PCI: acpiphp: Re-enumerate devices when host bridge receives Bus Check

When a PCI host bridge device receives a Bus Check notification, we
must re-enumerate starting with the bridge to discover changes (devices
that have been added or removed).

Prior to 668192b678 ("PCI: acpiphp: Move host bridge hotplug to
pci_root.c"), this happened in _handle_hotplug_event_bridge().  After that
commit, _handle_hotplug_event_bridge() is not installed for host bridges,
and the host bridge notify handler, _handle_hotplug_event_root() did not
re-enumerate.

This patch adds re-enumeration to _handle_hotplug_event_root().

This fixes cases where we don't notice the addition or removal of
PCI devices, e.g., the PCI-to-USB ExpressCard in the bugzilla below.

[bhelgaas: changelog, references]
Reference: https://lkml.kernel.org/r/CAAh6nkmbKR3HTqm5ommevsBwhL_u0N8Rk7Wsms_LfP=nBgKNew@mail.gmail.com
Reference: https://bugzilla.kernel.org/show_bug.cgi?id=57961
Reported-by: Gavin Guo <tuffkidtt@gmail.com>
Tested-by: Gavin Guo <tuffkidtt@gmail.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Jiang Liu <jiang.liu@huawei.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
CC: stable@vger.kernel.org	# v3.9+

drivers/acpi/pci_root.c

@@ -641,7 +641,9 @@ static void _handle_hotplug_event_root(struct work_struct *work)
 		/* bus enumerate */
 		printk(KERN_DEBUG "%s: Bus check notify on %s\n", __func__,
 				 (char *)buffer.pointer);
-		if (!root)
+		if (root)
+			acpiphp_check_host_bridge(handle);
+		else
 			handle_root_bridge_insertion(handle);
 
 		break;

drivers/pci/hotplug/acpiphp_glue.c

@@ -950,6 +950,20 @@ check_sub_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
 	return AE_OK ;
 }
 
+void acpiphp_check_host_bridge(acpi_handle handle)
+{
+	struct acpiphp_bridge *bridge;
+
+	bridge = acpiphp_handle_to_bridge(handle);
+	if (bridge) {
+		acpiphp_check_bridge(bridge);
+		put_bridge(bridge);
+	}
+
+	acpi_walk_namespace(ACPI_TYPE_DEVICE, handle,
+		ACPI_UINT32_MAX, check_sub_bridges, NULL, NULL, NULL);
+}
+
 static void _handle_hotplug_event_bridge(struct work_struct *work)
 {
 	struct acpiphp_bridge *bridge;

include/linux/pci-acpi.h

@@ -60,11 +60,13 @@ static inline void acpi_pci_slot_remove(struct pci_bus *bus) { }
 void acpiphp_init(void);
 void acpiphp_enumerate_slots(struct pci_bus *bus, acpi_handle handle);
 void acpiphp_remove_slots(struct pci_bus *bus);
+void acpiphp_check_host_bridge(acpi_handle handle);
 #else
 static inline void acpiphp_init(void) { }
 static inline void acpiphp_enumerate_slots(struct pci_bus *bus,
 					   acpi_handle handle) { }
 static inline void acpiphp_remove_slots(struct pci_bus *bus) { }
+static inline void acpiphp_check_host_bridge(acpi_handle handle) { }
 #endif
 
 #else	/* CONFIG_ACPI */