sched/core: Remove unlikely() annotation from sched_move_task()

The check for 'running' in sched_move_task() has an unlikely() around it. That
is, it is unlikely that the task being moved is running. That use to be
true. But with a couple of recent updates, it is now likely that the task
will be running.

The first change came from ea86cb4b7621 ("sched/cgroup: Fix
cpu_cgroup_fork() handling") that moved around the use case of
sched_move_task() in do_fork() where the call is now done after the task is
woken (hence it is running).

The second change came from 8e5bfa8c1f84 ("sched/autogroup: Do not use
autogroup->tg in zombie threads") where sched_move_task() is called by the
exit path, by the task that is exiting. Hence it too is running.

Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Link: http://lkml.kernel.org/r/20170206110426.27ca6426@gandalf.local.home
Signed-off-by: Ingo Molnar <mingo@kernel.org>

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index e4aa470ed45435ef3b4ad3f74b435d5ce8cf7c6d..34e2291a9a6c163be3dfd774ed110bf07ab0e890 100644 (file)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6404,14 +6404,14 @@ void sched_move_task(struct task_struct *tsk)
 
        if (queued)
                dequeue_task(rq, tsk, DEQUEUE_SAVE | DEQUEUE_MOVE);
-       if (unlikely(running))
+       if (running)
                put_prev_task(rq, tsk);
 
        sched_change_group(tsk, TASK_MOVE_GROUP);
 
        if (queued)
                enqueue_task(rq, tsk, ENQUEUE_RESTORE | ENQUEUE_MOVE);
-       if (unlikely(running))
+       if (running)
                set_curr_task(rq, tsk);
 
        task_rq_unlock(rq, tsk, &rf);