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Commit 2b1e315d authored by Dmitry Adamushko's avatar Dmitry Adamushko Committed by Ingo Molnar
Browse files

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: default avatarIngo Molnar <mingo@elte.hu>
Signed-off-by: default avatarDmitry Adamushko <dmitry.adamushko@gmail.com>
Reviewed-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 8651a86c

kernel/sched_fair.c

+5 −20
Original line number Diff line number Diff line
@@ -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);

}



/*