From ab2515c4b98f7bc4fa11cad9fa0f811d63a72a26 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Tue, 5 Apr 2011 17:23:52 +0200 Subject: [PATCH] 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: Frank Rowand Signed-off-by: Peter Zijlstra Cc: Mike Galbraith Cc: Nick Piggin Cc: Linus Torvalds Cc: Andrew Morton Link: http://lkml.kernel.org/r/20110405152729.273362517@chello.nl Signed-off-by: Ingo Molnar --- kernel/sched.c | 17 +++-------------- 1 file changed, 3 insertions(+), 14 deletions(-) diff --git a/kernel/sched.c b/kernel/sched.c index f155127..7c5494d 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -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 -- 2.7.4