PCI: update pci_create_slot() to take a 'hotplug' param

Slot detection drivers can co-exist with hotplug drivers. The names
of the detected/claimed slots may be different depending on module
load order.

For legacy reasons, we need to allow hotplug drivers to override
the slot name if a detection driver is loaded first (and they find
the same slots).

Creating and overriding slot names should be an atomic operation,
otherwise you get a locking nightmare as various drivers race to
call pci_create_slot().

pci_create_slot() is already serialized by grabbing the pci_bus_sem.

We update the API and add a 'hotplug' param, which is:

	set if the caller is a hotplug driver
	NULL if the caller is a detection driver

pci_create_slot() does not actually use the 'hotplug' parameter in this
patch. A later patch will add the logic that uses it.

Cc: kristen.c.accardi@intel.com
Cc: matthew@wil.cx
Acked-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/acpi/pci_slot.c

@@ -150,7 +150,7 @@ register_slot(acpi_handle handle, u32 lvl, void *context, void **rv)
 	}
 
 	snprintf(name, sizeof(name), "%u", (u32)sun);
-	pci_slot = pci_create_slot(pci_bus, device, name);
+	pci_slot = pci_create_slot(pci_bus, device, name, NULL);
 	if (IS_ERR(pci_slot)) {
 		err("pci_create_slot returned %ld\n", PTR_ERR(pci_slot));
 		kfree(slot);

drivers/pci/hotplug/pci_hotplug_core.c

@@ -579,7 +579,7 @@ int pci_hp_register(struct hotplug_slot *slot, struct pci_bus *bus, int slot_nr,
 	 * driver and call it here again. If we've already created the
 	 * pci_slot, the interface will simply bump the refcount.
 	 */
-	pci_slot = pci_create_slot(bus, slot_nr, name);
+	pci_slot = pci_create_slot(bus, slot_nr, name, slot);
 	if (IS_ERR(pci_slot))
 		return PTR_ERR(pci_slot);
 

drivers/pci/slot.c

@@ -83,6 +83,7 @@ static struct kobj_type pci_slot_ktype = {
  * @parent: struct pci_bus of parent bridge
  * @slot_nr: PCI_SLOT(pci_dev->devfn) or -1 for placeholder
  * @name: user visible string presented in /sys/bus/pci/slots/<name>
+ * @hotplug: set if caller is hotplug driver, NULL otherwise
  *
  * PCI slots have first class attributes such as address, speed, width,
  * and a &struct pci_slot is used to manage them. This interface will
@@ -111,7 +112,8 @@ static struct kobj_type pci_slot_ktype = {
  */
 
 struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
-				 const char *name)
+				 const char *name,
+				 struct hotplug_slot *hotplug)
 {
 	struct pci_dev *dev;
 	struct pci_slot *slot;

include/linux/pci.h

@@ -510,7 +510,8 @@ struct pci_bus *pci_create_bus(struct device *parent, int bus,
 struct pci_bus *pci_add_new_bus(struct pci_bus *parent, struct pci_dev *dev,
 				int busnr);
 struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr,
-				 const char *name);
+				 const char *name,
+				 struct hotplug_slot *hotplug);
 void pci_destroy_slot(struct pci_slot *slot);
 void pci_renumber_slot(struct pci_slot *slot, int slot_nr);
 int pci_scan_slot(struct pci_bus *bus, int devfn);