diff --git a/drivers/staging/dst/thread_pool.c b/drivers/staging/dst/thread_pool.c new file mode 100644 index 000000000000..c35754d5ec6d --- /dev/null +++ b/drivers/staging/dst/thread_pool.c @@ -0,0 +1,345 @@ +/* + * 2007+ Copyright (c) Evgeniy Polyakov + * All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include +#include +#include +#include + +/* + * Thread pool abstraction allows to schedule a work to be performed + * on behalf of kernel thread. One does not operate with threads itself, + * instead user provides setup and cleanup callbacks for thread pool itself, + * and action and cleanup callbacks for each submitted work. + * + * Each worker has private data initialized at creation time and data, + * provided by user at scheduling time. + * + * When action is being performed, thread can not be used by other users, + * instead they will sleep until there is free thread to pick their work. + */ +struct thread_pool_worker +{ + struct list_head worker_entry; + + struct task_struct *thread; + + struct thread_pool *pool; + + int error; + int has_data; + int need_exit; + unsigned int id; + + wait_queue_head_t wait; + + void *private; + void *schedule_data; + + int (* action)(void *private, void *schedule_data); + void (* cleanup)(void *private); +}; + +static void thread_pool_exit_worker(struct thread_pool_worker *w) +{ + kthread_stop(w->thread); + + w->cleanup(w->private); + kfree(w); +} + +/* + * Called to mark thread as ready and allow users to schedule new work. + */ +static void thread_pool_worker_make_ready(struct thread_pool_worker *w) +{ + struct thread_pool *p = w->pool; + + mutex_lock(&p->thread_lock); + + if (!w->need_exit) { + list_move_tail(&w->worker_entry, &p->ready_list); + w->has_data = 0; + mutex_unlock(&p->thread_lock); + + wake_up(&p->wait); + } else { + p->thread_num--; + list_del(&w->worker_entry); + mutex_unlock(&p->thread_lock); + + thread_pool_exit_worker(w); + } +} + +/* + * Thread action loop: waits until there is new work. + */ +static int thread_pool_worker_func(void *data) +{ + struct thread_pool_worker *w = data; + + while (!kthread_should_stop()) { + wait_event_interruptible(w->wait, + kthread_should_stop() || w->has_data); + + if (kthread_should_stop()) + break; + + if (!w->has_data) + continue; + + w->action(w->private, w->schedule_data); + thread_pool_worker_make_ready(w); + } + + return 0; +} + +/* + * Remove single worker without specifying which one. + */ +void thread_pool_del_worker(struct thread_pool *p) +{ + struct thread_pool_worker *w = NULL; + + while (!w) { + wait_event(p->wait, !list_empty(&p->ready_list) || !p->thread_num); + + dprintk("%s: locking list_empty: %d, thread_num: %d.\n", + __func__, list_empty(&p->ready_list), p->thread_num); + + mutex_lock(&p->thread_lock); + if (!list_empty(&p->ready_list)) { + w = list_first_entry(&p->ready_list, + struct thread_pool_worker, + worker_entry); + + dprintk("%s: deleting w: %p, thread_num: %d, list: %p [%p.%p].\n", + __func__, w, p->thread_num, &p->ready_list, + p->ready_list.prev, p->ready_list.next); + + p->thread_num--; + list_del(&w->worker_entry); + } + mutex_unlock(&p->thread_lock); + } + + if (w) + thread_pool_exit_worker(w); + dprintk("%s: deleted w: %p, thread_num: %d.