From 2b46b5673ca67d23302c2afac045def988a3cade Mon Sep 17 00:00:00 2001 From: Michael Neuling Date: Tue, 20 Nov 2007 15:18:40 +1100 Subject: [PATCH] [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 Signed-off-by: Paul Mackerras --- arch/powerpc/kernel/time.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/powerpc/kernel/time.c b/arch/powerpc/kernel/time.c index c0d77723ba11..a925a8eae121 100644 --- a/arch/powerpc/kernel/time.c +++ b/arch/powerpc/kernel/time.c @@ -241,8 +241,9 @@ void account_system_vtime(struct task_struct *tsk) /* 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; }