/*-
 * Copyright (c) 2000 Doug Rabson
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/libkern.h>
#include <sys/limits.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/smp.h>
#include <sys/taskqueue.h>
#include <machine/stdarg.h>

static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
static void	*taskqueue_giant_ih;
static void	*taskqueue_ih;

struct taskqueue_busy {
	struct task	*tb_running;
	TAILQ_ENTRY(taskqueue_busy) tb_link;
};

struct task * const TB_DRAIN_WAITER = (struct task *)0x1;

struct taskqueue {
	STAILQ_HEAD(, task)	tq_queue;
	taskqueue_enqueue_fn	tq_enqueue;
	void			*tq_context;
	char			*tq_name;
	TAILQ_HEAD(, taskqueue_busy) tq_active;
	struct mtx		tq_mutex;
#ifdef __HAIKU__
	sem_id tq_sem;
	thread_id *tq_threads;
	thread_id tq_thread_storage;
	int tq_threadcount;
#else
	struct thread		**tq_threads;
#endif
	int			tq_tcount;
	int			tq_spin;
	int			tq_flags;
	int			tq_callouts;
	taskqueue_callback_fn	tq_callbacks[TASKQUEUE_NUM_CALLBACKS];
	void			*tq_cb_contexts[TASKQUEUE_NUM_CALLBACKS];
};

#define	TQ_FLAGS_ACTIVE		(1 << 0)
#define	TQ_FLAGS_BLOCKED	(1 << 1)
#define	TQ_FLAGS_UNLOCKED_ENQUEUE	(1 << 2)

#define	DT_CALLOUT_ARMED	(1 << 0)
#define	DT_DRAIN_IN_PROGRESS	(1 << 1)

#define	TQ_LOCK(tq)							\
	do {								\
		if ((tq)->tq_spin)					\
			mtx_lock_spin(&(tq)->tq_mutex);			\
		else							\
			mtx_lock(&(tq)->tq_mutex);			\
	} while (0)
#define	TQ_ASSERT_LOCKED(tq)	mtx_assert(&(tq)->tq_mutex, MA_OWNED)

#define	TQ_UNLOCK(tq)							\
	do {								\
		if ((tq)->tq_spin)					\
			mtx_unlock_spin(&(tq)->tq_mutex);		\
		else							\
			mtx_unlock(&(tq)->tq_mutex);			\
	} while (0)
#define	TQ_ASSERT_UNLOCKED(tq)	mtx_assert(&(tq)->tq_mutex, MA_NOTOWNED)

void
_timeout_task_init(struct taskqueue *queue, struct timeout_task *timeout_task,
	int priority, task_fn_t func, void *context)
{

	TASK_INIT(&timeout_task->t, priority, func, context);
	callout_init_mtx(&timeout_task->c, &queue->tq_mutex,
		CALLOUT_RETURNUNLOCKED);
	timeout_task->q = queue;
	timeout_task->f = 0;
}

static struct taskqueue *
_taskqueue_create(const char *name, int mflags,
		 taskqueue_enqueue_fn enqueue, void *context,
		 int mtxflags, const char *mtxname __unused)
{
	struct taskqueue *queue;
	char *tq_name;

	tq_name = malloc(TASKQUEUE_NAMELEN, M_TASKQUEUE, mflags | M_ZERO);
	if (tq_name == NULL)
		return (NULL);

	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
	if (queue == NULL) {
		free(tq_name, M_TASKQUEUE);
		return (NULL);
	}

	snprintf(tq_name, TASKQUEUE_NAMELEN, "%s", (name) ? name : "taskqueue");

	STAILQ_INIT(&queue->tq_queue);
	TAILQ_INIT(&queue->tq_active);
	queue->tq_enqueue = enqueue;
	queue->tq_context = context;
	queue->tq_name = tq_name;
	queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
	queue->tq_flags |= TQ_FLAGS_ACTIVE;
	if (enqueue == taskqueue_thread_enqueue)
		queue->tq_flags |= TQ_FLAGS_UNLOCKED_ENQUEUE;
	mtx_init(&queue->tq_mutex, tq_name, NULL, mtxflags);

	return (queue);
}

struct taskqueue *
taskqueue_create(const char *name, int mflags,
		 taskqueue_enqueue_fn enqueue, void *context)
{

	return _taskqueue_create(name, mflags, enqueue, context,
			MTX_DEF, name);
}

void
taskqueue_set_callback(struct taskqueue *queue,
	enum taskqueue_callback_type cb_type, taskqueue_callback_fn callback,
	void *context)
{

