s390/3270: fix garbled output on 3270 tty view

The tty3270_update function tries to optimize the output stream by skipping the TO_SBA command to position the output offset if the TO_RA command of the previous line ended at the same offset. But some lines do not have the TO_RA at the end, namely those with a length equal to the number of columns. Make sure there is a TO_RA at the end of the previous line to avoid funny looking output. Signed-off-by: Martin Schwidefsky <[email protected]>
olifre · May 4, 2016 · 2e63a3a · 2e63a3a
1 parent b512353
commit 2e63a3a
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/drivers/s390/char/tty3270.c b/drivers/s390/char/tty3270.c
@@ -405,7 +405,10 @@ tty3270_update(struct tty3270 *tp)
 			if (raw3270_request_add_data(wrq, str, len) != 0)
 				break;
 			list_del_init(&s->update);
-			sba = s->string + s->len - 3;
+			if (s->string[s->len - 4] == TO_RA)
+				sba = s->string + s->len - 3;
+			else
+				sba = invalid_sba;
 		}
 		if (list_empty(&tp->update))
 			updated |= TTY_UPDATE_LIST;