PCI: augment bus resource table with a list

Previously we used a table of size PCI_BUS_NUM_RESOURCES (16) for resources
forwarded to a bus by its upstream bridge.  We've increased this size
several times when the table overflowed.

But there's no good limit on the number of resources because host bridges
and subtractive decode bridges can forward any number of ranges to their
secondary buses.

This patch reduces the table to only PCI_BRIDGE_RESOURCE_NUM (4) entries,
which corresponds to the number of windows a PCI-to-PCI (3) or CardBus (4)
bridge can positively decode.  Any additional resources, e.g., PCI host
bridge windows or subtractively-decoded regions, are kept in a list.

I'd prefer a single list rather than this split table/list approach, but
that requires simultaneous changes to every architecture.  This approach
only requires immediate changes where we set up (a) host bridges with more
than four windows and (b) subtractive-decode P2P bridges, and we can
incrementally change other architectures to use the list.

Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

3 files changed, 7 insertions, 32 deletions

diff --git a/arch/x86/pci/acpi.c b/arch/x86/pci/acpi.c
index 959e548a703..a2f8cdb8c1d 100644
--- a/arch/x86/pci/acpi.c
+++ b/arch/x86/pci/acpi.c
@@ -45,20 +45,6 @@ count_resource(struct acpi_resource *acpi_res, void *data)
 	return AE_OK;
 }
 
-static int
-bus_has_transparent_bridge(struct pci_bus *bus)
-{
-	struct pci_dev *dev;
-
-	list_for_each_entry(dev, &bus->devices, bus_list) {
-		u16 class = dev->class >> 8;
-
-		if (class == PCI_CLASS_BRIDGE_PCI && dev->transparent)
-			return true;
-	}
-	return false;
-}
-
 static void
 align_resource(struct acpi_device *bridge, struct resource *res)
 {
@@ -92,12 +78,8 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
 	acpi_status status;
 	unsigned long flags;
 	struct resource *root;
-	int max_root_bus_resources = PCI_BUS_NUM_RESOURCES;
 	u64 start, end;
 
-	if (bus_has_transparent_bridge(info->bus))
-		max_root_bus_resources -= 3;
-
 	status = resource_to_addr(acpi_res, &addr);
 	if (!ACPI_SUCCESS(status))
 		return AE_OK;
@@ -115,15 +97,6 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
 
 	start = addr.minimum + addr.translation_offset;
 	end = start + addr.address_length - 1;
-	if (info->res_num >= max_root_bus_resources) {
-		if (pci_probe & PCI_USE__CRS)
-			printk(KERN_WARNING "PCI: Failed to allocate "
-			       "0x%lx-0x%lx from %s for %s due to _CRS "
-			       "returning more than %d resource descriptors\n",
-			       (unsigned long) start, (unsigned long) end,
-			       root->name, info->name, max_root_bus_resources);
-		return AE_OK;
-	}
 
 	res = &info->res[info->res_num];
 	res->name = info->name;
@@ -143,7 +116,7 @@ setup_resource(struct acpi_resource *acpi_res, void *data)
 		dev_err(&info->bridge->dev,
 			"can't allocate host bridge window %pR\n", res);
 	} else {
-		info->bus->resource[info->res_num] = res;
+		pci_bus_add_resource(info->bus, res, 0);
 		info->res_num++;
 		if (addr.translation_offset)
 			dev_info(&info->bridge->dev, "host bridge window %pR "
@@ -164,7 +137,9 @@ get_current_resources(struct acpi_device *device, int busnum,
 	struct pci_root_info info;
 	size_t size;
 
-	if (!(pci_probe & PCI_USE__CRS))
+	if (pci_probe & PCI_USE__CRS)
+		pci_bus_remove_resources(bus);
+	else
 		dev_info(&device->dev,
 			 "ignoring host bridge windows from ACPI; "
 			 "boot with \"pci=use_crs\" to use them\n");
diff --git a/arch/x86/pci/bus_numa.c b/arch/x86/pci/bus_numa.c
index f939d603adf..12d54ff3654 100644
--- a/arch/x86/pci/bus_numa.c
+++ b/arch/x86/pci/bus_numa.c
@@ -36,13 +36,14 @@ void x86_pci_root_bus_res_quirks(struct pci_bus *b)
 	printk(KERN_DEBUG "PCI: peer root bus %02x res updated from pci conf\n",
 			b->number);
 
+	pci_bus_remove_resources(b);
 	info = &pci_root_info[i];
 	for (j = 0; j < info->res_num; j++) {
 		struct resource *res;
 		struct resource *root;
 
 		res = &info->res[j];
-		b->resource[j] = res;
+		pci_bus_add_resource(b, res, 0);
 		if (res->flags & IORESOURCE_IO)
 			root = &ioport_resource;
 		else
diff --git a/arch/x86/pci/bus_numa.h b/arch/x86/pci/bus_numa.h
index adbc23fe82a..731b64ee8d8 100644
--- a/arch/x86/pci/bus_numa.h
+++ b/arch/x86/pci/bus_numa.h
@@ -2,8 +2,7 @@
 
 /*
  * sub bus (transparent) will use entres from 3 to store extra from
- * root, so need to make sure we have enough slot there, Should we
- * increase PCI_BUS_NUM_RESOURCES?
+ * root, so need to make sure we have enough slot there.
  */
 #define RES_NUM 16
 struct pci_root_info {