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

This reverts commit 82e3e767c2.

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>
This commit is contained in:
Bjorn Helgaas 2010-12-16 10:38:20 -07:00 committed by Jesse Barnes
parent 49c2fa08a7
commit ac57cd5ee1
1 changed files with 21 additions and 49 deletions
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70
drivers/pci/bus.c
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@ -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;