[GIT PULL] scheduler fixes

[Ingo Molnar]

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

   # HEAD: f3d133ee0a17d5694c6f21873eec9863e11fa423 sched/rt: Restore 
rt_runtime after disabling RT_RUNTIME_SHARE

Misc fixes:

 - a deadline scheduler related bug fix which triggered a kernel warning
 - an RT_RUNTIME_SHARE fix
 - a stop_machine preemption fix
 - a potential NULL dereference fix in sched_domain_debug_one()

 Thanks,

        Ingo

------------------>
Daniel Bristot de Oliveira (1):
      sched/deadline: Update rq_clock of later_rq when pushing a task

Hailong Liu (1):
      sched/rt: Restore rt_runtime after disabling RT_RUNTIME_SHARE

Isaac J. Manjarres (1):
      stop_machine: Disable preemption after queueing stopper threads

Yi Wang (1):
      sched/topology: Check variable group before dereferencing it


 kernel/sched/deadline.c |  8 +++++++-
 kernel/sched/rt.c       |  2 ++
 kernel/sched/topology.c |  2 +-
 kernel/stop_machine.c   | 10 +++++++++-
 4 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 10c7b51c0d1f..b5fbdde6afa9 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2090,8 +2090,14 @@ static int push_dl_task(struct rq *rq)
        sub_rq_bw(&next_task->dl, &rq->dl);
        set_task_cpu(next_task, later_rq->cpu);
        add_rq_bw(&next_task->dl, &later_rq->dl);
+
+       /*
+        * Update the later_rq clock here, because the clock is used
+        * by the cpufreq_update_util() inside __add_running_bw().
+        */
+       update_rq_clock(later_rq);
        add_running_bw(&next_task->dl, &later_rq->dl);
-       activate_task(later_rq, next_task, 0);
+       activate_task(later_rq, next_task, ENQUEUE_NOCLOCK);
        ret = 1;
 
        resched_curr(later_rq);
diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 572567078b60..eaaec8364f96 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -836,6 +836,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth 
*rt_b, int overrun)
                 * can be time-consuming. Try to avoid it when possible.
                 */
                raw_spin_lock(&rt_rq->rt_runtime_lock);
+               if (!sched_feat(RT_RUNTIME_SHARE) && rt_rq->rt_runtime != 
RUNTIME_INF)
+                       rt_rq->rt_runtime = rt_b->rt_runtime;
                skip = !rt_rq->rt_time && !rt_rq->rt_nr_running;
                raw_spin_unlock(&rt_rq->rt_runtime_lock);
                if (skip)
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index 05a831427bc7..56a0fed30c0a 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -47,7 +47,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, 
int cpu, int level,
        if (!cpumask_test_cpu(cpu, sched_domain_span(sd))) {
                printk(KERN_ERR "ERROR: domain->span does not contain CPU%d\n", 
cpu);
        }
-       if (!cpumask_test_cpu(cpu, sched_group_span(group))) {
+       if (group && !cpumask_test_cpu(cpu, sched_group_span(group))) {
                printk(KERN_ERR "ERROR: domain->groups does not contain 
CPU%d\n", cpu);
        }
 
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 1ff523dae6e2..e190d1ef3a23 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -260,6 +260,15 @@ static int cpu_stop_queue_two_works(int cpu1, struct 
cpu_stop_work *work1,
        err = 0;
        __cpu_stop_queue_work(stopper1, work1, &wakeq);
        __cpu_stop_queue_work(stopper2, work2, &wakeq);
+       /*
+        * The waking up of stopper threads has to happen
+        * in the same scheduling context as the queueing.
+        * Otherwise, there is a possibility of one of the
+        * above stoppers being woken up by another CPU,
+        * and preempting us. This will cause us to n ot
+        * wake up the other stopper forever.
+        */
+       preempt_disable();
 unlock:
        raw_spin_unlock(&stopper2->lock);
        raw_spin_unlock_irq(&stopper1->lock);
@@ -271,7 +280,6 @@ static int cpu_stop_queue_two_works(int cpu1, struct 
cpu_stop_work *work1,
        }
 
        if (!err) {
-               preempt_disable();
                wake_up_q(&wakeq);
                preempt_enable();
        }