linux-kernel - [PATCH 3/11] drivers/isdn/hardware/mISDN: Move a dereference below a NULL test

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Message-ID: <Pine.LNX.4.64.0812161612170.20444@pc-004.diku.dk>
Date:	Tue, 16 Dec 2008 16:12:42 +0100 (CET)
From:	Julia Lawall <julia@...u.dk>
To:	kkeil@...e.de, isdn4linux@...tserv.isdn4linux.de,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH 3/11] drivers/isdn/hardware/mISDN: Move a dereference below
 a NULL test

From: Julia Lawall <julia@...u.dk>

In each case, 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@...u.dk>

---
 drivers/isdn/hardware/mISDN/hfcmulti.c         |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/isdn/hardware/mISDN/hfcmulti.c b/drivers/isdn/hardware/mISDN/hfcmulti.c
index 1eac03f..4dd85a5 100644
--- a/drivers/isdn/hardware/mISDN/hfcmulti.c
+++ b/drivers/isdn/hardware/mISDN/hfcmulti.c
@@ -3607,7 +3607,7 @@ hfcm_bctrl(struct mISDNchannel *ch, u_int cmd, void *arg)
 static void
 ph_state_change(struct dchannel *dch)
 {
-	struct hfc_multi *hc = dch->hw;
+	struct hfc_multi *hc;
 	int ch, i;
 
 	if (!dch) {
@@ -3615,6 +3615,7 @@ ph_state_change(struct dchannel *dch)
 		    __func__);
 		return;
 	}
+	hc = dch->hw;
 	ch = dch->slot;
 
 	if (hc->type == 1) {
--
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