Messages in this thread Patch in this message | | | Date | Thu, 30 Jul 2009 16:12:59 +0200 | From | Daniel Mack <> | Subject | Re: [PATCH] ds2760: fix integer overflow for time_to_empty_now |
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On Thu, Jul 30, 2009 at 06:00:41PM +0400, Anton Vorontsov wrote: > On Fri, Jul 24, 2009 at 03:19:33PM +0200, Daniel Mack wrote: > > 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@caiaq.de> > > Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu> > > Cc: Matt Reimer <mreimer@vpop.net> > > Cc: Anton Vorontsov <cbou@mail.ru> > > > > Signed-off-by: Daniel Mack <daniel@caiaq.de> > > --- > > drivers/power/ds2760_battery.c | 4 ++-- > > 1 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/power/ds2760_battery.c b/drivers/power/ds2760_battery.c > > index d545fee..5d30dc0 100644 > > --- a/drivers/power/ds2760_battery.c > > +++ b/drivers/power/ds2760_battery.c > > @@ -212,8 +212,8 @@ static int ds2760_battery_read_status(struct ds2760_device_info *di) > > di->rem_capacity = 100; > > > > if (di->current_uA) > > - di->life_sec = -((di->accum_current_uAh - di->empty_uAh) * > > - 3600L) / di->current_uA; > > + di->life_sec = -((di->accum_current_uAh - di->empty_uAh) * 36L) > > + / (di->current_uA / 100L); > > 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. But checking for values >= 100 of current_uA helps. Thanks for spotting this.
Daniel
From c60e23e2ba6667bec882338bfe3cb12304ee1ab6 Mon Sep 17 00:00:00 2001 From: Daniel Mack <daniel@caiaq.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@caiaq.de> Cc: Szabolcs Gyurko <szabolcs.gyurko@tlt.hu> Cc: Matt Reimer <mreimer@vpop.net> Cc: Anton Vorontsov <cbou@mail.ru>
Signed-off-by: Daniel Mack <daniel@caiaq.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
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