#include <linux/completion.h>

#include <linux/export.h>

#include <linux/cpumask.h>

#include <linux/err.h>

#include <linux/cpu.h>

#include <linux/padata.h>

#include <linux/mutex.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/sysfs.h>

#include <linux/rcupdate.h>

#define PADATA_WORK_ONSTACK 1 /* Work's memory is on stack */

struct padata_work {

};

static DEFINE_SPINLOCK(padata_works_lock);

static struct padata_work *padata_works;

static LIST_HEAD(padata_free_works);

struct padata_mt_job_state {

};

static void padata_free_pd(struct parallel_data *pd);

static void __init padata_mt_helper(struct work_struct *work);

static int padata_index_to_cpu(struct parallel_data *pd, int cpu_index)

{

int cpu, target_cpu;

target_cpu = cpumask_first(pd->cpumask.pcpu);

for (cpu = 0; cpu < cpu_index; cpu++)

target_cpu = cpumask_next(target_cpu, pd->cpumask.pcpu);

return target_cpu;

}

static int padata_cpu_hash(struct parallel_data *pd, unsigned int seq_nr)

{

/*

int cpu_index = seq_nr % cpumask_weight(pd->cpumask.pcpu);

return padata_index_to_cpu(pd, cpu_index);

}

static struct padata_work *padata_work_alloc(void)

{

struct padata_work *pw;

lockdep_assert_held(&padata_works_lock);

if (list_empty(&padata_free_works))

return NULL; /* No more work items allowed to be queued. */

pw = list_first_entry(&padata_free_works, struct padata_work, pw_list);

list_del(&pw->pw_list);

return pw;

}

static void __ref padata_work_init(struct padata_work *pw, work_func_t work_fn,

void *data, int flags)

{

if (flags & PADATA_WORK_ONSTACK)

INIT_WORK_ONSTACK(&pw->pw_work, work_fn);

else

INIT_WORK(&pw->pw_work, work_fn);

pw->pw_data = data;

}

static int __init padata_work_alloc_mt(int nworks, void *data,

struct list_head *head)

{

int i;

spin_lock(&padata_works_lock);

/* Start at 1 because the current task participates in the job. */

for (i = 1; i < nworks; ++i) {

struct padata_work *pw = padata_work_alloc();

if (!pw)

break;

padata_work_init(pw, padata_mt_helper, data, 0);

list_add(&pw->pw_list, head);

}

spin_unlock(&padata_works_lock);

return i;

}

static void padata_work_free(struct padata_work *pw)

{

lockdep_assert_held(&padata_works_lock);

list_add(&pw->pw_list, &padata_free_works);

}

static void __init padata_works_free(struct list_head *works)

{

struct padata_work *cur, *next;

if (list_empty(works))

return;

spin_lock(&padata_works_lock);

list_for_each_entry_safe(cur, next, works, pw_list) {

list_del(&cur->pw_list);

padata_work_free(cur);

}

spin_unlock(&padata_works_lock);

}

static void padata_parallel_worker(struct work_struct *parallel_work)

{

struct padata_work *pw = container_of(parallel_work, struct padata_work,

pw_work);

struct padata_priv *padata = pw->pw_data;

local_bh_disable();

padata->parallel(padata);

spin_lock(&padata_works_lock);

padata_work_free(pw);

spin_unlock(&padata_works_lock);

local_bh_enable();

}

int padata_do_parallel(struct padata_shell *ps,

struct padata_priv *padata, int *cb_cpu)

{

struct padata_instance *pinst = ps->pinst;

int i, cpu, cpu_index, err;

struct parallel_data *pd;

struct padata_work *pw;

rcu_read_lock_bh();

pd = rcu_dereference_bh(ps->pd);

err = -EINVAL;

if (!(pinst->flags & PADATA_INIT) || pinst->flags & PADATA_INVALID)

goto out;

if (!cpumask_test_cpu(*cb_cpu, pd->cpumask.cbcpu)) {

if (cpumask_empty(pd->cpumask.cbcpu))

goto out;

