1 files changed, 41 insertions, 0 deletions

diff --git a/drivers/char/tty_port.c b/drivers/char/tty_port.c
index 6fadb19d630b..553b0e9d8d17 100644
--- a/drivers/char/tty_port.c
+++ b/drivers/char/tty_port.c
@@ -23,6 +23,7 @@ void tty_port_init(struct tty_port *port)
         init_waitqueue_head(&port->open_wait);
         init_waitqueue_head(&port->close_wait);
         mutex_init(&port->mutex);
+        spin_lock_init(&port->lock);
         port->close_delay = (50 * HZ) / 100;
         port->closing_wait = (3000 * HZ) / 100;
 }
@@ -53,3 +54,43 @@ void tty_port_free_xmit_buf(struct tty_port *port)
 EXPORT_SYMBOL(tty_port_free_xmit_buf);
 
 
+/**
+ *      tty_port_tty_get        -       get a tty reference
+ *      @port: tty port
+ *
+ *      Return a refcount protected tty instance or NULL if the port is not
+ *      associated with a tty (eg due to close or hangup)
+ */
+
+struct tty_struct *tty_port_tty_get(struct tty_port *port)
+{
+        unsigned long flags;
+        struct tty_struct *tty;
+
+        spin_lock_irqsave(&port->lock, flags);
+        tty = tty_kref_get(port->tty);
+        spin_unlock_irqrestore(&port->lock, flags);
+        return tty;
+}
+EXPORT_SYMBOL(tty_port_tty_get);
+
+/**
+ *      tty_port_tty_set        -       set the tty of a port
+ *      @port: tty port
+ *      @tty: the tty
+ *
+ *      Associate the port and tty pair. Manages any internal refcounts.
+ *      Pass NULL to deassociate a port
+ */
+
+void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
+{
+        unsigned long flags;
+
+        spin_lock_irqsave(&port->lock, flags);
+        if (port->tty)
+                tty_kref_put(port->tty);
+        port->tty = tty;
+        spin_unlock_irqrestore(&port->lock, flags);
+}
+EXPORT_SYMBOL(tty_port_tty_set);