usb: core: switch bus numbering to using idr

USB bus numbering is based on directly dealing with bitmaps and
defines a separate list of busses.
This can be simplified and unified by using existing idr functionality.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 9 insertions, 23 deletions

diff --git a/drivers/usb/core/devices.c b/drivers/usb/core/devices.c
index b35a6a52210f..6118a04f0b84 100644
--- a/drivers/usb/core/devices.c
+++ b/drivers/usb/core/devices.c
@@ -110,13 +110,6 @@ static const char format_endpt[] =
 /* E:  Ad=xx(s) Atr=xx(ssss) MxPS=dddd Ivl=D?s */
   "E:  Ad=%02x(%c) Atr=%02x(%-4s) MxPS=%4d Ivl=%d%cs\n";
 
-
-/*
- * Need access to the driver and USB bus lists.
- * extern struct list_head usb_bus_list;
- * However, these will come from functions that return ptrs to each of them.
- */
-
 /*
  * Wait for an connect/disconnect event to happen. We initialize
  * the event counter with an odd number, and each event will increment
@@ -618,6 +611,7 @@ static ssize_t usb_device_read(struct file *file, char __user *buf,
 	struct usb_bus *bus;
 	ssize_t ret, total_written = 0;
 	loff_t skip_bytes = *ppos;
+	int id;
 
 	if (*ppos < 0)
 		return -EINVAL;
@@ -628,7 +622,7 @@ static ssize_t usb_device_read(struct file *file, char __user *buf,
 
 	mutex_lock(&usb_bus_list_lock);
 	/* print devices for all busses */
-	list_for_each_entry(bus, &usb_bus_list, bus_list) {
+	idr_for_each_entry(&usb_bus_idr, bus, id) {
 		/* recurse through all children of the root hub */
 		if (!bus_to_hcd(bus)->rh_registered)
 			continue;
diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 232c8c93dd3a..cf3eb22dbeb4 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -90,12 +90,11 @@ unsigned long usb_hcds_loaded;
 EXPORT_SYMBOL_GPL(usb_hcds_loaded);
 
 /* host controllers we manage */
-LIST_HEAD (usb_bus_list);
-EXPORT_SYMBOL_GPL (usb_bus_list);
+DEFINE_IDR (usb_bus_idr);
+EXPORT_SYMBOL_GPL (usb_bus_idr);
 
 /* used when allocating bus numbers */
 #define USB_MAXBUS		64
-static DECLARE_BITMAP(busmap, USB_MAXBUS);
 
 /* used when updating list of hcds */
 DEFINE_MUTEX(usb_bus_list_lock);	/* exported only for usbfs */
@@ -996,8 +995,6 @@ static void usb_bus_init (struct usb_bus *bus)
 	bus->bandwidth_int_reqs  = 0;
 	bus->bandwidth_isoc_reqs = 0;
 	mutex_init(&bus->usb_address0_mutex);
-
-	INIT_LIST_HEAD (&bus->bus_list);
 }
 
 /*-------------------------------------------------------------------------*/
@@ -1018,16 +1015,12 @@ static int usb_register_bus(struct usb_bus *bus)
 	int busnum;
 
 	mutex_lock(&usb_bus_list_lock);
-	busnum = find_next_zero_bit(busmap, USB_MAXBUS, 1);
-	if (busnum >= USB_MAXBUS) {
-		printk (KERN_ERR "%s: too many buses\n", usbcore_name);
+	busnum = idr_alloc(&usb_bus_idr, bus, 1, USB_MAXBUS, GFP_KERNEL);
+	if (busnum < 0) {
+		pr_err("%s: failed to get bus number\n", usbcore_name);
 		goto error_find_busnum;
 	}
-	set_bit(busnum, busmap);
 	bus->busnum = busnum;
-
-	/* Add it to the local list of buses */
-	list_add (&bus->bus_list, &usb_bus_list);
 	mutex_unlock(&usb_bus_list_lock);
 
 	usb_notify_add_bus(bus);
@@ -1059,12 +1052,10 @@ static void usb_deregister_bus (struct usb_bus *bus)
 	 * itself up
 	 */
 	mutex_lock(&usb_bus_list_lock);
-	list_del (&bus->bus_list);
+	idr_remove(&usb_bus_idr, bus->busnum);
 	mutex_unlock(&usb_bus_list_lock);
 
 	usb_notify_remove_bus(bus);
-
-	clear_bit(bus->busnum, busmap);
 }
 
 /**
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 16ade41759cd..524c9822d2bb 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -1115,6 +1115,7 @@ static void __exit usb_exit(void)
 	bus_unregister(&usb_bus_type);
 	usb_acpi_unregister();
 	usb_debugfs_cleanup();
+	idr_destroy(&usb_bus_idr);
 }
 
 subsys_initcall(usb_init);