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Groups > linux.kernel > #1503214 > unrolled thread
| Started by | Geert Uytterhoeven <geert+renesas@glider.be> |
|---|---|
| First post | 2016-10-18 18:40 +0200 |
| Last post | 2016-10-19 17:50 +0200 |
| Articles | 3 — 3 participants |
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[PATCH v2] tty: serial_core: Fix serial console crash on port shutdown Geert Uytterhoeven <geert+renesas@glider.be> - 2016-10-18 18:40 +0200
Re: [v2] tty: serial_core: Fix serial console crash on port shutdown Mugunthan V N <mugunthanvnm@ti.com> - 2016-10-19 11:10 +0200
Re: [PATCH v2] tty: serial_core: Fix serial console crash on port shutdown "Niklas Söderlund" <niklas.soderlund@ragnatech.se> - 2016-10-19 17:50 +0200
| From | Geert Uytterhoeven <geert+renesas@glider.be> |
|---|---|
| Date | 2016-10-18 18:40 +0200 |
| Subject | [PATCH v2] tty: serial_core: Fix serial console crash on port shutdown |
| Message-ID | <stFAK-4gM-27@gated-at.bofh.it> |
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>
---
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
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| From | Mugunthan V N <mugunthanvnm@ti.com> |
|---|---|
| Date | 2016-10-19 11:10 +0200 |
| Subject | Re: [v2] tty: serial_core: Fix serial console crash on port shutdown |
| Message-ID | <stV2N-7yU-5@gated-at.bofh.it> |
| In reply to | #1503214 |
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 <niklas.soderlund+renesas@ragnatech.se>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Acked-by: Rob Herring <robh@kernel.org>
Fixes some junk characters seen on boot console on TI platforms.
Tested-by: Mugunthan V N <mugunthanvnm@ti.com>
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++;
>
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| From | "Niklas Söderlund" <niklas.soderlund@ragnatech.se> |
|---|---|
| Date | 2016-10-19 17:50 +0200 |
| Subject | Re: [PATCH v2] tty: serial_core: Fix serial console crash on port shutdown |
| Message-ID | <su1hU-3b7-29@gated-at.bofh.it> |
| In reply to | #1503214 |
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>
> ---
> 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
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