TTY: introduce tty_port_destroy

After commit "TTY: move tty buffers to tty_port", the tty buffers are
not freed in some drivers. This is because tty_port_destructor is not
called whenever a tty_port is freed. This was an assumption I counted
with but was unfortunately untrue.

Those using refcounting are safe now, but for those which do not we
introduce a function to be called right before the tty_port is freed
by the drivers.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 16 insertions, 1 deletions

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index fdc42c2d565f..b7ff59d3db88 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -122,12 +122,26 @@ void tty_port_free_xmit_buf(struct tty_port *port)
 }
 EXPORT_SYMBOL(tty_port_free_xmit_buf);
 
+/**
+ * tty_port_destroy -- destroy inited port
+ * @port: tty port to be doestroyed
+ *
+ * When a port was initialized using tty_port_init, one has to destroy the
+ * port by this function. Either indirectly by using tty_port refcounting
+ * (tty_port_put) or directly if refcounting is not used.
+ */
+void tty_port_destroy(struct tty_port *port)
+{
+        tty_buffer_free_all(port);
+}
+EXPORT_SYMBOL(tty_port_destroy);
+
 static void tty_port_destructor(struct kref *kref)
 {
         struct tty_port *port = container_of(kref, struct tty_port, kref);
         if (port->xmit_buf)
                 free_page((unsigned long)port->xmit_buf);
-        tty_buffer_free_all(port);
+        tty_port_destroy(port);
         if (port->ops && port->ops->destruct)
                 port->ops->destruct(port);
         else
diff --git a/include/linux/tty.h b/include/linux/tty.h
index d7ff88fb8967..8db1b569c37a 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -455,6 +455,7 @@ extern struct device *tty_port_register_device_attr(struct tty_port *port,
                 const struct attribute_group **attr_grp);
 extern int tty_port_alloc_xmit_buf(struct tty_port *port);
 extern void tty_port_free_xmit_buf(struct tty_port *port);
+extern void tty_port_destroy(struct tty_port *port);
 extern void tty_port_put(struct tty_port *port);
 
 static inline struct tty_port *tty_port_get(struct tty_port *port)