powerpc/mpic_timer: fix convert ticks to time subtraction overflow
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>
diff --git a/arch/powerpc/sysdev/mpic_timer.c b/arch/powerpc/sysdev/mpic_timer.c
index 70dcf9c..9d9b062 100644
--- a/arch/powerpc/sysdev/mpic_timer.c
+++ b/arch/powerpc/sysdev/mpic_timer.c
@@ -97,8 +97,11 @@
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;
}