[GIT pull] smp fix for 4.13

[Thomas Gleixner]

Linus,

please pull the latest smp-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git 
smp-urgent-for-linus

Replace the bogus BUG_ON in the cpu hotplug code.

Thanks,

        tglx

------------------>
Thomas Gleixner (1):
      smp/hotplug: Replace BUG_ON and react useful


 kernel/cpu.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index ab860453841d..eee033134262 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -279,7 +279,8 @@ static int bringup_wait_for_ap(unsigned int cpu)
 
        /* Wait for the CPU to reach CPUHP_AP_ONLINE_IDLE */
        wait_for_completion(&st->done);
-       BUG_ON(!cpu_online(cpu));
+       if (WARN_ON_ONCE((!cpu_online(cpu))))
+               return -ECANCELED;
 
        /* Unpark the stopper thread and the hotplug thread of the target cpu */
        stop_machine_unpark(cpu);