cpu/hotplug: Move scheduler cpu_online notifier to hotplug core

KAGA-KOKO · KAGA-KOKO · commit 949338e35131 · 2016-03-01T20:36:55.000+01:00
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@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: Rik van Riel <riel@redhat.com> Cc: Rafael Wysocki <rafael.j.wysocki@intel.com> Cc: "Srivatsa S. Bhat" <srivatsa@mit.edu> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Sebastian Siewior <bigeasy@linutronix.de> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Paul McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Paul Turner <pjt@google.com> Link: http://lkml.kernel.org/r/20160226182341.200791046@linutronix.de Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git 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,
diff --git a/kernel/cpu.c b/kernel/cpu.c
@@ -666,6 +666,19 @@ void notify_cpu_starting(unsigned int cpu)
 	}
 }
 
+/*
+ * 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,
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
@@ -5692,16 +5692,6 @@ static int sched_cpu_active(struct notifier_block *nfb,
 		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;
