[mirror_spl-debian.git] / modules / spl / spl-taskq.c

/*
 *  This file is part of the SPL: Solaris Porting Layer.
 *
 *  Copyright (c) 2008 Lawrence Livermore National Security, LLC.
 *  Produced at Lawrence Livermore National Laboratory
 *  Written by:
 *          Brian Behlendorf <behlendorf1@llnl.gov>,
 *          Herb Wartens <wartens2@llnl.gov>,
 *          Jim Garlick <garlick@llnl.gov>
 *  UCRL-CODE-235197
 *
 *  This 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 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.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA.
 */

#include <sys/taskq.h>
#include <sys/kmem.h>

#ifdef DEBUG_SUBSYSTEM
#undef DEBUG_SUBSYSTEM
#endif

#define DEBUG_SUBSYSTEM S_TASKQ

typedef struct spl_task {
        spinlock_t              t_lock;
        struct list_head        t_list;
        taskqid_t               t_id;
        task_func_t             *t_func;
        void                    *t_arg;
} spl_task_t;

/* NOTE: Must be called with tq->tq_lock held, returns a list_t which
 * is not attached to the free, work, or pending taskq lists.
 */
static spl_task_t *
task_alloc(taskq_t *tq, uint_t flags)
{
        spl_task_t *t;
        int count = 0;
        ENTRY;

        ASSERT(tq);
        ASSERT(flags & (TQ_SLEEP | TQ_NOSLEEP));               /* One set */
        ASSERT(!((flags & TQ_SLEEP) && (flags & TQ_NOSLEEP))); /* Not both */
        ASSERT(spin_is_locked(&tq->tq_lock));
retry:
        /* Aquire spl_task_t's from free list if available */
        if (!list_empty(&tq->tq_free_list) && !(flags & TQ_NEW)) {
                t = list_entry(tq->tq_free_list.next, spl_task_t, t_list);
                list_del_init(&t->t_list);
                RETURN(t);
        }

        /* Free list is empty and memory allocs are prohibited */
        if (flags & TQ_NOALLOC)
                RETURN(NULL);

        /* Hit maximum spl_task_t pool size */
        if (tq->tq_nalloc >= tq->tq_maxalloc) {
                if (flags & TQ_NOSLEEP)
                        RETURN(NULL);

                /* Sleep periodically polling the free list for an available
                 * spl_task_t.  If a full second passes and we have not found
                 * one gives up and return a NULL to the caller. */
                if (flags & TQ_SLEEP) {
                        spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
                        schedule_timeout(HZ / 100);
                        spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
                        if (count < 100)
                                GOTO(retry, count++);

                        RETURN(NULL);
                }

                /* Unreachable, TQ_SLEEP xor TQ_NOSLEEP */
                SBUG();
        }

	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
        t = kmem_alloc(sizeof(spl_task_t), flags & (TQ_SLEEP | TQ_NOSLEEP));
        spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);

	if (t) {
		spin_lock_init(&t->t_lock);
                INIT_LIST_HEAD(&t->t_list);
		t->t_id = 0;
		t->t_func = NULL;
		t->t_arg = NULL;
		tq->tq_nalloc++;
	}

        RETURN(t);
}

/* NOTE: Must be called with tq->tq_lock held, expectes the spl_task_t
 * to already be removed from the free, work, or pending taskq lists.
 */
static void
task_free(taskq_t *tq, spl_task_t *t)
{
        ENTRY;

        ASSERT(tq);
        ASSERT(t);
	ASSERT(spin_is_locked(&tq->tq_lock));
	ASSERT(list_empty(&t->t_list));

        kmem_free(t, sizeof(spl_task_t));
        tq->tq_nalloc--;

