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Offline Alvajoy123

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Linux
« on: September 04, 2017, 02:02:11 am »
hello everyone long time no see
sorry for everything that happen but i have to start off new and fresh
so to start off i want to say my program name is linux as you can see
and i will be using the code that kotu gave to to me
Code: [Select]
/* CPU control.
 * (C) 2001, 2002, 2003, 2004 Rusty Russell
 *
 * This code is licenced under the GPL.
 */
#include <linux/proc_fs.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/notifier.h>
#include <linux/sched/signal.h>
#include <linux/sched/hotplug.h>
#include <linux/sched/task.h>
#include <linux/unistd.h>
#include <linux/cpu.h>
#include <linux/oom.h>
#include <linux/rcupdate.h>
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/kthread.h>
#include <linux/stop_machine.h>
#include <linux/mutex.h>
#include <linux/gfp.h>
#include <linux/suspend.h>
#include <linux/lockdep.h>
#include <linux/tick.h>
#include <linux/irq.h>
#include <linux/smpboot.h>
#include <linux/relay.h>
#include <linux/slab.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
 * @thread: Pointer to the hotplug thread
 * @should_run: Thread should execute
 * @rollback: Perform a rollback
 * @single: Single callback invocation
 * @bringup: Single callback bringup or teardown selector
 * @cb_state: The state for a single callback (install/uninstall)
 * @result: Result of the operation
 * @done: Signal completion to the issuer of the task
 */
struct cpuhp_cpu_state {
enum cpuhp_state state;
enum cpuhp_state target;
#ifdef CONFIG_SMP
struct task_struct *thread;
bool should_run;
bool rollback;
bool single;
bool bringup;
struct hlist_node *node;
enum cpuhp_state cb_state;
int result;
struct completion done;
#endif
};

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
 * @cant_stop: Bringup/teardown can't be stopped at this step
 */
struct cpuhp_step {
const char *name;
union {
int (*single)(unsigned int cpu);
int (*multi)(unsigned int cpu,
struct hlist_node *node);
} startup;
union {
int (*single)(unsigned int cpu);
int (*multi)(unsigned int cpu,
struct hlist_node *node);
} teardown;
struct hlist_head list;
bool skip_onerr;
bool cant_stop;
bool multi_instance;
};

static DEFINE_MUTEX(cpuhp_state_mutex);
static struct cpuhp_step cpuhp_bp_states[];
static struct cpuhp_step cpuhp_ap_states[];

static bool cpuhp_is_ap_state(enum cpuhp_state state)
{
/*
* The extra check for CPUHP_TEARDOWN_CPU is only for documentation
* purposes as that state is handled explicitly in cpu_down.
*/
return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
}

static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
{
struct cpuhp_step *sp;

sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;
return sp + state;
}

/**
 * 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
 * @bringup: True if the bringup callback should be invoked
 *
 * Called from cpu hotplug and from the state register machinery.
 */
static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
bool bringup, struct hlist_node *node)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
struct cpuhp_step *step = cpuhp_get_step(state);
int (*cbm)(unsigned int cpu, struct hlist_node *node);
int (*cb)(unsigned int cpu);
int ret, cnt;

if (!step->multi_instance) {
cb = bringup ? step->startup.single : step->teardown.single;
if (!cb)
return 0;
trace_cpuhp_enter(cpu, st->target, state, cb);
ret = cb(cpu);
trace_cpuhp_exit(cpu, st->state, state, ret);
return ret;
}
cbm = bringup ? step->startup.multi : step->teardown.multi;
if (!cbm)
return 0;

/* Single invocation for instance add/remove */
if (node) {
trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
ret = cbm(cpu, node);
trace_cpuhp_exit(cpu, st->state, state, ret);
return ret;
}

/* State transition. Invoke on all instances */
cnt = 0;
hlist_for_each(node, &step->list) {
trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
ret = cbm(cpu, node);
trace_cpuhp_exit(cpu, st->state, state, ret);
if (ret)
goto err;
cnt++;
}
return 0;
err:
/* Rollback the instances if one failed */
cbm = !bringup ? step->startup.multi : step->teardown.multi;
if (!cbm)
return ret;

hlist_for_each(node, &step->list) {
if (!cnt--)
break;
cbm(cpu, node);
}
return ret;
}

#ifdef CONFIG_SMP
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);
bool cpuhp_tasks_frozen;
EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen);

/*
 * The following two APIs (cpu_maps_update_begin/done) must be used when
 * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
 */
void cpu_maps_update_begin(void)
{
mutex_lock(&cpu_add_remove_lock);
}

void cpu_maps_update_done(void)
{
mutex_unlock(&cpu_add_remove_lock);
}

/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
 * Should always be manipulated under cpu_add_remove_lock
 */
static int cpu_hotplug_disabled;

#ifdef CONFIG_HOTPLUG_CPU

static struct {
struct task_struct *active_writer;
/* wait queue to wake up the active_writer */
wait_queue_head_t wq;
/* verifies that no writer will get active while readers are active */
struct mutex lock;
/*
* Also blocks the new readers during
* an ongoing cpu hotplug operation.
*/
atomic_t refcount;

#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
} cpu_hotplug = {
.active_writer = NULL,
.wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq),
.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
#ifdef CONFIG_DEBUG_LOCK_ALLOC
.dep_map = STATIC_LOCKDEP_MAP_INIT("cpu_hotplug.dep_map", &cpu_hotplug.dep_map),
#endif
};

/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
#define cpuhp_lock_acquire_tryread() \
  lock_map_acquire_tryread(&cpu_hotplug.dep_map)
#define cpuhp_lock_acquire()      lock_map_acquire(&cpu_hotplug.dep_map)
#define cpuhp_lock_release()      lock_map_release(&cpu_hotplug.dep_map)


void get_online_cpus(void)
{
might_sleep();
if (cpu_hotplug.active_writer == current)
return;
cpuhp_lock_acquire_read();
mutex_lock(&cpu_hotplug.lock);
atomic_inc(&cpu_hotplug.refcount);
mutex_unlock(&cpu_hotplug.lock);
}
EXPORT_SYMBOL_GPL(get_online_cpus);

void put_online_cpus(void)
{
int refcount;

if (cpu_hotplug.active_writer == current)
return;

refcount = atomic_dec_return(&cpu_hotplug.refcount);
if (WARN_ON(refcount < 0)) /* try to fix things up */
atomic_inc(&cpu_hotplug.refcount);

if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq))
wake_up(&cpu_hotplug.wq);

cpuhp_lock_release();

}
EXPORT_SYMBOL_GPL(put_online_cpus);

/*
 * This ensures that the hotplug operation can begin only when the
 * refcount goes to zero.
 *
 * Note that during a cpu-hotplug operation, the new readers, if any,
 * will be blocked by the cpu_hotplug.lock
 *
 * Since cpu_hotplug_begin() is always called after invoking
 * cpu_maps_update_begin(), we can be sure that only one writer is active.
 *
 * Note that theoretically, there is a possibility of a livelock:
 * - Refcount goes to zero, last reader wakes up the sleeping
 *   writer.
 * - Last reader unlocks the cpu_hotplug.lock.
 * - A new reader arrives at this moment, bumps up the refcount.
 * - The writer acquires the cpu_hotplug.lock finds the refcount
 *   non zero and goes to sleep again.
 *
 * However, this is very difficult to achieve in practice since
 * get_online_cpus() not an api which is called all that often.
 *
 */
void cpu_hotplug_begin(void)
{
DEFINE_WAIT(wait);

cpu_hotplug.active_writer = current;
cpuhp_lock_acquire();

for (;;) {
mutex_lock(&cpu_hotplug.lock);
prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE);
if (likely(!atomic_read(&cpu_hotplug.refcount)))
break;
mutex_unlock(&cpu_hotplug.lock);
schedule();
}
finish_wait(&cpu_hotplug.wq, &wait);
}

void cpu_hotplug_done(void)
{
cpu_hotplug.active_writer = NULL;
mutex_unlock(&cpu_hotplug.lock);
cpuhp_lock_release();
}

/*
 * Wait for currently running CPU hotplug operations to complete (if any) and
 * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
 * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
 * hotplug path before performing hotplug operations. So acquiring that lock
 * guarantees mutual exclusion from any currently running hotplug operations.
 */
void cpu_hotplug_disable(void)
{
cpu_maps_update_begin();
cpu_hotplug_disabled++;
cpu_maps_update_done();
}
EXPORT_SYMBOL_GPL(cpu_hotplug_disable);

static void __cpu_hotplug_enable(void)
{
if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
return;
cpu_hotplug_disabled--;
}

void cpu_hotplug_enable(void)
{
cpu_maps_update_begin();
__cpu_hotplug_enable();
cpu_maps_update_done();
}
EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
#endif /* CONFIG_HOTPLUG_CPU */

/* Notifier wrappers for transitioning to state machine */

static int bringup_wait_for_ap(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

wait_for_completion(&st->done);
return st->result;
}

static int bringup_cpu(unsigned int cpu)
{
struct task_struct *idle = idle_thread_get(cpu);
int ret;

/*
* Some architectures have to walk the irq descriptors to
* setup the vector space for the cpu which comes online.
* Prevent irq alloc/free across the bringup.
*/
irq_lock_sparse();

/* Arch-specific enabling code. */
ret = __cpu_up(cpu, idle);
irq_unlock_sparse();
if (ret)
return ret;
ret = bringup_wait_for_ap(cpu);
BUG_ON(!cpu_online(cpu));
return ret;
}

/*
 * Hotplug state machine related functions
 */
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_get_step(st->state);

if (!step->skip_onerr)
cpuhp_invoke_callback(cpu, st->state, true, NULL);
}
}

static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
enum cpuhp_state target)
{
enum cpuhp_state prev_state = st->state;
int ret = 0;

for (; st->state > target; st->state--) {
ret = cpuhp_invoke_callback(cpu, st->state, false, NULL);
if (ret) {
st->target = prev_state;
undo_cpu_down(cpu, st);
break;
}
}
return ret;
}

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_get_step(st->state);

if (!step->skip_onerr)
cpuhp_invoke_callback(cpu, st->state, false, NULL);
}
}

static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
      enum cpuhp_state target)
{
enum cpuhp_state prev_state = st->state;
int ret = 0;

while (st->state < target) {
st->state++;
ret = cpuhp_invoke_callback(cpu, st->state, true, NULL);
if (ret) {
st->target = prev_state;
undo_cpu_up(cpu, st);
break;
}
}
return ret;
}

/*
 * The cpu hotplug threads manage the bringup and teardown of the cpus
 */
static void cpuhp_create(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

init_completion(&st->done);
}

static int cpuhp_should_run(unsigned int cpu)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);

return st->should_run;
}

/* Execute the teardown callbacks. Used to be CPU_DOWN_PREPARE */
static int cpuhp_ap_offline(unsigned int cpu, struct cpuhp_cpu_state *st)
{
enum cpuhp_state target = max((int)st->target, CPUHP_TEARDOWN_CPU);

return cpuhp_down_callbacks(cpu, st, target);
}

/* Execute the online startup callbacks. Used to be CPU_ONLINE */
static int cpuhp_ap_online(unsigned int cpu, struct cpuhp_cpu_state *st)
{
return cpuhp_up_callbacks(cpu, st, st->target);
}

/*
 * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke
 * callbacks when a state gets [un]installed at runtime.
 */
static void cpuhp_thread_fun(unsigned int cpu)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
int ret = 0;

/*
* Paired with the mb() in cpuhp_kick_ap_work and
* cpuhp_invoke_ap_callback, so the work set is consistent visible.
*/
smp_mb();
if (!st->should_run)
return;

st->should_run = false;

