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cpu/hotplug: Convert to a state machine for the control processor 

Move the split out steps into a callback array and let the cpu_up/down
code iterate through the array functions. For now most of the
callbacks are asymmetric to resemble the current hotplug maze.

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/20160226182340.671816690@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner 2016-02-26 18:43:28 +00:00
parent 5ba9ac8e2c
commit cff7d378d3
4 changed files with 193 additions and 44 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/cpu.h
View File

@ -16,6 +16,7 @@
#include <linux/node.h>
#include <linux/compiler.h>
#include <linux/cpumask.h>
#include <linux/cpuhotplug.h>
struct device;
struct device_node;
@ -27,6 +28,9 @@ struct cpu {
struct device dev;
};
extern void boot_cpu_init(void);
extern void boot_cpu_state_init(void);
extern int register_cpu(struct cpu *cpu, int num);
extern struct device *get_cpu_device(unsigned cpu);
extern bool cpu_is_hotpluggable(unsigned cpu);
@ -267,11 +271,6 @@ static inline int disable_nonboot_cpus(void) { return 0; }
static inline void enable_nonboot_cpus(void) {}
#endif /* !CONFIG_PM_SLEEP_SMP */
enum cpuhp_state {
CPUHP_OFFLINE,
CPUHP_ONLINE,
};
void cpu_startup_entry(enum cpuhp_state state);
void cpu_idle_poll_ctrl(bool enable);

13
include/linux/cpuhotplug.h Normal file
View File

@ -0,0 +1,13 @@
#ifndef __CPUHOTPLUG_H
#define __CPUHOTPLUG_H
enum cpuhp_state {
CPUHP_OFFLINE,
CPUHP_CREATE_THREADS,
CPUHP_NOTIFY_PREPARE,
CPUHP_BRINGUP_CPU,
CPUHP_NOTIFY_ONLINE,
CPUHP_ONLINE,
};
#endif

15
init/main.c
View File

@ -452,20 +452,6 @@ void __init parse_early_param(void)
done = 1;
}
/*
* Activate the first processor.
*/
static void __init boot_cpu_init(void)
{
int cpu = smp_processor_id();
/* Mark the boot cpu "present", "online" etc for SMP and UP case */
set_cpu_online(cpu, true);
set_cpu_active(cpu, true);
set_cpu_present(cpu, true);
set_cpu_possible(cpu, true);
}
void __init __weak smp_setup_processor_id(void)
{
}
@ -530,6 +516,7 @@ asmlinkage __visible void __init start_kernel(void)
setup_command_line(command_line);
setup_nr_cpu_ids();
setup_per_cpu_areas();
boot_cpu_state_init();
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
build_all_zonelists(NULL, NULL);