	EXIT;
}

/* NOTE: Must be called with tq->tq_lock held, either destroyes the
 * spl_task_t if too many exist or moves it to the free list for later use.
 */
static void
task_done(taskq_t *tq, spl_task_t *t)
{
	ENTRY;
	ASSERT(tq);
	ASSERT(t);
	ASSERT(spin_is_locked(&tq->tq_lock));

	list_del_init(&t->t_list);

        if (tq->tq_nalloc <= tq->tq_minalloc) {
		t->t_id = 0;
		t->t_func = NULL;
		t->t_arg = NULL;
                list_add_tail(&t->t_list, &tq->tq_free_list);
	} else {
		task_free(tq, t);
	}

        EXIT;
}

/* Taskqid's are handed out in a monotonically increasing fashion per
 * taskq_t.  We don't handle taskqid wrapping yet, but fortuntely it isi
 * a 64-bit value so this is probably never going to happen.  The lowest
 * pending taskqid is stored in the taskq_t to make it easy for any
 * taskq_wait()'ers to know if the tasks they're waiting for have
 * completed.  Unfortunately, tq_task_lowest is kept up to date is
 * a pretty brain dead way, something more clever should be done.
 */
static int
taskq_wait_check(taskq_t *tq, taskqid_t id)
{
	RETURN(tq->tq_lowest_id >= id);
}

/* Expected to wait for all previously scheduled tasks to complete.  We do
 * not need to wait for tasked scheduled after this call to complete.  In
 * otherwords we do not need to drain the entire taskq. */
void
__taskq_wait_id(taskq_t *tq, taskqid_t id)
{
	ENTRY;
	ASSERT(tq);

	wait_event(tq->tq_wait_waitq, taskq_wait_check(tq, id));

	EXIT;
}
EXPORT_SYMBOL(__taskq_wait_id);

void
__taskq_wait(taskq_t *tq)
{
	taskqid_t id;
	ENTRY;
	ASSERT(tq);

	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	id = tq->tq_next_id;
	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);

	__taskq_wait_id(tq, id);

	EXIT;

}
EXPORT_SYMBOL(__taskq_wait);

int
__taskq_member(taskq_t *tq, void *t)
{
        int i;
        ENTRY;

	ASSERT(tq);
        ASSERT(t);

        for (i = 0; i < tq->tq_nthreads; i++)
                if (tq->tq_threads[i] == (struct task_struct *)t)
                        RETURN(1);

        RETURN(0);
}
EXPORT_SYMBOL(__taskq_member);

taskqid_t
__taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t flags)
{
        spl_task_t *t;
	taskqid_t rc = 0;
        ENTRY;

        ASSERT(tq);
        ASSERT(func);
        if (unlikely(in_atomic() && (flags & TQ_SLEEP))) {
		CERROR("May schedule while atomic: %s/0x%08x/%d\n",
                       current->comm, preempt_count(), current->pid);
		SBUG();
	}

        spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);

	/* Taskq being destroyed and all tasks drained */
	if (!(tq->tq_flags & TQ_ACTIVE))
		GOTO(out, rc = 0);

	/* Do not queue the task unless there is idle thread for it */
	ASSERT(tq->tq_nactive <= tq->tq_nthreads);
	if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads))
		GOTO(out, rc = 0);

        if ((t = task_alloc(tq, flags)) == NULL)
		GOTO(out, rc = 0);

	spin_lock(&t->t_lock);
	list_add_tail(&t->t_list, &tq->tq_pend_list);
	t->t_id = rc = tq->tq_next_id;
	tq->tq_next_id++;
        t->t_func = func;
        t->t_arg = arg;
	spin_unlock(&t->t_lock);

	wake_up(&tq->tq_work_waitq);
out:
	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	RETURN(rc);
}
EXPORT_SYMBOL(__taskq_dispatch);

/* NOTE: Must be called with tq->tq_lock held */
static taskqid_t
taskq_lowest_id(taskq_t *tq)
{
	taskqid_t lowest_id = ~0;
        spl_task_t *t;
	ENTRY;

