linux-kernel - [PATCH 9/10] drivers/mmc: Move a dereference below a NULL test

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Message-ID: <Pine.LNX.4.64.0907191729580.16542@ask.diku.dk>
Date:	Sun, 19 Jul 2009 17:30:26 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	jarkko.lavinen@...ia.com, linux-omap@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH 9/10] drivers/mmc: Move a dereference below a NULL test

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

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,E1;
identifier i,fld;
statement S;
@@

- T i = E->fld;
+ T i;
  ... when != E=E1
      when != i
  BUG_ON (E == NULL||
-     i
+     E->fld
       == NULL || ...);
+ i = E->fld;
// </smpl>

Signed-off-by: Julia Lawall <julia@...u.dk>

---
 drivers/mmc/host/omap.c             |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/omap.c b/drivers/mmc/host/omap.c
index e7a331d..89281ab 100644
--- a/drivers/mmc/host/omap.c
+++ b/drivers/mmc/host/omap.c
@@ -255,11 +255,12 @@ static void mmc_omap_slot_release_work(struct work_struct *work)
 
 static void mmc_omap_release_slot(struct mmc_omap_slot *slot, int clk_enabled)
 {
-	struct mmc_omap_host *host = slot->host;
+	struct mmc_omap_host *host;
 	unsigned long flags;
 	int i;
 
-	BUG_ON(slot == NULL || host->mmc == NULL);
+	BUG_ON(slot == NULL || slot->host->mmc == NULL);
+	host = slot->host;
 
 	if (clk_enabled)
 		/* Keeps clock running for at least 8 cycles on valid freq */
--
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