On Mon, Feb 6, 2012 at 12:45 PM, Yinghai Lu [off-list ref] wrote:

On Mon, Feb 6, 2012 at 10:59 AM, Bjorn Helgaas [off-list ref] wrote:

quoted

On Sat, Feb 4, 2012 at 10:57 PM, Yinghai Lu [off-list ref] wrote:

quoted

will use them insert/update busn res in pci_bus

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
 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.

quoted

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?

I don't understand your question.  I assume you mean there's a case
where remove/update/reinsert doesn't work, but I don't see why that
would be a problem.  Can you show an example?