On Wed, 16 Sep 2009, Jason Wessel wrote:
> During the 2.6.32 development usb serial tty interface was changed.
> This change caused the usb serial driver to crash when used as a
> system console.
>
> The open and close of the raw hardware has to be protected by the
> serial->console variable so either the console code does the open and
> close or the higher level tty based driver executes the open and
> close.
>
> * In serial_open() the raw open must be protected by serial->console
> * In serial_down() the test_and_clear_bit must be executed before
> leaving the function if the device is a serial console
> * serial_release() should no longer protect for the console condition
> due to the 2.6.32 interface changes. The actual low level close
> protection is accounted for in serial_down()
>
> Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
> Cc: Greg KH <gregkh@xxxxxxx>
> Cc: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
>
> ---
> drivers/usb/serial/usb-serial.c | 28 +++++++++++++---------------
> 1 files changed, 13 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
> index ff75a35..3d35ed2 100644
> --- a/drivers/usb/serial/usb-serial.c
> +++ b/drivers/usb/serial/usb-serial.c
> @@ -267,10 +267,14 @@ static int serial_open(struct tty_struct *tty, struct file *filp)
> if (mutex_lock_interruptible(&port->mutex))
> return -ERESTARTSYS;
> mutex_lock(&serial->disc_mutex);
> - if (serial->disconnected)
> + if (serial->disconnected) {
> retval = -ENODEV;
> - else
> - retval = port->serial->type->open(tty, port);
> + } else {
> + if (port->console)
> + retval = 0;
> + else
> + retval = port->serial->type->open(tty, port);
> + }
> mutex_unlock(&serial->disc_mutex);
> mutex_unlock(&port->mutex);
> if (retval)
This part of the patch shouldn't be necessary. The console device
should always be open.
> @@ -294,6 +298,12 @@ static void serial_down(struct usb_serial_port *port)
> {
> struct usb_serial_driver *drv = port->serial->type;
>
> + /* Don't call the close method if the hardware hasn't been
> + * initialized.
> + */
> + if (!test_and_clear_bit(ASYNCB_INITIALIZED, &port->port.flags))
> + return;
> +
> /*
> * The console is magical. Do not hang up the console hardware
> * or there will be tears.
I don't understand this. Why would you want to clear the
ASYNCB_INITIALIZED flag for the console device? Since you're not going
to deinitialize the hardware, the flag should remain set.
> @@ -301,12 +311,6 @@ static void serial_down(struct usb_serial_port *port)
> if (port->console)
> return;
>
> - /* Don't call the close method if the hardware hasn't been
> - * initialized.
> - */
> - if (!test_and_clear_bit(ASYNCB_INITIALIZED, &port->port.flags))
> - return;
> -
> mutex_lock(&port->mutex);
> if (drv->close)
> drv->close(port);
And of course, without the previous hunk this hunk is unnecessary.
> @@ -353,12 +357,6 @@ static void serial_release(struct tty_struct *tty)
> struct usb_serial *serial;
> struct module *owner;
>
> - /* The console is magical. Do not hang up the console hardware
> - * or there will be tears.
> - */
> - if (port->console)
> - return;
> -
> dbg("%s - port %d", __func__, port->number);
>
> /* Standard shutdown processing */
This also doesn't make sense. The console never should get closed or
released.
Alan Stern
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