[GIT pull] sched fix for 4.9

[Thomas Gleixner]

Linus,

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

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

A revert of a commit which pointelessly widened a preempt disabled section
which in turn caused might_sleep() to trigger. The patch intended to
prevent usage of smp_processor_id() in preemptible context, but the usage
in that case is fine because the thread is pinned on a single cpu and
therefore cannot be migrated off.

Thanks,

        tglx

------------------>
Ingo Molnar (1):
      Revert "sched/core: Do not use smp_processor_id() with preempt enabled in 
smpboot_thread_fn()"


 kernel/smpboot.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/smpboot.c b/kernel/smpboot.c
index fc0d8270f69e..13bc43d1fb22 100644
--- a/kernel/smpboot.c
+++ b/kernel/smpboot.c
@@ -122,12 +122,12 @@ static int smpboot_thread_fn(void *data)
 
                if (kthread_should_park()) {
                        __set_current_state(TASK_RUNNING);
+                       preempt_enable();
                        if (ht->park && td->status == HP_THREAD_ACTIVE) {
                                BUG_ON(td->cpu != smp_processor_id());
                                ht->park(td->cpu);
                                td->status = HP_THREAD_PARKED;
                        }
-                       preempt_enable();
                        kthread_parkme();
                        /* We might have been woken for stop */
                        continue;