200
kernel/cpu.c
View File

@ -22,10 +22,64 @@
#include <linux/lockdep.h>
#include <linux/tick.h>
#include <linux/irq.h>
#include <trace/events/power.h>
#define CREATE_TRACE_POINTS
#include <trace/events/cpuhp.h>
#include "smpboot.h"
/**
* cpuhp_cpu_state - Per cpu hotplug state storage
* @state: The current cpu state
* @target: The target state
*/
struct cpuhp_cpu_state {
enum cpuhp_state state;
enum cpuhp_state target;
};
static DEFINE_PER_CPU(struct cpuhp_cpu_state, cpuhp_state);
/**
* cpuhp_step - Hotplug state machine step
* @name: Name of the step
* @startup: Startup function of the step
* @teardown: Teardown function of the step
* @skip_onerr: Do not invoke the functions on error rollback
* Will go away once the notifiers are gone
*/
struct cpuhp_step {
const char *name;
int (*startup)(unsigned int cpu);
int (*teardown)(unsigned int cpu);
bool skip_onerr;
};
static struct cpuhp_step cpuhp_bp_states[];
/**
* cpuhp_invoke_callback _ Invoke the callbacks for a given state
* @cpu: The cpu for which the callback should be invoked
* @step: The step in the state machine
* @cb: The callback function to invoke
*
* Called from cpu hotplug and from the state register machinery
*/
static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state step,
int (*cb)(unsigned int))
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int ret = 0;
if (cb) {
trace_cpuhp_enter(cpu, st->target, step, cb);
ret = cb(cpu);
trace_cpuhp_exit(cpu, st->state, step, ret);
}
return ret;
}
#ifdef CONFIG_SMP
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);
@ -454,10 +508,29 @@ static int notify_dead(unsigned int cpu)
return 0;
}
#else
#define notify_down_prepare NULL
#define takedown_cpu NULL
#define notify_dead NULL
#endif
#ifdef CONFIG_HOTPLUG_CPU
static void undo_cpu_down(unsigned int cpu, struct cpuhp_cpu_state *st)
{
for (st->state++; st->state < st->target; st->state++) {
struct cpuhp_step *step = cpuhp_bp_states + st->state;
if (!step->skip_onerr)
cpuhp_invoke_callback(cpu, st->state, step->startup);
}
}
/* Requires cpu_add_remove_lock to be held */
static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
{
int err;
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int prev_state, ret = 0;
bool hasdied = false;
if (num_online_cpus() == 1)
return -EBUSY;
@ -469,20 +542,25 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
cpuhp_tasks_frozen = tasks_frozen;
err = notify_down_prepare(cpu);
if (err)
goto out_release;
err = takedown_cpu(cpu);
if (err)
goto out_release;
prev_state = st->state;
st->target = CPUHP_OFFLINE;
for (; st->state > st->target; st->state--) {
struct cpuhp_step *step = cpuhp_bp_states + st->state;
notify_dead(cpu);
ret = cpuhp_invoke_callback(cpu, st->state, step->teardown);
if (ret) {
st->target = prev_state;
undo_cpu_down(cpu, st);
break;
}
}
hasdied = prev_state != st->state && st->state == CPUHP_OFFLINE;
out_release:
cpu_hotplug_done();
if (!err)
/* This post dead nonsense must die */
if (!ret && hasdied)
cpu_notify_nofail(CPU_POST_DEAD, cpu);
return err;
return ret;
}
int cpu_down(unsigned int cpu)
@ -537,11 +615,22 @@ void smpboot_thread_init(void)
register_cpu_notifier(&smpboot_thread_notifier);
}
static void undo_cpu_up(unsigned int cpu, struct cpuhp_cpu_state *st)
{
for (st->state--; st->state > st->target; st->state--) {
struct cpuhp_step *step = cpuhp_bp_states + st->state;
if (!step->skip_onerr)
cpuhp_invoke_callback(cpu, st->state, step->teardown);
}
}
/* Requires cpu_add_remove_lock to be held */
static int _cpu_up(unsigned int cpu, int tasks_frozen)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
struct task_struct *idle;
int ret;
int prev_state, ret = 0;
cpu_hotplug_begin();
@ -550,6 +639,7 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen)
goto out;
}
/* Let it fail before we try to bring the cpu up */
idle = idle_thread_get(cpu);
if (IS_ERR(idle)) {
ret = PTR_ERR(idle);
@ -558,22 +648,22 @@ static int _cpu_up(unsigned int cpu, int tasks_frozen)
cpuhp_tasks_frozen = tasks_frozen;
ret = smpboot_create_threads(cpu);
if (ret)
goto out;
prev_state = st->state;
st->target = CPUHP_ONLINE;
while (st->state < st->target) {
struct cpuhp_step *step;
ret = notify_prepare(cpu);
if (ret)
goto out;
ret = bringup_cpu(cpu);
if (ret)
goto out;
notify_online(cpu);
st->state++;
step = cpuhp_bp_states + st->state;
ret = cpuhp_invoke_callback(cpu, st->state, step->startup);
if (ret) {
st->target = prev_state;
undo_cpu_up(cpu, st);
break;
}
}
out:
cpu_hotplug_done();
return ret;
}
@ -767,6 +857,44 @@ void notify_cpu_starting(unsigned int cpu)
#endif /* CONFIG_SMP */
/* Boot processor state steps */
static struct cpuhp_step cpuhp_bp_states[] = {
[CPUHP_OFFLINE] = {
.name = "offline",
.startup = NULL,
.teardown = NULL,
},
#ifdef CONFIG_SMP
[CPUHP_CREATE_THREADS]= {
.name = "threads:create",
.startup = smpboot_create_threads,
.teardown = NULL,
},
[CPUHP_NOTIFY_PREPARE] = {
.name = "notify:prepare",
.startup = notify_prepare,
.teardown = notify_dead,
.skip_onerr = true,
},
[CPUHP_BRINGUP_CPU] = {
.name = "cpu:bringup",
.startup = bringup_cpu,
.teardown = takedown_cpu,
.skip_onerr = true,
},
[CPUHP_NOTIFY_ONLINE] = {
.name = "notify:online",
.startup = notify_online,
.teardown = notify_down_prepare,
},
#endif
[CPUHP_ONLINE] = {
.name = "online",
.startup = NULL,
.teardown = NULL,
},
};
/*
* cpu_bit_bitmap[] is a special, "compressed" data structure that
* represents all NR_CPUS bits binary values of 1<<nr.
@ -826,3 +954,25 @@ void init_cpu_online(const struct cpumask *src)
{
cpumask_copy(&__cpu_online_mask, src);
}
/*
* Activate the first processor.
*/
void __init boot_cpu_init(void)
{
int cpu = smp_processor_id();
/* Mark the boot cpu "present", "online" etc for SMP and UP case */
set_cpu_online(cpu, true);
set_cpu_active(cpu, true);
set_cpu_present(cpu, true);
set_cpu_possible(cpu, true);
}
/*
* Must be called _AFTER_ setting up the per_cpu areas
*/
void __init boot_cpu_state_init(void)
{
per_cpu_ptr(&cpuhp_state, smp_processor_id())->state = CPUHP_ONLINE;
}