linux-kernel - [PATCH 1/2] char: hide sparse expensive pointer subtraction warning in specialix.c

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Date:	Fri, 22 Feb 2008 10:51:05 -0800
From:	Harvey Harrison <harvey.harrison@...il.com>
To:	Andrew Morton <akpm@...ux-foundation.org>,
	Bernd Petrovitsch <bernd@...mix.at>
Cc:	LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH 1/2] char: hide sparse expensive pointer subtraction
	warning in specialix.c

The warnings come from two static inlines so the ugliness in hiding them
is well contained.
drivers/char/specialix.c:238:19: warning: potentially expensive pointer subtraction
drivers/char/specialix.c:245:19: warning: potentially expensive pointer subtraction

Signed-off-by: Harvey Harrison <harvey.harrison@...il.com>
---
Bernd noticed that I'm an idiot.  I was only hiding them to see what else
was in the file.  This patch is at least functionally correct.

Brown-paper-bagged-by: Harvey Harrison

 drivers/char/specialix.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/char/specialix.c b/drivers/char/specialix.c
index c0e08c7..34c7de6 100644
--- a/drivers/char/specialix.c
+++ b/drivers/char/specialix.c
@@ -228,21 +228,21 @@ static inline int sx_paranoia_check(struct specialix_port const * port,
 /* Get board number from pointer */
 static inline int board_No (struct specialix_board * bp)
 {
-	return bp - sx_board;
+	return ((char *)bp - (char *)sx_board) / sizeof(*bp);
 }
 
 
 /* Get port number from pointer */
 static inline int port_No (struct specialix_port const * port)
 {
-	return SX_PORT(port - sx_port);
+	return SX_PORT(((char *)port - (char *)sx_port) / sizeof(*port));
 }
 
 
 /* Get pointer to board from pointer to port */
 static inline struct specialix_board * port_Board(struct specialix_port const * port)
 {
-	return &sx_board[SX_BOARD(port - sx_port)];
+	return &sx_board[SX_BOARD(port_No(port))];
 }
 
 
-- 
1.5.4.2.200.g99e75


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