s390/3270: handle reconnect of a tty with a different size

If an existing 3270 terminal disconnects and reconnects with a
different size, the 3270 driver still works with the old size.
If the new dimensions are larger the output merely looks funny,
if the new dimensions are smaller the terminal is unusable.

To fix this restart the size detection after a unit check has
been received.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/raw3270.c

@@ -90,6 +90,8 @@ module_param(tubxcorrect, bool, 0);
  */
 DECLARE_WAIT_QUEUE_HEAD(raw3270_wait_queue);
 
+static void __raw3270_disconnect(struct raw3270 *rp);
+
 /*
  * Encode array for 12 bit 3270 addresses.
  */
@@ -336,8 +338,11 @@ raw3270_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
 			set_bit(RAW3270_FLAGS_BUSY, &rp->flags);
 		/* Handle disconnected devices */
 		if ((irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) &&
-		    (irb->ecw[0] & SNS0_INTERVENTION_REQ))
+		    (irb->ecw[0] & SNS0_INTERVENTION_REQ)) {
 			set_bit(RAW3270_FLAGS_BUSY, &rp->flags);
+			if (rp->state > RAW3270_STATE_RESET)
+				__raw3270_disconnect(rp);
+		}
 		/* Call interrupt handler of the view */
 		if (view)
 			view->fn->intv(view, rq, irb);
@@ -347,8 +352,7 @@ raw3270_irq (struct ccw_device *cdev, unsigned long intparm, struct irb *irb)
 		/* Device busy, do not start I/O */
 		return;
 
-	if (rq) {
-		BUG_ON(list_empty(&rq->list));
+	if (rq && !list_empty(&rq->list)) {
 		/* The request completed, remove from queue and do callback. */
 		list_del_init(&rq->list);
 		if (rq->callback)
@@ -634,6 +638,28 @@ raw3270_reset(struct raw3270_view *view)
 	return rc;
 }
 
+static void
+__raw3270_disconnect(struct raw3270 *rp)
+{
+	struct raw3270_request *rq;
+	struct raw3270_view *view;
+
+	rp->state = RAW3270_STATE_INIT;
+	rp->view = &rp->init_view;
+	/* Cancel all queued requests */
+	while (!list_empty(&rp->req_queue)) {
+		rq = list_entry(rp->req_queue.next,struct raw3270_request,list);
+		view = rq->view;
+		rq->rc = -EACCES;
+		list_del_init(&rq->list);
+		if (rq->callback)
+			rq->callback(rq, rq->callback_data);
+		raw3270_put_view(view);
+	}
+	/* Start from scratch */
+	__raw3270_reset_device(rp);
+}
+
 static void
 raw3270_init_irq(struct raw3270_view *view, struct raw3270_request *rq,
 		 struct irb *irb)

drivers/s390/char/tty3270.c

@@ -318,6 +318,27 @@ tty3270_blank_line(struct tty3270 *tp)
 		tp->nr_up++;
 }
 
+/*
+ * Create a blank screen and remove all lines from the history.
+ */
+static void
+tty3270_blank_screen(struct tty3270 *tp)
+{
+	struct string *s, *n;
+	int i;
+
+	for (i = 0; i < tp->view.rows - 2; i++)
+		tp->screen[i].len = 0;
+	tp->nr_up = 0;
+	list_for_each_entry_safe(s, n, &tp->lines, list) {
+		list_del(&s->list);
+		if (!list_empty(&s->update))
+			list_del(&s->update);
+		tp->nr_lines--;
+		free_string(&tp->freemem, s);
+	}
+}
+
 /*
  * Write request completion callback.
  */
@@ -816,6 +837,7 @@ static void tty3270_resize_work(struct work_struct *work)
 		return;
 	/* Switch to new output size */
 	spin_lock_bh(&tp->view.lock);
+	tty3270_blank_screen(tp);
 	oscreen = tp->screen;
 	orows = tp->view.rows;
 	tp->view.model = tp->n_model;
@@ -826,7 +848,6 @@ static void tty3270_resize_work(struct work_struct *work)
 	free_string(&tp->freemem, tp->status);
 	tty3270_create_prompt(tp);
 	tty3270_create_status(tp);
-	tp->nr_up = 0;
 	while (tp->nr_lines < tp->view.rows - 2)
 		tty3270_blank_line(tp);
 	tp->update_flags = TTY_UPDATE_ALL;
@@ -848,6 +869,8 @@ tty3270_resize(struct raw3270_view *view, int model, int rows, int cols)
 {
 	struct tty3270 *tp = container_of(view, struct tty3270, view);
 
+	if (tp->n_model == model && tp->n_rows == rows && tp->n_cols == cols)
+		return;
 	tp->n_model = model;
 	tp->n_rows = rows;
 	tp->n_cols = cols;