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    SubjectRe: [PATCH] ds2760: fix integer overflow for time_to_empty_now
    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.

    --
    Anton Vorontsov
    email: cbouatmailru@gmail.com
    irc://irc.freenode.net/bd2


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