From: Francesco Dolcini <francesco.dolcini@toradex.com>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Jiri Slaby <jirislaby@kernel.org>,
Shawn Guo <shawnguo@kernel.org>,
Sascha Hauer <s.hauer@pengutronix.de>,
Pengutronix Kernel Team <kernel@pengutronix.de>,
Fabio Estevam <festevam@gmail.com>,
NXP Linux Team <linux-imx@nxp.com>,
Stefan Agner <stefan@agner.ch>,
linux-serial@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/2] serial: imx: fix crash when un/re-binding console
Date: Thu, 14 Oct 2021 12:28:00 +0200 [thread overview]
Message-ID: <20211014102800.GC554920@francesco-nb.int.toradex.com> (raw)
In-Reply-To: <20211014080153.GA554920@francesco-nb.int.toradex.com>
On Thu, Oct 14, 2021 at 10:01:53AM +0200, Francesco Dolcini wrote:
> Hello Greg,
>
> On Thu, Oct 14, 2021 at 09:33:55AM +0200, Greg Kroah-Hartman wrote:
> > On Thu, Oct 14, 2021 at 09:10:52AM +0200, Francesco Dolcini wrote:
> > > From: Stefan Agner <stefan@agner.ch>
> > >
> > > If the device used as a serial console gets un/re-binded, then
> > > register_console() will call imx_uart_setup_console() again.
> > > Drop __init so that imx_uart_setup_console() can be safely called
> > > at runtime.
> > >
> > > Signed-off-by: Stefan Agner <stefan@agner.ch>
> > > Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
> > > ---
> > > drivers/tty/serial/imx.c | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > What commit does this "fix"?
>
> root@colibri-imx6ull-06746657:~# cat /sys/devices/virtual/tty/console/active
> tty1 ttymxc0
> root@colibri-imx6ull-06746657:~# echo -n N > /sys/devices/virtual/tty/console/subsystem/ttymxc0/console
> root@colibri-imx6ull-06746657:~# echo -n Y > /sys/devices/virtual/tty/console/subsystem/ttymxc0/console
>
> struct console ->setup is called at that time, but imx_uart_console_setup() is gone ...
This specific way I described here to reproduce the issue was introduced with
a3cb39d258ef serial: core: Allow detach and attach serial device for console
that is kernel 5.9+
(Andy added to to:)
But the original report was about bind/unbind of the uart driver, I guess this is possible since
way more time.
>
> According to the original report from Stefan the issue is the same with unbind/bind of the console,
> see https://marc.info/?l=linux-serial&m=154221779312036&w=2.
>
>
> > Should this go to stable kernels? If so, how far back?
> This is present also in 4.19 kernel, I feel like the issue is there since it is possible to unbind
> a console driver (since ever considering the current LTS releases?). I could
> investigate this a little bit more.
>
> We have this patch in our kernel branch since 3 years but for some reason we never managed to upstream it.
>
>
> Francesco
next prev parent reply other threads:[~2021-10-14 10:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-14 7:10 Francesco Dolcini
2021-10-14 7:10 ` [PATCH 1/2] serial: imx: fix crash when un/re-binding console Francesco Dolcini
2021-10-14 7:33 ` Greg Kroah-Hartman
2021-10-14 8:01 ` Francesco Dolcini
2021-10-14 8:10 ` Uwe Kleine-König
2021-10-14 9:12 ` Francesco Dolcini
2021-10-14 10:28 ` Francesco Dolcini [this message]
2021-10-14 7:10 ` [PATCH 2/2] serial: imx: disable console clocks on unregister Francesco Dolcini
2021-10-14 7:17 ` [PATCH 0/2] serial: imx: fix unbind/bind console Francesco Dolcini
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