tty: usb-serial krefs

Use kref in the USB serial drivers so that we don't free tty structures
from under the URB receive handlers as has historically been the case if
you were unlucky. This also gives us a framework for general tty drivers to
use tty_port objects and refcount.

Contains two err->dev_err changes merged together to fix clashes in the
-next tree.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 23 insertions, 21 deletions

diff --git a/drivers/usb/serial/ti_usb_3410_5052.c b/drivers/usb/serial/ti_usb_3410_5052.c
index 9a3e495c769c..c90237d48b0e 100644
--- a/drivers/usb/serial/ti_usb_3410_5052.c
+++ b/drivers/usb/serial/ti_usb_3410_5052.c
@@ -179,7 +179,7 @@ static int ti_set_mcr(struct ti_port *tport, unsigned int mcr);
 static int ti_get_lsr(struct ti_port *tport);
 static int ti_get_serial_info(struct ti_port *tport,
 	struct serial_struct __user *ret_arg);
-static int ti_set_serial_info(struct ti_port *tport,
+static int ti_set_serial_info(struct tty_struct *tty, struct ti_port *tport,
 	struct serial_struct __user *new_arg);
 static void ti_handle_new_msr(struct ti_port *tport, __u8 msr);
 
@@ -857,8 +857,8 @@ static int ti_ioctl(struct tty_struct *tty, struct file *file,
 				(struct serial_struct __user *)arg);
 	case TIOCSSERIAL:
 		dbg("%s - (%d) TIOCSSERIAL", __func__, port->number);
-		return ti_set_serial_info(tport,
-					(struct serial_struct __user *)arg);
+		return ti_set_serial_info(tty, tport,
+				(struct serial_struct __user *)arg);
 	case TIOCMIWAIT:
 		dbg("%s - (%d) TIOCMIWAIT", __func__, port->number);
 		cprev = tport->tp_icount;
@@ -1211,6 +1211,7 @@ static void ti_bulk_in_callback(struct urb *urb)
 	struct device *dev = &urb->dev->dev;
 	int status = urb->status;
 	int retval = 0;
+	struct tty_struct *tty;
 
 	dbg("%s", __func__);
 
@@ -1239,20 +1240,22 @@ static void ti_bulk_in_callback(struct urb *urb)
 		return;
 	}
 
-	if (port->port.tty && urb->actual_length) {
+	tty = tty_port_tty_get(&port->port);
+	if (tty && urb->actual_length) {
 		usb_serial_debug_data(debug, dev, __func__,
 			urb->actual_length, urb->transfer_buffer);
 
 		if (!tport->tp_is_open)
 			dbg("%s - port closed, dropping data", __func__);
 		else
-			ti_recv(&urb->dev->dev, port->port.tty,
+			ti_recv(&urb->dev->dev, tty,
 						urb->transfer_buffer,
 						urb->actual_length);
 
 		spin_lock(&tport->tp_lock);
 		tport->tp_icount.rx += urb->actual_length;
 		spin_unlock(&tport->tp_lock);
+		tty_kref_put(tty);
 	}
 
 exit:
@@ -1330,7 +1333,7 @@ static void ti_send(struct ti_port *tport)
 {
 	int count, result;
 	struct usb_serial_port *port = tport->tp_port;
-	struct tty_struct *tty = port->port.tty;	/* FIXME */
+	struct tty_struct *tty = tty_port_tty_get(&port->port);	/* FIXME */
 	unsigned long flags;
 
 
@@ -1338,19 +1341,15 @@ static void ti_send(struct ti_port *tport)
 
 	spin_lock_irqsave(&tport->tp_lock, flags);
 
-	if (tport->tp_write_urb_in_use) {
-		spin_unlock_irqrestore(&tport->tp_lock, flags);
-		return;
-	}
+	if (tport->tp_write_urb_in_use)
+		goto unlock;
 
 	count = ti_buf_get(tport->tp_write_buf,
 				port->write_urb->transfer_buffer,
 				port->bulk_out_size);
 
-	if (count == 0) {
-		spin_unlock_irqrestore(&tport->tp_lock, flags);
-		return;
-	}
+	if (count == 0)
+		goto unlock;
 
 	tport->tp_write_urb_in_use = 1;
 
@@ -1380,7 +1379,13 @@ static void ti_send(struct ti_port *tport)
 	/* more room in the buffer for new writes, wakeup */
 	if (tty)
 		tty_wakeup(tty);
+	tty_kref_put(tty);
 	wake_up_interruptible(&tport->tp_write_wait);
+	return;
+unlock:
+	spin_unlock_irqrestore(&tport->tp_lock, flags);
+	tty_kref_put(tty);
+	return;
 }
 
 
@@ -1464,20 +1469,16 @@ static int ti_get_serial_info(struct ti_port *tport,
 }
 
 
-static int ti_set_serial_info(struct ti_port *tport,
+static int ti_set_serial_info(struct tty_struct *tty, struct ti_port *tport,
 	struct serial_struct __user *new_arg)
 {
-	struct usb_serial_port *port = tport->tp_port;
 	struct serial_struct new_serial;
 
 	if (copy_from_user(&new_serial, new_arg, sizeof(new_serial)))
 		return -EFAULT;
 
 	tport->tp_flags = new_serial.flags & TI_SET_SERIAL_FLAGS;
-	/* FIXME */
-	if (port->port.tty)
-		port->port.tty->low_latency =
-			(tport->tp_flags & ASYNC_LOW_LATENCY) ? 1 : 0;
+	tty->low_latency = (tport->tp_flags & ASYNC_LOW_LATENCY) ? 1 : 0;
 	tport->tp_closing_wait = new_serial.closing_wait;
 
 	return 0;
@@ -1510,7 +1511,7 @@ static void ti_handle_new_msr(struct ti_port *tport, __u8 msr)
 	tport->tp_msr = msr & TI_MSR_MASK;
 
 	/* handle CTS flow control */
-	tty = tport->tp_port->port.tty;
+	tty = tty_port_tty_get(&tport->tp_port->port);
 	if (tty && C_CRTSCTS(tty)) {
 		if (msr & TI_MSR_CTS) {
 			tty->hw_stopped = 0;
@@ -1519,6 +1520,7 @@ static void ti_handle_new_msr(struct ti_port *tport, __u8 msr)
 			tty->hw_stopped = 1;
 		}
 	}
+	tty_kref_put(tty);
 }