tty: serial: replace del_timer by del_timer_sync

Author: Julia Lawall <Julia.Lawall@lip6.fr>

Use del_timer_sync to ensure that the timer is stopped on all CPUs before
the driver exists.

This change was suggested by Thomas Gleixner.

The semantic patch that makes this change is as follows:
(http://coccinelle.lip6.fr/)

// 
@r@
declarer name module_exit;
identifier ex;
@@

module_exit(ex);

@@
identifier r.ex;
@@

ex(...) {
  <...
- del_timer
+ del_timer_sync
    (...)
  ...>
}
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Greg Kroah-Hartman 

---
 drivers/tty/serial/mux.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 
diff --git a/drivers/tty/serial/mux.c b/drivers/tty/serial/mux.c
index 9b27d34..be127d0 100644
--- a/drivers/tty/serial/mux.c
+++ b/drivers/tty/serial/mux.c
@@ -613,7 +613,7 @@ static void __exit mux_exit(void)
 {
 	/* Delete the Mux timer. */
 	if(port_cnt > 0) {
-		del_timer(&mux_timer);
+		del_timer_sync(&mux_timer);
 #ifdef CONFIG_SERIAL_MUX_CONSOLE
 		unregister_console(&mux_console);
 #endif