diff options
| -rw-r--r-- | arch/i386/kernel/smpboot.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c index eba7f53f8b4a6..7007e1783797a 100644 --- a/arch/i386/kernel/smpboot.c +++ b/arch/i386/kernel/smpboot.c @@ -1029,6 +1029,16 @@ int __devinit smp_prepare_cpu(int cpu) int apicid, ret; lock_cpu_hotplug(); + + /* + * On x86, CPU0 is never offlined. Trying to bring up an + * already-booted CPU will hang. So check for that case. + */ + if (cpu_online(cpu)) { + ret = -EINVAL; + goto exit; + } + apicid = x86_cpu_to_apicid[cpu]; if (apicid == BAD_APICID) { ret = -ENODEV; |