/* Select an alternate fallback CPU and notify the caller. */

cpu_index = *cb_cpu % cpumask_weight(pd->cpumask.cbcpu);

cpu = cpumask_first(pd->cpumask.cbcpu);

for (i = 0; i < cpu_index; i++)

cpu = cpumask_next(cpu, pd->cpumask.cbcpu);

*cb_cpu = cpu;

}

err = -EBUSY;

if ((pinst->flags & PADATA_RESET))

goto out;

refcount_inc(&pd->refcnt);

padata->pd = pd;

padata->cb_cpu = *cb_cpu;

spin_lock(&padata_works_lock);

padata->seq_nr = ++pd->seq_nr;

pw = padata_work_alloc();

spin_unlock(&padata_works_lock);

if (!pw) {

/* Maximum works limit exceeded, run in the current task. */

padata->parallel(padata);

}

rcu_read_unlock_bh();

if (pw) {

padata_work_init(pw, padata_parallel_worker, padata, 0);

queue_work(pinst->parallel_wq, &pw->pw_work);

}

return 0;

out:

rcu_read_unlock_bh();

return err;

}

EXPORT_SYMBOL(padata_do_parallel);

static struct padata_priv *padata_find_next(struct parallel_data *pd,

bool remove_object)

{

struct padata_priv *padata;

struct padata_list *reorder;

int cpu = pd->cpu;

reorder = per_cpu_ptr(pd->reorder_list, cpu);

spin_lock(&reorder->lock);

if (list_empty(&reorder->list)) {

spin_unlock(&reorder->lock);

return NULL;

}

padata = list_entry(reorder->list.next, struct padata_priv, list);

/*

if (padata->seq_nr != pd->processed) {

spin_unlock(&reorder->lock);

return NULL;

}

if (remove_object) {

list_del_init(&padata->list);

++pd->processed;

pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, false);

}

spin_unlock(&reorder->lock);

return padata;

}

static void padata_reorder(struct parallel_data *pd)

{

struct padata_instance *pinst = pd->ps->pinst;

int cb_cpu;

struct padata_priv *padata;

struct padata_serial_queue *squeue;

struct padata_list *reorder;

/*

if (!spin_trylock_bh(&pd->lock))

return;

while (1) {

padata = padata_find_next(pd, true);

/*

if (!padata)

break;

cb_cpu = padata->cb_cpu;

squeue = per_cpu_ptr(pd->squeue, cb_cpu);

spin_lock(&squeue->serial.lock);

list_add_tail(&padata->list, &squeue->serial.list);

spin_unlock(&squeue->serial.lock);

queue_work_on(cb_cpu, pinst->serial_wq, &squeue->work);

}

spin_unlock_bh(&pd->lock);

/*

smp_mb();

reorder = per_cpu_ptr(pd->reorder_list, pd->cpu);

if (!list_empty(&reorder->list) && padata_find_next(pd, false))

queue_work(pinst->serial_wq, &pd->reorder_work);

}

static void invoke_padata_reorder(struct work_struct *work)

{

struct parallel_data *pd;

local_bh_disable();

pd = container_of(work, struct parallel_data, reorder_work);

padata_reorder(pd);

local_bh_enable();

}

static void padata_serial_worker(struct work_struct *serial_work)

{

struct padata_serial_queue *squeue;

struct parallel_data *pd;

LIST_HEAD(local_list);

int cnt;

local_bh_disable();

squeue = container_of(serial_work, struct padata_serial_queue, work);

pd = squeue->pd;

spin_lock(&squeue->serial.lock);

list_replace_init(&squeue->serial.list, &local_list);

spin_unlock(&squeue->serial.lock);

cnt = 0;

while (!list_empty(&local_list)) {

struct padata_priv *padata;

padata = list_entry(local_list.next,

struct padata_priv, list);

list_del_init(&padata->list);

padata->serial(padata);

cnt++;

}

local_bh_enable();

if (refcount_sub_and_test(cnt, &pd->refcnt))

padata_free_pd(pd);

}

void padata_do_serial(struct padata_priv *padata)

