[GIT pull] timer fix for 4.17

[Thomas Gleixner]

Linus,

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

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

Address the for_each_cpu() oddity on UP kernels in the tick broadcast code
which causes boot failures because the CPU0 bit is always reported as set
independent of the cpumask content.

Thanks,

        tglx

------------------>
Dexuan Cui (1):
      tick/broadcast: Use for_each_cpu() specially on UP kernels


 kernel/time/tick-broadcast.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index b398c2ea69b2..aa2094d5dd27 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -612,6 +612,14 @@ static void tick_handle_oneshot_broadcast(struct 
clock_event_device *dev)
        now = ktime_get();
        /* Find all expired events */
        for_each_cpu(cpu, tick_broadcast_oneshot_mask) {
+               /*
+                * Required for !SMP because for_each_cpu() reports
+                * unconditionally CPU0 as set on UP kernels.
+                */
+               if (!IS_ENABLED(CONFIG_SMP) &&
+                   cpumask_empty(tick_broadcast_oneshot_mask))
+                       break;
+
                td = &per_cpu(tick_cpu_device, cpu);
                if (td->evtdev->next_event <= now) {
                        cpumask_set_cpu(cpu, tmpmask);