/* Single callback invocation for [un]install ? */
if (st->single) {
if (st->cb_state < CPUHP_AP_ONLINE) {
local_irq_disable();
ret = cpuhp_invoke_callback(cpu, st->cb_state,
    st->bringup, st->node);
local_irq_enable();
} else {
ret = cpuhp_invoke_callback(cpu, st->cb_state,
    st->bringup, st->node);
}
} else if (st->rollback) {
BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE);

undo_cpu_down(cpu, st);
st->rollback = false;
} else {
/* Cannot happen .... */
BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE);

/* Regular hotplug work */
if (st->state < st->target)
ret = cpuhp_ap_online(cpu, st);
else if (st->state > st->target)
ret = cpuhp_ap_offline(cpu, st);
}
st->result = ret;
complete(&st->done);
}

/* Invoke a single callback on a remote cpu */
static int
cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup,
struct hlist_node *node)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

if (!cpu_online(cpu))
return 0;

/*
* If we are up and running, use the hotplug thread. For early calls
* we invoke the thread function directly.
*/
if (!st->thread)
return cpuhp_invoke_callback(cpu, state, bringup, node);

st->cb_state = state;
st->single = true;
st->bringup = bringup;
st->node = node;

/*
* Make sure the above stores are visible before should_run becomes
* true. Paired with the mb() above in cpuhp_thread_fun()
*/
smp_mb();
st->should_run = true;
wake_up_process(st->thread);
wait_for_completion(&st->done);
return st->result;
}

/* Regular hotplug invocation of the AP hotplug thread */
static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state *st)
{
st->result = 0;
st->single = false;
/*
* Make sure the above stores are visible before should_run becomes
* true. Paired with the mb() above in cpuhp_thread_fun()
*/
smp_mb();
st->should_run = true;
wake_up_process(st->thread);
}

static int cpuhp_kick_ap_work(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
enum cpuhp_state state = st->state;

trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work);
__cpuhp_kick_ap_work(st);
wait_for_completion(&st->done);
trace_cpuhp_exit(cpu, st->state, state, st->result);
return st->result;
}

static struct smp_hotplug_thread cpuhp_threads = {
.store = &cpuhp_state.thread,
.create = &cpuhp_create,
.thread_should_run = cpuhp_should_run,
.thread_fn = cpuhp_thread_fun,
.thread_comm = "cpuhp/%u",
.selfparking = true,
};

void __init cpuhp_threads_init(void)
{
BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));
kthread_unpark(this_cpu_read(cpuhp_state.thread));
}

#ifdef CONFIG_HOTPLUG_CPU
/**
 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
 * @cpu: a CPU id
 *
 * This function walks all processes, finds a valid mm struct for each one and
 * then clears a corresponding bit in mm's cpumask.  While this all sounds
 * trivial, there are various non-obvious corner cases, which this function
 * tries to solve in a safe manner.
 *
 * Also note that the function uses a somewhat relaxed locking scheme, so it may
 * be called only for an already offlined CPU.
 */
void clear_tasks_mm_cpumask(int cpu)
{
struct task_struct *p;

/*
* This function is called after the cpu is taken down and marked
* offline, so its not like new tasks will ever get this cpu set in
* their mm mask. -- Peter Zijlstra
* Thus, we may use rcu_read_lock() here, instead of grabbing
* full-fledged tasklist_lock.
*/
WARN_ON(cpu_online(cpu));
rcu_read_lock();
for_each_process(p) {
struct task_struct *t;

/*
* Main thread might exit, but other threads may still have
* a valid mm. Find one.
*/
t = find_lock_task_mm(p);
if (!t)
continue;
cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
task_unlock(t);
}
rcu_read_unlock();
}

static inline void check_for_tasks(int dead_cpu)
{
struct task_struct *g, *p;

read_lock(&tasklist_lock);
for_each_process_thread(g, p) {
if (!p->on_rq)
continue;
/*
* We do the check with unlocked task_rq(p)->lock.
* Order the reading to do not warn about a task,
* which was running on this cpu in the past, and
* it's just been woken on another cpu.
*/
rmb();
if (task_cpu(p) != dead_cpu)
continue;

pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
}
read_unlock(&tasklist_lock);
}

/* Take this CPU down. */
static int take_cpu_down(void *_param)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
int err, cpu = smp_processor_id();

/* Ensure this CPU doesn't handle any more interrupts. */
err = __cpu_disable();
if (err < 0)
return err;

/*
* We get here while we are in CPUHP_TEARDOWN_CPU state and we must not
* do this step again.
*/
WARN_ON(st->state != CPUHP_TEARDOWN_CPU);
st->state--;
/* Invoke the former CPU_DYING callbacks */
for (; st->state > target; st->state--)
cpuhp_invoke_callback(cpu, st->state, false, NULL);

/* Give up timekeeping duties */
tick_handover_do_timer();
/* Park the stopper thread */
stop_machine_park(cpu);
return 0;
}

static int takedown_cpu(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int err;

/* Park the smpboot threads */
kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
smpboot_park_threads(cpu);

/*
* Prevent irq alloc/free while the dying cpu reorganizes the
* interrupt affinities.
*/
irq_lock_sparse();

/*
* So now all preempt/rcu users must observe !cpu_active().
*/
err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
if (err) {
/* CPU refused to die */
irq_unlock_sparse();
/* Unpark the hotplug thread so we can rollback there */
kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread);
return err;
}
BUG_ON(cpu_online(cpu));

/*
* The CPUHP_AP_SCHED_MIGRATE_DYING callback will have removed all
* runnable tasks from the cpu, there's only the idle task left now
* that the migration thread is done doing the stop_machine thing.
*
* Wait for the stop thread to go away.
*/
wait_for_completion(&st->done);
BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);

/* Interrupts are moved away from the dying cpu, reenable alloc/free */
irq_unlock_sparse();

hotplug_cpu__broadcast_tick_pull(cpu);
/* This actually kills the CPU. */
__cpu_die(cpu);

tick_cleanup_dead_cpu(cpu);
return 0;
}

static void cpuhp_complete_idle_dead(void *arg)
{
struct cpuhp_cpu_state *st = arg;

complete(&st->done);
}

void cpuhp_report_idle_dead(void)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);

BUG_ON(st->state != CPUHP_AP_OFFLINE);
rcu_report_dead(smp_processor_id());
st->state = CPUHP_AP_IDLE_DEAD;
/*
* We cannot call complete after rcu_report_dead() so we delegate it
* to an online cpu.
*/
smp_call_function_single(cpumask_first(cpu_online_mask),
cpuhp_complete_idle_dead, st, 0);
}

#else
#define takedown_cpu NULL
#endif

#ifdef CONFIG_HOTPLUG_CPU

/* Requires cpu_add_remove_lock to be held */
static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
   enum cpuhp_state target)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int prev_state, ret = 0;

if (num_online_cpus() == 1)
return -EBUSY;

if (!cpu_present(cpu))
return -EINVAL;

cpu_hotplug_begin();

cpuhp_tasks_frozen = tasks_frozen;

prev_state = st->state;
st->target = target;
/*
* If the current CPU state is in the range of the AP hotplug thread,
* then we need to kick the thread.
*/
if (st->state > CPUHP_TEARDOWN_CPU) {
ret = cpuhp_kick_ap_work(cpu);
/*
* The AP side has done the error rollback already. Just
* return the error code..
*/
if (ret)
goto out;

/*
* We might have stopped still in the range of the AP hotplug
* thread. Nothing to do anymore.
*/
if (st->state > CPUHP_TEARDOWN_CPU)
goto out;
}
/*
* The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
* to do the further cleanups.
*/
ret = cpuhp_down_callbacks(cpu, st, target);
if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {
st->target = prev_state;
st->rollback = true;
cpuhp_kick_ap_work(cpu);
}

out:
cpu_hotplug_done();
return ret;
}

static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
{
int err;

cpu_maps_update_begin();

if (cpu_hotplug_disabled) {
err = -EBUSY;
goto out;
}

err = _cpu_down(cpu, 0, target);

out:
cpu_maps_update_done();
return err;
}
int cpu_down(unsigned int cpu)
{
return do_cpu_down(cpu, CPUHP_OFFLINE);
}
EXPORT_SYMBOL(cpu_down);
#endif /*CONFIG_HOTPLUG_CPU*/

/**
 * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU
 * @cpu: cpu that just started
 *
 * It must be called by the arch code on the new cpu, before the new cpu
 * enables interrupts and before the "boot" cpu returns from __cpu_up().
 */
void notify_cpu_starting(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);

rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */
while (st->state < target) {
st->state++;
cpuhp_invoke_callback(cpu, st->state, true, NULL);
}
}

/*
 * Called from the idle task. We need to set active here, so we can kick off
 * the stopper thread and unpark the smpboot threads. If the target state is
 * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the
 * cpu further.
 */
void cpuhp_online_idle(enum cpuhp_state state)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
unsigned int cpu = smp_processor_id();

/* Happens for the boot cpu */
if (state != CPUHP_AP_ONLINE_IDLE)
return;

st->state = CPUHP_AP_ONLINE_IDLE;

/* Unpark the stopper thread and the hotplug thread of this cpu */
stop_machine_unpark(cpu);
kthread_unpark(st->thread);

/* Should we go further up ? */
if (st->target > CPUHP_AP_ONLINE_IDLE)
__cpuhp_kick_ap_work(st);
else
complete(&st->done);
}

/* Requires cpu_add_remove_lock to be held */
static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
struct task_struct *idle;
int ret = 0;

cpu_hotplug_begin();

if (!cpu_present(cpu)) {
ret = -EINVAL;
goto out;
}

/*
* The caller of do_cpu_up might have raced with another
* caller. Ignore it for now.
*/
if (st->state >= target)
goto out;

if (st->state == CPUHP_OFFLINE) {
/* Let it fail before we try to bring the cpu up */
idle = idle_thread_get(cpu);
if (IS_ERR(idle)) {
ret = PTR_ERR(idle);
goto out;
}
}

cpuhp_tasks_frozen = tasks_frozen;

st->target = target;
/*
* If the current CPU state is in the range of the AP hotplug thread,
* then we need to kick the thread once more.
*/
if (st->state > CPUHP_BRINGUP_CPU) {
ret = cpuhp_kick_ap_work(cpu);
/*
* The AP side has done the error rollback already. Just
* return the error code..
*/
if (ret)
goto out;
}

/*
* Try to reach the target state. We max out on the BP at
* CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
* responsible for bringing it up to the target state.
*/
target = min((int)target, CPUHP_BRINGUP_CPU);
ret = cpuhp_up_callbacks(cpu, st, target);
out:
cpu_hotplug_done();
return ret;
}

static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
{
int err = 0;

if (!cpu_possible(cpu)) {
pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
       cpu);
#if defined(CONFIG_IA64)
pr_err("please check additional_cpus= boot parameter\n");
#endif
return -EINVAL;
}

err = try_online_node(cpu_to_node(cpu));
if (err)
return err;

cpu_maps_update_begin();

if (cpu_hotplug_disabled) {
err = -EBUSY;
goto out;
}

err = _cpu_up(cpu, 0, target);
out:
cpu_maps_update_done();
return err;
}

int cpu_up(unsigned int cpu)
{
return do_cpu_up(cpu, CPUHP_ONLINE);
}
EXPORT_SYMBOL_GPL(cpu_up);

#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;

int freeze_secondary_cpus(int primary)
{
int cpu, error = 0;

cpu_maps_update_begin();
if (!cpu_online(primary))
primary = cpumask_first(cpu_online_mask);
/*
* We take down all of the non-boot CPUs in one shot to avoid races
* with the userspace trying to use the CPU hotplug at the same time
*/
cpumask_clear(frozen_cpus);

pr_info("Disabling non-boot CPUs ...\n");
for_each_online_cpu(cpu) {
if (cpu == primary)
continue;
trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
if (!error)
cpumask_set_cpu(cpu, frozen_cpus);
else {
pr_err("Error taking CPU%d down: %d\n", cpu, error);
break;
}
}

if (!error)
BUG_ON(num_online_cpus() > 1);
else
pr_err("Non-boot CPUs are not disabled\n");

