Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...

Pull scheduler fix from Thomas Gleixner:
 "A single bugfix to prevent a pinned thread which queues stomp machine
  work to be preempted by the stopper thread on its CPU which causes a
  live lock as it is unable to wake the second CPUs stopper thread"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  stop_machine: Atomically queue and wake stopper threads

diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index e190d1ef3a23b005279fb3e950c0db355895eeec..69eb76daed34de53c31a7f0505bca84172119af6 100644 (file)
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -81,6 +81,7 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
        unsigned long flags;
        bool enabled;
 
+       preempt_disable();
        raw_spin_lock_irqsave(&stopper->lock, flags);
        enabled = stopper->enabled;
        if (enabled)
@@ -90,6 +91,7 @@ static bool cpu_stop_queue_work(unsigned int cpu, struct cpu_stop_work *work)
        raw_spin_unlock_irqrestore(&stopper->lock, flags);
 
        wake_up_q(&wakeq);
+       preempt_enable();
 
        return enabled;
 }