{

struct parallel_data *pd = padata->pd;

int hashed_cpu = padata_cpu_hash(pd, padata->seq_nr);

struct padata_list *reorder = per_cpu_ptr(pd->reorder_list, hashed_cpu);

struct padata_priv *cur;

struct list_head *pos;

spin_lock(&reorder->lock);

/* Sort in ascending order of sequence number. */

list_for_each_prev(pos, &reorder->list) {

cur = list_entry(pos, struct padata_priv, list);

if (cur->seq_nr < padata->seq_nr)

break;

}

list_add(&padata->list, pos);

spin_unlock(&reorder->lock);

/*

smp_mb();

padata_reorder(pd);

}

EXPORT_SYMBOL(padata_do_serial);

static int padata_setup_cpumasks(struct padata_instance *pinst)

{

struct workqueue_attrs *attrs;

int err;

attrs = alloc_workqueue_attrs();

if (!attrs)

return -ENOMEM;

/* Restrict parallel_wq workers to pd->cpumask.pcpu. */

cpumask_copy(attrs->cpumask, pinst->cpumask.pcpu);

err = apply_workqueue_attrs(pinst->parallel_wq, attrs);

free_workqueue_attrs(attrs);

return err;

}

static void __init padata_mt_helper(struct work_struct *w)

{

struct padata_work *pw = container_of(w, struct padata_work, pw_work);

struct padata_mt_job_state *ps = pw->pw_data;

struct padata_mt_job *job = ps->job;

bool done;

spin_lock(&ps->lock);

while (job->size > 0) {

unsigned long start, size, end;

start = job->start;

/* So end is chunk size aligned if enough work remains. */

size = roundup(start + 1, ps->chunk_size) - start;

size = min(size, job->size);

end = start + size;

job->start = end;

job->size -= size;

spin_unlock(&ps->lock);

job->thread_fn(start, end, job->fn_arg);

spin_lock(&ps->lock);

}

++ps->nworks_fini;

done = (ps->nworks_fini == ps->nworks);

spin_unlock(&ps->lock);

if (done)

complete(&ps->completion);

}

void __init padata_do_multithreaded(struct padata_mt_job *job)

{

/* In case threads finish at different times. */

static const unsigned long load_balance_factor = 4;

struct padata_work my_work, *pw;

struct padata_mt_job_state ps;

LIST_HEAD(works);

int nworks;

if (job->size == 0)

return;

/* Ensure at least one thread when size < min_chunk. */

nworks = max(job->size / max(job->min_chunk, job->align), 1ul);

nworks = min(nworks, job->max_threads);

if (nworks == 1) {

/* Single thread, no coordination needed, cut to the chase. */

job->thread_fn(job->start, job->start + job->size, job->fn_arg);

return;

}

spin_lock_init(&ps.lock);

init_completion(&ps.completion);

ps.job = job;

ps.nworks = padata_work_alloc_mt(nworks, &ps, &works);

ps.nworks_fini = 0;

/*

ps.chunk_size = job->size / (ps.nworks * load_balance_factor);

ps.chunk_size = max(ps.chunk_size, job->min_chunk);

ps.chunk_size = roundup(ps.chunk_size, job->align);

list_for_each_entry(pw, &works, pw_list)

queue_work(system_unbound_wq, &pw->pw_work);

/* Use the current thread, which saves starting a workqueue worker. */

padata_work_init(&my_work, padata_mt_helper, &ps, PADATA_WORK_ONSTACK);

padata_mt_helper(&my_work.pw_work);

/* Wait for all the helpers to finish. */

wait_for_completion(&ps.completion);

destroy_work_on_stack(&my_work.pw_work);

padata_works_free(&works);

}

static void __padata_list_init(struct padata_list *pd_list)

{

INIT_LIST_HEAD(&pd_list->list);

spin_lock_init(&pd_list->lock);

}

static void padata_init_squeues(struct parallel_data *pd)

{

int cpu;

struct padata_serial_queue *squeue;

for_each_cpu(cpu, pd->cpumask.cbcpu) {

squeue = per_cpu_ptr(pd->squeue, cpu);

squeue->pd = pd;

__padata_list_init(&squeue->serial);

INIT_WORK(&squeue->work, padata_serial_worker);