/*
* Make sure the CPUs won't be enabled by someone else. We need to do
* this even in case of failure as all disable_nonboot_cpus() users are
* supposed to do enable_nonboot_cpus() on the failure path.
*/
cpu_hotplug_disabled++;

cpu_maps_update_done();
return error;
}

void __weak arch_enable_nonboot_cpus_begin(void)
{
}

void __weak arch_enable_nonboot_cpus_end(void)
{
}

void enable_nonboot_cpus(void)
{
int cpu, error;

/* Allow everyone to use the CPU hotplug again */
cpu_maps_update_begin();
__cpu_hotplug_enable();
if (cpumask_empty(frozen_cpus))
goto out;

pr_info("Enabling non-boot CPUs ...\n");

arch_enable_nonboot_cpus_begin();

for_each_cpu(cpu, frozen_cpus) {
trace_suspend_resume(TPS("CPU_ON"), cpu, true);
error = _cpu_up(cpu, 1, CPUHP_ONLINE);
trace_suspend_resume(TPS("CPU_ON"), cpu, false);
if (!error) {
pr_info("CPU%d is up\n", cpu);
continue;
}
pr_warn("Error taking CPU%d up: %d\n", cpu, error);
}

arch_enable_nonboot_cpus_end();

cpumask_clear(frozen_cpus);
out:
cpu_maps_update_done();
}

static int __init alloc_frozen_cpus(void)
{
if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
return -ENOMEM;
return 0;
}
core_initcall(alloc_frozen_cpus);

/*
 * When callbacks for CPU hotplug notifications are being executed, we must
 * ensure that the state of the system with respect to the tasks being frozen
 * or not, as reported by the notification, remains unchanged *throughout the
 * duration* of the execution of the callbacks.
 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 *
 * This synchronization is implemented by mutually excluding regular CPU
 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 * Hibernate notifications.
 */
static int
cpu_hotplug_pm_callback(struct notifier_block *nb,
unsigned long action, void *ptr)
{
switch (action) {

case PM_SUSPEND_PREPARE:
case PM_HIBERNATION_PREPARE:
cpu_hotplug_disable();
break;

case PM_POST_SUSPEND:
case PM_POST_HIBERNATION:
cpu_hotplug_enable();
break;

default:
return NOTIFY_DONE;
}

return NOTIFY_OK;
}


static int __init cpu_hotplug_pm_sync_init(void)
{
/*
* cpu_hotplug_pm_callback has higher priority than x86
* bsp_pm_callback which depends on cpu_hotplug_pm_callback
* to disable cpu hotplug to avoid cpu hotplug race.
*/
pm_notifier(cpu_hotplug_pm_callback, 0);
return 0;
}
core_initcall(cpu_hotplug_pm_sync_init);

#endif /* CONFIG_PM_SLEEP_SMP */

int __boot_cpu_id;

#endif /* CONFIG_SMP */

/* Boot processor state steps */
static struct cpuhp_step cpuhp_bp_states[] = {
[CPUHP_OFFLINE] = {
.name = "offline",
.startup.single = NULL,
.teardown.single = NULL,
},
#ifdef CONFIG_SMP
[CPUHP_CREATE_THREADS]= {
.name = "threads:prepare",
.startup.single = smpboot_create_threads,
.teardown.single = NULL,
.cant_stop = true,
},
[CPUHP_PERF_PREPARE] = {
.name = "perf:prepare",
.startup.single = perf_event_init_cpu,
.teardown.single = perf_event_exit_cpu,
},
[CPUHP_WORKQUEUE_PREP] = {
.name = "workqueue:prepare",
.startup.single = workqueue_prepare_cpu,
.teardown.single = NULL,
},
[CPUHP_HRTIMERS_PREPARE] = {
.name = "hrtimers:prepare",
.startup.single = hrtimers_prepare_cpu,
.teardown.single = hrtimers_dead_cpu,
},
[CPUHP_SMPCFD_PREPARE] = {
.name = "smpcfd:prepare",
.startup.single = smpcfd_prepare_cpu,
.teardown.single = smpcfd_dead_cpu,
},
[CPUHP_RELAY_PREPARE] = {
.name = "relay:prepare",
.startup.single = relay_prepare_cpu,
.teardown.single = NULL,
},
[CPUHP_SLAB_PREPARE] = {
.name = "slab:prepare",
.startup.single = slab_prepare_cpu,
.teardown.single = slab_dead_cpu,
},
[CPUHP_RCUTREE_PREP] = {
.name = "RCU/tree:prepare",
.startup.single = rcutree_prepare_cpu,
.teardown.single = rcutree_dead_cpu,
},
/*
* On the tear-down path, timers_dead_cpu() must be invoked
* before blk_mq_queue_reinit_notify() from notify_dead(),
* otherwise a RCU stall occurs.
*/
[CPUHP_TIMERS_DEAD] = {
.name = "timers:dead",
.startup.single = NULL,
.teardown.single = timers_dead_cpu,
},
/* Kicks the plugged cpu into life */
[CPUHP_BRINGUP_CPU] = {
.name = "cpu:bringup",
.startup.single = bringup_cpu,
.teardown.single = NULL,
.cant_stop = true,
},
[CPUHP_AP_SMPCFD_DYING] = {
.name = "smpcfd:dying",
.startup.single = NULL,
.teardown.single = smpcfd_dying_cpu,
},
/*
* Handled on controll processor until the plugged processor manages
* this itself.
*/
[CPUHP_TEARDOWN_CPU] = {
.name = "cpu:teardown",
.startup.single = NULL,
.teardown.single = takedown_cpu,
.cant_stop = true,
},
#else
[CPUHP_BRINGUP_CPU] = { },
#endif
};

/* 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,
},
/* First state is scheduler control. Interrupts are disabled */
[CPUHP_AP_SCHED_STARTING] = {
.name = "sched:starting",
.startup.single = sched_cpu_starting,
.teardown.single = sched_cpu_dying,
},
[CPUHP_AP_RCUTREE_DYING] = {
.name = "RCU/tree:dying",
.startup.single = NULL,
.teardown.single = rcutree_dying_cpu,
},
/* 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:online",
.startup.single = smpboot_unpark_threads,
.teardown.single = NULL,
},
[CPUHP_AP_PERF_ONLINE] = {
.name = "perf:online",
.startup.single = perf_event_init_cpu,
.teardown.single = perf_event_exit_cpu,
},
[CPUHP_AP_WORKQUEUE_ONLINE] = {
.name = "workqueue:online",
.startup.single = workqueue_online_cpu,
.teardown.single = workqueue_offline_cpu,
},
[CPUHP_AP_RCUTREE_ONLINE] = {
.name = "RCU/tree:online",
.startup.single = rcutree_online_cpu,
.teardown.single = rcutree_offline_cpu,
},
#endif
/*
* The dynamically registered state space is here
*/

#ifdef CONFIG_SMP
/* Last state is scheduler control setting the cpu active */
[CPUHP_AP_ACTIVE] = {
.name = "sched:active",
.startup.single = sched_cpu_activate,
.teardown.single = sched_cpu_deactivate,
},
#endif

/* CPU is fully up and running. */
[CPUHP_ONLINE] = {
.name = "online",
.startup.single = NULL,
.teardown.single = NULL,
},
};

/* Sanity check for callbacks */
static int cpuhp_cb_check(enum cpuhp_state state)
{
if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
return -EINVAL;
return 0;
}

/*
 * Returns a free for dynamic slot assignment of the Online state. The states
 * are protected by the cpuhp_slot_states mutex and an empty slot is identified
 * by having no name assigned.
 */
static int cpuhp_reserve_state(enum cpuhp_state state)
{
enum cpuhp_state i, end;
struct cpuhp_step *step;

switch (state) {
case CPUHP_AP_ONLINE_DYN:
step = cpuhp_ap_states + CPUHP_AP_ONLINE_DYN;
end = CPUHP_AP_ONLINE_DYN_END;
break;
case CPUHP_BP_PREPARE_DYN:
step = cpuhp_bp_states + CPUHP_BP_PREPARE_DYN;
end = CPUHP_BP_PREPARE_DYN_END;
break;
default:
return -EINVAL;
}

for (i = state; i <= end; i++, step++) {
if (!step->name)
return i;
}
WARN(1, "No more dynamic states available for CPU hotplug\n");
return -ENOSPC;
}

static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name,
int (*startup)(unsigned int cpu),
int (*teardown)(unsigned int cpu),
bool multi_instance)
{
/* (Un)Install the callbacks for further cpu hotplug operations */
struct cpuhp_step *sp;
int ret = 0;

if (state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN) {
ret = cpuhp_reserve_state(state);
if (ret < 0)
return ret;
state = ret;
}
sp = cpuhp_get_step(state);
if (name && sp->name)
return -EBUSY;

sp->startup.single = startup;
sp->teardown.single = teardown;
sp->name = name;
sp->multi_instance = multi_instance;
INIT_HLIST_HEAD(&sp->list);
return ret;
}

static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
{
return cpuhp_get_step(state)->teardown.single;
}

/*
 * Call the startup/teardown function for a step either on the AP or
 * on the current CPU.
 */
static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup,
    struct hlist_node *node)
{
struct cpuhp_step *sp = cpuhp_get_step(state);
int ret;

if ((bringup && !sp->startup.single) ||
    (!bringup && !sp->teardown.single))
return 0;
/*
* The non AP bound callbacks can fail on bringup. On teardown
* e.g. module removal we crash for now.
*/
#ifdef CONFIG_SMP
if (cpuhp_is_ap_state(state))
ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node);
else
ret = cpuhp_invoke_callback(cpu, state, bringup, node);
#else
ret = cpuhp_invoke_callback(cpu, state, bringup, node);
#endif
BUG_ON(ret && !bringup);
return ret;
}

/*
 * Called from __cpuhp_setup_state on a recoverable failure.
 *
 * Note: The teardown callbacks for rollback are not allowed to fail!
 */
static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
   struct hlist_node *node)
{
int cpu;

/* Roll back the already executed steps on the other cpus */
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpu >= failedcpu)
break;

/* Did we invoke the startup call on that cpu ? */
if (cpustate >= state)
cpuhp_issue_call(cpu, state, false, node);
}
}

int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
       bool invoke)
{
struct cpuhp_step *sp;
int cpu;
int ret;

sp = cpuhp_get_step(state);
if (sp->multi_instance == false)
return -EINVAL;

get_online_cpus();
mutex_lock(&cpuhp_state_mutex);

if (!invoke || !sp->startup.multi)
goto add_node;

/*
* Try to call the startup callback for each present cpu
* depending on the hotplug state of the cpu.
*/
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpustate < state)
continue;

ret = cpuhp_issue_call(cpu, state, true, node);
if (ret) {
if (sp->teardown.multi)
cpuhp_rollback_install(cpu, state, node);
goto unlock;
}
}
add_node:
ret = 0;
hlist_add_head(node, &sp->list);
unlock:
mutex_unlock(&cpuhp_state_mutex);
put_online_cpus();
return ret;
}
EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);

/**
 * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
 * @state: The state to setup
 * @invoke: If true, the startup function is invoked for cpus where
 * cpu state >= @state
 * @startup: startup callback function
 * @teardown: teardown callback function
 * @multi_instance: State is set up for multiple instances which get
 * added afterwards.
 *
 * Returns:
 *   On success:
 *      Positive state number if @state is CPUHP_AP_ONLINE_DYN
 *      0 for all other states
 *   On failure: proper (negative) error code
 */
int __cpuhp_setup_state(enum cpuhp_state state,
const char *name, bool invoke,
int (*startup)(unsigned int cpu),
int (*teardown)(unsigned int cpu),
bool multi_instance)
{
int cpu, ret = 0;
bool dynstate;

if (cpuhp_cb_check(state) || !name)
return -EINVAL;

get_online_cpus();
mutex_lock(&cpuhp_state_mutex);

ret = cpuhp_store_callbacks(state, name, startup, teardown,
    multi_instance);

dynstate = state == CPUHP_AP_ONLINE_DYN;
if (ret > 0 && dynstate) {
state = ret;
ret = 0;
}

if (ret || !invoke || !startup)
goto out;

