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powerpc/mpic_timer: fix convert ticks to time subtraction overflow

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In some cases tmp_sec may be greater than ticks, because in the process
of calculation ticks and tmp_sec will be rounded.

Signed-off-by: Wang Dongsheng <dongsheng.wang@freescale.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
This commit is contained in:
Wang Dongsheng 2014-01-06 13:23:31 +08:00 committed by Scott Wood
parent 0fd79588f9
commit d2dc13b533
1 changed files with 5 additions and 2 deletions
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7
arch/powerpc/sysdev/mpic_timer.c
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@ -97,8 +97,11 @@ static void convert_ticks_to_time(struct timer_group_priv *priv,
time->tv_sec = (__kernel_time_t)div_u64(ticks, priv->timerfreq);
tmp_sec = (u64)time->tv_sec * (u64)priv->timerfreq;
time->tv_usec = (__kernel_suseconds_t)
div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
time->tv_usec = 0;
if (tmp_sec <= ticks)
time->tv_usec = (__kernel_suseconds_t)
div_u64((ticks - tmp_sec) * 1000000, priv->timerfreq);
return;
}