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>

1 files changed, 24 insertions, 1 deletions

diff --git a/drivers/s390/char/tty3270.c b/drivers/s390/char/tty3270.c
index d6da18612ba8..402eff3c1634 100644
--- a/drivers/s390/char/tty3270.c
+++ b/drivers/s390/char/tty3270.c
@@ -319,6 +319,27 @@ tty3270_blank_line(struct tty3270 *tp)
 }
 
 /*
+ * 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.
  */
 static void
@@ -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;