/*
* Try to call the startup callback for each present cpu
* depending on the hotplug state of the cpu.
*/
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpustate < state)
continue;

ret = cpuhp_issue_call(cpu, state, true, NULL);
if (ret) {
if (teardown)
cpuhp_rollback_install(cpu, state, NULL);
cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
goto out;
}
}
out:
mutex_unlock(&cpuhp_state_mutex);
put_online_cpus();
/*
* If the requested state is CPUHP_AP_ONLINE_DYN, return the
* dynamically allocated state in case of success.
*/
if (!ret && dynstate)
return state;
return ret;
}
EXPORT_SYMBOL(__cpuhp_setup_state);

int __cpuhp_state_remove_instance(enum cpuhp_state state,
  struct hlist_node *node, bool invoke)
{
struct cpuhp_step *sp = cpuhp_get_step(state);
int cpu;

BUG_ON(cpuhp_cb_check(state));

if (!sp->multi_instance)
return -EINVAL;

get_online_cpus();
mutex_lock(&cpuhp_state_mutex);

if (!invoke || !cpuhp_get_teardown_cb(state))
goto remove;
/*
* Call the teardown callback for each present cpu depending
* on the hotplug state of the cpu. This function is not
* allowed to fail currently!
*/
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpustate >= state)
cpuhp_issue_call(cpu, state, false, node);
}

remove:
hlist_del(node);
mutex_unlock(&cpuhp_state_mutex);
put_online_cpus();

return 0;
}
EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);

/**
 * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state
 * @state: The state to remove
 * @invoke: If true, the teardown function is invoked for cpus where
 * cpu state >= @state
 *
 * The teardown callback is currently not allowed to fail. Think
 * about module removal!
 */
void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
{
struct cpuhp_step *sp = cpuhp_get_step(state);
int cpu;

BUG_ON(cpuhp_cb_check(state));

get_online_cpus();

mutex_lock(&cpuhp_state_mutex);
if (sp->multi_instance) {
WARN(!hlist_empty(&sp->list),
     "Error: Removing state %d which has instances left.\n",
     state);
goto remove;
}

if (!invoke || !cpuhp_get_teardown_cb(state))
goto remove;

/*
* Call the teardown callback for each present cpu depending
* on the hotplug state of the cpu. This function is not
* allowed to fail currently!
*/
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpustate >= state)
cpuhp_issue_call(cpu, state, false, NULL);
}
remove:
cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
mutex_unlock(&cpuhp_state_mutex);
put_online_cpus();
}
EXPORT_SYMBOL(__cpuhp_remove_state);

#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
static ssize_t show_cpuhp_state(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);

return sprintf(buf, "%d\n", st->state);
}
static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);

static ssize_t write_cpuhp_target(struct device *dev,
  struct device_attribute *attr,
  const char *buf, size_t count)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
struct cpuhp_step *sp;
int target, ret;

ret = kstrtoint(buf, 10, &target);
if (ret)
return ret;

#ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
return -EINVAL;
#else
if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
return -EINVAL;
#endif

ret = lock_device_hotplug_sysfs();
if (ret)
return ret;

mutex_lock(&cpuhp_state_mutex);
sp = cpuhp_get_step(target);
ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
mutex_unlock(&cpuhp_state_mutex);
if (ret)
goto out;

if (st->state < target)
ret = do_cpu_up(dev->id, target);
else
ret = do_cpu_down(dev->id, target);
out:
unlock_device_hotplug();
return ret ? ret : count;
}

static ssize_t show_cpuhp_target(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);

return sprintf(buf, "%d\n", st->target);
}
static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);

static struct attribute *cpuhp_cpu_attrs[] = {
&dev_attr_state.attr,
&dev_attr_target.attr,
NULL
};

static struct attribute_group cpuhp_cpu_attr_group = {
.attrs = cpuhp_cpu_attrs,
.name = "hotplug",
NULL
};

static ssize_t show_cpuhp_states(struct device *dev,
struct device_attribute *attr, char *buf)
{
ssize_t cur, res = 0;
int i;

mutex_lock(&cpuhp_state_mutex);
for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
struct cpuhp_step *sp = cpuhp_get_step(i);

if (sp->name) {
cur = sprintf(buf, "%3d: %s\n", i, sp->name);
buf += cur;
res += cur;
}
}
mutex_unlock(&cpuhp_state_mutex);
return res;
}
static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);

static struct attribute *cpuhp_cpu_root_attrs[] = {
&dev_attr_states.attr,
NULL
};

static struct attribute_group cpuhp_cpu_root_attr_group = {
.attrs = cpuhp_cpu_root_attrs,
.name = "hotplug",
NULL
};

static int __init cpuhp_sysfs_init(void)
{
int cpu, ret;

ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
&cpuhp_cpu_root_attr_group);
if (ret)
return ret;

for_each_possible_cpu(cpu) {
struct device *dev = get_cpu_device(cpu);

if (!dev)
continue;
ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
if (ret)
return ret;
}
return 0;
}
device_initcall(cpuhp_sysfs_init);
#endif

/*
 * cpu_bit_bitmap[] is a special, "compressed" data structure that
 * represents all NR_CPUS bits binary values of 1<<nr.
 *
 * It is used by cpumask_of() to get a constant address to a CPU
 * mask value that has a single bit set only.
 */

/* cpu_bit_bitmap[0] is empty - so we can back into it */
#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)

const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {

MASK_DECLARE_8(0), MASK_DECLARE_8(8),
MASK_DECLARE_8(16), MASK_DECLARE_8(24),
#if BITS_PER_LONG > 32
MASK_DECLARE_8(32), MASK_DECLARE_8(40),
MASK_DECLARE_8(48), MASK_DECLARE_8(56),
#endif
};
EXPORT_SYMBOL_GPL(cpu_bit_bitmap);

const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
EXPORT_SYMBOL(cpu_all_bits);

#ifdef CONFIG_INIT_ALL_POSSIBLE
struct cpumask __cpu_possible_mask __read_mostly
= {CPU_BITS_ALL};
#else
struct cpumask __cpu_possible_mask __read_mostly;
#endif
EXPORT_SYMBOL(__cpu_possible_mask);

struct cpumask __cpu_online_mask __read_mostly;
EXPORT_SYMBOL(__cpu_online_mask);

struct cpumask __cpu_present_mask __read_mostly;
EXPORT_SYMBOL(__cpu_present_mask);

struct cpumask __cpu_active_mask __read_mostly;
EXPORT_SYMBOL(__cpu_active_mask);

void init_cpu_present(const struct cpumask *src)
{
cpumask_copy(&__cpu_present_mask, src);
}

void init_cpu_possible(const struct cpumask *src)
{
cpumask_copy(&__cpu_possible_mask, src);
}

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);

#ifdef CONFIG_SMP
__boot_cpu_id = cpu;
#endif
}

/*
 * 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;
}

END OF FILE
fell free to ask questions or send me an email


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Offline kotu

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Re: Linux
« Reply #1 on: September 04, 2017, 02:22:03 am »
hello everyone long time no see
sorry for everything that happen but i have to start off new and fresh
so to start off i want to say my program name is linux as you can see
and i will be using the code that kotu gave to to me
Code: [Select]
/* CPU control.
 * (C) 2001, 2002, 2003, 2004 Rusty Russell
 *
 * This code is licenced under the GPL.
 */
#include <linux/proc_fs.h>
#include <linux/smp.h>
#include <linux/init.h>
#include <linux/notifier.h>
#include <linux/sched/signal.h>
#include <linux/sched/hotplug.h>
#include <linux/sched/task.h>
#include <linux/unistd.h>
#include <linux/cpu.h>
#include <linux/oom.h>
#include <linux/rcupdate.h>
#include <linux/export.h>
#include <linux/bug.h>
#include <linux/kthread.h>
#include <linux/stop_machine.h>
#include <linux/mutex.h>
#include <linux/gfp.h>
#include <linux/suspend.h>
#include <linux/lockdep.h>
#include <linux/tick.h>
#include <linux/irq.h>
#include <linux/smpboot.h>
#include <linux/relay.h>
#include <linux/slab.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
 * @thread: Pointer to the hotplug thread
 * @should_run: Thread should execute
 * @rollback: Perform a rollback
 * @single: Single callback invocation
 * @bringup: Single callback bringup or teardown selector
 * @cb_state: The state for a single callback (install/uninstall)
 * @result: Result of the operation
 * @done: Signal completion to the issuer of the task
 */
struct cpuhp_cpu_state {
enum cpuhp_state state;
enum cpuhp_state target;
#ifdef CONFIG_SMP
struct task_struct *thread;
bool should_run;
bool rollback;
bool single;
bool bringup;
struct hlist_node *node;
enum cpuhp_state cb_state;
int result;
struct completion done;
#endif
};

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
 * @cant_stop: Bringup/teardown can't be stopped at this step
 */
struct cpuhp_step {
const char *name;
union {
int (*single)(unsigned int cpu);
int (*multi)(unsigned int cpu,
struct hlist_node *node);
} startup;
union {
int (*single)(unsigned int cpu);
int (*multi)(unsigned int cpu,
struct hlist_node *node);
} teardown;
struct hlist_head list;
bool skip_onerr;
bool cant_stop;
bool multi_instance;
};

static DEFINE_MUTEX(cpuhp_state_mutex);
static struct cpuhp_step cpuhp_bp_states[];
static struct cpuhp_step cpuhp_ap_states[];

static bool cpuhp_is_ap_state(enum cpuhp_state state)
{
/*
* The extra check for CPUHP_TEARDOWN_CPU is only for documentation
* purposes as that state is handled explicitly in cpu_down.
*/
return state > CPUHP_BRINGUP_CPU && state != CPUHP_TEARDOWN_CPU;
}

static struct cpuhp_step *cpuhp_get_step(enum cpuhp_state state)
{
struct cpuhp_step *sp;

sp = cpuhp_is_ap_state(state) ? cpuhp_ap_states : cpuhp_bp_states;
return sp + state;
}

/**
 * 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
 * @bringup: True if the bringup callback should be invoked
 *
 * Called from cpu hotplug and from the state register machinery.
 */
static int cpuhp_invoke_callback(unsigned int cpu, enum cpuhp_state state,
bool bringup, struct hlist_node *node)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
struct cpuhp_step *step = cpuhp_get_step(state);
int (*cbm)(unsigned int cpu, struct hlist_node *node);
int (*cb)(unsigned int cpu);
int ret, cnt;

if (!step->multi_instance) {
cb = bringup ? step->startup.single : step->teardown.single;
if (!cb)
return 0;
trace_cpuhp_enter(cpu, st->target, state, cb);
ret = cb(cpu);
trace_cpuhp_exit(cpu, st->state, state, ret);
return ret;
}
cbm = bringup ? step->startup.multi : step->teardown.multi;
if (!cbm)
return 0;

/* Single invocation for instance add/remove */
if (node) {
trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
ret = cbm(cpu, node);
trace_cpuhp_exit(cpu, st->state, state, ret);
return ret;
}

/* State transition. Invoke on all instances */
cnt = 0;
hlist_for_each(node, &step->list) {
trace_cpuhp_multi_enter(cpu, st->target, state, cbm, node);
ret = cbm(cpu, node);
trace_cpuhp_exit(cpu, st->state, state, ret);
if (ret)
goto err;
cnt++;
}
return 0;
err:
/* Rollback the instances if one failed */
cbm = !bringup ? step->startup.multi : step->teardown.multi;
if (!cbm)
return ret;

hlist_for_each(node, &step->list) {
if (!cnt--)
break;
cbm(cpu, node);
}
return ret;
}

#ifdef CONFIG_SMP
/* Serializes the updates to cpu_online_mask, cpu_present_mask */
static DEFINE_MUTEX(cpu_add_remove_lock);
bool cpuhp_tasks_frozen;
EXPORT_SYMBOL_GPL(cpuhp_tasks_frozen);

