Re: [PATCH v2] tty: serial_core: Fix serial console crash on port shutdown
From: "Niklas Söderlund" <niklas.soderlund@ragnatech.se>
Date: 2016-10-19 15:47:36
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Hi Geert, On 2016-10-18 18:35:40 +0200, Geert Uytterhoeven wrote:
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 <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Rob Herring <robh@kernel.org>It fixes the issue I was seeing with systemd as a init system. Tested-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
quoted hunk ↗ jump to hunk
--- 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
-- Regards, Niklas Söderlund