Merge tag 'usb-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb

Pull USB patches from Greg Kroah-Hartman:
 "Here's the big USB merge for 3.9-rc1

  Nothing major, lots of gadget fixes, and of course, xhci stuff.

  All of this has been in linux-next for a while, with the exception of
  the last 3 patches, which were reverts of patches in the tree that
  caused problems, they went in yesterday."

* tag 'usb-3.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (190 commits)
  Revert "USB: EHCI: make ehci-vt8500 a separate driver"
  Revert "USB: EHCI: make ehci-orion a separate driver"
  Revert "USB: update host controller Kconfig entries"
  USB: update host controller Kconfig entries
  USB: EHCI: make ehci-orion a separate driver
  USB: EHCI: make ehci-vt8500 a separate driver
  USB: usb-storage: unusual_devs update for Super TOP SATA bridge
  USB: ehci-omap: Fix autoloading of module
  USB: ehci-omap: Don't free gpios that we didn't request
  USB: option: add Huawei "ACM" devices using protocol = vendor
  USB: serial: fix null-pointer dereferences on disconnect
  USB: option: add Yota / Megafon M100-1 4g modem
  drivers/usb: add missing GENERIC_HARDIRQS dependencies
  USB: storage: properly handle the endian issues of idProduct
  testusb: remove all mentions of 'usbfs'
  usb: gadget: imx_udc: make it depend on BROKEN
  usb: omap_control_usb: fix compile warning
  ARM: OMAP: USB: Add phy binding information
  ARM: OMAP2: MUSB: Specify omap4 has mailbox
  ARM: OMAP: devices: create device for usb part of control module
  ...

1 files changed, 22 insertions, 6 deletions

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 64bda135ba7e..a19ed74d770d 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -361,15 +361,21 @@ static int serial_write_room(struct tty_struct *tty)
 static int serial_chars_in_buffer(struct tty_struct *tty)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	struct usb_serial *serial = port->serial;
+	int count = 0;
 
 	dev_dbg(tty->dev, "%s - port %d\n", __func__, port->number);
 
+	mutex_lock(&serial->disc_mutex);
 	/* if the device was unplugged then any remaining characters
 	   fell out of the connector ;) */
-	if (port->serial->disconnected)
-		return 0;
-	/* pass on to the driver specific version of this function */
-	return port->serial->type->chars_in_buffer(tty);
+	if (serial->disconnected)
+		count = 0;
+	else
+		count = serial->type->chars_in_buffer(tty);
+	mutex_unlock(&serial->disc_mutex);
+
+	return count;
 }
 
 static void serial_throttle(struct tty_struct *tty)
@@ -688,10 +694,20 @@ static int serial_carrier_raised(struct tty_port *port)
 static void serial_dtr_rts(struct tty_port *port, int on)
 {
 	struct usb_serial_port *p = container_of(port, struct usb_serial_port, port);
-	struct usb_serial_driver *drv = p->serial->type;
+	struct usb_serial *serial = p->serial;
+	struct usb_serial_driver *drv = serial->type;
 
-	if (drv->dtr_rts)
+	if (!drv->dtr_rts)
+		return;
+	/*
+	 * Work-around bug in the tty-layer which can result in dtr_rts
+	 * being called after a disconnect (and tty_unregister_device
+	 * has returned). Remove once bug has been squashed.
+	 */
+	mutex_lock(&serial->disc_mutex);
+	if (!serial->disconnected)
 		drv->dtr_rts(p, on);
+	mutex_unlock(&serial->disc_mutex);
 }
 
 static const struct tty_port_operations serial_port_ops = {