/*
 * The following two APIs (cpu_maps_update_begin/done) must be used when
 * attempting to serialize the updates to cpu_online_mask & cpu_present_mask.
 */
void cpu_maps_update_begin(void)
{
mutex_lock(&cpu_add_remove_lock);
}

void cpu_maps_update_done(void)
{
mutex_unlock(&cpu_add_remove_lock);
}

/* If set, cpu_up and cpu_down will return -EBUSY and do nothing.
 * Should always be manipulated under cpu_add_remove_lock
 */
static int cpu_hotplug_disabled;

#ifdef CONFIG_HOTPLUG_CPU

static struct {
struct task_struct *active_writer;
/* wait queue to wake up the active_writer */
wait_queue_head_t wq;
/* verifies that no writer will get active while readers are active */
struct mutex lock;
/*
* Also blocks the new readers during
* an ongoing cpu hotplug operation.
*/
atomic_t refcount;

#ifdef CONFIG_DEBUG_LOCK_ALLOC
struct lockdep_map dep_map;
#endif
} cpu_hotplug = {
.active_writer = NULL,
.wq = __WAIT_QUEUE_HEAD_INITIALIZER(cpu_hotplug.wq),
.lock = __MUTEX_INITIALIZER(cpu_hotplug.lock),
#ifdef CONFIG_DEBUG_LOCK_ALLOC
.dep_map = STATIC_LOCKDEP_MAP_INIT("cpu_hotplug.dep_map", &cpu_hotplug.dep_map),
#endif
};

/* Lockdep annotations for get/put_online_cpus() and cpu_hotplug_begin/end() */
#define cpuhp_lock_acquire_read() lock_map_acquire_read(&cpu_hotplug.dep_map)
#define cpuhp_lock_acquire_tryread() \
  lock_map_acquire_tryread(&cpu_hotplug.dep_map)
#define cpuhp_lock_acquire()      lock_map_acquire(&cpu_hotplug.dep_map)
#define cpuhp_lock_release()      lock_map_release(&cpu_hotplug.dep_map)


void get_online_cpus(void)
{
might_sleep();
if (cpu_hotplug.active_writer == current)
return;
cpuhp_lock_acquire_read();
mutex_lock(&cpu_hotplug.lock);
atomic_inc(&cpu_hotplug.refcount);
mutex_unlock(&cpu_hotplug.lock);
}
EXPORT_SYMBOL_GPL(get_online_cpus);

void put_online_cpus(void)
{
int refcount;

if (cpu_hotplug.active_writer == current)
return;

refcount = atomic_dec_return(&cpu_hotplug.refcount);
if (WARN_ON(refcount < 0)) /* try to fix things up */
atomic_inc(&cpu_hotplug.refcount);

if (refcount <= 0 && waitqueue_active(&cpu_hotplug.wq))
wake_up(&cpu_hotplug.wq);

cpuhp_lock_release();

}
EXPORT_SYMBOL_GPL(put_online_cpus);

/*
 * This ensures that the hotplug operation can begin only when the
 * refcount goes to zero.
 *
 * Note that during a cpu-hotplug operation, the new readers, if any,
 * will be blocked by the cpu_hotplug.lock
 *
 * Since cpu_hotplug_begin() is always called after invoking
 * cpu_maps_update_begin(), we can be sure that only one writer is active.
 *
 * Note that theoretically, there is a possibility of a livelock:
 * - Refcount goes to zero, last reader wakes up the sleeping
 *   writer.
 * - Last reader unlocks the cpu_hotplug.lock.
 * - A new reader arrives at this moment, bumps up the refcount.
 * - The writer acquires the cpu_hotplug.lock finds the refcount
 *   non zero and goes to sleep again.
 *
 * However, this is very difficult to achieve in practice since
 * get_online_cpus() not an api which is called all that often.
 *
 */
void cpu_hotplug_begin(void)
{
DEFINE_WAIT(wait);

cpu_hotplug.active_writer = current;
cpuhp_lock_acquire();

for (;;) {
mutex_lock(&cpu_hotplug.lock);
prepare_to_wait(&cpu_hotplug.wq, &wait, TASK_UNINTERRUPTIBLE);
if (likely(!atomic_read(&cpu_hotplug.refcount)))
break;
mutex_unlock(&cpu_hotplug.lock);
schedule();
}
finish_wait(&cpu_hotplug.wq, &wait);
}

void cpu_hotplug_done(void)
{
cpu_hotplug.active_writer = NULL;
mutex_unlock(&cpu_hotplug.lock);
cpuhp_lock_release();
}

/*
 * Wait for currently running CPU hotplug operations to complete (if any) and
 * disable future CPU hotplug (from sysfs). The 'cpu_add_remove_lock' protects
 * the 'cpu_hotplug_disabled' flag. The same lock is also acquired by the
 * hotplug path before performing hotplug operations. So acquiring that lock
 * guarantees mutual exclusion from any currently running hotplug operations.
 */
void cpu_hotplug_disable(void)
{
cpu_maps_update_begin();
cpu_hotplug_disabled++;
cpu_maps_update_done();
}
EXPORT_SYMBOL_GPL(cpu_hotplug_disable);

static void __cpu_hotplug_enable(void)
{
if (WARN_ONCE(!cpu_hotplug_disabled, "Unbalanced cpu hotplug enable\n"))
return;
cpu_hotplug_disabled--;
}

void cpu_hotplug_enable(void)
{
cpu_maps_update_begin();
__cpu_hotplug_enable();
cpu_maps_update_done();
}
EXPORT_SYMBOL_GPL(cpu_hotplug_enable);
#endif /* CONFIG_HOTPLUG_CPU */

/* Notifier wrappers for transitioning to state machine */

static int bringup_wait_for_ap(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

wait_for_completion(&st->done);
return st->result;
}

static int bringup_cpu(unsigned int cpu)
{
struct task_struct *idle = idle_thread_get(cpu);
int ret;

/*
* Some architectures have to walk the irq descriptors to
* setup the vector space for the cpu which comes online.
* Prevent irq alloc/free across the bringup.
*/
irq_lock_sparse();

/* Arch-specific enabling code. */
ret = __cpu_up(cpu, idle);
irq_unlock_sparse();
if (ret)
return ret;
ret = bringup_wait_for_ap(cpu);
BUG_ON(!cpu_online(cpu));
return ret;
}

/*
 * Hotplug state machine related functions
 */
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_get_step(st->state);

if (!step->skip_onerr)
cpuhp_invoke_callback(cpu, st->state, true, NULL);
}
}

static int cpuhp_down_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
enum cpuhp_state target)
{
enum cpuhp_state prev_state = st->state;
int ret = 0;

for (; st->state > target; st->state--) {
ret = cpuhp_invoke_callback(cpu, st->state, false, NULL);
if (ret) {
st->target = prev_state;
undo_cpu_down(cpu, st);
break;
}
}
return ret;
}

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_get_step(st->state);

if (!step->skip_onerr)
cpuhp_invoke_callback(cpu, st->state, false, NULL);
}
}

static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st,
      enum cpuhp_state target)
{
enum cpuhp_state prev_state = st->state;
int ret = 0;

while (st->state < target) {
st->state++;
ret = cpuhp_invoke_callback(cpu, st->state, true, NULL);
if (ret) {
st->target = prev_state;
undo_cpu_up(cpu, st);
break;
}
}
return ret;
}

/*
 * The cpu hotplug threads manage the bringup and teardown of the cpus
 */
static void cpuhp_create(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

init_completion(&st->done);
}

static int cpuhp_should_run(unsigned int cpu)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);

return st->should_run;
}

/* Execute the teardown callbacks. Used to be CPU_DOWN_PREPARE */
static int cpuhp_ap_offline(unsigned int cpu, struct cpuhp_cpu_state *st)
{
enum cpuhp_state target = max((int)st->target, CPUHP_TEARDOWN_CPU);

return cpuhp_down_callbacks(cpu, st, target);
}

/* Execute the online startup callbacks. Used to be CPU_ONLINE */
static int cpuhp_ap_online(unsigned int cpu, struct cpuhp_cpu_state *st)
{
return cpuhp_up_callbacks(cpu, st, st->target);
}

/*
 * Execute teardown/startup callbacks on the plugged cpu. Also used to invoke
 * callbacks when a state gets [un]installed at runtime.
 */
static void cpuhp_thread_fun(unsigned int cpu)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
int ret = 0;

/*
* Paired with the mb() in cpuhp_kick_ap_work and
* cpuhp_invoke_ap_callback, so the work set is consistent visible.
*/
smp_mb();
if (!st->should_run)
return;

st->should_run = false;

/* Single callback invocation for [un]install ? */
if (st->single) {
if (st->cb_state < CPUHP_AP_ONLINE) {
local_irq_disable();
ret = cpuhp_invoke_callback(cpu, st->cb_state,
    st->bringup, st->node);
local_irq_enable();
} else {
ret = cpuhp_invoke_callback(cpu, st->cb_state,
    st->bringup, st->node);
}
} else if (st->rollback) {
BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE);

undo_cpu_down(cpu, st);
st->rollback = false;
} else {
/* Cannot happen .... */
BUG_ON(st->state < CPUHP_AP_ONLINE_IDLE);

/* Regular hotplug work */
if (st->state < st->target)
ret = cpuhp_ap_online(cpu, st);
else if (st->state > st->target)
ret = cpuhp_ap_offline(cpu, st);
}
st->result = ret;
complete(&st->done);
}

/* Invoke a single callback on a remote cpu */
static int
cpuhp_invoke_ap_callback(int cpu, enum cpuhp_state state, bool bringup,
struct hlist_node *node)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);

if (!cpu_online(cpu))
return 0;

/*
* If we are up and running, use the hotplug thread. For early calls
* we invoke the thread function directly.
*/
if (!st->thread)
return cpuhp_invoke_callback(cpu, state, bringup, node);

st->cb_state = state;
st->single = true;
st->bringup = bringup;
st->node = node;

/*
* Make sure the above stores are visible before should_run becomes
* true. Paired with the mb() above in cpuhp_thread_fun()
*/
smp_mb();
st->should_run = true;
wake_up_process(st->thread);
wait_for_completion(&st->done);
return st->result;
}

/* Regular hotplug invocation of the AP hotplug thread */
static void __cpuhp_kick_ap_work(struct cpuhp_cpu_state *st)
{
st->result = 0;
st->single = false;
/*
* Make sure the above stores are visible before should_run becomes
* true. Paired with the mb() above in cpuhp_thread_fun()
*/
smp_mb();
st->should_run = true;
wake_up_process(st->thread);
}

static int cpuhp_kick_ap_work(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
enum cpuhp_state state = st->state;

trace_cpuhp_enter(cpu, st->target, state, cpuhp_kick_ap_work);
__cpuhp_kick_ap_work(st);
wait_for_completion(&st->done);
trace_cpuhp_exit(cpu, st->state, state, st->result);
return st->result;
}

static struct smp_hotplug_thread cpuhp_threads = {
.store = &cpuhp_state.thread,
.create = &cpuhp_create,
.thread_should_run = cpuhp_should_run,
.thread_fn = cpuhp_thread_fun,
.thread_comm = "cpuhp/%u",
.selfparking = true,
};

void __init cpuhp_threads_init(void)
{
BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));
kthread_unpark(this_cpu_read(cpuhp_state.thread));
}

#ifdef CONFIG_HOTPLUG_CPU
/**
 * clear_tasks_mm_cpumask - Safely clear tasks' mm_cpumask for a CPU
 * @cpu: a CPU id
 *
 * This function walks all processes, finds a valid mm struct for each one and
 * then clears a corresponding bit in mm's cpumask.  While this all sounds
 * trivial, there are various non-obvious corner cases, which this function
 * tries to solve in a safe manner.
 *
 * Also note that the function uses a somewhat relaxed locking scheme, so it may
 * be called only for an already offlined CPU.
 */
void clear_tasks_mm_cpumask(int cpu)
{
struct task_struct *p;