	ASSERT(tq);
	ASSERT(spin_is_locked(&tq->tq_lock));

	list_for_each_entry(t, &tq->tq_pend_list, t_list)
		if (t->t_id < lowest_id)
			lowest_id = t->t_id;

	list_for_each_entry(t, &tq->tq_work_list, t_list)
		if (t->t_id < lowest_id)
			lowest_id = t->t_id;

	RETURN(lowest_id);
}

static int
taskq_thread(void *args)
{
        DECLARE_WAITQUEUE(wait, current);
        sigset_t blocked;
	taskqid_t id;
        taskq_t *tq = args;
        spl_task_t *t;
	ENTRY;

        ASSERT(tq);
        current->flags |= PF_NOFREEZE;

        sigfillset(&blocked);
        sigprocmask(SIG_BLOCK, &blocked, NULL);
        flush_signals(current);

        spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
        tq->tq_nthreads++;
        wake_up(&tq->tq_wait_waitq);
        set_current_state(TASK_INTERRUPTIBLE);

        while (!kthread_should_stop()) {

		add_wait_queue(&tq->tq_work_waitq, &wait);
		if (list_empty(&tq->tq_pend_list)) {
			spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
			schedule();
			spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
		} else {
			__set_current_state(TASK_RUNNING);
		}

		remove_wait_queue(&tq->tq_work_waitq, &wait);
                if (!list_empty(&tq->tq_pend_list)) {
                        t = list_entry(tq->tq_pend_list.next, spl_task_t, t_list);
                        list_del_init(&t->t_list);
			list_add_tail(&t->t_list, &tq->tq_work_list);
                        tq->tq_nactive++;
			spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);

			/* Perform the requested task */
                        t->t_func(t->t_arg);

			spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
                        tq->tq_nactive--;
			id = t->t_id;
                        task_done(tq, t);

			/* Update the lowest remaining taskqid yet to run */
			if (tq->tq_lowest_id == id) {
				tq->tq_lowest_id = taskq_lowest_id(tq);
				ASSERT(tq->tq_lowest_id > id);
			}

                        wake_up_all(&tq->tq_wait_waitq);
		}

		set_current_state(TASK_INTERRUPTIBLE);

        }

	__set_current_state(TASK_RUNNING);
        tq->tq_nthreads--;
        spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);

	RETURN(0);
}

taskq_t *
__taskq_create(const char *name, int nthreads, pri_t pri,
               int minalloc, int maxalloc, uint_t flags)
{
        taskq_t *tq;
        struct task_struct *t;
        int rc = 0, i, j = 0;
        ENTRY;

        ASSERT(name != NULL);
        ASSERT(pri <= maxclsyspri);
        ASSERT(minalloc >= 0);
        ASSERT(maxalloc <= INT_MAX);
        ASSERT(!(flags & (TASKQ_CPR_SAFE | TASKQ_DYNAMIC))); /* Unsupported */

        tq = kmem_alloc(sizeof(*tq), KM_SLEEP);
        if (tq == NULL)
                RETURN(NULL);

        tq->tq_threads = kmem_alloc(nthreads * sizeof(t), KM_SLEEP);
        if (tq->tq_threads == NULL) {
                kmem_free(tq, sizeof(*tq));
                RETURN(NULL);
        }

        spin_lock_init(&tq->tq_lock);
        spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
        tq->tq_name      = name;
        tq->tq_nactive   = 0;
	tq->tq_nthreads  = 0;
        tq->tq_pri       = pri;
        tq->tq_minalloc  = minalloc;
        tq->tq_maxalloc  = maxalloc;
	tq->tq_nalloc    = 0;
        tq->tq_flags     = (flags | TQ_ACTIVE);
	tq->tq_next_id   = 1;
	tq->tq_lowest_id = 1;
        INIT_LIST_HEAD(&tq->tq_free_list);
        INIT_LIST_HEAD(&tq->tq_work_list);
        INIT_LIST_HEAD(&tq->tq_pend_list);
        init_waitqueue_head(&tq->tq_work_waitq);
        init_waitqueue_head(&tq->tq_wait_waitq);

