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 <[email protected]>
Signed-off-by: Geert Uytterhoeven <[email protected]>
Acked-by: Rob Herring <[email protected]>
---
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
On Tuesday 18 October 2016 10:05 PM, 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 <[email protected]>
> Signed-off-by: Geert Uytterhoeven <[email protected]>
> Acked-by: Rob Herring <[email protected]>
Fixes some junk characters seen on boot console on TI platforms.
Tested-by: Mugunthan V N <[email protected]>
Regards
Mugunthan V N
> ---
> 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++;
>
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 S?derlund <[email protected]>
> Signed-off-by: Geert Uytterhoeven <[email protected]>
> Acked-by: Rob Herring <[email protected]>
It fixes the issue I was seeing with systemd as a init system.
Tested-by: Niklas S?derlund <[email protected]>
> ---
> 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 S?derlund