mtd: speedtest: fix integer overflow

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=e70727e442eb61581f836a9a0ca0c3b70d8a3ff2
Commit:     e70727e442eb61581f836a9a0ca0c3b70d8a3ff2
Parent:     5d9d9936209e589569a97985285b3282310cf2db
Author:     David Lambert <dave at lambsys.com>
AuthorDate: Mon Mar 7 12:00:46 2011 +0200
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Fri Mar 11 14:22:49 2011 +0000

    mtd: speedtest: fix integer overflow
    
    32-bit integers used in 'calc_speed()' may overflow and lead to
    incorrect results. Use 64-bit integers instead.
    
    Signed-off-by: David Lambert <dave at lambsys.com>
    Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy at nokia.com>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/tests/mtd_speedtest.c |   14 +++++++-------
 1 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/tests/mtd_speedtest.c b/drivers/mtd/tests/mtd_speedtest.c
index 3ce6fce..627d4e2 100644
--- a/drivers/mtd/tests/mtd_speedtest.c
+++ b/drivers/mtd/tests/mtd_speedtest.c
@@ -314,16 +314,16 @@ static inline void stop_timing(void)
 
 static long calc_speed(void)
 {
-	long ms, k, speed;
+	uint64_t k;
+	long ms;
 
 	ms = (finish.tv_sec - start.tv_sec) * 1000 +
 	     (finish.tv_usec - start.tv_usec) / 1000;
-	k = goodebcnt * mtd->erasesize / 1024;
-	if (ms)
-		speed = (k * 1000) / ms;
-	else
-		speed = 0;
-	return speed;
+	if (ms == 0)
+		return 0;
+	k = goodebcnt * (mtd->erasesize / 1024) * 1000;
+	do_div(k, ms);
+	return k;
 }
 
 static int scan_for_bad_eraseblocks(void)