        if (flags & TASKQ_PREPOPULATE)
                for (i = 0; i < minalloc; i++)
                        task_done(tq, task_alloc(tq, TQ_SLEEP | TQ_NEW));

        spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);

        for (i = 0; i < nthreads; i++) {
                t = kthread_create(taskq_thread, tq, "%s/%d", name, i);
                if (t) {
                        tq->tq_threads[i] = t;
                        kthread_bind(t, i % num_online_cpus());
                        set_user_nice(t, PRIO_TO_NICE(pri));
                        wake_up_process(t);
			j++;
                } else {
                        tq->tq_threads[i] = NULL;
                        rc = 1;
                }
        }

        /* Wait for all threads to be started before potential destroy */
	wait_event(tq->tq_wait_waitq, tq->tq_nthreads == j);

        if (rc) {
                __taskq_destroy(tq);
                tq = NULL;
        }

        RETURN(tq);
}
EXPORT_SYMBOL(__taskq_create);

void
__taskq_destroy(taskq_t *tq)
{
	spl_task_t *t;
	int i, nthreads;
	ENTRY;

	ASSERT(tq);
	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
        tq->tq_flags &= ~TQ_ACTIVE;
	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);

	/* TQ_ACTIVE cleared prevents new tasks being added to pending */
        __taskq_wait(tq);

	nthreads = tq->tq_nthreads;
	for (i = 0; i < nthreads; i++)
		if (tq->tq_threads[i])
			kthread_stop(tq->tq_threads[i]);

        spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);

        while (!list_empty(&tq->tq_free_list)) {
		t = list_entry(tq->tq_free_list.next, spl_task_t, t_list);
	        list_del_init(&t->t_list);
                task_free(tq, t);
        }

        ASSERT(tq->tq_nthreads == 0);
        ASSERT(tq->tq_nalloc == 0);
        ASSERT(list_empty(&tq->tq_free_list));
        ASSERT(list_empty(&tq->tq_work_list));
        ASSERT(list_empty(&tq->tq_pend_list));

        spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
        kmem_free(tq->tq_threads, nthreads * sizeof(spl_task_t *));
        kmem_free(tq, sizeof(taskq_t));

