[patch 12/20] cpu/hotplug: Move scheduler cpu_online notifier to hotplug core

From: Thomas Gleixner
Date: Fri Feb 26 2016 - 13:47:47 EST


Move the scheduler cpu online notifier part to the hotplug core. This is
anyway the highest priority callback and we need that functionality right now
for the next changes.

Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
include/linux/cpuhotplug.h | 1 +
kernel/cpu.c | 18 ++++++++++++++++++
kernel/sched/core.c | 10 ----------
3 files changed, 19 insertions(+), 10 deletions(-)

Index: b/include/linux/cpuhotplug.h
===================================================================
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -10,6 +10,7 @@ enum cpuhp_state {
CPUHP_AP_NOTIFY_STARTING,
CPUHP_AP_ONLINE,
CPUHP_TEARDOWN_CPU,
+ CPUHP_CPU_SET_ACTIVE,
CPUHP_NOTIFY_ONLINE,
CPUHP_ONLINE_DYN,
CPUHP_ONLINE_DYN_END = CPUHP_ONLINE_DYN + 30,
Index: b/kernel/cpu.c
===================================================================
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -666,6 +666,19 @@ void notify_cpu_starting(unsigned int cp
}
}

+/*
+ * Called from the idle task. We need to set active here, so we can kick off
+ * the stopper thread.
+ */
+static int cpuhp_set_cpu_active(unsigned int cpu)
+{
+ /* The cpu is marked online, set it active now */
+ set_cpu_active(cpu, true);
+ /* Unpark the stopper thread */
+ stop_machine_unpark(cpu);
+ return 0;
+}
+
static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
{
for (st->state--; st->state > st->target; st->state--) {
@@ -941,6 +954,11 @@ static struct cpuhp_step cpuhp_bp_states
.teardown = takedown_cpu,
.cant_stop = true,
},
+ [CPUHP_CPU_SET_ACTIVE] = {
+ .name = "cpu:active",
+ .startup = cpuhp_set_cpu_active,
+ .teardown = NULL,
+ },
[CPUHP_NOTIFY_ONLINE] = {
.name = "notify:online",
.startup = notify_online,
Index: b/kernel/sched/core.c
===================================================================
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -5692,16 +5692,6 @@ static int sched_cpu_active(struct notif
set_cpu_rq_start_time();
return NOTIFY_OK;

- case CPU_ONLINE:
- /*
- * At this point a starting CPU has marked itself as online via
- * set_cpu_online(). But it might not yet have marked itself
- * as active, which is essential from here on.
- */
- set_cpu_active(cpu, true);
- stop_machine_unpark(cpu);
- return NOTIFY_OK;
-
case CPU_DOWN_FAILED:
set_cpu_active(cpu, true);
return NOTIFY_OK;