}

}

static void padata_init_reorder_list(struct parallel_data *pd)

{

int cpu;

struct padata_list *list;

for_each_cpu(cpu, pd->cpumask.pcpu) {

list = per_cpu_ptr(pd->reorder_list, cpu);

__padata_list_init(list);

}

}

static struct parallel_data *padata_alloc_pd(struct padata_shell *ps)

{

struct padata_instance *pinst = ps->pinst;

struct parallel_data *pd;

pd = kzalloc(sizeof(struct parallel_data), GFP_KERNEL);

if (!pd)

goto err;

pd->reorder_list = alloc_percpu(struct padata_list);

if (!pd->reorder_list)

goto err_free_pd;

pd->squeue = alloc_percpu(struct padata_serial_queue);

if (!pd->squeue)

goto err_free_reorder_list;

pd->ps = ps;

if (!alloc_cpumask_var(&pd->cpumask.pcpu, GFP_KERNEL))

goto err_free_squeue;

if (!alloc_cpumask_var(&pd->cpumask.cbcpu, GFP_KERNEL))

goto err_free_pcpu;

cpumask_and(pd->cpumask.pcpu, pinst->cpumask.pcpu, cpu_online_mask);

cpumask_and(pd->cpumask.cbcpu, pinst->cpumask.cbcpu, cpu_online_mask);

padata_init_reorder_list(pd);

padata_init_squeues(pd);

pd->seq_nr = -1;

refcount_set(&pd->refcnt, 1);

spin_lock_init(&pd->lock);

pd->cpu = cpumask_first(pd->cpumask.pcpu);

INIT_WORK(&pd->reorder_work, invoke_padata_reorder);

return pd;

err_free_pcpu:

free_cpumask_var(pd->cpumask.pcpu);

err_free_squeue:

free_percpu(pd->squeue);

err_free_reorder_list:

free_percpu(pd->reorder_list);

err_free_pd:

kfree(pd);

err:

return NULL;

}

static void padata_free_pd(struct parallel_data *pd)

{

free_cpumask_var(pd->cpumask.pcpu);

free_cpumask_var(pd->cpumask.cbcpu);

free_percpu(pd->reorder_list);

free_percpu(pd->squeue);

kfree(pd);

}

static void __padata_start(struct padata_instance *pinst)

{

pinst->flags |= PADATA_INIT;

}

static void __padata_stop(struct padata_instance *pinst)

{

if (!(pinst->flags & PADATA_INIT))

return;

pinst->flags &= ~PADATA_INIT;

synchronize_rcu();

}

static int padata_replace_one(struct padata_shell *ps)

{

struct parallel_data *pd_new;

pd_new = padata_alloc_pd(ps);

if (!pd_new)

return -ENOMEM;

ps->opd = rcu_dereference_protected(ps->pd, 1);

rcu_assign_pointer(ps->pd, pd_new);

return 0;

}

static int padata_replace(struct padata_instance *pinst)

{

struct padata_shell *ps;

int err = 0;

pinst->flags |= PADATA_RESET;

list_for_each_entry(ps, &pinst->pslist, list) {

err = padata_replace_one(ps);

if (err)

break;

}

synchronize_rcu();

list_for_each_entry_continue_reverse(ps, &pinst->pslist, list)

if (refcount_dec_and_test(&ps->opd->refcnt))

padata_free_pd(ps->opd);

pinst->flags &= ~PADATA_RESET;

return err;

}

static bool padata_validate_cpumask(struct padata_instance *pinst,

const struct cpumask *cpumask)

{

if (!cpumask_intersects(cpumask, cpu_online_mask)) {

pinst->flags |= PADATA_INVALID;

return false;

}

pinst->flags &= ~PADATA_INVALID;

return true;

}

static int __padata_set_cpumasks(struct padata_instance *pinst,

cpumask_var_t pcpumask,

cpumask_var_t cbcpumask)

{

int valid;

int err;

valid = padata_validate_cpumask(pinst, pcpumask);

if (!valid) {

__padata_stop(pinst);

goto out_replace;

