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

Thomas Gleixner
2016-03-10T12:06:08Z

[-- Attachment #1: cpu-hotplug--Document-states-better.patch --]
[-- Type: text/plain, Size: 3097 bytes --]

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)