sched: yield fix

fix yield bugs due to the current-not-in-rbtree changes: the task is
not in the rbtree so rbtree-removal is a no-no.

[ From: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>: build fix. ]

also, nice code size reduction:

kernel/sched.o:
   text    data     bss     dec     hex filename
  38323    3506      24   41853    a37d sched.o.before
  38236    3506      24   41766    a326 sched.o.after

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 5384a977c9a7beaa30a1b0269bb708660453bd6d..fcd6900849b35ab9445c8cfbee59792943224a47 100644 (file)
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -739,9 +739,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int sleep)
 static void yield_task_fair(struct rq *rq)
 {
        struct cfs_rq *cfs_rq = task_cfs_rq(rq->curr);
-       struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
        struct sched_entity *rightmost, *se = &rq->curr->se;
-       struct rb_node *parent;
 
        /*
         * Are we the only task in the tree?
@@ -755,39 +753,26 @@ static void yield_task_fair(struct rq *rq)
                 * Dequeue and enqueue the task to update its
                 * position within the tree:
                 */
-               dequeue_entity(cfs_rq, se, 0);
-               enqueue_entity(cfs_rq, se, 0);
+               update_curr(cfs_rq);
 
                return;
        }
        /*
         * Find the rightmost entry in the rbtree:
         */
-       do {
-               parent = *link;
-               link = &parent->rb_right;
-       } while (*link);
-
-       rightmost = rb_entry(parent, struct sched_entity, run_node);
+       rightmost = __pick_last_entity(cfs_rq);
        /*
         * Already in the rightmost position?
         */
-       if (unlikely(rightmost == se))
+       if (unlikely(rightmost->vruntime < se->vruntime))
                return;
 
        /*
         * Minimally necessary key value to be last in the tree:
+        * Upon rescheduling, sched_class::put_prev_task() will place
+        * 'current' within the tree based on its new key value.
         */
        se->vruntime = rightmost->vruntime + 1;
-
-       if (cfs_rq->rb_leftmost == &se->run_node)
-               cfs_rq->rb_leftmost = rb_next(&se->run_node);
-       /*
-        * Relink the task to the rightmost position:
-        */
-       rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
-       rb_link_node(&se->run_node, parent, link);
-       rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
 }
 
 /*