staging: dgap: unwind on error in dgap_tty_register_ports()

- The dgap_tty_register_ports() needs to handle if the
tty_port_register_device() fails.
Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/dgap/dgap.c

@@ -4143,6 +4143,7 @@ static int dgap_tty_register_ports(struct board_t *brd)
 {
 	struct channel_t *ch;
 	int i;
+	int ret;
 
 	brd->serial_ports = kcalloc(brd->nasync, sizeof(*brd->serial_ports),
 					GFP_KERNEL);
@@ -4152,8 +4153,8 @@ static int dgap_tty_register_ports(struct board_t *brd)
 	brd->printer_ports = kcalloc(brd->nasync, sizeof(*brd->printer_ports),
 					GFP_KERNEL);
 	if (!brd->printer_ports) {
-		kfree(brd->serial_ports);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto free_serial_ports;
 	}
 
 	for (i = 0; i < brd->nasync; i++) {
@@ -4170,6 +4171,11 @@ static int dgap_tty_register_ports(struct board_t *brd)
 					brd->serial_driver,
 					brd->firstminor + i, NULL);
 
+		if (IS_ERR(classp)) {
+			ret = PTR_ERR(classp);
+			goto unregister_ttys;
+		}
+
 		dgap_create_tty_sysfs(&ch->ch_tun, classp);
 		ch->ch_tun.un_sysfs = classp;
 
@@ -4177,12 +4183,46 @@ static int dgap_tty_register_ports(struct board_t *brd)
 					brd->print_driver,
 					brd->firstminor + i, NULL);
 
+		if (IS_ERR(classp)) {
+			ret = PTR_ERR(classp);
+			goto unregister_ttys;
+		}
+
 		dgap_create_tty_sysfs(&ch->ch_pun, classp);
 		ch->ch_pun.un_sysfs = classp;
 	}
 	dgap_create_ports_sysfiles(brd);
 
 	return 0;
+
+unregister_ttys:
+	while (i >= 0) {
+		ch = brd->channels[i];
+		if (ch->ch_tun.un_sysfs) {
+			dgap_remove_tty_sysfs(ch->ch_tun.un_sysfs);
+			tty_unregister_device(brd->serial_driver, i);
+		}
+
+		if (ch->ch_pun.un_sysfs) {
+			dgap_remove_tty_sysfs(ch->ch_pun.un_sysfs);
+			tty_unregister_device(brd->print_driver, i);
+		}
+		i--;
+	}
+
+	for (i = 0; i < brd->nasync; i++) {
+		tty_port_destroy(&brd->serial_ports[i]);
+		tty_port_destroy(&brd->printer_ports[i]);
+	}
+
+	kfree(brd->printer_ports);
+	brd->printer_ports = NULL;
+
+free_serial_ports:
+	kfree(brd->serial_ports);
+	brd->serial_ports = NULL;
+
+	return ret;
 }
 
 /*