[PATCH] USB: usb_sg_cancel() + disconnect, fewer messages

One tester reported that disconnecting in the middle of a scatterlist
operation would give a lot of confusing messages.  This should improve
that situation a bunch:  most of the messages were pointless.  It also
resolves some related FIXMEs for both queue cleanup modes (cancelation,
and after transport fault).

  - now only urbs in flight have non-null urb->dev, so we can avoid
    trying to unlink unsubmitted or (common) already-completed urbs.

  - it's ok to get -EBUSY unlink status, it just means the urb's
    already being given back (though since it's in flight, it's
    not an error to try unlinking).

Also, the relevant diagnostics now use dev_*() driver model calls,
making the kernel strings smaller and the output more useful.

drivers/usb/core/message.c

@@ -246,21 +246,22 @@ static void sg_complete (struct urb *urb, struct pt_regs *regs)
 		io->status = urb->status;
 
 		/* the previous urbs, and this one, completed already.
-		 * unlink the later ones so they won't rx/tx bad data,
-		 *
-		 * FIXME don't bother unlinking urbs that haven't yet been
-		 * submitted; those non-error cases shouldn't be syslogged
+		 * unlink pending urbs so they won't rx/tx bad data.
 		 */
 		for (i = 0, found = 0; i < io->entries; i++) {
+			if (!io->urbs [i])
+				continue;
 			if (found) {
 				status = usb_unlink_urb (io->urbs [i]);
-				if (status && status != -EINPROGRESS)
-					err ("sg_complete, unlink --> %d",
-							status);
+				if (status != -EINPROGRESS && status != -EBUSY)
+					dev_err (&io->dev->dev,
+						"%s, unlink --> %d\n",
+						__FUNCTION__, status);
 			} else if (urb == io->urbs [i])
 				found = 1;
 		}
 	}
+	urb->dev = 0;
 
 	/* on the last completion, signal usb_sg_wait() */
 	io->bytes += urb->actual_length;
@@ -356,7 +357,7 @@ int usb_sg_init (
 			goto nomem;
 		}
 
-		io->urbs [i]->dev = dev;
+		io->urbs [i]->dev = 0;
 		io->urbs [i]->pipe = pipe;
 		io->urbs [i]->interval = period;
 		io->urbs [i]->transfer_flags = urb_flags;
@@ -448,6 +449,7 @@ void usb_sg_wait (struct usb_sg_request *io)
 	for (i = 0; i < io->entries && !io->status; i++) {
 		int	retval;
 
+		io->urbs [i]->dev = io->dev;
 		retval = usb_submit_urb (io->urbs [i], SLAB_ATOMIC);
 
 		/* after we submit, let completions or cancelations fire;
@@ -459,9 +461,9 @@ void usb_sg_wait (struct usb_sg_request *io)
 		case -ENXIO:	// hc didn't queue this one
 		case -EAGAIN:
 		case -ENOMEM:
+			io->urbs [i]->dev = 0;
 			retval = 0;
 			i--;
-			// FIXME:  should it usb_sg_cancel() on INTERRUPT?
 			yield ();
 			break;
 
@@ -477,8 +479,10 @@ void usb_sg_wait (struct usb_sg_request *io)
 
 			/* fail any uncompleted urbs */
 		default:
+			io->urbs [i]->dev = 0;
 			io->urbs [i]->status = retval;
-			dbg ("usb_sg_msg, submit --> %d", retval);
+			dev_dbg (&io->dev->dev, "%s, submit --> %d\n",
+				__FUNCTION__, retval);
 			usb_sg_cancel (io);
 		}
 		spin_lock_irqsave (&io->lock, flags);
@@ -521,9 +525,9 @@ void usb_sg_cancel (struct usb_sg_request *io)
 			if (!io->urbs [i]->dev)
 				continue;
 			retval = usb_unlink_urb (io->urbs [i]);
-			if (retval && retval != -EINPROGRESS)
-				warn ("usb_sg_cancel, unlink --> %d", retval);
-			// FIXME don't warn on "not yet submitted" error
+			if (retval != -EINPROGRESS && retval != -EBUSY)
+				dev_warn (&io->dev->dev, "%s, unlink --> %d\n",
+					__FUNCTION__, retval);
 		}
 	}
 	spin_unlock_irqrestore (&io->lock, flags);