2 files changed, 93 insertions, 21 deletions

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index 17e15d11bd3..408f6b2a5fa 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -79,34 +79,99 @@ static struct acpi_bus_type *acpi_get_bus_type(struct device *dev)
 	return ret;
 }
 
-static acpi_status do_acpi_find_child(acpi_handle handle, u32 lvl_not_used,
-				      void *addr_p, void **ret_p)
+static acpi_status acpi_dev_present(acpi_handle handle, u32 lvl_not_used,
+				  void *not_used, void **ret_p)
 {
-	unsigned long long addr, sta;
-	acpi_status status;
+	struct acpi_device *adev = NULL;
 
-	status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &addr);
-	if (ACPI_SUCCESS(status) && addr == *((u64 *)addr_p)) {
+	acpi_bus_get_device(handle, &adev);
+	if (adev) {
 		*ret_p = handle;
-		status = acpi_bus_get_status_handle(handle, &sta);
-		if (ACPI_SUCCESS(status) && (sta & ACPI_STA_DEVICE_ENABLED))
-			return AE_CTRL_TERMINATE;
+		return AE_CTRL_TERMINATE;
 	}
 	return AE_OK;
 }
 
-acpi_handle acpi_get_child(acpi_handle parent, u64 address)
+static bool acpi_extra_checks_passed(acpi_handle handle, bool is_bridge)
 {
-	void *ret = NULL;
+	unsigned long long sta;
+	acpi_status status;
+
+	status = acpi_bus_get_status_handle(handle, &sta);
+	if (ACPI_FAILURE(status) || !(sta & ACPI_STA_DEVICE_ENABLED))
+		return false;
+
+	if (is_bridge) {
+		void *test = NULL;
+
+		/* Check if this object has at least one child device. */
+		acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
+				    acpi_dev_present, NULL, NULL, &test);
+		return !!test;
+	}
+	return true;
+}
+
+struct find_child_context {
+	u64 addr;
+	bool is_bridge;
+	acpi_handle ret;
+	bool ret_checked;
+};
+
+static acpi_status do_find_child(acpi_handle handle, u32 lvl_not_used,
+				 void *data, void **not_used)
+{
+	struct find_child_context *context = data;
+	unsigned long long addr;
+	acpi_status status;
 
-	if (!parent)
-		return NULL;
+	status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &addr);
+	if (ACPI_FAILURE(status) || addr != context->addr)
+		return AE_OK;
 
-	acpi_walk_namespace(ACPI_TYPE_DEVICE, parent, 1, NULL,
-			    do_acpi_find_child, &address, &ret);
-	return (acpi_handle)ret;
+	if (!context->ret) {
+		/* This is the first matching object.  Save its handle. */
+		context->ret = handle;
+		return AE_OK;
+	}
+	/*
+	 * There is more than one matching object with the same _ADR value.
+	 * That really is unexpected, so we are kind of beyond the scope of the
+	 * spec here.  We have to choose which one to return, though.
+	 *
+	 * First, check if the previously found object is good enough and return
+	 * its handle if so.  Second, check the same for the object that we've
+	 * just found.
+	 */
+	if (!context->ret_checked) {
+		if (acpi_extra_checks_passed(context->ret, context->is_bridge))
+			return AE_CTRL_TERMINATE;
+		else
+			context->ret_checked = true;
+	}
+	if (acpi_extra_checks_passed(handle, context->is_bridge)) {
+		context->ret = handle;
+		return AE_CTRL_TERMINATE;
+	}
+	return AE_OK;
+}
+
+acpi_handle acpi_find_child(acpi_handle parent, u64 addr, bool is_bridge)
+{
+	if (parent) {
+		struct find_child_context context = {
+			.addr = addr,
+			.is_bridge = is_bridge,
+		};
+
+		acpi_walk_namespace(ACPI_TYPE_DEVICE, parent, 1, do_find_child,
+				    NULL, &context, NULL);
+		return context.ret;
+	}
+	return NULL;
 }
-EXPORT_SYMBOL(acpi_get_child);
+EXPORT_SYMBOL_GPL(acpi_find_child);
 
 int acpi_bind_one(struct device *dev, acpi_handle handle)
 {
diff --git a/drivers/pci/pci-acpi.c b/drivers/pci/pci-acpi.c
index dbdc5f7e2b2..01e264fb50e 100644
--- a/drivers/pci/pci-acpi.c
+++ b/drivers/pci/pci-acpi.c
@@ -317,13 +317,20 @@ void acpi_pci_remove_bus(struct pci_bus *bus)
 /* ACPI bus type */
 static int acpi_pci_find_device(struct device *dev, acpi_handle *handle)
 {
-	struct pci_dev * pci_dev;
-	u64	addr;
+	struct pci_dev *pci_dev = to_pci_dev(dev);
+	bool is_bridge;
+	u64 addr;
 
-	pci_dev = to_pci_dev(dev);
+	/*
+	 * pci_is_bridge() is not suitable here, because pci_dev->subordinate
+	 * is set only after acpi_pci_find_device() has been called for the
+	 * given device.
+	 */
+	is_bridge = pci_dev->hdr_type == PCI_HEADER_TYPE_BRIDGE
+			|| pci_dev->hdr_type == PCI_HEADER_TYPE_CARDBUS;
 	/* Please ref to ACPI spec for the syntax of _ADR */
 	addr = (PCI_SLOT(pci_dev->devfn) << 16) | PCI_FUNC(pci_dev->devfn);
-	*handle = acpi_get_child(DEVICE_ACPI_HANDLE(dev->parent), addr);
+	*handle = acpi_find_child(ACPI_HANDLE(dev->parent), addr, is_bridge);
 	if (!*handle)
 		return -ENODEV;
 	return 0;