rtc: test before subtraction on unsigned

new_alarm is unsigned so test before the subtraction.

[akpm@linux-foundation.org: time-wrapping fix]
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: David Brownell <david-b@pacbell.net>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/rtc/rtc-ds1374.c b/drivers/rtc/rtc-ds1374.c
index a5b0fc0..4d32e32 100644 (file)
--- a/drivers/rtc/rtc-ds1374.c
+++ b/drivers/rtc/rtc-ds1374.c
@@ -222,16 +222,16 @@ static int ds1374_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
        rtc_tm_to_time(&alarm->time, &new_alarm);
        rtc_tm_to_time(&now, &itime);
 
-       new_alarm -= itime;
-
        /* This can happen due to races, in addition to dates that are
         * truly in the past.  To avoid requiring the caller to check for
         * races, dates in the past are assumed to be in the recent past
         * (i.e. not something that we'd rather the caller know about via
         * an error), and the alarm is set to go off as soon as possible.
         */
-       if (new_alarm <= 0)
+       if (time_before_eq(new_alarm, itime))
                new_alarm = 1;
+       else
+               new_alarm -= itime;
 
        mutex_lock(&ds1374->mutex);