/*
* This function is called after the cpu is taken down and marked
* offline, so its not like new tasks will ever get this cpu set in
* their mm mask. -- Peter Zijlstra
* Thus, we may use rcu_read_lock() here, instead of grabbing
* full-fledged tasklist_lock.
*/
WARN_ON(cpu_online(cpu));
rcu_read_lock();
for_each_process(p) {
struct task_struct *t;

/*
* Main thread might exit, but other threads may still have
* a valid mm. Find one.
*/
t = find_lock_task_mm(p);
if (!t)
continue;
cpumask_clear_cpu(cpu, mm_cpumask(t->mm));
task_unlock(t);
}
rcu_read_unlock();
}

static inline void check_for_tasks(int dead_cpu)
{
struct task_struct *g, *p;

read_lock(&tasklist_lock);
for_each_process_thread(g, p) {
if (!p->on_rq)
continue;
/*
* We do the check with unlocked task_rq(p)->lock.
* Order the reading to do not warn about a task,
* which was running on this cpu in the past, and
* it's just been woken on another cpu.
*/
rmb();
if (task_cpu(p) != dead_cpu)
continue;

pr_warn("Task %s (pid=%d) is on cpu %d (state=%ld, flags=%x)\n",
p->comm, task_pid_nr(p), dead_cpu, p->state, p->flags);
}
read_unlock(&tasklist_lock);
}

/* Take this CPU down. */
static int take_cpu_down(void *_param)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
enum cpuhp_state target = max((int)st->target, CPUHP_AP_OFFLINE);
int err, cpu = smp_processor_id();

/* Ensure this CPU doesn't handle any more interrupts. */
err = __cpu_disable();
if (err < 0)
return err;

/*
* We get here while we are in CPUHP_TEARDOWN_CPU state and we must not
* do this step again.
*/
WARN_ON(st->state != CPUHP_TEARDOWN_CPU);
st->state--;
/* Invoke the former CPU_DYING callbacks */
for (; st->state > target; st->state--)
cpuhp_invoke_callback(cpu, st->state, false, NULL);

/* Give up timekeeping duties */
tick_handover_do_timer();
/* Park the stopper thread */
stop_machine_park(cpu);
return 0;
}

static int takedown_cpu(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int err;

/* Park the smpboot threads */
kthread_park(per_cpu_ptr(&cpuhp_state, cpu)->thread);
smpboot_park_threads(cpu);

/*
* Prevent irq alloc/free while the dying cpu reorganizes the
* interrupt affinities.
*/
irq_lock_sparse();

/*
* So now all preempt/rcu users must observe !cpu_active().
*/
err = stop_machine(take_cpu_down, NULL, cpumask_of(cpu));
if (err) {
/* CPU refused to die */
irq_unlock_sparse();
/* Unpark the hotplug thread so we can rollback there */
kthread_unpark(per_cpu_ptr(&cpuhp_state, cpu)->thread);
return err;
}
BUG_ON(cpu_online(cpu));

/*
* The CPUHP_AP_SCHED_MIGRATE_DYING callback will have removed all
* runnable tasks from the cpu, there's only the idle task left now
* that the migration thread is done doing the stop_machine thing.
*
* Wait for the stop thread to go away.
*/
wait_for_completion(&st->done);
BUG_ON(st->state != CPUHP_AP_IDLE_DEAD);

/* Interrupts are moved away from the dying cpu, reenable alloc/free */
irq_unlock_sparse();

hotplug_cpu__broadcast_tick_pull(cpu);
/* This actually kills the CPU. */
__cpu_die(cpu);

tick_cleanup_dead_cpu(cpu);
return 0;
}

static void cpuhp_complete_idle_dead(void *arg)
{
struct cpuhp_cpu_state *st = arg;

complete(&st->done);
}

void cpuhp_report_idle_dead(void)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);

BUG_ON(st->state != CPUHP_AP_OFFLINE);
rcu_report_dead(smp_processor_id());
st->state = CPUHP_AP_IDLE_DEAD;
/*
* We cannot call complete after rcu_report_dead() so we delegate it
* to an online cpu.
*/
smp_call_function_single(cpumask_first(cpu_online_mask),
cpuhp_complete_idle_dead, st, 0);
}

#else
#define takedown_cpu NULL
#endif

#ifdef CONFIG_HOTPLUG_CPU

/* Requires cpu_add_remove_lock to be held */
static int __ref _cpu_down(unsigned int cpu, int tasks_frozen,
   enum cpuhp_state target)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int prev_state, ret = 0;

if (num_online_cpus() == 1)
return -EBUSY;

if (!cpu_present(cpu))
return -EINVAL;

cpu_hotplug_begin();

cpuhp_tasks_frozen = tasks_frozen;

prev_state = st->state;
st->target = target;
/*
* If the current CPU state is in the range of the AP hotplug thread,
* then we need to kick the thread.
*/
if (st->state > CPUHP_TEARDOWN_CPU) {
ret = cpuhp_kick_ap_work(cpu);
/*
* The AP side has done the error rollback already. Just
* return the error code..
*/
if (ret)
goto out;

/*
* We might have stopped still in the range of the AP hotplug
* thread. Nothing to do anymore.
*/
if (st->state > CPUHP_TEARDOWN_CPU)
goto out;
}
/*
* The AP brought itself down to CPUHP_TEARDOWN_CPU. So we need
* to do the further cleanups.
*/
ret = cpuhp_down_callbacks(cpu, st, target);
if (ret && st->state > CPUHP_TEARDOWN_CPU && st->state < prev_state) {
st->target = prev_state;
st->rollback = true;
cpuhp_kick_ap_work(cpu);
}

out:
cpu_hotplug_done();
return ret;
}

static int do_cpu_down(unsigned int cpu, enum cpuhp_state target)
{
int err;

cpu_maps_update_begin();

if (cpu_hotplug_disabled) {
err = -EBUSY;
goto out;
}

err = _cpu_down(cpu, 0, target);

out:
cpu_maps_update_done();
return err;
}
int cpu_down(unsigned int cpu)
{
return do_cpu_down(cpu, CPUHP_OFFLINE);
}
EXPORT_SYMBOL(cpu_down);
#endif /*CONFIG_HOTPLUG_CPU*/

/**
 * notify_cpu_starting(cpu) - Invoke the callbacks on the starting CPU
 * @cpu: cpu that just started
 *
 * It must be called by the arch code on the new cpu, before the new cpu
 * enables interrupts and before the "boot" cpu returns from __cpu_up().
 */
void notify_cpu_starting(unsigned int cpu)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
enum cpuhp_state target = min((int)st->target, CPUHP_AP_ONLINE);

rcu_cpu_starting(cpu); /* Enables RCU usage on this CPU. */
while (st->state < target) {
st->state++;
cpuhp_invoke_callback(cpu, st->state, true, NULL);
}
}

/*
 * Called from the idle task. We need to set active here, so we can kick off
 * the stopper thread and unpark the smpboot threads. If the target state is
 * beyond CPUHP_AP_ONLINE_IDLE we kick cpuhp thread and let it bring up the
 * cpu further.
 */
void cpuhp_online_idle(enum cpuhp_state state)
{
struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
unsigned int cpu = smp_processor_id();

/* Happens for the boot cpu */
if (state != CPUHP_AP_ONLINE_IDLE)
return;

st->state = CPUHP_AP_ONLINE_IDLE;

/* Unpark the stopper thread and the hotplug thread of this cpu */
stop_machine_unpark(cpu);
kthread_unpark(st->thread);

/* Should we go further up ? */
if (st->target > CPUHP_AP_ONLINE_IDLE)
__cpuhp_kick_ap_work(st);
else
complete(&st->done);
}

/* Requires cpu_add_remove_lock to be held */
static int _cpu_up(unsigned int cpu, int tasks_frozen, enum cpuhp_state target)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
struct task_struct *idle;
int ret = 0;

cpu_hotplug_begin();

if (!cpu_present(cpu)) {
ret = -EINVAL;
goto out;
}

/*
* The caller of do_cpu_up might have raced with another
* caller. Ignore it for now.
*/
if (st->state >= target)
goto out;

if (st->state == CPUHP_OFFLINE) {
/* Let it fail before we try to bring the cpu up */
idle = idle_thread_get(cpu);
if (IS_ERR(idle)) {
ret = PTR_ERR(idle);
goto out;
}
}

cpuhp_tasks_frozen = tasks_frozen;

st->target = target;
/*
* If the current CPU state is in the range of the AP hotplug thread,
* then we need to kick the thread once more.
*/
if (st->state > CPUHP_BRINGUP_CPU) {
ret = cpuhp_kick_ap_work(cpu);
/*
* The AP side has done the error rollback already. Just
* return the error code..
*/
if (ret)
goto out;
}

/*
* Try to reach the target state. We max out on the BP at
* CPUHP_BRINGUP_CPU. After that the AP hotplug thread is
* responsible for bringing it up to the target state.
*/
target = min((int)target, CPUHP_BRINGUP_CPU);
ret = cpuhp_up_callbacks(cpu, st, target);
out:
cpu_hotplug_done();
return ret;
}

static int do_cpu_up(unsigned int cpu, enum cpuhp_state target)
{
int err = 0;

if (!cpu_possible(cpu)) {
pr_err("can't online cpu %d because it is not configured as may-hotadd at boot time\n",
       cpu);
#if defined(CONFIG_IA64)
pr_err("please check additional_cpus= boot parameter\n");
#endif
return -EINVAL;
}

err = try_online_node(cpu_to_node(cpu));
if (err)
return err;

cpu_maps_update_begin();

if (cpu_hotplug_disabled) {
err = -EBUSY;
goto out;
}

err = _cpu_up(cpu, 0, target);
out:
cpu_maps_update_done();
return err;
}

int cpu_up(unsigned int cpu)
{
return do_cpu_up(cpu, CPUHP_ONLINE);
}
EXPORT_SYMBOL_GPL(cpu_up);

#ifdef CONFIG_PM_SLEEP_SMP
static cpumask_var_t frozen_cpus;

int freeze_secondary_cpus(int primary)
{
int cpu, error = 0;

cpu_maps_update_begin();
if (!cpu_online(primary))
primary = cpumask_first(cpu_online_mask);
/*
* We take down all of the non-boot CPUs in one shot to avoid races
* with the userspace trying to use the CPU hotplug at the same time
*/
cpumask_clear(frozen_cpus);

pr_info("Disabling non-boot CPUs ...\n");
for_each_online_cpu(cpu) {
if (cpu == primary)
continue;
trace_suspend_resume(TPS("CPU_OFF"), cpu, true);
error = _cpu_down(cpu, 1, CPUHP_OFFLINE);
trace_suspend_resume(TPS("CPU_OFF"), cpu, false);
if (!error)
cpumask_set_cpu(cpu, frozen_cpus);
else {
pr_err("Error taking CPU%d down: %d\n", cpu, error);
break;
}
}

if (!error)
BUG_ON(num_online_cpus() > 1);
else
pr_err("Non-boot CPUs are not disabled\n");

/*
* Make sure the CPUs won't be enabled by someone else. We need to do
* this even in case of failure as all disable_nonboot_cpus() users are
* supposed to do enable_nonboot_cpus() on the failure path.
*/
cpu_hotplug_disabled++;

cpu_maps_update_done();
return error;
}

void __weak arch_enable_nonboot_cpus_begin(void)
{
}

void __weak arch_enable_nonboot_cpus_end(void)
{
}

void enable_nonboot_cpus(void)
{
int cpu, error;

