--- /dev/null
+/*
+ * 2007+ Copyright (c) Evgeniy Polyakov <zbr@ioremap.net>
+ * 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 <linux/kernel.h>
+#include <linux/dst.h>
+#include <linux/kthread.h>
+#include <linux/slab.h>
+
+/*
+ * 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 && p->thread_num) {
+ 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; i<num; ++i) {
+ err = thread_pool_add_worker(p, name, i, init,
+ cleanup, private);
+ if (err)
+ goto err_out_free_all;
+ }
+
+ return p;
+
+err_out_free_all:
+ list_for_each_entry_safe(w, tmp, &p->ready_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);
+}
projects / linux-2.6-omap-h63xx.git / blobdiff