}

valid = padata_validate_cpumask(pinst, cbcpumask);

if (!valid)

__padata_stop(pinst);

out_replace:

cpumask_copy(pinst->cpumask.pcpu, pcpumask);

cpumask_copy(pinst->cpumask.cbcpu, cbcpumask);

err = padata_setup_cpumasks(pinst) ?: padata_replace(pinst);

if (valid)

__padata_start(pinst);

return err;

}

int padata_set_cpumask(struct padata_instance *pinst, int cpumask_type,

cpumask_var_t cpumask)

{

struct cpumask *serial_mask, *parallel_mask;

int err = -EINVAL;

cpus_read_lock();

mutex_lock(&pinst->lock);

switch (cpumask_type) {

case PADATA_CPU_PARALLEL:

serial_mask = pinst->cpumask.cbcpu;

parallel_mask = cpumask;

break;

case PADATA_CPU_SERIAL:

parallel_mask = pinst->cpumask.pcpu;

serial_mask = cpumask;

break;

default:

goto out;

}

err = __padata_set_cpumasks(pinst, parallel_mask, serial_mask);

out:

mutex_unlock(&pinst->lock);

cpus_read_unlock();

return err;

}

EXPORT_SYMBOL(padata_set_cpumask);

#ifdef CONFIG_HOTPLUG_CPU

static int __padata_add_cpu(struct padata_instance *pinst, int cpu)

{

int err = 0;

if (cpumask_test_cpu(cpu, cpu_online_mask)) {

err = padata_replace(pinst);

if (padata_validate_cpumask(pinst, pinst->cpumask.pcpu) &&

padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))

__padata_start(pinst);

}

return err;

}

static int __padata_remove_cpu(struct padata_instance *pinst, int cpu)

{

int err = 0;

if (!cpumask_test_cpu(cpu, cpu_online_mask)) {

if (!padata_validate_cpumask(pinst, pinst->cpumask.pcpu) ||

!padata_validate_cpumask(pinst, pinst->cpumask.cbcpu))

__padata_stop(pinst);

err = padata_replace(pinst);

}

return err;

}

static inline int pinst_has_cpu(struct padata_instance *pinst, int cpu)

{

return cpumask_test_cpu(cpu, pinst->cpumask.pcpu) ||

cpumask_test_cpu(cpu, pinst->cpumask.cbcpu);

}

static int padata_cpu_online(unsigned int cpu, struct hlist_node *node)

{

struct padata_instance *pinst;

int ret;

pinst = hlist_entry_safe(node, struct padata_instance, cpu_online_node);

if (!pinst_has_cpu(pinst, cpu))

return 0;

mutex_lock(&pinst->lock);

ret = __padata_add_cpu(pinst, cpu);

mutex_unlock(&pinst->lock);

return ret;

}

static int padata_cpu_dead(unsigned int cpu, struct hlist_node *node)

{

struct padata_instance *pinst;

int ret;

pinst = hlist_entry_safe(node, struct padata_instance, cpu_dead_node);

if (!pinst_has_cpu(pinst, cpu))

return 0;

mutex_lock(&pinst->lock);

ret = __padata_remove_cpu(pinst, cpu);

mutex_unlock(&pinst->lock);

return ret;

}

static enum cpuhp_state hp_online;

static void __padata_free(struct padata_instance *pinst)

{

#ifdef CONFIG_HOTPLUG_CPU

cpuhp_state_remove_instance_nocalls(CPUHP_PADATA_DEAD,

&pinst->cpu_dead_node);

cpuhp_state_remove_instance_nocalls(hp_online, &pinst->cpu_online_node);

WARN_ON(!list_empty(&pinst->pslist));

free_cpumask_var(pinst->cpumask.pcpu);

free_cpumask_var(pinst->cpumask.cbcpu);

destroy_workqueue(pinst->serial_wq);

destroy_workqueue(pinst->parallel_wq);

kfree(pinst);

}

#define kobj2pinst(_kobj) \

container_of(_kobj, struct padata_instance, kobj)

#define attr2pentry(_attr) \

container_of(_attr, struct padata_sysfs_entry, attr)

static void padata_sysfs_release(struct kobject *kobj)

