[PATCH] usbcore: add comment to updated hcd.h

On Fri, 29 Oct 2004, David Brownell wrote:

> Could you add a comment there that the HCD is
> now _required_ to return a pointer that usbcore
> can pass to kfree?  Since that's a layering
> violation (in anticipation of later changes to
> make it not be one!), it's surprising ... and
> in any case, the memory lifecycle is no longer
> described just by the calls in this header!

That's a reasonable request, and here's an extra patch to add the comment.
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/usb/core/hcd.h

@@ -191,6 +191,12 @@ struct hc_driver {
 	int	(*get_frame_number) (struct usb_hcd *hcd);
 
 	/* memory lifecycle */
+	/* Note: The absence of hcd_free reflects a temporary situation;
+	 * in the near future hcd_alloc will disappear as well and all
+	 * allocations/deallocations will be handled by usbcore.  For the
+	 * moment, drivers are required to return a pointer that the core
+	 * can pass to kfree, i.e., the struct usb_hcd must be the _first_
+	 * member of a larger driver-specific structure. */
 	struct usb_hcd	*(*hcd_alloc) (void);
 
 	/* manage i/o requests, device state */