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>

1 files changed, 21 insertions, 49 deletions

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 003170ea2e39..5624db8c9ad0 100644
--- 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;