[PATCH 4/5] drivers/net: Move a dereference below a NULL test

From: Julia Lawall
Date: Sat Jul 11 2009 - 03:52:46 EST


From: Julia Lawall <julia@xxxxxxx>

If the NULL test is necessary, then the dereference should be moved below
the NULL test.

The semantic patch that makes this change is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
type T;
expression E;
identifier i,fld;
statement S;
@@

- T i = E->fld;
+ T i;
... when != E
when != i
if (E == NULL) S
+ i = E->fld;
// </smpl>

Signed-off-by: Julia Lawall <julia@xxxxxxx>

---
drivers/net/tun.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff -u -p a/drivers/net/tun.c b/drivers/net/tun.c
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -486,11 +486,12 @@ static unsigned int tun_chr_poll(struct
{
struct tun_file *tfile = file->private_data;
struct tun_struct *tun = __tun_get(tfile);
- struct sock *sk = tun->sk;
+ struct sock *sk;
unsigned int mask = 0;

if (!tun)
return POLLERR;
+ sk = tun->sk;

DBG(KERN_INFO "%s: tun_chr_poll\n", tun->dev->name);

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