	KASSERT(((cb_type >= TASKQUEUE_CALLBACK_TYPE_MIN) &&
		(cb_type <= TASKQUEUE_CALLBACK_TYPE_MAX)),
		("Callback type %d not valid, must be %d-%d", cb_type,
		TASKQUEUE_CALLBACK_TYPE_MIN, TASKQUEUE_CALLBACK_TYPE_MAX));
	KASSERT((queue->tq_callbacks[cb_type] == NULL),
		("Re-initialization of taskqueue callback?"));

	queue->tq_callbacks[cb_type] = callback;
	queue->tq_cb_contexts[cb_type] = context;
}

void
taskqueue_free(struct taskqueue *queue)
{

	TQ_LOCK(queue);
	queue->tq_flags &= ~TQ_FLAGS_ACTIVE;
	taskqueue_terminate(queue->tq_threads, queue);
	KASSERT(TAILQ_EMPTY(&queue->tq_active), ("Tasks still running?"));
	KASSERT(queue->tq_callouts == 0, ("Armed timeout tasks"));
#ifdef __HAIKU__
	TQ_UNLOCK(queue);
#endif
	mtx_destroy(&queue->tq_mutex);
	free(queue->tq_threads, M_TASKQUEUE);
	free(queue->tq_name, M_TASKQUEUE);
	free(queue, M_TASKQUEUE);
}

static int
taskqueue_enqueue_locked(struct taskqueue *queue, struct task *task)
{
	struct task *ins;
	struct task *prev;

	KASSERT(task->ta_func != NULL, ("enqueueing task with NULL func"));
	/*
	 * Count multiple enqueues.
	 */
	if (task->ta_pending) {
		if (task->ta_pending < USHRT_MAX)
			task->ta_pending++;
		TQ_UNLOCK(queue);
		return (0);
	}

	/*
	 * Optimise the case when all tasks have the same priority.
	 */
	prev = STAILQ_LAST(&queue->tq_queue, task, ta_link);
	if (!prev || prev->ta_priority >= task->ta_priority) {
		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
	} else {
		prev = NULL;
		for (ins = STAILQ_FIRST(&queue->tq_queue); ins;
			 prev = ins, ins = STAILQ_NEXT(ins, ta_link))
			if (ins->ta_priority < task->ta_priority)
				break;

		if (prev)
			STAILQ_INSERT_AFTER(&queue->tq_queue, prev, task, ta_link);
		else
			STAILQ_INSERT_HEAD(&queue->tq_queue, task, ta_link);
	}

	task->ta_pending = 1;
	if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) != 0)
		TQ_UNLOCK(queue);
	if ((queue->tq_flags & TQ_FLAGS_BLOCKED) == 0)
		queue->tq_enqueue(queue->tq_context);
	if ((queue->tq_flags & TQ_FLAGS_UNLOCKED_ENQUEUE) == 0)
		TQ_UNLOCK(queue);

	/* Return with lock released. */
	return (0);
}

int
taskqueue_enqueue(struct taskqueue *queue, struct task *task)
{
	int res;

	TQ_LOCK(queue);
	res = taskqueue_enqueue_locked(queue, task);
	/* The lock is released inside. */

	return (res);
}

static void
taskqueue_timeout_func(void *arg)
{
	struct taskqueue *queue;
	struct timeout_task *timeout_task;

	timeout_task = arg;
	queue = timeout_task->q;
	KASSERT((timeout_task->f & DT_CALLOUT_ARMED) != 0, ("Stray timeout"));
	timeout_task->f &= ~DT_CALLOUT_ARMED;
	queue->tq_callouts--;
	taskqueue_enqueue_locked(timeout_task->q, &timeout_task->t);
	/* The lock is released inside. */
}

int
taskqueue_enqueue_timeout(struct taskqueue *queue,
	struct timeout_task *timeout_task, int _ticks)
{
	int res;

	TQ_LOCK(queue);
	KASSERT(timeout_task->q == NULL || timeout_task->q == queue,
		("Migrated queue"));
	KASSERT(!queue->tq_spin, ("Timeout for spin-queue"));
	timeout_task->q = queue;
	res = timeout_task->t.ta_pending;
	if (timeout_task->f & DT_DRAIN_IN_PROGRESS) {
		/* Do nothing */
		TQ_UNLOCK(queue);
		res = -1;
	} else if (_ticks == 0) {
		taskqueue_enqueue_locked(queue, &timeout_task->t);
		/* The lock is released inside. */
	} else {
		if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
			res++;
		} else {
			queue->tq_callouts++;
			timeout_task->f |= DT_CALLOUT_ARMED;
			if (_ticks < 0)
				_ticks = -_ticks; /* Ignore overflow. */
		}
		if (_ticks > 0) {
			callout_reset(&timeout_task->c, _ticks,
				taskqueue_timeout_func, timeout_task);
		}
		TQ_UNLOCK(queue);
	}
	return (res);
}

static void
taskqueue_task_nop_fn(void *context, int pending)
{
}

void
taskqueue_block(struct taskqueue *queue)
{

	TQ_LOCK(queue);
	queue->tq_flags |= TQ_FLAGS_BLOCKED;
	TQ_UNLOCK(queue);
}

void
taskqueue_unblock(struct taskqueue *queue)
{

	TQ_LOCK(queue);
	queue->tq_flags &= ~TQ_FLAGS_BLOCKED;
	if (!STAILQ_EMPTY(&queue->tq_queue))
		queue->tq_enqueue(queue->tq_context);
	TQ_UNLOCK(queue);
}

static void
taskqueue_run_locked(struct taskqueue *queue)
{
	struct taskqueue_busy tb;
	struct taskqueue_busy *tb_first;
	struct task *task;
	int pending;

