/* 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];
p->rt.rt_rq = task_group(p)->rt_rq[cpu];
p->rt.parent = task_group(p)->rt_se[cpu];
#endif
+ rcu_read_unlock();
}
#else
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.
*
* just go back and repeat.
*/
rq = task_rq_lock(p, &flags);
- trace_sched_wait_task(rq, p);
+ trace_sched_wait_task(p);
running = task_running(rq, p);
on_rq = p->se.on_rq;
ncsw = 0;
success = 1;
out_running:
- trace_sched_wakeup(rq, p, success);
+ trace_sched_wakeup(p, success);
check_preempt_curr(rq, p, wake_flags);
p->state = TASK_RUNNING;
rq = task_rq_lock(p, &flags);
activate_task(rq, p, 0);
- trace_sched_wakeup_new(rq, p, 1);
+ trace_sched_wakeup_new(p, 1);
check_preempt_curr(rq, p, WF_FORK);
#ifdef CONFIG_SMP
if (p->sched_class->task_woken)
struct mm_struct *mm, *oldmm;
prepare_task_switch(rq, prev, next);
- trace_sched_switch(rq, prev, next);
+ trace_sched_switch(prev, next);
mm = next->mm;
oldmm = prev->active_mm;
/*
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;
* the mutex owner just released it and exited.
*/
if (probe_kernel_address(&owner->cpu, cpu))
- goto out;
+ return 0;
#else
cpu = owner->cpu;
#endif
* 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);
cpu_relax();
}
-out:
+
return 1;
}
#endif
if (!x->done) {
DECLARE_WAITQUEUE(wait, current);
- wait.flags |= WQ_FLAG_EXCLUSIVE;
- __add_wait_queue_tail(&x->wait, &wait);
+ __add_wait_queue_tail_exclusive(&x->wait, &wait);
do {
if (signal_pending_state(state, current)) {
timeout = -ERESTARTSYS;
#ifndef CONFIG_SMP
void synchronize_sched_expedited(void)
+{
+ barrier();
+}
+EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
+
+#else /* #ifndef CONFIG_SMP */
+
+static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
+
+static int synchronize_sched_expedited_cpu_stop(void *data)
{
/*
* There must be a full memory barrier on each affected CPU
* necessary. Do smp_mb() anyway for documentation and
* robustness against future implementation changes.
*/
- smp_mb();
-}
-EXPORT_SYMBOL_GPL(synchronize_sched_expedited);
-
-#else /* #ifndef CONFIG_SMP */
-
-static atomic_t synchronize_sched_expedited_count = ATOMIC_INIT(0);
-
-static int synchronize_sched_expedited_cpu_stop(void *data)
-{
+ smp_mb(); /* See above comment block. */
return 0;
}
get_online_cpus();
}
atomic_inc(&synchronize_sched_expedited_count);
+ smp_mb__after_atomic_inc(); /* ensure post-GP actions seen after GP. */
put_online_cpus();
}
EXPORT_SYMBOL_GPL(synchronize_sched_expedited);