[PATCH] OHCI urb unlink fixes

Fix two OHCI unlink issues.

   * All EDs now get a 1 msec delay before re-linking, even those
     which were seemingly "clean" unlink cases.  This gets rid of
     some list corruption issues ("bad entry") by getting rid of
     a fast-path carried over from 2.4 usb-ohci.

   * In case of unlink-during-submit, we must giveback() right away.
     This is a reasonably rare case.

There have been recent reports of problems here.  The "bad entry"
showed up with usbtest tests #11 and #12, or "stir4200", and maybe
in other cases.  The unlink-during-submit shows up in usbtest.

drivers/usb/host/ohci-hcd.c

@@ -229,11 +229,21 @@ static int ohci_urb_enqueue (
 		goto fail;
 	}
 
+	/* in case of unlink-during-submit */
+	spin_lock (&urb->lock);
+	if (urb->status != -EINPROGRESS) {
+		spin_unlock (&urb->lock);
+
+		finish_urb (ohci, urb, 0);
+		retval = 0;
+		goto fail;
+	}
+
 	/* schedule the ed if needed */
 	if (ed->state == ED_IDLE) {
 		retval = ed_schedule (ohci, ed);
 		if (retval < 0)
-			goto fail;
+			goto fail0;
 		if (ed->type == PIPE_ISOCHRONOUS) {
 			u16	frame = OHCI_FRAME_NO(ohci->hcca);
 
@@ -257,6 +267,8 @@ static int ohci_urb_enqueue (
 	urb->hcpriv = urb_priv;
 	td_submit_urb (ohci, urb);
 
+fail0:
+	spin_unlock (&urb->lock);
 fail:
 	if (retval)
 		urb_free_priv (ohci, urb_priv);

drivers/usb/host/ohci-q.c

@@ -331,19 +331,6 @@ static void ed_deschedule (struct ohci_hcd *ohci, struct ed *ed)
 		periodic_unlink (ohci, ed);
 		break;
 	}
-
-	/* NOTE: Except for a couple of exceptionally clean unlink cases
-	 * (like unlinking the only c/b ED, with no TDs) HCs may still be
-	 * caching this operational ED (or its address).  Safe unlinking
-	 * involves not marking it ED_IDLE till INTR_SF; we always do that
-	 * if td_list isn't empty.  Otherwise the race is small; but ...
-	 */
-	if (ed->state == ED_OPER) {
-		ed->state = ED_IDLE;
-		ed->hwINFO &= ~(ED_SKIP | ED_DEQUEUE);
-		ed->hwHeadP &= ~ED_H;
-		wmb ();
-	}
 }
 
 
@@ -665,6 +652,7 @@ static void td_submit_urb (
 
 	/* start periodic dma if needed */
 	if (periodic) {
+		wmb ();
 		ohci->hc_control |= OHCI_CTRL_PLE|OHCI_CTRL_IE;
 		writel (ohci->hc_control, &ohci->regs->control);
 	}
@@ -1053,7 +1041,7 @@ dl_done_list (struct ohci_hcd *ohci, struct td *td, struct pt_regs *regs)
 
 		/* clean schedule:  unlink EDs that are no longer busy */
 		if (list_empty (&ed->td_list))
-			ed_deschedule (ohci, ed);
+			start_ed_unlink (ohci, ed);
 		/* ... reenabling halted EDs only after fault cleanup */
 		else if ((ed->hwINFO & (ED_SKIP | ED_DEQUEUE)) == ED_SKIP) {
 			td = list_entry (ed->td_list.next, struct td, td_list);