[POWERPC] Fix possible division by zero in scaled time accounting
If we get no user time and no system time allocated since the last
account_system_vtime, the system to user time ratio estimate can end
up dividing by zero.
This was causing a problem noticed by Balbir Singh.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c
index c0d7772..a925a8e 100644
--- a/arch/powerpc/kernel/time.c
+++ b/arch/powerpc/kernel/time.c
@@ -241,8 +241,9 @@
/* deltascaled includes both user and system time.
* Hence scale it based on the purr ratio to estimate
* the system time */
- deltascaled = deltascaled * get_paca()->system_time /
- (get_paca()->system_time + get_paca()->user_time);
+ if (get_paca()->user_time)
+ deltascaled = deltascaled * get_paca()->system_time /
+ (get_paca()->system_time + get_paca()->user_time);
delta += get_paca()->system_time;
get_paca()->system_time = 0;
}