linux-kernel - [PATCH 7/10] drivers/serial: Move a dereference below a NULL test

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Date:	Sun, 19 Jul 2009 17:29:37 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	pfg@....com, linux-ia64@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: [PATCH 7/10] drivers/serial: 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;
// </smpl>

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

---
 drivers/serial/ioc3_serial.c |    3 ++-
 drivers/serial/ioc4_serial.c |    3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/serial/ioc3_serial.c b/drivers/serial/ioc3_serial.c
index ae3699d..6d5c91b 100644
--- a/drivers/serial/ioc3_serial.c
+++ b/drivers/serial/ioc3_serial.c
@@ -1117,13 +1117,14 @@ static inline int do_read(struct uart_port *the_port, char *buf, int len)
 	struct ioc3_port *port = get_ioc3_port(the_port);
 	struct ring *inring;
 	struct ring_entry *entry;
-	struct port_hooks *hooks = port->ip_hooks;
+	struct port_hooks *hooks;
 	int byte_num;
 	char *sc;
 	int loop_counter;
 
 	BUG_ON(!(len >= 0));
 	BUG_ON(!port);
+	hooks = port->ip_hooks;
 
 	/* There is a nasty timing issue in the IOC3. When the rx_timer
 	 * expires or the rx_high condition arises, we take an interrupt.
diff --git a/drivers/serial/ioc4_serial.c b/drivers/serial/ioc4_serial.c
index 6bab63c..aeca2f8 100644
--- a/drivers/serial/ioc4_serial.c
+++ b/drivers/serial/ioc4_serial.c
@@ -2067,13 +2067,14 @@ static inline int do_read(struct uart_port *the_port, unsigned char *buf,
 	struct ioc4_port *port = get_ioc4_port(the_port, 0);
 	struct ring *inring;
 	struct ring_entry *entry;
-	struct hooks *hooks = port->ip_hooks;
+	struct hooks *hooks;
 	int byte_num;
 	char *sc;
 	int loop_counter;
 
 	BUG_ON(!(len >= 0));
 	BUG_ON(!port);
+	hooks = port->ip_hooks;
 
 	/* There is a nasty timing issue in the IOC4. When the rx_timer
 	 * expires or the rx_high condition arises, we take an interrupt.
--
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