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Message-ID: <20091006150555.9431.34664.stgit@localhost.localdomain>
Date: Tue, 06 Oct 2009 16:06:11 +0100
From: Alan Cox <alan@...ux.intel.com>
To: greg@...ah.com, linux-kernel@...r.kernel.org,
linux-usb@...r.kernel.org
Subject: [PATCH 1/5] tty_port: add "tty_port_open" helper
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@...ux.intel.com>
---
drivers/char/tty_port.c | 36 ++++++++++++++++++++++++++++-
drivers/usb/serial/usb-serial.c | 49 ++++++++++++++++-----------------------
include/linux/tty.h | 10 +++++++-
3 files changed, 64 insertions(+), 31 deletions(-)
diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index a4bbb28..2512262 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -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);
}
/**
@@ -375,3 +376,36 @@ 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);
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index aa6b2ae..95c34da 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -246,41 +246,31 @@ 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);
+ 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;
+}
- /* 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);
- }
+static int serial_open(struct tty_struct *tty, struct file *filp)
+{
+ struct usb_serial_port *port = tty->driver_data;
- /* Now do the correct tty layer semantics */
- retval = tty_port_block_til_ready(&port->port, tty, filp);
- return retval;
+ dbg("%s - port %d", __func__, port->number);
+ return tty_port_open(&port->port, tty, filp);
}
/**
@@ -724,6 +714,7 @@ 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,
diff --git a/include/linux/tty.h b/include/linux/tty.h
index ed24493..262c5da 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -191,9 +191,15 @@ 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 {
@@ -468,6 +474,8 @@ 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;
--
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