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tty_port: add "tty_port_open" helper

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For the moment this just moves the USB logic over and fixes the 'what if
we open and hangup at the same time' race noticed by Oliver Neukum.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This commit is contained in:
Alan Cox 2009-10-06 16:06:11 +01:00 committed by Greg Kroah-Hartman
parent 894cb91770
commit 64bc397914
3 changed files with 65 additions and 32 deletions
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36
drivers/char/tty_port.c
View File

@ -99,10 +99,11 @@ EXPORT_SYMBOL(tty_port_tty_set);
static void tty_port_shutdown(struct tty_port *port)
{
mutex_lock(&port->mutex);
if (port->ops->shutdown &&
test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags))
port->ops->shutdown(port);
mutex_unlock(&port->mutex);
}
/**
@ -381,3 +382,36 @@ void tty_port_close(struct tty_port *port, struct tty_struct *tty,
tty_port_tty_set(port, NULL);
}
EXPORT_SYMBOL(tty_port_close);
int tty_port_open(struct tty_port *port, struct tty_struct *tty,
struct file *filp)
{
spin_lock_irq(&port->lock);
if (!tty_hung_up_p(filp))
++port->count;
spin_unlock_irq(&port->lock);
tty_port_tty_set(port, tty);
/*
* Do the device-specific open only if the hardware isn't
* already initialized. Serialize open and shutdown using the
* port mutex.
*/
mutex_lock(&port->mutex);
if (!test_bit(ASYNCB_INITIALIZED, &port->flags)) {
if (port->ops->activate) {
int retval = port->ops->activate(port, tty);
if (retval) {
mutex_unlock(&port->mutex);
return retval;
}
}
set_bit(ASYNCB_INITIALIZED, &port->flags);
}
mutex_unlock(&port->mutex);
return tty_port_block_til_ready(port, tty, filp);
}
EXPORT_SYMBOL(tty_port_open);

51
drivers/usb/serial/usb-serial.c
View File

@ -247,43 +247,33 @@ static int serial_install(struct tty_driver *driver, struct tty_struct *tty)
return retval;
}
static int serial_open(struct tty_struct *tty, struct file *filp)
static int serial_activate(struct tty_port *tport, struct tty_struct *tty)
{
struct usb_serial_port *port = tty->driver_data;
struct usb_serial_port *port =
container_of(tport, struct usb_serial_port, port);
struct usb_serial *serial = port->serial;
int retval;
dbg("%s - port %d", __func__, port->number);
spin_lock_irq(&port->port.lock);
if (!tty_hung_up_p(filp))
++port->port.count;
spin_unlock_irq(&port->port.lock);
tty_port_tty_set(&port->port, tty);
/* Do the device-specific open only if the hardware isn't
* already initialized.
*/
if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {
if (mutex_lock_interruptible(&port->mutex))
return -ERESTARTSYS;
mutex_lock(&serial->disc_mutex);
if (serial->disconnected)
retval = -ENODEV;
else
retval = port->serial->type->open(tty, port);
mutex_unlock(&serial->disc_mutex);
mutex_unlock(&port->mutex);
if (retval)
return retval;
set_bit(ASYNCB_INITIALIZED, &port->port.flags);
}
/* Now do the correct tty layer semantics */
retval = tty_port_block_til_ready(&port->port, tty, filp);
if (mutex_lock_interruptible(&port->mutex))
return -ERESTARTSYS;
mutex_lock(&serial->disc_mutex);
if (serial->disconnected)
retval = -ENODEV;
else
retval = port->serial->type->open(tty, port);
mutex_unlock(&serial->disc_mutex);
mutex_unlock(&port->mutex);
return retval;
}
static int serial_open(struct tty_struct *tty, struct file *filp)
{
struct usb_serial_port *port = tty->driver_data;
dbg("%s - port %d", __func__, port->number);
return tty_port_open(&port->port, tty, filp);
}
/**
* serial_down - shut down hardware
* @port: port to shut down
@ -725,6 +715,7 @@ static void serial_dtr_rts(struct tty_port *port, int on)
static const struct tty_port_operations serial_port_ops = {
.carrier_raised = serial_carrier_raised,
.dtr_rts = serial_dtr_rts,
.activate = serial_activate,
};
int usb_serial_probe(struct usb_interface *interface,

10
include/linux/tty.h
View File

@ -190,9 +190,15 @@ struct tty_port_operations {
/* Control the DTR line */
void (*dtr_rts)(struct tty_port *port, int raise);
/* Called when the last close completes or a hangup finishes
IFF the port was initialized. Do not use to free resources */
IFF the port was initialized. Do not use to free resources. Called
under the port mutex to serialize against activate/shutdowns */
void (*shutdown)(struct tty_port *port);
void (*drop)(struct tty_port *port);
/* Called under the port mutex from tty_port_open, serialized using
the port mutex */
/* FIXME: long term getting the tty argument *out* of this would be
good for consoles */
int (*activate)(struct tty_port *port, struct tty_struct *tty);
};
struct tty_port {
@ -467,6 +473,8 @@ extern int tty_port_close_start(struct tty_port *port,
extern void tty_port_close_end(struct tty_port *port, struct tty_struct *tty);
extern void tty_port_close(struct tty_port *port,
struct tty_struct *tty, struct file *filp);
extern int tty_port_open(struct tty_port *port,
struct tty_struct *tty, struct file *filp);
extern inline int tty_port_users(struct tty_port *port)
{
return port->count + port->blocked_open;