[PATCH] USB: ohci minor tweaks

Two small updates:

  - Report short control reads correctly in an exotic case
    that our regression tests cover.  (Haven't run them with
    ohci for a long time, it seems...)

  - IRQ non-delivery bugs (ACPI, APIC, etc) can prevent urbs
    from unlinking.  This prints a warning when that sort of
    non-USB bug is biting.

drivers/usb/host/ohci-hcd.c

@@ -319,6 +319,7 @@ ohci_endpoint_disable (struct usb_hcd *hcd, struct hcd_dev *dev, int ep)
 	int			epnum = ep & USB_ENDPOINT_NUMBER_MASK;
 	unsigned long		flags;
 	struct ed		*ed;
+	unsigned		limit = 1000;
 
 	/* ASSERT:  any requests/urbs are being unlinked */
 	/* ASSERT:  nobody can be submitting urbs for this any more */
@@ -337,6 +338,8 @@ ohci_endpoint_disable (struct usb_hcd *hcd, struct hcd_dev *dev, int ep)
 		ed->state = ED_IDLE;
 	switch (ed->state) {
 	case ED_UNLINK:		/* wait for hw to finish? */
+		/* major IRQ delivery trouble loses INTR_SF too... */
+		WARN_ON (limit-- == 0);
 		spin_unlock_irqrestore (&ohci->lock, flags);
 		set_current_state (TASK_UNINTERRUPTIBLE);
 		schedule_timeout (1);

drivers/usb/host/ohci-q.c

@@ -43,6 +43,16 @@ finish_urb (struct ohci_hcd *ohci, struct urb *urb, struct pt_regs *regs)
 	spin_lock (&urb->lock);
 	if (likely (urb->status == -EINPROGRESS))
 		urb->status = 0;
+	/* report short control reads right even though the data TD always
+	 * has TD_R set.  (much simpler, but creates the 1-td limit.)
+	 */
+	if (unlikely (urb->transfer_flags & URB_SHORT_NOT_OK)
+			&& unlikely (usb_pipecontrol (urb->pipe))
+			&& urb->actual_length < urb->transfer_buffer_length
+			&& usb_pipein (urb->pipe)
+			&& urb->status == 0) {
+		urb->status = -EREMOTEIO;
+	}
 	spin_unlock (&urb->lock);
 
 	// what lock protects these?