/* Allow everyone to use the CPU hotplug again */
cpu_maps_update_begin();
__cpu_hotplug_enable();
if (cpumask_empty(frozen_cpus))
goto out;

pr_info("Enabling non-boot CPUs ...\n");

arch_enable_nonboot_cpus_begin();

for_each_cpu(cpu, frozen_cpus) {
trace_suspend_resume(TPS("CPU_ON"), cpu, true);
error = _cpu_up(cpu, 1, CPUHP_ONLINE);
trace_suspend_resume(TPS("CPU_ON"), cpu, false);
if (!error) {
pr_info("CPU%d is up\n", cpu);
continue;
}
pr_warn("Error taking CPU%d up: %d\n", cpu, error);
}

arch_enable_nonboot_cpus_end();

cpumask_clear(frozen_cpus);
out:
cpu_maps_update_done();
}

static int __init alloc_frozen_cpus(void)
{
if (!alloc_cpumask_var(&frozen_cpus, GFP_KERNEL|__GFP_ZERO))
return -ENOMEM;
return 0;
}
core_initcall(alloc_frozen_cpus);

/*
 * When callbacks for CPU hotplug notifications are being executed, we must
 * ensure that the state of the system with respect to the tasks being frozen
 * or not, as reported by the notification, remains unchanged *throughout the
 * duration* of the execution of the callbacks.
 * Hence we need to prevent the freezer from racing with regular CPU hotplug.
 *
 * This synchronization is implemented by mutually excluding regular CPU
 * hotplug and Suspend/Hibernate call paths by hooking onto the Suspend/
 * Hibernate notifications.
 */
static int
cpu_hotplug_pm_callback(struct notifier_block *nb,
unsigned long action, void *ptr)
{
switch (action) {

case PM_SUSPEND_PREPARE:
case PM_HIBERNATION_PREPARE:
cpu_hotplug_disable();
break;

case PM_POST_SUSPEND:
case PM_POST_HIBERNATION:
cpu_hotplug_enable();
break;

default:
return NOTIFY_DONE;
}

return NOTIFY_OK;
}


static int __init cpu_hotplug_pm_sync_init(void)
{
/*
* cpu_hotplug_pm_callback has higher priority than x86
* bsp_pm_callback which depends on cpu_hotplug_pm_callback
* to disable cpu hotplug to avoid cpu hotplug race.
*/
pm_notifier(cpu_hotplug_pm_callback, 0);
return 0;
}
core_initcall(cpu_hotplug_pm_sync_init);

#endif /* CONFIG_PM_SLEEP_SMP */

int __boot_cpu_id;

#endif /* CONFIG_SMP */

/* Boot processor state steps */
static struct cpuhp_step cpuhp_bp_states[] = {
[CPUHP_OFFLINE] = {
.name = "offline",
.startup.single = NULL,
.teardown.single = NULL,
},
#ifdef CONFIG_SMP
[CPUHP_CREATE_THREADS]= {
.name = "threads:prepare",
.startup.single = smpboot_create_threads,
.teardown.single = NULL,
.cant_stop = true,
},
[CPUHP_PERF_PREPARE] = {
.name = "perf:prepare",
.startup.single = perf_event_init_cpu,
.teardown.single = perf_event_exit_cpu,
},
[CPUHP_WORKQUEUE_PREP] = {
.name = "workqueue:prepare",
.startup.single = workqueue_prepare_cpu,
.teardown.single = NULL,
},
[CPUHP_HRTIMERS_PREPARE] = {
.name = "hrtimers:prepare",
.startup.single = hrtimers_prepare_cpu,
.teardown.single = hrtimers_dead_cpu,
},
[CPUHP_SMPCFD_PREPARE] = {
.name = "smpcfd:prepare",
.startup.single = smpcfd_prepare_cpu,
.teardown.single = smpcfd_dead_cpu,
},
[CPUHP_RELAY_PREPARE] = {
.name = "relay:prepare",
.startup.single = relay_prepare_cpu,
.teardown.single = NULL,
},
[CPUHP_SLAB_PREPARE] = {
.name = "slab:prepare",
.startup.single = slab_prepare_cpu,
.teardown.single = slab_dead_cpu,
},
[CPUHP_RCUTREE_PREP] = {
.name = "RCU/tree:prepare",
.startup.single = rcutree_prepare_cpu,
.teardown.single = rcutree_dead_cpu,
},
/*
* On the tear-down path, timers_dead_cpu() must be invoked
* before blk_mq_queue_reinit_notify() from notify_dead(),
* otherwise a RCU stall occurs.
*/
[CPUHP_TIMERS_DEAD] = {
.name = "timers:dead",
.startup.single = NULL,
.teardown.single = timers_dead_cpu,
},
/* Kicks the plugged cpu into life */
[CPUHP_BRINGUP_CPU] = {
.name = "cpu:bringup",
.startup.single = bringup_cpu,
.teardown.single = NULL,
.cant_stop = true,
},
[CPUHP_AP_SMPCFD_DYING] = {
.name = "smpcfd:dying",
.startup.single = NULL,
.teardown.single = smpcfd_dying_cpu,
},
/*
* Handled on controll processor until the plugged processor manages
* this itself.
*/
[CPUHP_TEARDOWN_CPU] = {
.name = "cpu:teardown",
.startup.single = NULL,
.teardown.single = takedown_cpu,
.cant_stop = true,
},
#else
[CPUHP_BRINGUP_CPU] = { },
#endif
};

/* 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,
},
/* First state is scheduler control. Interrupts are disabled */
[CPUHP_AP_SCHED_STARTING] = {
.name = "sched:starting",
.startup.single = sched_cpu_starting,
.teardown.single = sched_cpu_dying,
},
[CPUHP_AP_RCUTREE_DYING] = {
.name = "RCU/tree:dying",
.startup.single = NULL,
.teardown.single = rcutree_dying_cpu,
},
/* 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:online",
.startup.single = smpboot_unpark_threads,
.teardown.single = NULL,
},
[CPUHP_AP_PERF_ONLINE] = {
.name = "perf:online",
.startup.single = perf_event_init_cpu,
.teardown.single = perf_event_exit_cpu,
},
[CPUHP_AP_WORKQUEUE_ONLINE] = {
.name = "workqueue:online",
.startup.single = workqueue_online_cpu,
.teardown.single = workqueue_offline_cpu,
},
[CPUHP_AP_RCUTREE_ONLINE] = {
.name = "RCU/tree:online",
.startup.single = rcutree_online_cpu,
.teardown.single = rcutree_offline_cpu,
},
#endif
/*
* The dynamically registered state space is here
*/

#ifdef CONFIG_SMP
/* Last state is scheduler control setting the cpu active */
[CPUHP_AP_ACTIVE] = {
.name = "sched:active",
.startup.single = sched_cpu_activate,
.teardown.single = sched_cpu_deactivate,
},
#endif

/* CPU is fully up and running. */
[CPUHP_ONLINE] = {
.name = "online",
.startup.single = NULL,
.teardown.single = NULL,
},
};

/* Sanity check for callbacks */
static int cpuhp_cb_check(enum cpuhp_state state)
{
if (state <= CPUHP_OFFLINE || state >= CPUHP_ONLINE)
return -EINVAL;
return 0;
}

/*
 * Returns a free for dynamic slot assignment of the Online state. The states
 * are protected by the cpuhp_slot_states mutex and an empty slot is identified
 * by having no name assigned.
 */
static int cpuhp_reserve_state(enum cpuhp_state state)
{
enum cpuhp_state i, end;
struct cpuhp_step *step;

switch (state) {
case CPUHP_AP_ONLINE_DYN:
step = cpuhp_ap_states + CPUHP_AP_ONLINE_DYN;
end = CPUHP_AP_ONLINE_DYN_END;
break;
case CPUHP_BP_PREPARE_DYN:
step = cpuhp_bp_states + CPUHP_BP_PREPARE_DYN;
end = CPUHP_BP_PREPARE_DYN_END;
break;
default:
return -EINVAL;
}

for (i = state; i <= end; i++, step++) {
if (!step->name)
return i;
}
WARN(1, "No more dynamic states available for CPU hotplug\n");
return -ENOSPC;
}

static int cpuhp_store_callbacks(enum cpuhp_state state, const char *name,
int (*startup)(unsigned int cpu),
int (*teardown)(unsigned int cpu),
bool multi_instance)
{
/* (Un)Install the callbacks for further cpu hotplug operations */
struct cpuhp_step *sp;
int ret = 0;

if (state == CPUHP_AP_ONLINE_DYN || state == CPUHP_BP_PREPARE_DYN) {
ret = cpuhp_reserve_state(state);
if (ret < 0)
return ret;
state = ret;
}
sp = cpuhp_get_step(state);
if (name && sp->name)
return -EBUSY;

sp->startup.single = startup;
sp->teardown.single = teardown;
sp->name = name;
sp->multi_instance = multi_instance;
INIT_HLIST_HEAD(&sp->list);
return ret;
}

static void *cpuhp_get_teardown_cb(enum cpuhp_state state)
{
return cpuhp_get_step(state)->teardown.single;
}

/*
 * Call the startup/teardown function for a step either on the AP or
 * on the current CPU.
 */
static int cpuhp_issue_call(int cpu, enum cpuhp_state state, bool bringup,
    struct hlist_node *node)
{
struct cpuhp_step *sp = cpuhp_get_step(state);
int ret;

if ((bringup && !sp->startup.single) ||
    (!bringup && !sp->teardown.single))
return 0;
/*
* The non AP bound callbacks can fail on bringup. On teardown
* e.g. module removal we crash for now.
*/
#ifdef CONFIG_SMP
if (cpuhp_is_ap_state(state))
ret = cpuhp_invoke_ap_callback(cpu, state, bringup, node);
else
ret = cpuhp_invoke_callback(cpu, state, bringup, node);
#else
ret = cpuhp_invoke_callback(cpu, state, bringup, node);
#endif
BUG_ON(ret && !bringup);
return ret;
}

/*
 * Called from __cpuhp_setup_state on a recoverable failure.
 *
 * Note: The teardown callbacks for rollback are not allowed to fail!
 */
static void cpuhp_rollback_install(int failedcpu, enum cpuhp_state state,
   struct hlist_node *node)
{
int cpu;

/* Roll back the already executed steps on the other cpus */
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpu >= failedcpu)
break;

/* Did we invoke the startup call on that cpu ? */
if (cpustate >= state)
cpuhp_issue_call(cpu, state, false, node);
}
}

int __cpuhp_state_add_instance(enum cpuhp_state state, struct hlist_node *node,
       bool invoke)
{
struct cpuhp_step *sp;
int cpu;
int ret;

sp = cpuhp_get_step(state);
if (sp->multi_instance == false)
return -EINVAL;

get_online_cpus();
mutex_lock(&cpuhp_state_mutex);

if (!invoke || !sp->startup.multi)
goto add_node;

/*
* Try to call the startup callback for each present cpu
* depending on the hotplug state of the cpu.
*/
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpustate < state)
continue;

ret = cpuhp_issue_call(cpu, state, true, node);
if (ret) {
if (sp->teardown.multi)
cpuhp_rollback_install(cpu, state, node);
goto unlock;
}
}
add_node:
ret = 0;
hlist_add_head(node, &sp->list);
unlock:
mutex_unlock(&cpuhp_state_mutex);
put_online_cpus();
return ret;
}
EXPORT_SYMBOL_GPL(__cpuhp_state_add_instance);

/**
 * __cpuhp_setup_state - Setup the callbacks for an hotplug machine state
 * @state: The state to setup
 * @invoke: If true, the startup function is invoked for cpus where
 * cpu state >= @state
 * @startup: startup callback function
 * @teardown: teardown callback function
 * @multi_instance: State is set up for multiple instances which get
 * added afterwards.
 *
 * Returns:
 *   On success:
 *      Positive state number if @state is CPUHP_AP_ONLINE_DYN
 *      0 for all other states
 *   On failure: proper (negative) error code
 */
int __cpuhp_setup_state(enum cpuhp_state state,
const char *name, bool invoke,
int (*startup)(unsigned int cpu),
int (*teardown)(unsigned int cpu),
bool multi_instance)
{
int cpu, ret = 0;
bool dynstate;

if (cpuhp_cb_check(state) || !name)
return -EINVAL;

get_online_cpus();
mutex_lock(&cpuhp_state_mutex);

ret = cpuhp_store_callbacks(state, name, startup, teardown,
    multi_instance);

dynstate = state == CPUHP_AP_ONLINE_DYN;
if (ret > 0 && dynstate) {
state = ret;
ret = 0;
}

if (ret || !invoke || !startup)
goto out;

