Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ab2515c4 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched: Drop rq->lock from first part of wake_up_new_task() 



Since p->pi_lock now protects all things needed to call
select_task_rq() avoid the double remote rq->lock acquisition and rely
on p->pi_lock.

Reviewed-by: default avatarFrank Rowand <frank.rowand@am.sony.com>
Signed-off-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110405152729.273362517@chello.nl


Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 0122ec5b

kernel/sched.c

+3 −14
Original line number Diff line number Diff line
@@ -2736,28 +2736,18 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags) 
{

	unsigned long flags;

	struct rq *rq;

	int cpu __maybe_unused = get_cpu();



	raw_spin_lock_irqsave(&p->pi_lock, flags);

#ifdef CONFIG_SMP

	rq = task_rq_lock(p, &flags);

	p->state = TASK_WAKING;



	/*

	 * Fork balancing, do it here and not earlier because:

	 *  - cpus_allowed can change in the fork path

	 *  - any previously selected cpu might disappear through hotplug

	 *

	 * We set TASK_WAKING so that select_task_rq() can drop rq->lock

	 * without people poking at ->cpus_allowed.

	 */

	cpu = select_task_rq(p, SD_BALANCE_FORK, 0);

	set_task_cpu(p, cpu);



	p->state = TASK_RUNNING;

	task_rq_unlock(rq, p, &flags);

	set_task_cpu(p, select_task_rq(p, SD_BALANCE_FORK, 0));

#endif



	rq = task_rq_lock(p, &flags);

	rq = __task_rq_lock(p);

	activate_task(rq, p, 0);

	p->on_rq = 1;

	trace_sched_wakeup_new(p, true);
@@ -2767,7 +2757,6 @@ void wake_up_new_task(struct task_struct *p, unsigned long clone_flags) 
		p->sched_class->task_woken(rq, p);

#endif

	task_rq_unlock(rq, p, &flags);

	put_cpu();

}



#ifdef CONFIG_PREEMPT_NOTIFIERS