ACPI / hotplug / PCI: Remove entries from bus->devices in reverse order

According to the changelog of commit 29ed1f29b68a (PCI: pciehp: Fix null
pointer deref when hot-removing SR-IOV device) it is unsafe to walk the
bus->devices list of a PCI bus and remove devices from it in direct order,
because that may lead to NULL pointer dereferences related to virtual
functions.

For this reason, change all of the bus->devices list walks in
acpiphp_glue.c during which devices may be removed to be carried out in
reverse order.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Mika Westerberg <mika.westerberg@linux.intel.com>

diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
index cd929aed3613314068ed7a4baf2bb6e5c6cb9f1f..6a4b4b734fbd9a66a40abad26c57268a1a05db75 100644 (file)
--- a/drivers/pci/hotplug/acpiphp_glue.c
+++ b/drivers/pci/hotplug/acpiphp_glue.c
@@ -742,7 +742,7 @@ static void trim_stale_devices(struct pci_dev *dev)
 
                /* The device is a bridge. so check the bus below it. */
                pm_runtime_get_sync(&dev->dev);
-               list_for_each_entry_safe(child, tmp, &bus->devices, bus_list)
+               list_for_each_entry_safe_reverse(child, tmp, &bus->devices, bus_list)
                        trim_stale_devices(child);
 
                pm_runtime_put(&dev->dev);
@@ -773,8 +773,8 @@ static void acpiphp_check_bridge(struct acpiphp_bridge *bridge)
                        ; /* do nothing */
                } else if (get_slot_status(slot) == ACPI_STA_ALL) {
                        /* remove stale devices if any */
-                       list_for_each_entry_safe(dev, tmp, &bus->devices,
-                                                bus_list)
+                       list_for_each_entry_safe_reverse(dev, tmp,
+                                                        &bus->devices, bus_list)
                                if (PCI_SLOT(dev->devfn) == slot->device)
                                        trim_stale_devices(dev);
 
@@ -805,7 +805,7 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus)
        int i;
        unsigned long type_mask = IORESOURCE_IO | IORESOURCE_MEM;
 
-       list_for_each_entry_safe(dev, tmp, &bus->devices, bus_list) {
+       list_for_each_entry_safe_reverse(dev, tmp, &bus->devices, bus_list) {
                for (i=0; i<PCI_BRIDGE_RESOURCES; i++) {
                        struct resource *res = &dev->resource[i];
                        if ((res->flags & type_mask) && !res->start &&