From cc34321d5806b7919531a1d951bb6deb62c163c9 Mon Sep 17 00:00:00 2001 From: Heiko Carstens Date: Wed, 3 Aug 2011 16:44:27 +0200 Subject: [PATCH] [S390] cpu hotplug: on cpu start wait until being marked active This is the same as fd8a7de1 "x86: cpu-hotplug: Prevent softirq wakeup on wrong CPU". Unlike on x86 this doesn't fix a bug on s390 since we do not have threaded interrupt handlers. However we want to keep the same initialization order like on x86. This should prevent bugs caused by code which assumes (and relies on) the init order is the same on each architecture. Signed-off-by: Heiko Carstens --- arch/s390/kernel/smp.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 70f4b9604575..86371fdd68e7 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -473,7 +473,12 @@ int __cpuinit start_secondary(void *cpuvoid) S390_lowcore.restart_psw.addr = PSW_ADDR_AMODE | (unsigned long) psw_restart_int_handler; __ctl_set_bit(0, 28); /* Enable lowcore protection */ - /* Switch on interrupts */ + /* + * Wait until the cpu which brought this one up marked it + * active before enabling interrupts. + */ + while (!cpumask_test_cpu(smp_processor_id(), cpu_active_mask)) + cpu_relax(); local_irq_enable(); /* cpu_idle will call schedule for us */ cpu_idle(); -- 2.30.2