/*
* Try to call the startup callback for each present cpu
* depending on the hotplug state of the cpu.
*/
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpustate < state)
continue;

ret = cpuhp_issue_call(cpu, state, true, NULL);
if (ret) {
if (teardown)
cpuhp_rollback_install(cpu, state, NULL);
cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
goto out;
}
}
out:
mutex_unlock(&cpuhp_state_mutex);
put_online_cpus();
/*
* If the requested state is CPUHP_AP_ONLINE_DYN, return the
* dynamically allocated state in case of success.
*/
if (!ret && dynstate)
return state;
return ret;
}
EXPORT_SYMBOL(__cpuhp_setup_state);

int __cpuhp_state_remove_instance(enum cpuhp_state state,
  struct hlist_node *node, bool invoke)
{
struct cpuhp_step *sp = cpuhp_get_step(state);
int cpu;

BUG_ON(cpuhp_cb_check(state));

if (!sp->multi_instance)
return -EINVAL;

get_online_cpus();
mutex_lock(&cpuhp_state_mutex);

if (!invoke || !cpuhp_get_teardown_cb(state))
goto remove;
/*
* Call the teardown callback for each present cpu depending
* on the hotplug state of the cpu. This function is not
* allowed to fail currently!
*/
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpustate >= state)
cpuhp_issue_call(cpu, state, false, node);
}

remove:
hlist_del(node);
mutex_unlock(&cpuhp_state_mutex);
put_online_cpus();

return 0;
}
EXPORT_SYMBOL_GPL(__cpuhp_state_remove_instance);

/**
 * __cpuhp_remove_state - Remove the callbacks for an hotplug machine state
 * @state: The state to remove
 * @invoke: If true, the teardown function is invoked for cpus where
 * cpu state >= @state
 *
 * The teardown callback is currently not allowed to fail. Think
 * about module removal!
 */
void __cpuhp_remove_state(enum cpuhp_state state, bool invoke)
{
struct cpuhp_step *sp = cpuhp_get_step(state);
int cpu;

BUG_ON(cpuhp_cb_check(state));

get_online_cpus();

mutex_lock(&cpuhp_state_mutex);
if (sp->multi_instance) {
WARN(!hlist_empty(&sp->list),
     "Error: Removing state %d which has instances left.\n",
     state);
goto remove;
}

if (!invoke || !cpuhp_get_teardown_cb(state))
goto remove;

/*
* Call the teardown callback for each present cpu depending
* on the hotplug state of the cpu. This function is not
* allowed to fail currently!
*/
for_each_present_cpu(cpu) {
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);
int cpustate = st->state;

if (cpustate >= state)
cpuhp_issue_call(cpu, state, false, NULL);
}
remove:
cpuhp_store_callbacks(state, NULL, NULL, NULL, false);
mutex_unlock(&cpuhp_state_mutex);
put_online_cpus();
}
EXPORT_SYMBOL(__cpuhp_remove_state);

#if defined(CONFIG_SYSFS) && defined(CONFIG_HOTPLUG_CPU)
static ssize_t show_cpuhp_state(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);

return sprintf(buf, "%d\n", st->state);
}
static DEVICE_ATTR(state, 0444, show_cpuhp_state, NULL);

static ssize_t write_cpuhp_target(struct device *dev,
  struct device_attribute *attr,
  const char *buf, size_t count)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);
struct cpuhp_step *sp;
int target, ret;

ret = kstrtoint(buf, 10, &target);
if (ret)
return ret;

#ifdef CONFIG_CPU_HOTPLUG_STATE_CONTROL
if (target < CPUHP_OFFLINE || target > CPUHP_ONLINE)
return -EINVAL;
#else
if (target != CPUHP_OFFLINE && target != CPUHP_ONLINE)
return -EINVAL;
#endif

ret = lock_device_hotplug_sysfs();
if (ret)
return ret;

mutex_lock(&cpuhp_state_mutex);
sp = cpuhp_get_step(target);
ret = !sp->name || sp->cant_stop ? -EINVAL : 0;
mutex_unlock(&cpuhp_state_mutex);
if (ret)
goto out;

if (st->state < target)
ret = do_cpu_up(dev->id, target);
else
ret = do_cpu_down(dev->id, target);
out:
unlock_device_hotplug();
return ret ? ret : count;
}

static ssize_t show_cpuhp_target(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, dev->id);

return sprintf(buf, "%d\n", st->target);
}
static DEVICE_ATTR(target, 0644, show_cpuhp_target, write_cpuhp_target);

static struct attribute *cpuhp_cpu_attrs[] = {
&dev_attr_state.attr,
&dev_attr_target.attr,
NULL
};

static struct attribute_group cpuhp_cpu_attr_group = {
.attrs = cpuhp_cpu_attrs,
.name = "hotplug",
NULL
};

static ssize_t show_cpuhp_states(struct device *dev,
struct device_attribute *attr, char *buf)
{
ssize_t cur, res = 0;
int i;

mutex_lock(&cpuhp_state_mutex);
for (i = CPUHP_OFFLINE; i <= CPUHP_ONLINE; i++) {
struct cpuhp_step *sp = cpuhp_get_step(i);

if (sp->name) {
cur = sprintf(buf, "%3d: %s\n", i, sp->name);
buf += cur;
res += cur;
}
}
mutex_unlock(&cpuhp_state_mutex);
return res;
}
static DEVICE_ATTR(states, 0444, show_cpuhp_states, NULL);

static struct attribute *cpuhp_cpu_root_attrs[] = {
&dev_attr_states.attr,
NULL
};

static struct attribute_group cpuhp_cpu_root_attr_group = {
.attrs = cpuhp_cpu_root_attrs,
.name = "hotplug",
NULL
};

static int __init cpuhp_sysfs_init(void)
{
int cpu, ret;

ret = sysfs_create_group(&cpu_subsys.dev_root->kobj,
&cpuhp_cpu_root_attr_group);
if (ret)
return ret;

for_each_possible_cpu(cpu) {
struct device *dev = get_cpu_device(cpu);

if (!dev)
continue;
ret = sysfs_create_group(&dev->kobj, &cpuhp_cpu_attr_group);
if (ret)
return ret;
}
return 0;
}
device_initcall(cpuhp_sysfs_init);
#endif

/*
 * cpu_bit_bitmap[] is a special, "compressed" data structure that
 * represents all NR_CPUS bits binary values of 1<<nr.
 *
 * It is used by cpumask_of() to get a constant address to a CPU
 * mask value that has a single bit set only.
 */

/* cpu_bit_bitmap[0] is empty - so we can back into it */
#define MASK_DECLARE_1(x) [x+1][0] = (1UL << (x))
#define MASK_DECLARE_2(x) MASK_DECLARE_1(x), MASK_DECLARE_1(x+1)
#define MASK_DECLARE_4(x) MASK_DECLARE_2(x), MASK_DECLARE_2(x+2)
#define MASK_DECLARE_8(x) MASK_DECLARE_4(x), MASK_DECLARE_4(x+4)

const unsigned long cpu_bit_bitmap[BITS_PER_LONG+1][BITS_TO_LONGS(NR_CPUS)] = {

MASK_DECLARE_8(0), MASK_DECLARE_8(8),
MASK_DECLARE_8(16), MASK_DECLARE_8(24),
#if BITS_PER_LONG > 32
MASK_DECLARE_8(32), MASK_DECLARE_8(40),
MASK_DECLARE_8(48), MASK_DECLARE_8(56),
#endif
};
EXPORT_SYMBOL_GPL(cpu_bit_bitmap);

const DECLARE_BITMAP(cpu_all_bits, NR_CPUS) = CPU_BITS_ALL;
EXPORT_SYMBOL(cpu_all_bits);

#ifdef CONFIG_INIT_ALL_POSSIBLE
struct cpumask __cpu_possible_mask __read_mostly
= {CPU_BITS_ALL};
#else
struct cpumask __cpu_possible_mask __read_mostly;
#endif
EXPORT_SYMBOL(__cpu_possible_mask);

struct cpumask __cpu_online_mask __read_mostly;
EXPORT_SYMBOL(__cpu_online_mask);

struct cpumask __cpu_present_mask __read_mostly;
EXPORT_SYMBOL(__cpu_present_mask);

struct cpumask __cpu_active_mask __read_mostly;
EXPORT_SYMBOL(__cpu_active_mask);

void init_cpu_present(const struct cpumask *src)
{
cpumask_copy(&__cpu_present_mask, src);
}

void init_cpu_possible(const struct cpumask *src)
{
cpumask_copy(&__cpu_possible_mask, src);
}

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);

#ifdef CONFIG_SMP
__boot_cpu_id = cpu;
#endif
}

/*
 * 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;
}

END OF FILE
fell free to ask questions or send me an email

thanks
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Offline _iPhoenix_

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Re: Linux
« Reply #2 on: September 04, 2017, 02:51:41 pm »
The code kotu gave you is inapplicable for the calculators.

You cannot just have code for a PC and expect it to work on a calc.

This is an overly ambitious project, the original Linux had the experience of several experienced programmers, a better language (no offense to @MateoConLechuga and team) and much better hardware.

Also, that is not the full code, Linux is a complex program requiring more space (even when assembled) than that calc can hold.
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Offline mazhat

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Re: Linux
« Reply #3 on: September 04, 2017, 04:47:35 pm »
Welcome back.
I recommend a smaller project, like an RPG (it's a popular choice).

Ignoring that, putting Linux on your calculator sounds expensive on storage,
so take that into account. If a lot of memory is taken, then programs might not
be able to be used on it (defeating the purpose). I wish you more than luck.

@_iPhoenix_  I don't think he understands. Just let him do it and he'll understand when he gets there.
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Offline Adriweb

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Re: Linux
« Reply #4 on: September 04, 2017, 05:05:44 pm »
This is an overly ambitious project, the original Linux had the experience of several experienced programmers, a better language (no offense to @MateoConLechuga and team) and much better hardware.
While your first two points are true, the other two are not: the Linux kernel is written in C (that's what we have that too, and more), and has been known to run on ridiculously small hardware :)
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Offline _iPhoenix_

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Re: Linux
« Reply #5 on: September 04, 2017, 06:18:04 pm »
Yes, but, to my knowledge, you can do much more with normal C, and have different functions, being written for different devices.
The device you linked had more storage that the CE, and that was the point I was making.
  • Calculators owned: A sentient TI-84+ CE, TI-85
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Offline kotu

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Re: Linux
« Reply #6 on: September 08, 2017, 10:01:01 am »
I don't think you guys understand - Alvajoy123 is going to write Linux for PCs


Don't underestimate him - remember he used to shout..
"Books are everything"

After I told him to buy some books

 8)
« Last Edit: October 01, 2017, 10:28:57 pm by p2 »
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Offline shak0579

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Re: Linux
« Reply #7 on: October 01, 2017, 09:13:58 pm »
HELLO

Offline Alvajoy123

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Re: Linux
« Reply #8 on: October 01, 2017, 09:17:02 pm »
Welcome back.
I recommend a smaller project, like an RPG (it's a popular choice).

Ignoring that, putting Linux on your calculator sounds expensive on storage,
so take that into account. If a lot of memory is taken, then programs might not
be able to be used on it (defeating the purpose). I wish you more than luck.

@_iPhoenix_  I don't think he understands. Just let him do it and he'll understand when he gets there.

i have been working on a halo game (2D)
  • Calculators owned: TI-84+CE
??? ??? ???
Qestions are hard to ask that why we have ???
http://huggle.jdf2.org/sig/Alvajoy123.png

 


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