[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <20090730174030.GY19257@buzzloop.caiaq.de>
Date: Thu, 30 Jul 2009 19:40:30 +0200
From: Daniel Mack <daniel@...aq.de>
To: Anton Vorontsov <avorontsov@...mvista.com>
Cc: linux-kernel@...r.kernel.org,
Szabolcs Gyurko <szabolcs.gyurko@....hu>,
Matt Reimer <mreimer@...p.net>, Anton Vorontsov <cbou@...l.ru>
Subject: Re: [PATCH] ds2760: fix integer overflow for time_to_empty_now
On Thu, Jul 30, 2009 at 06:26:16PM +0400, Anton Vorontsov wrote:
> > > Hm... "(di->current_uA / 100L)" might result to 0, so you'll get
> > > div by zero. Removing the parenthesis will help.
> >
> > Hmm, no, then it gets the precedence wrong.
>
> Ah.
>
> > But checking for values >=
> > 100 of current_uA helps. Thanks for spotting this.
>
> Yeah, that'll be fine indeed.
Just wanted to make sure you noticed that there was a new patch attached
to this mail :) I copied it again here.
Daniel
>From c60e23e2ba6667bec882338bfe3cb12304ee1ab6 Mon Sep 17 00:00:00 2001
From: Daniel Mack <daniel@...aq.de>
Date: Fri, 24 Jul 2009 15:08:11 +0200
Subject: [PATCH] ds2760: fix integer overflow for time_to_empty_now
On the device we're currently developing, battery sizes of ~2.8Ah and
current flow of ~600mA are typical.
With that values, the life_sec computation overflows due to the
multiplication by 3600.
Signed-off-by: Daniel Mack <daniel@...aq.de>
Cc: Szabolcs Gyurko <szabolcs.gyurko@....hu>
Cc: Matt Reimer <mreimer@...p.net>
Cc: Anton Vorontsov <cbou@...l.ru>
Signed-off-by: Daniel Mack <daniel@...aq.de>
---
drivers/power/ds2760_battery.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/power/ds2760_battery.c b/drivers/power/ds2760_battery.c
index d545fee..2ef29dd 100644
--- a/drivers/power/ds2760_battery.c
+++ b/drivers/power/ds2760_battery.c
@@ -211,9 +211,9 @@ static int ds2760_battery_read_status(struct ds2760_device_info *di)
if (di->rem_capacity > 100)
di->rem_capacity = 100;
- if (di->current_uA)
- di->life_sec = -((di->accum_current_uAh - di->empty_uAh) *
- 3600L) / di->current_uA;
+ if (di->current_uA >= 100L)
+ di->life_sec = -((di->accum_current_uAh - di->empty_uAh) * 36L)
+ / (di->current_uA / 100L);
else
di->life_sec = 0;
--
1.6.3.3
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists