* RE: Bug in mtd_speedtest?
2011-03-04 17:53 ` David Lambert
@ 2011-03-07 4:11 ` Jon Povey
2011-03-07 10:09 ` Artem Bityutskiy
1 sibling, 0 replies; 5+ messages in thread
From: Jon Povey @ 2011-03-07 4:11 UTC (permalink / raw)
To: David Lambert; +Cc: linux-mtd@lists.infradead.org
linux-mtd-bounces@lists.infradead.org wrote:
> Artem,
> Please find attached patch.
The comments make lines over 80 chars and are not needed,
it is clear enough from the code what it does.
--
Jon Povey
jon.povey@racelogic.co.uk
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* Re: Bug in mtd_speedtest?
2011-03-04 17:53 ` David Lambert
2011-03-07 4:11 ` Jon Povey
@ 2011-03-07 10:09 ` Artem Bityutskiy
1 sibling, 0 replies; 5+ messages in thread
From: Artem Bityutskiy @ 2011-03-07 10:09 UTC (permalink / raw)
To: David Lambert; +Cc: linux-mtd@lists.infradead.org
On Fri, 2011-03-04 at 11:53 -0600, David Lambert wrote:
> Artem,
> Please find attached patch.
Thank you, but you made pretty good job to prevent me from applying
it! :-)
> Index: mtd_speedtest.c
> ===================================================================
> RCS
> file: /home/cvsroot/ECMB/src/snapgear/linux-2.6.30.1.x/drivers/mtd/tests/mtd_speedtest.c,v
> retrieving revision 1.1.1.1
> diff -u -r1.1.1.1 mtd_speedtest.c
This means git am won't work... neither patch -p1 ...
Also, not author name (From:), not commit message, not Signed-off-by...
> --- mtd_speedtest.c 10 Aug 2009 19:42:00 -0000 1.1.1.1
> +++ mtd_speedtest.c 4 Mar 2011 17:51:23 -0000
> @@ -281,13 +281,14 @@
>
> 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;
> - speed = (k * 1000) / ms;
> - return speed;
> + ms = (finish.tv_sec - start.tv_sec) * 1000 + /* Time in milli-seconds from start to ...*/
> + (finish.tv_usec - start.tv_usec) / 1000; /* finish */
This would not pass scripts/checkpatch.pl. Please, kill the comments.
Also, I you use spaces instead of tabs...
> + k = (goodebcnt * (mtd->erasesize / 1024) * 1000); /* Number of kBytes transferred * 1000 */
> + do_div(k, ms); /* k now contains number of kBytes/second */
The old code had a check against ms == 0, you removed it, why?
> + return k;
Anyway, since I anyway spent 20 minutes with this patch, here is what I
ended up. I've pushed it to my l2 tree. If I made a mistake or you are
unhappy about it, please, send your *properly formatted* version
instead.
Thanks!
>From 008cfa97a772a83407a7e2657c0c5bfe36c7fc7f Mon Sep 17 00:00:00 2001
From: David Lambert <dave@lambsys.com>
Date: Mon, 7 Mar 2011 12:00:46 +0200
Subject: [PATCH] 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@lambsys.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.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..22b51c1 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)
--
1.7.2.3
--
Best Regards,
Artem Bityutskiy (Артём Битюцкий)
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