{

struct padata_instance *pinst = kobj2pinst(kobj);

__padata_free(pinst);

}

struct padata_sysfs_entry {

};

static ssize_t show_cpumask(struct padata_instance *pinst,

struct attribute *attr, char *buf)

{

struct cpumask *cpumask;

ssize_t len;

mutex_lock(&pinst->lock);

if (!strcmp(attr->name, "serial_cpumask"))

cpumask = pinst->cpumask.cbcpu;

else

cpumask = pinst->cpumask.pcpu;

len = snprintf(buf, PAGE_SIZE, "%*pb\n",

nr_cpu_ids, cpumask_bits(cpumask));

mutex_unlock(&pinst->lock);

return len < PAGE_SIZE ? len : -EINVAL;

}

static ssize_t store_cpumask(struct padata_instance *pinst,

struct attribute *attr,

const char *buf, size_t count)

{

cpumask_var_t new_cpumask;

ssize_t ret;

int mask_type;

if (!alloc_cpumask_var(&new_cpumask, GFP_KERNEL))

return -ENOMEM;

ret = bitmap_parse(buf, count, cpumask_bits(new_cpumask),

nr_cpumask_bits);

if (ret < 0)

goto out;

mask_type = !strcmp(attr->name, "serial_cpumask") ?

PADATA_CPU_SERIAL : PADATA_CPU_PARALLEL;

ret = padata_set_cpumask(pinst, mask_type, new_cpumask);

if (!ret)

ret = count;

out:

free_cpumask_var(new_cpumask);

return ret;

}

#define PADATA_ATTR_RW(_name, _show_name, _store_name) \

static struct padata_sysfs_entry _name##_attr = \

__ATTR(_name, 0644, _show_name, _store_name)

#define PADATA_ATTR_RO(_name, _show_name) \

static struct padata_sysfs_entry _name##_attr = \

__ATTR(_name, 0400, _show_name, NULL)

PADATA_ATTR_RW(serial_cpumask, show_cpumask, store_cpumask);

PADATA_ATTR_RW(parallel_cpumask, show_cpumask, store_cpumask);

static struct attribute *padata_default_attrs[] = {

&serial_cpumask_attr.attr,

&parallel_cpumask_attr.attr,

NULL,

};

ATTRIBUTE_GROUPS(padata_default);

static ssize_t padata_sysfs_show(struct kobject *kobj,

struct attribute *attr, char *buf)

{

struct padata_instance *pinst;

struct padata_sysfs_entry *pentry;

ssize_t ret = -EIO;

pinst = kobj2pinst(kobj);

pentry = attr2pentry(attr);

if (pentry->show)

ret = pentry->show(pinst, attr, buf);

return ret;

}

static ssize_t padata_sysfs_store(struct kobject *kobj, struct attribute *attr,

const char *buf, size_t count)

{

struct padata_instance *pinst;

struct padata_sysfs_entry *pentry;

ssize_t ret = -EIO;

pinst = kobj2pinst(kobj);

pentry = attr2pentry(attr);

if (pentry->show)

ret = pentry->store(pinst, attr, buf, count);

return ret;

}

static const struct sysfs_ops padata_sysfs_ops = {

.show = padata_sysfs_show,

.store = padata_sysfs_store,

};

static const struct kobj_type padata_attr_type = {

.sysfs_ops = &padata_sysfs_ops,

.default_groups = padata_default_groups,

.release = padata_sysfs_release,

};

struct padata_instance *padata_alloc(const char *name)

{

struct padata_instance *pinst;

pinst = kzalloc(sizeof(struct padata_instance), GFP_KERNEL);

if (!pinst)

goto err;

pinst->parallel_wq = alloc_workqueue("%s_parallel", WQ_UNBOUND, 0,

name);

if (!pinst->parallel_wq)

goto err_free_inst;

cpus_read_lock();

pinst->serial_wq = alloc_workqueue("%s_serial", WQ_MEM_RECLAIM |

WQ_CPU_INTENSIVE, 1, name);

if (!pinst->serial_wq)

goto err_put_cpus;