\n", + __func__, w, p->thread_num); +} + +/* + * Remove a worker with given ID. + */ +void thread_pool_del_worker_id(struct thread_pool *p, unsigned int id) +{ + struct thread_pool_worker *w; + int found = 0; + + mutex_lock(&p->thread_lock); + list_for_each_entry(w, &p->ready_list, worker_entry) { + if (w->id == id) { + found = 1; + p->thread_num--; + list_del(&w->worker_entry); + break; + } + } + + if (!found) { + list_for_each_entry(w, &p->active_list, worker_entry) { + if (w->id == id) { + w->need_exit = 1; + break; + } + } + } + mutex_unlock(&p->thread_lock); + + if (found) + thread_pool_exit_worker(w); +} + +/* + * Add new worker thread with given parameters. + * If initialization callback fails, return error. + */ +int thread_pool_add_worker(struct thread_pool *p, + char *name, + unsigned int id, + void *(* init)(void *private), + void (* cleanup)(void *private), + void *private) +{ + struct thread_pool_worker *w; + int err = -ENOMEM; + + w = kzalloc(sizeof(struct thread_pool_worker), GFP_KERNEL); + if (!w) + goto err_out_exit; + + w->pool = p; + init_waitqueue_head(&w->wait); + w->cleanup = cleanup; + w->id = id; + + w->thread = kthread_run(thread_pool_worker_func, w, "%s", name); + if (IS_ERR(w->thread)) { + err = PTR_ERR(w->thread); + goto err_out_free; + } + + w->private = init(private); + if (IS_ERR(w->private)) { + err = PTR_ERR(w->private); + goto err_out_stop_thread; + } + + mutex_lock(&p->thread_lock); + list_add_tail(&w->worker_entry, &p->ready_list); + p->thread_num++; + mutex_unlock(&p->thread_lock); + + return 0; + +err_out_stop_thread: + kthread_stop(w->thread); +err_out_free: + kfree(w); +err_out_exit: + return err; +} + +/* + * Destroy the whole pool. + */ +void thread_pool_destroy(struct thread_pool *p) +{ + while (p->thread_num) { + dprintk("%s: num: %d.\n", __func__, p->thread_num); + thread_pool_del_worker(p); + } + + kfree(p); +} + +/* + * Create a pool with given number of threads. + * They will have sequential IDs started from zero. + */ +struct thread_pool *thread_pool_create(int num, char *name, + void *(* init)(void *private), + void (* cleanup)(void *private), + void *private) +{ + struct thread_pool_worker *w, *tmp; + struct thread_pool *p; + int err = -ENOMEM; + int i; + + p = kzalloc(sizeof(struct thread_pool), GFP_KERNEL); + if (!p) + goto err_out_exit; + + init_waitqueue_head(&p->wait); + mutex_init(&p->thread_lock); + INIT_LIST_HEAD(&p->ready_list); + INIT_LIST_HEAD(&p->active_list); + p->thread_num = 0; + + for (i=0; iready_list, worker_entry) { + list_del(&w->worker_entry); + thread_pool_exit_worker(w); + } + kfree(p); +err_out_exit: + return ERR_PTR(err); +} + +/* + * Schedule execution of the action on a given thread, + * provided ID pointer has to match previously stored + * private data. + */ +int thread_pool_schedule_private(struct thread_pool *p, + int (* setup)(void *private, void *data), + int (* action)(void *private, void *data), + void *data, long timeout, void *id) +{ + struct thread_pool_worker *w, *tmp, *worker = NULL; + int err = 0; + + while (!worker && !err) { + timeout = wait_event_interruptible_timeout(p->wait, + !list_empty(&p->ready_list), + timeout); + + if (!timeout) { + err = -ETIMEDOUT; + break; + } + + worker = NULL; + mutex_lock(&p->thread_lock); + list_for_each_entry_safe(w, tmp, &p->ready_list, worker_entry) { + if (id && id != w->private) + continue; + + worker = w; + + list_move_tail(&w->worker_entry, &p->active_list); + + err = setup(w->private, data); + if (!err) { + w->schedule_data = data; + w->action = action; + w->has_data = 1; + wake_up(&w->wait); + } else { + list_move_tail(&w->worker_entry, &p->ready_list); + } + + break; + } + mutex_unlock(&p->thread_lock); + } + + return err; +} + +/* + * Schedule execution on arbitrary thread from the pool. + */ +int thread_pool_schedule(struct thread_pool *p, + int (* setup)(void *private, void *data), + int (* action)(void *private, void *data), + void *data, long timeout) +{ + return thread_pool_schedule_private(p, setup, + action, data, timeout, NULL); +}