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

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

diff --git a/kernel/sched.c b/kernel/sched.c
index b531d79..1d93cd0 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -323,6 +323,15 @@ static inline struct task_group *task_group(struct task_struct *p)
 /* Change a task's cfs_rq and parent entity if it moves across CPUs/groups */
 static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
 {
+       /*
+        * Strictly speaking this rcu_read_lock() is not needed since the
+        * task_group is tied to the cgroup, which in turn can never go away
+        * as long as there are tasks attached to it.
+        *
+        * However since task_group() uses task_subsys_state() which is an
+        * rcu_dereference() user, this quiets CONFIG_PROVE_RCU.
+        */
+       rcu_read_lock();
 #ifdef CONFIG_FAIR_GROUP_SCHED
        p->se.cfs_rq = task_group(p)->cfs_rq[cpu];
        p->se.parent = task_group(p)->se[cpu];
@@ -332,6 +341,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
        p->rt.rt_rq  = task_group(p)->rt_rq[cpu];
        p->rt.parent = task_group(p)->rt_se[cpu];
 #endif
+       rcu_read_unlock();
 }
 
 #else
@@ -2057,49 +2067,6 @@ static bool migrate_task(struct task_struct *p, int dest_cpu)
        return p->se.on_rq || task_running(rq, p);
 }
 
-/*
- * wait_task_context_switch -  wait for a thread to complete at least one
- *                             context switch.
- *
- * @p must not be current.
- */
-void wait_task_context_switch(struct task_struct *p)
-{
-       unsigned long nvcsw, nivcsw, flags;
-       int running;
-       struct rq *rq;
-
-       nvcsw   = p->nvcsw;
-       nivcsw  = p->nivcsw;
-       for (;;) {
-               /*
-                * The runqueue is assigned before the actual context
-                * switch. We need to take the runqueue lock.
-                *
-                * We could check initially without the lock but it is
-                * very likely that we need to take the lock in every
-                * iteration.
-                */
-               rq = task_rq_lock(p, &flags);
-               running = task_running(rq, p);
-               task_rq_unlock(rq, &flags);
-
-               if (likely(!running))
-                       break;
-               /*
-                * The switch count is incremented before the actual
-                * context switch. We thus wait for two switches to be
-                * sure at least one completed.
-                */
-               if ((p->nvcsw - nvcsw) > 1)
-                       break;
-               if ((p->nivcsw - nivcsw) > 1)
-                       break;
-
-               cpu_relax();
-       }
-}
-
 /*
  * wait_task_inactive - wait for a thread to unschedule.
  *
@@ -3641,7 +3608,7 @@ need_resched:
        preempt_disable();
        cpu = smp_processor_id();
        rq = cpu_rq(cpu);
-       rcu_sched_qs(cpu);
+       rcu_note_context_switch(cpu);
        prev = rq->curr;
        switch_count = &prev->nivcsw;
 
@@ -3724,7 +3691,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
         * the mutex owner just released it and exited.
         */
        if (probe_kernel_address(&owner->cpu, cpu))
-               goto out;
+               return 0;
 #else
        cpu = owner->cpu;
 #endif
@@ -3734,14 +3701,14 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
         * the cpu field may no longer be valid.
         */
        if (cpu >= nr_cpumask_bits)
-               goto out;
+               return 0;
 
        /*
         * We need to validate that we can do a
         * get_cpu() and that we have the percpu area.
         */
        if (!cpu_online(cpu))
-               goto out;
+               return 0;
 
        rq = cpu_rq(cpu);
 
@@ -3760,7 +3727,7 @@ int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
 
                cpu_relax();
        }
-out:
+
        return 1;
 }
 #endif