sched/rt: Sum number of all children tasks in hierarhy at ->rt_nr_running

{inc,dec}_rt_tasks() used to count entities which are directly queued
on the rt_rq. If an entity was not a task (i.e., it is some queue), its
children were not counted.

There is no problem here, but now we want to count number of all tasks
which are actually queued under the rt_rq in all the hierarchy (except
throttled rt queues).

Empty queues are not able to be queued and all of the places, which
use ->rt_nr_running, just compare it with zero, so we do not break
anything here.

Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1394835289.18748.31.camel@HP-250-G1-Notebook-PC
Cc: linux-kernel@vger.kernel.org
[ Twiddled the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/rt.c

@@ -1044,13 +1044,24 @@ void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
 
 #endif /* CONFIG_RT_GROUP_SCHED */
 
+static inline
+unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
+{
+	struct rt_rq *group_rq = group_rt_rq(rt_se);
+
+	if (group_rq)
+		return group_rq->rt_nr_running;
+	else
+		return 1;
+}
+
 static inline
 void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 {
 	int prio = rt_se_prio(rt_se);
 
 	WARN_ON(!rt_prio(prio));
-	rt_rq->rt_nr_running++;
+	rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
 
 	inc_rt_prio(rt_rq, prio);
 	inc_rt_migration(rt_se, rt_rq);
@@ -1062,7 +1073,7 @@ void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
 {
 	WARN_ON(!rt_prio(rt_se_prio(rt_se)));
 	WARN_ON(!rt_rq->rt_nr_running);
-	rt_rq->rt_nr_running--;
+	rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
 
 	dec_rt_prio(rt_rq, rt_se_prio(rt_se));
 	dec_rt_migration(rt_se, rt_rq);