PCI: Split out bridge window override of minimum allocation address

pci_bus_alloc_resource() avoids allocating space below the "min" supplied
by the caller (usually PCIBIOS_MIN_IO or PCIBIOS_MIN_MEM).  This is to
protect badly documented motherboard resources.  But if we're allocating
space inside an already-configured PCI-PCI bridge window, we ignore "min".

See 688d191821de ("pci: make bus resource start address override minimum IO
address").

This patch moves the check to make it more visible and simplify future
patches.  No functional change.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index fc1b74013743..6f2f47a7b6c6 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -147,11 +147,18 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
                     !(res->flags & IORESOURCE_PREFETCH))
                         continue;
 
+                /*
+                 * "min" is typically PCIBIOS_MIN_IO or PCIBIOS_MIN_MEM to
+                 * protect badly documented motherboard resources, but if
+                 * this is an already-configured bridge window, its start
+                 * overrides "min".
+                 */
+                if (r->start)
+                        min = r->start;
+
                 /* Ok, try it out.. */
-                ret = allocate_resource(r, res, size,
-                                        r->start ? : min,
-                                        max, align,
-                                        alignf, alignf_data);
+                ret = allocate_resource(r, res, size, min, max,
+                                        align, alignf, alignf_data);
                 if (ret == 0)
                         break;
         }