_max)
>> +{
>> + struct resource *res = &b->busn_res;
>> + struct resource *parent_res = &iobusn_resource;
>> + int ret;
>> +
>> + res->start = busn(pci_domain_nr(b), bus);
>> + res->end = busn(pci_domain_nr(b), bus_max);
>> + res->flags = IORESOURCE_BUS;
>> +
>> + if (!pci_is_root_bus(b))
>> + parent_res = &b->parent->busn_res;
>> +
>> + ret = insert_resource(parent_res, res);
>> +
>> + dev_printk(KERN_DEBUG, &b->dev,
>> + "busn_res: %pR %s inserted under %pR\n",
>> + res, ret ? "can not be" : "is", parent_res);
>> +}
>> +
>> +void pci_bus_update_busn_res_end(struct pci_bus *b, int bus_max)
>> +{
>> + struct resource *res = &b->busn_res;
>> + struct resource old_res = *res;
>> +
>> + res->end = busn_update_bus_nr(res->end, bus_max);
>
> I think this design is a mistake. Here's what you're doing:
>
> - initialize struct resource (keys are "start" and "end")
> - insert into tree (placed in tree by kernel/resource.c based on
> "start" and "end")
> - update "end"
>
> You "know" in this case that the update is safe because the caller has
> validated "bus_max." But that still breaks the kernel/resource.c
> encapsulation. If we change the kernel/resource.c implementation,
> this code might break.
the point is: I only want to reuse allocate_resource() to get right position.
and the code does not depends to kernel/resource.c much.
>
> I think it would be better to remove the bus resource from the tree,
> change its "end," then re-insert it.
how about parent buses that have extended top?
Yinghai
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