drivers/char/ppdev.c: put gotten port value

Author: Julia Lawall <julia@diku.dk>

parport_find_number() calls parport_get_port() on its result, so there
should be a corresponding call to parport_put_port() before dropping the
reference.  Similar code is found in the function register_device() in the
same file.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

  // 
  @exists@
  local idexpression struct parport * x;
  expression ra,rr;
  statement S1,S2;
  @@

  x = parport_find_number(...)
  ... when != x = rr
      when any
      when != parport_put_port(x,...)
      when != if (...) { ... parport_put_port(x,...) ...}
  (
  if(<+...x...+>) S1 else S2
  |
  if(...) { ... when != x = ra
       when forall
       when != parport_put_port(x,...)
  *return...;
  }
  )
  // 

Signed-off-by: Julia Lawall 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 

---
 drivers/char/ppdev.c | 1 +
 1 file changed, 1 insertion(+)
 
diff --git a/drivers/char/ppdev.c b/drivers/char/ppdev.c
index f176dba..3fcf80f 100644
--- a/drivers/char/ppdev.c
+++ b/drivers/char/ppdev.c
@@ -457,6 +457,7 @@ static int pp_do_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 			return -ENODEV;
 
 		modes = port->modes;
+		parport_put_port(port);
 		if (copy_to_user (argp, &modes, sizeof (modes))) {
 			return -EFAULT;
 		}