	EXIT;
}
EXPORT_SYMBOL(__taskq_destroy);
Commit	Line	Data
	1	/*
	2	* This file is part of the SPL: Solaris Porting Layer.
	3	*
	4	* Copyright (c) 2008 Lawrence Livermore National Security, LLC.
	5	* Produced at Lawrence Livermore National Laboratory
	6	* Written by:
	7	* Brian Behlendorf <behlendorf1@llnl.gov>,
	8	* Herb Wartens <wartens2@llnl.gov>,
	9	* Jim Garlick <garlick@llnl.gov>
	10	* UCRL-CODE-235197
	11	*
	12	* This is free software; you can redistribute it and/or modify it
	13	* under the terms of the GNU General Public License as published by
	14	* the Free Software Foundation; either version 2 of the License, or
	15	* (at your option) any later version.
	16	*
	17	* This is distributed in the hope that it will be useful, but WITHOUT
	18	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	19	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	20	* for more details.
	21	*
	22	* You should have received a copy of the GNU General Public License along
	23	* with this program; if not, write to the Free Software Foundation, Inc.,
	24	* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
	25	*/
	26
	27	#include <sys/taskq.h>
	28	#include <sys/kmem.h>
	29
	30	#ifdef DEBUG_SUBSYSTEM
	31	#undef DEBUG_SUBSYSTEM
	32	#endif
	33
	34	#define DEBUG_SUBSYSTEM S_TASKQ
	35
	36	typedef struct spl_task {
	37	spinlock_t t_lock;
	38	struct list_head t_list;
	39	taskqid_t t_id;
	40	task_func_t *t_func;
	41	void *t_arg;
	42	} spl_task_t;
	43
	44	/* NOTE: Must be called with tq->tq_lock held, returns a list_t which
	45	* is not attached to the free, work, or pending taskq lists.
	46	*/
	47	static spl_task_t *
	48	task_alloc(taskq_t *tq, uint_t flags)
	49	{
	50	spl_task_t *t;
	51	int count = 0;
	52	ENTRY;
	53
	54	ASSERT(tq);
	55	ASSERT(flags & (TQ_SLEEP \| TQ_NOSLEEP)); /* One set */
	56	ASSERT(!((flags & TQ_SLEEP) && (flags & TQ_NOSLEEP))); /* Not both */
	57	ASSERT(spin_is_locked(&tq->tq_lock));
	58	retry:
	59	/* Aquire spl_task_t's from free list if available */
	60	if (!list_empty(&tq->tq_free_list) && !(flags & TQ_NEW)) {
	61	t = list_entry(tq->tq_free_list.next, spl_task_t, t_list);
	62	list_del_init(&t->t_list);
	63	RETURN(t);
	64	}
	65
	66	/* Free list is empty and memory allocs are prohibited */
	67	if (flags & TQ_NOALLOC)
	68	RETURN(NULL);
	69
	70	/* Hit maximum spl_task_t pool size */
	71	if (tq->tq_nalloc >= tq->tq_maxalloc) {
	72	if (flags & TQ_NOSLEEP)
	73	RETURN(NULL);
	74
	75	/* Sleep periodically polling the free list for an available
	76	* spl_task_t. If a full second passes and we have not found
	77	* one gives up and return a NULL to the caller. */
	78	if (flags & TQ_SLEEP) {
	79	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	80	schedule_timeout(HZ / 100);
	81	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	82	if (count < 100)
	83	GOTO(retry, count++);
	84
	85	RETURN(NULL);
	86	}
	87
	88	/* Unreachable, TQ_SLEEP xor TQ_NOSLEEP */
	89	SBUG();
	90	}
	91
	92	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	93	t = kmem_alloc(sizeof(spl_task_t), flags & (TQ_SLEEP \| TQ_NOSLEEP));
	94	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	95
	96	if (t) {
	97	spin_lock_init(&t->t_lock);
	98	INIT_LIST_HEAD(&t->t_list);
	99	t->t_id = 0;
	100	t->t_func = NULL;
	101	t->t_arg = NULL;
	102	tq->tq_nalloc++;
	103	}
	104
	105	RETURN(t);
	106	}
	107
	108	/* NOTE: Must be called with tq->tq_lock held, expectes the spl_task_t
	109	* to already be removed from the free, work, or pending taskq lists.
	110	*/
	111	static void
	112	task_free(taskq_t tq, spl_task_t t)
	113	{
	114	ENTRY;
	115
	116	ASSERT(tq);
	117	ASSERT(t);
