Merge 3.0-rc2 + Linus's latest into usb-linus

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

diff --git a/kernel/sched.c b/kernel/sched.c
index cbb3a0e..3f2e502 100644 (file)
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -605,10 +605,10 @@ static inline int cpu_of(struct rq *rq)
 /*
  * Return the group to which this tasks belongs.
  *
- * We use task_subsys_state_check() and extend the RCU verification
- * with lockdep_is_held(&p->pi_lock) because cpu_cgroup_attach()
- * holds that lock for each task it moves into the cgroup. Therefore
- * by holding that lock, we pin the task to the current cgroup.
+ * We use task_subsys_state_check() and extend the RCU verification with
+ * pi->lock and rq->lock because cpu_cgroup_attach() holds those locks for each
+ * task it moves into the cgroup. Therefore by holding either of those locks,
+ * we pin the task to the current cgroup.
  */
 static inline struct task_group *task_group(struct task_struct *p)
 {
@@ -616,7 +616,8 @@ static inline struct task_group *task_group(struct task_struct *p)
        struct cgroup_subsys_state *css;
 
        css = task_subsys_state_check(p, cpu_cgroup_subsys_id,
-                       lockdep_is_held(&p->pi_lock));
+                       lockdep_is_held(&p->pi_lock) ||
+                       lockdep_is_held(&task_rq(p)->lock));
        tg = container_of(css, struct task_group, css);
 
        return autogroup_task_group(p, tg);
@@ -2200,6 +2201,16 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
                        !(task_thread_info(p)->preempt_count & PREEMPT_ACTIVE));
 
 #ifdef CONFIG_LOCKDEP
+       /*
+        * The caller should hold either p->pi_lock or rq->lock, when changing
+        * a task's CPU. ->pi_lock for waking tasks, rq->lock for runnable tasks.
+        *
+        * sched_move_task() holds both and thus holding either pins the cgroup,
+        * see set_task_rq().
+        *
+        * Furthermore, all task_rq users should acquire both locks, see
+        * task_rq_lock().
+        */
        WARN_ON_ONCE(debug_locks && !(lockdep_is_held(&p->pi_lock) ||
                                      lockdep_is_held(&task_rq(p)->lock)));
 #endif
@@ -2447,6 +2458,10 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
                }
                rcu_read_unlock();
        }
+
+       if (wake_flags & WF_MIGRATED)
+               schedstat_inc(p, se.statistics.nr_wakeups_migrate);
+
 #endif /* CONFIG_SMP */
 
        schedstat_inc(rq, ttwu_count);
@@ -2455,9 +2470,6 @@ ttwu_stat(struct task_struct *p, int cpu, int wake_flags)
        if (wake_flags & WF_SYNC)
                schedstat_inc(p, se.statistics.nr_wakeups_sync);
 
-       if (cpu != task_cpu(p))
-               schedstat_inc(p, se.statistics.nr_wakeups_migrate);
-
 #endif /* CONFIG_SCHEDSTATS */
 }
 
@@ -2600,6 +2612,7 @@ static void ttwu_queue(struct task_struct *p, int cpu)
 
 #if defined(CONFIG_SMP)
        if (sched_feat(TTWU_QUEUE) && cpu != smp_processor_id()) {
+               sched_clock_cpu(cpu); /* sync clocks x-cpu */
                ttwu_queue_remote(p, cpu);
                return;
        }
@@ -2674,8 +2687,10 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
                p->sched_class->task_waking(p);
 
        cpu = select_task_rq(p, SD_BALANCE_WAKE, wake_flags);
-       if (task_cpu(p) != cpu)
+       if (task_cpu(p) != cpu) {
+               wake_flags |= WF_MIGRATED;
                set_task_cpu(p, cpu);
+       }
 #endif /* CONFIG_SMP */
 
        ttwu_queue(p, cpu);