PCI: Make rescan bus increase bridge resource size if needed

Current rescan will not touch bridge MMIO and IO.

Try to reuse pci_assign_unassigned_bridge_resources(bridge) to update bridge
resources, if child devices need more resources.

Only do that for bridges whose children are all removed already; i.e. don't
release resources that could already be in use by drivers on child devices.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

3 files changed, 30 insertions, 1 deletions

diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c
index a3cd8cad532a..d9723039e99a 100644
--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -366,7 +366,10 @@ dev_bus_rescan_store(struct device *dev, struct device_attribute *attr,
 
         if (val) {
                 mutex_lock(&pci_remove_rescan_mutex);
-                pci_rescan_bus(bus);
+                if (!pci_is_root_bus(bus) && list_empty(&bus->devices))
+                        pci_rescan_bus_bridge_resize(bus->self);
+                else
+                        pci_rescan_bus(bus);
                 mutex_unlock(&pci_remove_rescan_mutex);
         }
         return count;
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 71eac9cd724d..0e84e8c2a6d0 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -1667,6 +1667,31 @@ EXPORT_SYMBOL(pci_scan_bus);
 
 #ifdef CONFIG_HOTPLUG
 /**
+ * pci_rescan_bus_bridge_resize - scan a PCI bus for devices.
+ * @bridge: PCI bridge for the bus to scan
+ *
+ * Scan a PCI bus and child buses for new devices, add them,
+ * and enable them, resizing bridge mmio/io resource if necessary
+ * and possible.  The caller must ensure the child devices are already
+ * removed for resizing to occur.
+ *
+ * Returns the max number of subordinate bus discovered.
+ */
+unsigned int __ref pci_rescan_bus_bridge_resize(struct pci_dev *bridge)
+{
+        unsigned int max;
+        struct pci_bus *bus = bridge->subordinate;
+
+        max = pci_scan_child_bus(bus);
+
+        pci_assign_unassigned_bridge_resources(bridge);
+
+        pci_bus_add_devices(bus);
+
+        return max;
+}
+
+/**
  * pci_rescan_bus - scan a PCI bus for devices.
  * @bus: PCI bus to scan
  *
diff --git a/include/linux/pci.h b/include/linux/pci.h
index f44276049f4a..87507aadf9a2 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -882,6 +882,7 @@ void set_pcie_hotplug_bridge(struct pci_dev *pdev);
 /* Functions for PCI Hotplug drivers to use */
 int pci_bus_find_capability(struct pci_bus *bus, unsigned int devfn, int cap);
 #ifdef CONFIG_HOTPLUG
+unsigned int pci_rescan_bus_bridge_resize(struct pci_dev *bridge);
 unsigned int pci_rescan_bus(struct pci_bus *bus);
 #endif