	KASSERT(queue != NULL, ("tq is NULL"));
	TQ_ASSERT_LOCKED(queue);
	tb.tb_running = NULL;

	while (STAILQ_FIRST(&queue->tq_queue)) {
		TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);

		/*
		 * Carefully remove the first task from the queue and
		 * zero its pending count.
		 */
		task = STAILQ_FIRST(&queue->tq_queue);
		KASSERT(task != NULL, ("task is NULL"));
		STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
		pending = task->ta_pending;
		task->ta_pending = 0;
		tb.tb_running = task;
		TQ_UNLOCK(queue);

		KASSERT(task->ta_func != NULL, ("task->ta_func is NULL"));
#ifdef __HAIKU__
		if ((task->ta_flags & TASK_NEEDSGIANT) != 0)
			mtx_lock(&Giant);
#endif
		task->ta_func(task->ta_context, pending);
#ifdef __HAIKU__
		if ((task->ta_flags & TASK_NEEDSGIANT) != 0)
			mtx_unlock(&Giant);
#endif

		TQ_LOCK(queue);
		tb.tb_running = NULL;

		TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
		tb_first = TAILQ_FIRST(&queue->tq_active);
	}
}

void
taskqueue_run(struct taskqueue *queue)
{

	TQ_LOCK(queue);
	taskqueue_run_locked(queue);
	TQ_UNLOCK(queue);
}

static int
task_is_running(struct taskqueue *queue, struct task *task)
{
	struct taskqueue_busy *tb;

	TQ_ASSERT_LOCKED(queue);
	TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
		if (tb->tb_running == task)
			return (1);
	}
	return (0);
}

static int
taskqueue_cancel_locked(struct taskqueue *queue, struct task *task,
	u_int *pendp)
{

	if (task->ta_pending > 0)
		STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
	if (pendp != NULL)
		*pendp = task->ta_pending;
	task->ta_pending = 0;
	return (task_is_running(queue, task) ? EBUSY : 0);
}

int
taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
{
	int error;

	TQ_LOCK(queue);
	error = taskqueue_cancel_locked(queue, task, pendp);
	TQ_UNLOCK(queue);

	return (error);
}

int
taskqueue_cancel_timeout(struct taskqueue *queue,
	struct timeout_task *timeout_task, u_int *pendp)
{
	u_int pending, pending1;
	int error;

	TQ_LOCK(queue);
	pending = !!(callout_stop(&timeout_task->c) > 0);
	error = taskqueue_cancel_locked(queue, &timeout_task->t, &pending1);
	if ((timeout_task->f & DT_CALLOUT_ARMED) != 0) {
		timeout_task->f &= ~DT_CALLOUT_ARMED;
		queue->tq_callouts--;
	}
	TQ_UNLOCK(queue);

	if (pendp != NULL)
		*pendp = pending + pending1;
	return (error);
}

void
taskqueue_drain_timeout(struct taskqueue *queue,
	struct timeout_task *timeout_task)
{

	/*
	 * Set flag to prevent timer from re-starting during drain:
	 */
	TQ_LOCK(queue);
	KASSERT((timeout_task->f & DT_DRAIN_IN_PROGRESS) == 0,
		("Drain already in progress"));
	timeout_task->f |= DT_DRAIN_IN_PROGRESS;
	TQ_UNLOCK(queue);

	callout_drain(&timeout_task->c);
	taskqueue_drain(queue, &timeout_task->t);

	/*
	 * Clear flag to allow timer to re-start:
	 */
	TQ_LOCK(queue);
	timeout_task->f &= ~DT_DRAIN_IN_PROGRESS;
	TQ_UNLOCK(queue);
}

int
taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
	const char *format, ...)
{
	char name[64];
	int error;
	va_list vl;

	va_start(vl, format);
	vsnprintf(name, sizeof(name), format, vl);
	va_end(vl);

	error = _taskqueue_start_threads(tqp, count, pri, name);
	return (error);
}

static inline void
taskqueue_run_callback(struct taskqueue *tq,
	enum taskqueue_callback_type cb_type)
{
	taskqueue_callback_fn tq_callback;

	TQ_ASSERT_UNLOCKED(tq);
	tq_callback = tq->tq_callbacks[cb_type];
	if (tq_callback != NULL)
		tq_callback(tq->tq_cb_contexts[cb_type]);
}

int
taskqueue_member(struct taskqueue *queue, struct thread *td)
{
	int i, j, ret = 0;

	for (i = 0, j = 0; ; i++) {
		if (queue->tq_threads[i] == NULL)
			continue;
		if (queue->tq_threads[i] == td) {
			ret = 1;
			break;
		}
		if (++j >= queue->tq_tcount)
			break;
	}
	return (ret);
}

struct taskqueue *
taskqueue_create_fast(const char *name, int mflags,
		 taskqueue_enqueue_fn enqueue, void *context)
{
	return _taskqueue_create(name, mflags, enqueue, context,
			MTX_SPIN, "fast_taskqueue");
}