[PATCH] usbcore: Make the core release hcd structures

This patch contains changes to usbcore making the core responsible for
deallocating memory for usb_hcd structures, rather than calling back into
the host controller drivers.  This solves a long-standing oops, since the
drivers may have been unloaded from memory by the time the release routine
is called.  (There probably are some Bugzilla entries caused by this, but
I don't know which ones.)

To really fix this up properly will require merging the HCD "glue" layer
into the higher core structures.  As things stand now, a usb_hcd contains
a usb_bus member, and the usb_bus is associated with a class_device: when
the class_device is released the usb_hcd gets deallocated.  It's awkward
in that neither the usb_hcd nor the usb_bus has its own reference count,
and the class_device is created when the bus is registered (not when it is
initialized).
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/usb/core/hcd-pci.c

@@ -38,14 +38,6 @@
 
 /*-------------------------------------------------------------------------*/
 
-static void hcd_pci_release(struct usb_bus *bus)
-{
-	struct usb_hcd *hcd = bus->hcpriv;
-
-	if (hcd)
-		hcd->driver->hcd_free(hcd);
-}
-
 /* configure so an HC device and id are always provided */
 /* always called with process context; sleeping is OK */
 
@@ -161,7 +153,7 @@ int usb_hcd_pci_probe (struct pci_dev *dev, const struct pci_device_id *id)
 
 	if ((retval = hcd_buffer_create (hcd)) != 0) {
 clean_3:
-		driver->hcd_free (hcd);
+		kfree (hcd);
 		goto clean_2;
 	}
 
@@ -195,8 +187,8 @@ int usb_hcd_pci_probe (struct pci_dev *dev, const struct pci_device_id *id)
 
 	usb_bus_init (&hcd->self);
 	hcd->self.op = &usb_hcd_operations;
+	hcd->self.release = &usb_hcd_release;
 	hcd->self.hcpriv = (void *) hcd;
-	hcd->self.release = &hcd_pci_release;
 	init_timer (&hcd->rh_timer);
 
 	INIT_LIST_HEAD (&hcd->dev_list);

drivers/usb/core/hcd.c

@@ -1622,3 +1622,13 @@ void usb_hc_died (struct usb_hcd *hcd)
 }
 EXPORT_SYMBOL (usb_hc_died);
 
+/*-------------------------------------------------------------------------*/
+
+void usb_hcd_release(struct usb_bus *bus)
+{
+	struct usb_hcd *hcd;
+
+	hcd = container_of (bus, struct usb_hcd, self);
+	kfree(hcd);
+}
+EXPORT_SYMBOL (usb_hcd_release);

drivers/usb/core/hcd.h

@@ -192,7 +192,6 @@ struct hc_driver {
 
 	/* memory lifecycle */
 	struct usb_hcd	*(*hcd_alloc) (void);
-	void		(*hcd_free) (struct usb_hcd *hcd);
 
 	/* manage i/o requests, device state */
 	int	(*urb_enqueue) (struct usb_hcd *hcd, struct urb *urb,
@@ -360,6 +359,8 @@ static inline int hcd_register_root (struct usb_device *usb_dev,
 	return usb_register_root_hub (usb_dev, hcd->self.controller);
 }
 
+extern void usb_hcd_release (struct usb_bus *);
+
 extern void usb_set_device_state(struct usb_device *udev,
 		enum usb_device_state new_state);