Revert "PCI: fix pci_bus_alloc_resource() hang, prefer positive decode"

This reverts commit 82e3e767c21fef2b1b38868e20eb4e470a1e38e3.

We're going back to considering bus resources in the order we found
them (in _CRS order, when we're using _CRS), so we don't need to
define any ordering.

Acked-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 003170e..5624db8 100644 (file)
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -64,57 +64,17 @@ void pci_bus_remove_resources(struct pci_bus *bus)
        }
 }
 
-static bool pci_bus_resource_better(struct resource *res1, bool pos1,
-                                   struct resource *res2, bool pos2)
-{
-       /* If exactly one is positive decode, always prefer that one */
-       if (pos1 != pos2)
-               return pos1 ? true : false;
-
-       /* Prefer the one that contains the highest address */
-       if (res1->end != res2->end)
-               return (res1->end > res2->end) ? true : false;
-
-       /* Otherwise, prefer the one with highest "center of gravity" */
-       if (res1->start != res2->start)
-               return (res1->start > res2->start) ? true : false;
-
-       /* Otherwise, choose one arbitrarily (but consistently) */
-       return (res1 > res2) ? true : false;
-}
-
-static bool pci_bus_resource_positive(struct pci_bus *bus, struct resource *res)
-{
-       struct pci_bus_resource *bus_res;
-
-       /*
-        * This relies on the fact that pci_bus.resource[] refers to P2P or
-        * CardBus bridge base/limit registers, which are always positively
-        * decoded.  The pci_bus.resources list contains host bridge or
-        * subtractively decoded resources.
-        */
-       list_for_each_entry(bus_res, &bus->resources, list) {
-               if (bus_res->res == res)
-                       return (bus_res->flags & PCI_SUBTRACTIVE_DECODE) ?
-                               false : true;
-       }
-       return true;
-}
-
 /*
- * Find the next-best bus resource after the cursor "res".  If the cursor is
- * NULL, return the best resource.  "Best" means that we prefer positive
- * decode regions over subtractive decode, then those at higher addresses.
+ * Find the highest-address bus resource below the cursor "res".  If the
+ * cursor is NULL, return the highest resource.
  */
 static struct resource *pci_bus_find_resource_prev(struct pci_bus *bus,
                                                   unsigned int type,
                                                   struct resource *res)
 {
-       bool res_pos, r_pos, prev_pos = false;
        struct resource *r, *prev = NULL;
        int i;
 
-       res_pos = pci_bus_resource_positive(bus, res);
        pci_bus_for_each_resource(bus, r, i) {
                if (!r)
                        continue;
@@ -122,14 +82,26 @@ static struct resource *pci_bus_find_resource_prev(struct pci_bus *bus,
                if ((r->flags & IORESOURCE_TYPE_BITS) != type)
                        continue;
 
-               r_pos = pci_bus_resource_positive(bus, r);
-               if (!res || pci_bus_resource_better(res, res_pos, r, r_pos)) {
-                       if (!prev || pci_bus_resource_better(r, r_pos,
-                                                            prev, prev_pos)) {
-                               prev = r;
-                               prev_pos = r_pos;
-                       }
+               /* If this resource is at or past the cursor, skip it */
+               if (res) {
+                       if (r == res)
+                               continue;
+                       if (r->end > res->end)
+                               continue;
+                       if (r->end == res->end && r->start > res->start)
+                               continue;
                }
+
+               if (!prev)
+                       prev = r;
+
+               /*
+                * A small resource is higher than a large one that ends at
+                * the same address.
+                */
+               if (r->end > prev->end ||
+                   (r->end == prev->end && r->start > prev->start))
+                       prev = r;
        }
 
        return prev;