Merge tag 'v3.10.107' into update

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / kernel / sched / core.c

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index b706645988e4cae3e46d578b66c2fdda06e927d5..3c359e0c83808e9a7802b1e7f6d25c8fd943ed14 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -192,14 +192,12 @@ struct static_key sched_feat_keys[__SCHED_FEAT_NR] = {
 
 static void sched_feat_disable(int i)
 {
-       if (static_key_enabled(&sched_feat_keys[i]))
-               static_key_slow_dec(&sched_feat_keys[i]);
+       static_key_disable(&sched_feat_keys[i]);
 }
 
 static void sched_feat_enable(int i)
 {
-       if (!static_key_enabled(&sched_feat_keys[i]))
-               static_key_slow_inc(&sched_feat_keys[i]);
+       static_key_enable(&sched_feat_keys[i]);
 }
 #else
 static void sched_feat_disable(int i) { };
@@ -1635,10 +1633,51 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
        success = 1; /* we're going to change ->state */
        cpu = task_cpu(p);
 
+       /*
+        * Ensure we load p->on_rq _after_ p->state, otherwise it would
+        * be possible to, falsely, observe p->on_rq == 0 and get stuck
+        * in smp_cond_load_acquire() below.
+        *
+        * sched_ttwu_pending()                 try_to_wake_up()
+        *   [S] p->on_rq = 1;                  [L] P->state
+        *       UNLOCK rq->lock  -----.
+        *                              \
+        *                               +---   RMB
+        * schedule()                   /
+        *       LOCK rq->lock    -----'
+        *       UNLOCK rq->lock
+        *
+        * [task p]
+        *   [S] p->state = UNINTERRUPTIBLE     [L] p->on_rq
+        *
+        * Pairs with the UNLOCK+LOCK on rq->lock from the
+        * last wakeup of our task and the schedule that got our task
+        * current.
+        */
+       smp_rmb();
        if (p->on_rq && ttwu_remote(p, wake_flags))
                goto stat;
 
 #ifdef CONFIG_SMP
+       /*
+        * Ensure we load p->on_cpu _after_ p->on_rq, otherwise it would be
+        * possible to, falsely, observe p->on_cpu == 0.
+        *
+        * One must be running (->on_cpu == 1) in order to remove oneself
+        * from the runqueue.
+        *
+        *  [S] ->on_cpu = 1;   [L] ->on_rq
+        *      UNLOCK rq->lock
+        *                      RMB
+        *      LOCK   rq->lock
+        *  [S] ->on_rq = 0;    [L] ->on_cpu
+        *
+        * Pairs with the full barrier implied in the UNLOCK+LOCK on rq->lock
+        * from the consecutive calls to schedule(); the first switching to our
+        * task, the second putting it to sleep.
+        */
+       smp_rmb();
+
        /*
         * If the owning (remote) cpu is still in the middle of schedule() with
         * this task as prev, wait until its done referencing the task.
@@ -1728,7 +1767,6 @@ out:
  */
 int wake_up_process(struct task_struct *p)
 {
-       WARN_ON(task_is_stopped_or_traced(p));
        return try_to_wake_up(p, TASK_NORMAL, 0);
 }
 EXPORT_SYMBOL(wake_up_process);
@@ -5108,7 +5146,8 @@ void show_state_filter(unsigned long state_filter)
        touch_all_softlockup_watchdogs();
 
 #ifdef CONFIG_SCHED_DEBUG
-       sysrq_sched_debug_show();
+       if (!state_filter)
+               sysrq_sched_debug_show();
 #endif
        rcu_read_unlock();
        /*
@@ -5622,6 +5661,7 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu)
 
        case CPU_UP_PREPARE:
                rq->calc_load_update = calc_load_update;
+               account_reset_rq(rq);
                break;
 
        case CPU_ONLINE: