usb: free DMA mappings if enqueue fails

This patch releases DMA resources if enqueue fails in the HCD.

Linux had this bug ever since we converted from virt_to_bus for 2.4.
It is difficult to hit. A user would need a significant memory pressure
or some other unusual condition.

It was reported to me by IBM. They ran a management application for
RSA II adapters which sent Bulk requests to an Interrupt endpoint.
Submissions got rejected by HCD due to an invalid interval value
and the swiotlb pool became depleted in the matter of hours.

We fixed the invalid interval issue in devio.c separately, but this
seems to be a bug worth fixing as well.
Signed-off-by: Pete Zaitcev <zaitcev@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/core/hcd.c

@@ -903,17 +903,32 @@ EXPORT_SYMBOL (usb_calc_bus_time);
 
 /*-------------------------------------------------------------------------*/
 
-static void urb_unlink (struct urb *urb)
+static void urb_unlink(struct usb_hcd *hcd, struct urb *urb)
 {
 	unsigned long		flags;
+	int at_root_hub = (urb->dev == hcd->self.root_hub);
 
 	/* clear all state linking urb to this dev (and hcd) */
-
 	spin_lock_irqsave (&hcd_data_lock, flags);
 	list_del_init (&urb->urb_list);
 	spin_unlock_irqrestore (&hcd_data_lock, flags);
-}
 
+	if (hcd->self.uses_dma && !at_root_hub) {
+		if (usb_pipecontrol (urb->pipe)
+			&& !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
+			dma_unmap_single (hcd->self.controller, urb->setup_dma,
+					sizeof (struct usb_ctrlrequest),
+					DMA_TO_DEVICE);
+		if (urb->transfer_buffer_length != 0
+			&& !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
+			dma_unmap_single (hcd->self.controller,
+					urb->transfer_dma,
+					urb->transfer_buffer_length,
+					usb_pipein (urb->pipe)
+					    ? DMA_FROM_DEVICE
+					    : DMA_TO_DEVICE);
+	}
+}
 
 /* may be called in any context with a valid urb->dev usecount
  * caller surrenders "ownership" of urb
@@ -1016,7 +1031,7 @@ doit:
 	status = hcd->driver->urb_enqueue (hcd, ep, urb, mem_flags);
 done:
 	if (unlikely (status)) {
-		urb_unlink (urb);
+		urb_unlink(hcd, urb);
 		atomic_dec (&urb->use_count);
 		if (urb->reject)
 			wake_up (&usb_kill_urb_queue);
@@ -1400,29 +1415,7 @@ EXPORT_SYMBOL (usb_bus_start_enum);
  */
 void usb_hcd_giveback_urb (struct usb_hcd *hcd, struct urb *urb)
 {
-	int at_root_hub;
-
-	at_root_hub = (urb->dev == hcd->self.root_hub);
-	urb_unlink (urb);
-
-	/* lower level hcd code should use *_dma exclusively if the
-	 * host controller does DMA */
-	if (hcd->self.uses_dma && !at_root_hub) {
-		if (usb_pipecontrol (urb->pipe)
-			&& !(urb->transfer_flags & URB_NO_SETUP_DMA_MAP))
-			dma_unmap_single (hcd->self.controller, urb->setup_dma,
-					sizeof (struct usb_ctrlrequest),
-					DMA_TO_DEVICE);
-		if (urb->transfer_buffer_length != 0
-			&& !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP))
-			dma_unmap_single (hcd->self.controller, 
-					urb->transfer_dma,
-					urb->transfer_buffer_length,
-					usb_pipein (urb->pipe)
-					    ? DMA_FROM_DEVICE
-					    : DMA_TO_DEVICE);
-	}
-
+	urb_unlink(hcd, urb);
 	usbmon_urb_complete (&hcd->self, urb);
 	usb_unanchor_urb(urb);