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Groups > linux.kernel > #1355061

[patch 01/15] cpu/hotplug: Document states better

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Requested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 kernel/cpu.c |   47 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1171,6 +1171,10 @@ static struct cpuhp_step cpuhp_bp_states
 		.teardown		= NULL,
 		.cant_stop		= true,
 	},
+	/*
+	 * Preparatory and dead notifiers. Will be replaced once the notifiers
+	 * are converted to states.
+	 */
 	[CPUHP_NOTIFY_PREPARE] = {
 		.name			= "notify:prepare",
 		.startup		= notify_prepare,
@@ -1178,12 +1182,17 @@ static struct cpuhp_step cpuhp_bp_states
 		.skip_onerr		= true,
 		.cant_stop		= true,
 	},
+	/* Kicks the plugged cpu into life */
 	[CPUHP_BRINGUP_CPU] = {
 		.name			= "cpu:bringup",
 		.startup		= bringup_cpu,
 		.teardown		= NULL,
 		.cant_stop		= true,
 	},
+	/*
+	 * Handled on controll processor until the plugged processor manages
+	 * this itself.
+	 */
 	[CPUHP_TEARDOWN_CPU] = {
 		.name			= "cpu:teardown",
 		.startup		= NULL,
@@ -1196,6 +1205,23 @@ static struct cpuhp_step cpuhp_bp_states
 /* Application processor state steps */
 static struct cpuhp_step cpuhp_ap_states[] = {
 #ifdef CONFIG_SMP
+	/* Final state before CPU kills itself */
+	[CPUHP_AP_IDLE_DEAD] = {
+		.name			= "idle:dead",
+	},
+	/*
+	 * Last state before CPU enters the idle loop to die. Transient state
+	 * for synchronization.
+	 */
+	[CPUHP_AP_OFFLINE] = {
+		.name			= "ap:offline",
+		.cant_stop		= true,
+	},
+	/*
+	 * Low level startup/teardown notifiers. Run with interrupts
+	 * disabled. Will be removed once the notifiers are converted to
+	 * states.
+	 */
 	[CPUHP_AP_NOTIFY_STARTING] = {
 		.name			= "notify:starting",
 		.startup		= notify_starting,
@@ -1203,17 +1229,32 @@ static struct cpuhp_step cpuhp_ap_states
 		.skip_onerr		= true,
 		.cant_stop		= true,
 	},
+	/* Entry state on starting. Interrupts enabled from here on. Transient
+	 * state for synchronsization */
+	[CPUHP_AP_ONLINE] = {
+		.name			= "ap:online",
+	},
+	/* Handle smpboot threads park/unpark */
 	[CPUHP_AP_SMPBOOT_THREADS] = {
 		.name			= "smpboot:threads",
 		.startup		= smpboot_unpark_threads,
 		.teardown		= smpboot_park_threads,
 	},
+	/*
+	 * Online/down_prepare notifiers. Will be removed once the notifiers
+	 * are converted to states.
+	 */
 	[CPUHP_AP_NOTIFY_ONLINE] = {
 		.name			= "notify:online",
 		.startup		= notify_online,
 		.teardown		= notify_down_prepare,
 	},
 #endif
+	/*
+	 * The dynamically registered state space is here
+	 */
+
+	/* CPU is fully up and running. */
 	[CPUHP_ONLINE] = {
 		.name			= "online",
 		.startup		= NULL,
@@ -1231,7 +1272,11 @@ static int cpuhp_cb_check(enum cpuhp_sta
 
 static bool cpuhp_is_ap_state(enum cpuhp_state state)
 {
-	return state > CPUHP_BRINGUP_CPU;
+	/*
+	 * The extra check for CPUHP_TEARDOWN_CPU is only for documentation
+	 * purposes as that state is handled explicitely in cpu_down.
+	 */
+	return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
 }
 
 static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)

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[patch 00/15] cpu/hotplug: Convert scheduler to hotplug state machine Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 14/15] sched/fair: Make ilb_notifier an explicit call Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 07/15] sched/hotplug: Convert cpu_[in]active notifiers to  state machine Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 01/15] cpu/hotplug: Document states better Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 10/15] sched/migration: Move calc_load_migrate() into CPU_DYING Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 13/15] sched/hotplug: Make activate() the last hotplug step Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 05/15] sched: Consolidate the notifier maze Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 09/15] sched/migration: Move prepare transition to  SCHED_STARTING state Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 08/15] sched,  hotplug: Move sync_rcu to be with set_cpu_active(false) Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 06/15] sched: Move sched_domains_numa_masks_clear() to  DOWN_PREPARE Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 11/15] sched/migration: Move CPU_ONLINE into scheduler state Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 03/15] sched: Make set_cpu_rq_start_time() a built in hotplug  state Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 12/15] sched/hotplug: Move migration CPU_DYING to  sched_cpu_dying() Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 15/15] sched: Make hrtick_notifier an explicit call Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:10 +0100
  [patch 04/15] sched: Allow hotplug notifiers to be setup early Thomas Gleixner <tglx@linutronix.de> - 2016-03-10 13:20 +0100

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