Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S941661AbcJYKkn (ORCPT ); Tue, 25 Oct 2016 06:40:43 -0400 Received: from mail-oi0-f68.google.com ([209.85.218.68]:34279 "EHLO mail-oi0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932843AbcJYKkj (ORCPT ); Tue, 25 Oct 2016 06:40:39 -0400 MIME-Version: 1.0 In-Reply-To: <20161024205649.32430-1-robh@kernel.org> References: <20161024205649.32430-1-robh@kernel.org> From: Geert Uytterhoeven Date: Tue, 25 Oct 2016 12:40:37 +0200 X-Google-Sender-Auth: qEYagkNA2gtagLFw6e3RtObt0sY Message-ID: Subject: Re: [PATCH] serial: core: fix console problems on uart_close To: Rob Herring Cc: Greg Kroah-Hartman , =?UTF-8?Q?Niklas_S=C3=B6derlund?= , Mike Galbraith , Mugunthan V N , Geert Uytterhoeven , "linux-kernel@vger.kernel.org" , Peter Hurley , Alan Cox , Jiri Slaby , "linux-serial@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by mail.home.local id u9PAeqcY021275 Content-Length: 2942 Lines: 73 Hi Rob, On Mon, Oct 24, 2016 at 10:56 PM, Rob Herring wrote: > Commit 761ed4a94582 ('tty: serial_core: convert uart_close to use > tty_port_close') started setting the ttyport console flag for serial > drivers. This is causing crashes, hangs, or garbage output on several > platforms because the serial shutdown is skipped and IRQs are left > enabled. No, for me it hangs because uart_tty_port_shutdown() is _not_ skipped when the UART is used as a serial console. Writing to the serial port while it's shut down hangs. > Partially revert commit 761ed4a94582 and drop reporting UART tty_ports > as a console leaving the console handling to the serial_core as it was > before. > > Fixes: 761ed4a94582ab29 ("tty: serial_core: convert uart_close to use tty_port_close") > Reported-by: Niklas Söderlund > Reported-by: Mike Galbraith > Reported-by: Mugunthan V N > Cc: Peter Hurley > Cc: Geert Uytterhoeven > Cc: Alan Cox > Cc: Greg Kroah-Hartman > Cc: Jiri Slaby > Cc: linux-serial@vger.kernel.org > Signed-off-by: Rob Herring > --- > Geert's fix seems to be inadequate for some systems as Mike reported[1]. > This fix works in Mike's case. > > Geert, Mugunthan, Can you all test this is enough to fix your issues. This doesn't work for me, as port->console is still false. It should be true when used as a serial console, to make sure tty_port_shutdown() skips an active serial console. Mike: I see you are using a PC, while I'm using an ARM board (with DT). Are you using a serial console? If yes, what's the value of port->console before and after the call to uart_console() that Rob's patch below removes? Thanks! > [1] https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1254753.html > > drivers/tty/serial/serial_core.c | 2 -- > 1 file changed, 2 deletions(-) > > diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c > index 6e4f63627479..664c99aeeca5 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. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds