Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938682AbcJRQfz (ORCPT ); Tue, 18 Oct 2016 12:35:55 -0400 Received: from laurent.telenet-ops.be ([195.130.137.89]:36284 "EHLO laurent.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754585AbcJRQfr (ORCPT ); Tue, 18 Oct 2016 12:35:47 -0400 From: Geert Uytterhoeven To: Greg Kroah-Hartman , Jiri Slaby Cc: =?UTF-8?q?Niklas=20S=C3=B6derlund?= , Rob Herring , Peter Hurley , Alan Cox , linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH v2] tty: serial_core: Fix serial console crash on port shutdown Date: Tue, 18 Oct 2016 18:35:40 +0200 Message-Id: <1476808540-2757-1-git-send-email-geert+renesas@glider.be> X-Mailer: git-send-email 1.9.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1916 Lines: 52 The port->console flag is always false, as uart_console() is called before the serial console has been registered. Hence for a serial port used as the console, uart_tty_port_shutdown() will still be called when userspace closes the port, powering it down. This may lead to a system lock up when the serial console driver writes to the serial port's registers. To fix this, move the setting of port->console after the call to uart_configure_port(), which registers the serial console. Fixes: 761ed4a94582ab29 ("tty: serial_core: convert uart_close to use tty_port_close") Reported-by: Niklas Söderlund Signed-off-by: Geert Uytterhoeven Acked-by: Rob Herring --- v2: - Add Acked-by, - Reworded one-line summary (incl. magic word "fix"). Can easily be reproduced on Renesas boards: 1. With systemd: hangs during boot, 2. Without systemd: "telinit n" to switch to a runlevel that doesn't run a getty on ttySC0, and trigger kernel console output => hang. --- drivers/tty/serial/serial_core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 6e4f63627479db8d..ce8899c13af3d97f 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -2746,8 +2746,6 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport) uport->cons = drv->cons; uport->minor = drv->tty_driver->minor_start + uport->line; - port->console = uart_console(uport); - /* * If this port is a console, then the spinlock is already * initialised. @@ -2761,6 +2759,8 @@ int uart_add_one_port(struct uart_driver *drv, struct uart_port *uport) uart_configure_port(drv, state, uport); + port->console = uart_console(uport); + num_groups = 2; if (uport->attr_group) num_groups++; -- 1.9.1