/*-
 * 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");
}