[PATCH v2 4/5] sched,idle: Simplify wake_up_idle_cpu

Andy Lutomirski
2014-06-04T17:31:36Z

Now that rq->idle's polling bit is a reliable indication that the cpu is
polling, use it.

Signed-off-by: Andy Lutomirski <luto@amacapital.net>
---
kernel/sched/core.c | 21 +--------------------
1 file changed, 1 insertion(+), 20 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index a002be7..f6e4621 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -628,26 +628,7 @@ static void wake_up_idle_cpu(int cpu)
if (cpu == smp_processor_id())
return;

- /*
- * This is safe, as this function is called with the timer
- * wheel base lock of (cpu) held. When the CPU is on the way
- * to idle and has not yet set rq->curr to idle then it will
- * be serialized on the timer wheel base lock and take the new
- * timer into account automatically.
- */
- if (rq->curr != rq->idle)
- return;
-
- /*
- * We can set TIF_RESCHED on the idle task of the other CPU
- * lockless. The worst case is that the other CPU runs the
- * idle task through an additional NOOP schedule()
- */
- set_tsk_need_resched(rq->idle);
-
- /* NEED_RESCHED must be visible before we test polling */
- smp_mb();
- if (!tsk_is_polling(rq->idle))
+ if (set_nr_and_not_polling(rq->idle))
smp_send_reschedule(cpu);
else
trace_sched_wake_idle_without_ipi(cpu);
--
1.9.3