/*-
 * Copyright (c) 2010 Isilon Systems, Inc.
 * Copyright (c) 2010 iX Systems, Inc.
 * Copyright (c) 2010 Panasas, Inc.
 * Copyright (c) 2013-2017 Mellanox Technologies, Ltd.
 * 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 unmodified, 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 ``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 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.
 */
#ifndef _LINUXKPI_LINUX_KTHREAD_H_
#define _LINUXKPI_LINUX_KTHREAD_H_

#include <linux/sched.h>

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/malloc.h>
#include <sys/queue.h>
#include <sys/taskqueue.h>
#include <sys/unistd.h>

struct task_struct;
struct kthread_work;

typedef void (*kthread_work_func_t)(struct kthread_work *work);

struct kthread_worker {
        struct task_struct      *task;
        struct taskqueue        *tq;
};

struct kthread_work {
        struct taskqueue        *tq;
        struct task             task;
        kthread_work_func_t     func;
};

#define kthread_run(fn, data, fmt, ...) ({                              \
        struct task_struct *__task;                                     \
        struct thread *__td;                                            \
                                                                        \
        if (kthread_add(linux_kthread_fn, NULL, NULL, &__td,            \
            RFSTOPPED, 0, fmt, ## __VA_ARGS__))                         \
                __task = NULL;                                          \
        else                                                            \
                __task = linux_kthread_setup_and_run(__td, fn, data);   \
        __task;                                                         \
})

int linux_kthread_stop(struct task_struct *);
bool linux_kthread_should_stop_task(struct task_struct *);
bool linux_kthread_should_stop(void);
int linux_kthread_park(struct task_struct *);
void linux_kthread_parkme(void);
bool linux_kthread_should_park(void);
void linux_kthread_unpark(struct task_struct *);
void linux_kthread_fn(void *);
struct task_struct *linux_kthread_setup_and_run(struct thread *,
    linux_task_fn_t *, void *arg);
int linux_in_atomic(void);

#define kthread_stop(task)              linux_kthread_stop(task)
#define kthread_should_stop()           linux_kthread_should_stop()
#define kthread_should_stop_task(task)  linux_kthread_should_stop_task(task)
#define kthread_park(task)              linux_kthread_park(task)
#define kthread_parkme()                linux_kthread_parkme()
#define kthread_should_park()           linux_kthread_should_park()
#define kthread_unpark(task)            linux_kthread_unpark(task)

#define in_atomic()                     linux_in_atomic()

/* Only kthread_(create|destroy)_worker interface is allowed */
#define kthread_init_worker(worker)     \
        _Static_assert(false, "pre-4.9 worker interface is not supported");

task_fn_t lkpi_kthread_work_fn;
task_fn_t lkpi_kthread_worker_init_fn;

#define kthread_create_worker(flags, fmt, ...) ({                       \
        struct kthread_worker *__w;                                     \
        struct task __task;                                             \
                                                                        \
        __w = malloc(sizeof(*__w), M_KMALLOC, M_WAITOK | M_ZERO);       \
        __w->tq = taskqueue_create("lkpi kthread taskq", M_WAITOK,      \
            taskqueue_thread_enqueue, &__w->tq);                        \
        taskqueue_start_threads(&__w->tq, 1, PWAIT, fmt, ##__VA_ARGS__);\
        TASK_INIT(&__task, 0, lkpi_kthread_worker_init_fn, __w);        \
        taskqueue_enqueue(__w->tq, &__task);                            \
        taskqueue_drain(__w->tq, &__task);                              \
        __w;                                                            \
})

static inline void
kthread_destroy_worker(struct kthread_worker *worker)
{
        taskqueue_drain_all(worker->tq);
        taskqueue_free(worker->tq);
        free(worker, M_KMALLOC);
}

static inline void
kthread_init_work(struct kthread_work *work, kthread_work_func_t func)
{
        work->tq = NULL;
        work->func = func;
        TASK_INIT(&work->task, 0, lkpi_kthread_work_fn, work);
}

static inline bool
kthread_queue_work(struct kthread_worker *worker, struct kthread_work *work)
{
        int error;

        error = taskqueue_enqueue_flags(worker->tq, &work->task,
            TASKQUEUE_FAIL_IF_CANCELING | TASKQUEUE_FAIL_IF_PENDING);
        if (error == 0)
                work->tq = worker->tq;
        return (error == 0);
}

static inline bool
kthread_cancel_work_sync(struct kthread_work *work)
{
        u_int pending = 0;

        if (work->tq != NULL &&
            taskqueue_cancel(work->tq, &work->task, &pending) != 0)
                taskqueue_drain(work->tq, &work->task);

        return (pending != 0);
}

static inline void
kthread_flush_work(struct kthread_work *work)
{
        if (work->tq != NULL)
                taskqueue_drain(work->tq, &work->task);
}

static inline void
kthread_flush_worker(struct kthread_worker *worker)
{
        taskqueue_drain_all(worker->tq);
}

#endif /* _LINUXKPI_LINUX_KTHREAD_H_ */