Merge branch 'stable-3.2' into pandora-3.2

[pandora-kernel.git] / kernel / sched.c

diff --git a/kernel/sched.c b/kernel/sched.c
index fb55429..0e092ab 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2084,19 +2084,6 @@ EXPORT_SYMBOL_GPL(account_system_vtime);
 
 #endif /* CONFIG_IRQ_TIME_ACCOUNTING */
 
-static inline void account_reset_rq(struct rq *rq)
-{
-#ifdef CONFIG_IRQ_TIME_ACCOUNTING
-       rq->prev_irq_time = 0;
-#endif
-#ifdef CONFIG_PARAVIRT
-       rq->prev_steal_time = 0;
-#endif
-#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING
-       rq->prev_steal_time_rq = 0;
-#endif
-}
-
 #ifdef CONFIG_PARAVIRT
 static inline u64 steal_ticks(u64 steal)
 {
@@ -2846,6 +2833,28 @@ 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;
 
@@ -5320,6 +5329,7 @@ int can_nice(const struct task_struct *p, const int nice)
        return (nice_rlim <= task_rlimit(p, RLIMIT_NICE) ||
                capable(CAP_SYS_NICE));
 }
+EXPORT_SYMBOL_GPL(can_nice);
 
 #ifdef __ARCH_WANT_SYS_NICE
 
@@ -6869,7 +6879,6 @@ 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:
@@ -8518,6 +8527,7 @@ void __init sched_init(void)
 #ifdef CONFIG_CGROUP_SCHED
        list_add(&root_task_group.list, &task_groups);
        INIT_LIST_HEAD(&root_task_group.children);
+       INIT_LIST_HEAD(&root_task_group.siblings);
        autogroup_init(&init_task);
 #endif /* CONFIG_CGROUP_SCHED */