PCI: Put pci_dev in device tree as early as possible

We want to put pci_dev structs in the device tree as soon as possible so
for_each_pci_dev() iteration will not miss them, but driver attachment
needs to be delayed until after pci_assign_unassigned_resources() to make
sure all devices have resources assigned first.

This patch moves device registering from pci_bus_add_devices() to
pci_device_add(), which happens earlier, leaving driver attachment in
pci_bus_add_devices().

It also removes unattached child bus handling in pci_bus_add_devices().
That's not needed because child bus via pci_add_new_bus() is already
in parent bus children list.

[bhelgaas: changelog]
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/pci/bus.c

@@ -161,73 +161,35 @@ pci_bus_alloc_resource(struct pci_bus *bus, struct resource *res,
 void __weak pcibios_resource_survey_bus(struct pci_bus *bus) { }
 
 /**
- * pci_bus_add_device - add a single device
+ * pci_bus_add_device - start driver for a single device
  * @dev: device to add
  *
- * This adds a single pci device to the global
- * device list and adds sysfs and procfs entries
+ * This adds add sysfs entries and start device drivers
  */
 int pci_bus_add_device(struct pci_dev *dev)
 {
 	int retval;
 
-	pci_fixup_device(pci_fixup_final, dev);
-
-	retval = pcibios_add_device(dev);
-	if (retval)
-		return retval;
-
-	dev->match_driver = false;
-	retval = device_add(&dev->dev);
-	if (retval)
-		return retval;
+	/*
+	 * Can not put in pci_device_add yet because resources
+	 * are not assigned yet for some devices.
+	 */
+	pci_create_sysfs_dev_files(dev);
 
 	dev->match_driver = true;
 	retval = device_attach(&dev->dev);
 	WARN_ON(retval < 0);
 
 	dev->is_added = 1;
-	pci_proc_attach_device(dev);
-	pci_create_sysfs_dev_files(dev);
+
 	return 0;
 }
 
 /**
- * pci_bus_add_child - add a child bus
- * @bus: bus to add
- *
- * This adds sysfs entries for a single bus
- */
-int pci_bus_add_child(struct pci_bus *bus)
-{
-	int retval;
-
-	if (bus->bridge)
-		bus->dev.parent = bus->bridge;
-
-	retval = device_register(&bus->dev);
-	if (retval)
-		return retval;
-
-	bus->is_added = 1;
-
-	/* Create legacy_io and legacy_mem files for this bus */
-	pci_create_legacy_files(bus);
-
-	return retval;
-}
-
-/**
- * pci_bus_add_devices - insert newly discovered PCI devices
+ * pci_bus_add_devices - start driver for PCI devices
  * @bus: bus to check for new devices
  *
- * Add newly discovered PCI devices (which are on the bus->devices
- * list) to the global PCI device list, add the sysfs and procfs
- * entries.  Where a bridge is found, add the discovered bus to
- * the parents list of child buses, and recurse (breadth-first
- * to be compatible with 2.4)
- *
- * Call hotplug for each new devices.
+ * Start driver for PCI devices and add some sysfs entries.
  */
 void pci_bus_add_devices(const struct pci_bus *bus)
 {
@@ -240,36 +202,20 @@ void pci_bus_add_devices(const struct pci_bus *bus)
 		if (dev->is_added)
 			continue;
 		retval = pci_bus_add_device(dev);
-		if (retval)
-			dev_err(&dev->dev, "Error adding device, continuing\n");
 	}
 
 	list_for_each_entry(dev, &bus->devices, bus_list) {
 		BUG_ON(!dev->is_added);
 
 		child = dev->subordinate;
-		/*
-		 * If there is an unattached subordinate bus, attach
-		 * it and then scan for unattached PCI devices.
-		 */
+
 		if (!child)
 			continue;
-		if (list_empty(&child->node)) {
-			down_write(&pci_bus_sem);
-			list_add_tail(&child->node, &dev->bus->children);
-			up_write(&pci_bus_sem);
-		}
 		pci_bus_add_devices(child);
 
-		/*
-		 * register the bus with sysfs as the parent is now
-		 * properly registered.
-		 */
 		if (child->is_added)
 			continue;
-		retval = pci_bus_add_child(child);
-		if (retval)
-			dev_err(&dev->dev, "Error adding bus, continuing\n");
+		child->is_added = 1;
 	}
 }
 

drivers/pci/iov.c

@@ -48,12 +48,7 @@ static struct pci_bus *virtfn_add_bus(struct pci_bus *bus, int busnr)
 		return NULL;
 
 	pci_bus_insert_busn_res(child, busnr, busnr);
-	child->dev.parent = bus->bridge;
-	rc = pci_bus_add_child(child);
-	if (rc) {
-		pci_remove_bus(child);
-		return NULL;
-	}
+	bus->is_added = 1;
 
 	return child;
 }
@@ -123,8 +118,6 @@ static int virtfn_add(struct pci_dev *dev, int id, int reset)
 	virtfn->is_virtfn = 1;
 
 	rc = pci_bus_add_device(virtfn);
-	if (rc)
-		goto failed1;
 	sprintf(buf, "virtfn%u", id);
 	rc = sysfs_create_link(&dev->dev.kobj, &virtfn->dev.kobj, buf);
 	if (rc)

drivers/pci/pci.h

@@ -203,7 +203,6 @@ extern int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type,
 				struct resource *res, unsigned int reg);
 extern int pci_resource_bar(struct pci_dev *dev, int resno,
 			    enum pci_bar_type *type);
-extern int pci_bus_add_child(struct pci_bus *bus);
 extern void pci_enable_ari(struct pci_dev *dev);
 /**
  * pci_ari_enabled - query ARI forwarding status

drivers/pci/probe.c

@@ -623,6 +623,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
 {
 	struct pci_bus *child;
 	int i;
+	int ret;
 
 	/*
 	 * Allocate a new bus, and inherit stuff from the parent..
@@ -637,8 +638,7 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
 	child->bus_flags = parent->bus_flags;
 
 	/* initialize some portions of the bus device, but don't register it
-	 * now as the parent is not properly set up yet.  This device will get
-	 * registered later in pci_bus_add_devices()
+	 * now as the parent is not properly set up yet.
 	 */
 	child->dev.class = &pcibus_class;
 	dev_set_name(&child->dev, "%04x:%02x", pci_domain_nr(child), busnr);
@@ -651,11 +651,14 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
 	child->primary = parent->busn_res.start;
 	child->busn_res.end = 0xff;
 
-	if (!bridge)
-		return child;
+	if (!bridge) {
+		child->dev.parent = parent->bridge;
+		goto add_dev;
+	}
 
 	child->self = bridge;
 	child->bridge = get_device(&bridge->dev);
+	child->dev.parent = child->bridge;
 	pci_set_bus_of_node(child);
 	pci_set_bus_speed(child);
 
@@ -666,6 +669,13 @@ static struct pci_bus *pci_alloc_child_bus(struct pci_bus *parent,
 	}
 	bridge->subordinate = child;
 
+add_dev:
+	ret = device_register(&child->dev);
+	WARN_ON(ret < 0);
+
+	/* Create legacy_io and legacy_mem files for this bus */
+	pci_create_legacy_files(child);
+
 	return child;
 }
 
@@ -1296,6 +1306,8 @@ static void pci_init_capabilities(struct pci_dev *dev)
 
 void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
 {
+	int ret;
+
 	device_initialize(&dev->dev);
 	dev->dev.release = pci_release_dev;
 
@@ -1326,6 +1338,17 @@ void pci_device_add(struct pci_dev *dev, struct pci_bus *bus)
 	down_write(&pci_bus_sem);
 	list_add_tail(&dev->bus_list, &bus->devices);
 	up_write(&pci_bus_sem);
+
+	pci_fixup_device(pci_fixup_final, dev);
+	ret = pcibios_add_device(dev);
+	WARN_ON(ret < 0);
+
+	/* Notifier could use PCI capabilities */
+	dev->match_driver = false;
+	ret = device_add(&dev->dev);
+	WARN_ON(ret < 0);
+
+	pci_proc_attach_device(dev);
 }
 
 struct pci_dev *__ref pci_scan_single_device(struct pci_bus *bus, int devfn)
@@ -1644,13 +1667,13 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 	char bus_addr[64];
 	char *fmt;
 
-
 	b = pci_alloc_bus();
 	if (!b)
 		return NULL;
 
 	b->sysdata = sysdata;
 	b->ops = ops;
+	b->number = b->busn_res.start = bus;
 	b2 = pci_find_bus(pci_domain_nr(b), bus);
 	if (b2) {
 		/* If we already got to this bus through a different bridge, ignore it */
@@ -1685,8 +1708,6 @@ struct pci_bus *pci_create_root_bus(struct device *parent, int bus,
 	/* Create legacy_io and legacy_mem files for this bus */
 	pci_create_legacy_files(b);
 
-	b->number = b->busn_res.start = bus;
-
 	if (parent)
 		dev_info(parent, "PCI host bridge to bus %s\n", dev_name(&b->dev));
 	else