[PATCH v8 06/22] PCI: split registration of PCI bus devices into two stages

[Yinghai Lu <yinghai@kernel.org>]

From: Jiang Liu <jiang.liu@huawei.com>

When handling BUS_NOTIFY_ADD_DEVICE event for a PCI bridge device,
the notification handler can't hold reference count to the new PCI bus
because the device object for the new bus (pci_dev->subordinate->dev)
hasn't been initialized yet.

Split the registration of PCI bus device into two stages as below,
so that the event handler could hold reference count to the new PCI bus
when handling BUS_NOTIFY_ADD_DEVICE event.

1) device_initialize(&pci_dev->dev)
2) device_initialize(&pci_dev->subordinate->dev)
3) notify BUS_NOTIFY_ADD_DEVICE event for pci_dev
4) device_add(&pci_dev->dev)
5) device_add(&pci_dev->subordinate->dev)

Signed-off-by: Jiang Liu <jiang.liu@huawei.com>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
 drivers/pci/bus.c    |    2 +-
 drivers/pci/probe.c  |    4 +++-
 drivers/pci/remove.c |   10 +++++-----
 3 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/bus.c b/drivers/pci/bus.c
index 847f3ca..5f9c728 100644
--- a/drivers/pci/bus.c
+++ b/drivers/pci/bus.c
@@ -200,7 +200,7 @@ int pci_bus_add_child(struct pci_bus *bus)
 	if (bus->bridge)
 		bus->dev.parent = bus->bridge;
 
-	retval = device_register(&bus->dev);
+	retval = device_add(&bus->dev);
 	if (retval)
 		return retval;
 
diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c
index 48b35e1..dc4fde3 100644
--- a/drivers/pci/probe.c
+++ b/drivers/pci/probe.c
@@ -642,6 +642,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
 	 */
 	child->dev.class = &pcibus_class;
 	dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child), busnr);
+	device_initialize(&child->dev);
 
 	/*
 	 * Set up the primary, secondary and subordinate
@@ -1678,7 +1679,8 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 	b->dev.class = &pcibus_class;
 	b->dev.parent = b->bridge;
 	dev_set_name(&b->dev, "%04x:%02x", pci_domain_nr(b), bus);
-	error = device_register(&b->dev);
+	device_initialize(&b->dev);
+	error = device_add(&b->dev);
 	if (error)
 		goto class_dev_reg_err;
 
diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c
index fc38c48..a1fdd0f 100644
--- a/drivers/pci/remove.c
+++ b/drivers/pci/remove.c
@@ -48,11 +48,11 @@ void pci_remove_bus(struct pci_bus *bus)
 	list_del(&bus->node);
 	pci_bus_release_busn_res(bus);
 	up_write(&pci_bus_sem);
-	if (!bus->is_added)
-		return;
-
-	pci_remove_legacy_files(bus);
-	device_unregister(&bus->dev);
+	if (bus->is_added) {
+		pci_remove_legacy_files(bus);
+		device_del(&bus->dev);
+	}
+	put_device(&bus->dev);
 }
 EXPORT_SYMBOL(pci_remove_bus);
 
-- 
1.7.10.4