From 6377981faf1a4425b0531e577736ef03df97c8f6 Mon Sep 17 00:00:00 2001 From: Martin Schwidefsky Date: Mon, 17 May 2010 10:00:03 +0200 Subject: [S390] idle time accounting vs. machine checks A machine check can interrupt the i/o and external interrupt handler anytime. If the machine check occurs while the interrupt handler is waking up from idle vtime_start_cpu can get executed a second time and the int_clock / async_enter_timer values in the lowcore get clobbered. This can confuse the cpu time accounting. To fix this problem two changes are needed. First the machine check handler has to use its own copies of int_clock and async_enter_timer, named mcck_clock and mcck_enter_timer. Second the nested execution of vtime_start_cpu has to be prevented. This is done in s390_idle_check by checking the wait bit in the program status word. Signed-off-by: Martin Schwidefsky --- arch/s390/kernel/nmi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'arch/s390/kernel/nmi.c') diff --git a/arch/s390/kernel/nmi.c b/arch/s390/kernel/nmi.c index 015e27da40e..ac151399ef3 100644 --- a/arch/s390/kernel/nmi.c +++ b/arch/s390/kernel/nmi.c @@ -255,7 +255,8 @@ void notrace s390_do_machine_check(struct pt_regs *regs) int umode; nmi_enter(); - s390_idle_check(); + s390_idle_check(regs, S390_lowcore.mcck_clock, + S390_lowcore.mcck_enter_timer); mci = (struct mci *) &S390_lowcore.mcck_interruption_code; mcck = &__get_cpu_var(cpu_mcck); -- cgit v1.2.3-18-g5258