tty: Fix USB kref leak

The sysrq code acquired a kref leak. Fix it by passing the tty separately
from the caller (thus effectively using the callers kref which all the
callers hold anyway)

Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 3d8dc56..ce57f6a 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -432,7 +432,7 @@
 	else {
 		/* Push data to tty */
 		for (i = 0; i < urb->actual_length; i++, ch++) {
-			if (!usb_serial_handle_sysrq_char(port, *ch))
+			if (!usb_serial_handle_sysrq_char(tty, port, *ch))
 				tty_insert_flip_char(tty, *ch, TTY_NORMAL);
 		}
 	}
@@ -534,11 +534,12 @@
 	}
 }
 
-int usb_serial_handle_sysrq_char(struct usb_serial_port *port, unsigned int ch)
+int usb_serial_handle_sysrq_char(struct tty_struct *tty,
+			struct usb_serial_port *port, unsigned int ch)
 {
 	if (port->sysrq && port->console) {
 		if (ch && time_before(jiffies, port->sysrq)) {
-			handle_sysrq(ch, tty_port_tty_get(&port->port));
+			handle_sysrq(ch, tty);
 			port->sysrq = 0;
 			return 1;
 		}