	118	ASSERT(spin_is_locked(&tq->tq_lock));
	119	ASSERT(list_empty(&t->t_list));
	120
	121	kmem_free(t, sizeof(spl_task_t));
	122	tq->tq_nalloc--;
	123
	124	EXIT;
	125	}
	126
	127	/* NOTE: Must be called with tq->tq_lock held, either destroyes the
	128	* spl_task_t if too many exist or moves it to the free list for later use.
	129	*/
	130	static void
	131	task_done(taskq_t tq, spl_task_t t)
	132	{
	133	ENTRY;
	134	ASSERT(tq);
	135	ASSERT(t);
	136	ASSERT(spin_is_locked(&tq->tq_lock));
	137
	138	list_del_init(&t->t_list);
	139
	140	if (tq->tq_nalloc <= tq->tq_minalloc) {
	141	t->t_id = 0;
	142	t->t_func = NULL;
	143	t->t_arg = NULL;
	144	list_add_tail(&t->t_list, &tq->tq_free_list);
	145	} else {
	146	task_free(tq, t);
	147	}
	148
	149	EXIT;
	150	}
	151
	152	/* Taskqid's are handed out in a monotonically increasing fashion per
	153	* taskq_t. We don't handle taskqid wrapping yet, but fortuntely it isi
	154	* a 64-bit value so this is probably never going to happen. The lowest
	155	* pending taskqid is stored in the taskq_t to make it easy for any
	156	* taskq_wait()'ers to know if the tasks they're waiting for have
	157	* completed. Unfortunately, tq_task_lowest is kept up to date is
	158	* a pretty brain dead way, something more clever should be done.
	159	*/
	160	static int
	161	taskq_wait_check(taskq_t *tq, taskqid_t id)
	162	{
	163	RETURN(tq->tq_lowest_id >= id);
	164	}
	165
	166	/* Expected to wait for all previously scheduled tasks to complete. We do
	167	* not need to wait for tasked scheduled after this call to complete. In
	168	* otherwords we do not need to drain the entire taskq. */
	169	void
	170	__taskq_wait_id(taskq_t *tq, taskqid_t id)
	171	{
	172	ENTRY;
	173	ASSERT(tq);
	174
	175	wait_event(tq->tq_wait_waitq, taskq_wait_check(tq, id));
	176
	177	EXIT;
	178	}
	179	EXPORT_SYMBOL(__taskq_wait_id);
	180
	181	void
	182	__taskq_wait(taskq_t *tq)
	183	{
	184	taskqid_t id;
	185	ENTRY;
	186	ASSERT(tq);
	187
	188	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	189	id = tq->tq_next_id;
	190	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	191
	192	__taskq_wait_id(tq, id);
	193
	194	EXIT;
	195
	196	}
	197	EXPORT_SYMBOL(__taskq_wait);
	198
	199	int
	200	__taskq_member(taskq_t tq, void t)
	201	{
	202	int i;
	203	ENTRY;
	204
	205	ASSERT(tq);
	206	ASSERT(t);
	207
	208	for (i = 0; i < tq->tq_nthreads; i++)
	209	if (tq->tq_threads[i] == (struct task_struct *)t)
	210	RETURN(1);
	211
	212	RETURN(0);
	213	}
	214	EXPORT_SYMBOL(__taskq_member);
	215
	216	taskqid_t
	217	__taskq_dispatch(taskq_t tq, task_func_t func, void arg, uint_t flags)
	218	{
	219	spl_task_t *t;
	220	taskqid_t rc = 0;
	221	ENTRY;
	222
	223	ASSERT(tq);
	224	ASSERT(func);
	225	if (unlikely(in_atomic() && (flags & TQ_SLEEP))) {
	226	CERROR("May schedule while atomic: %s/0x%08x/%d\n",
	227	current->comm, preempt_count(), current->pid);
	228	SBUG();
	229	}
	230
	231	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	232
	233	/* Taskq being destroyed and all tasks drained */
	234	if (!(tq->tq_flags & TQ_ACTIVE))
	235	GOTO(out, rc = 0);
	236
	237	/* Do not queue the task unless there is idle thread for it */
	238	ASSERT(tq->tq_nactive <= tq->tq_nthreads);
	239	if ((flags & TQ_NOQUEUE) && (tq->tq_nactive == tq->tq_nthreads))
	240	GOTO(out, rc = 0);
	241
	242	if ((t = task_alloc(tq, flags)) == NULL)
	243	GOTO(out, rc = 0);
	244
	245	spin_lock(&t->t_lock);
	246	list_add_tail(&t->t_list, &tq->tq_pend_list);
	247	t->t_id = rc = tq->tq_next_id;
	248	tq->tq_next_id++;
	249	t->t_func = func;
	250	t->t_arg = arg;
	251	spin_unlock(&t->t_lock);
	252
	253	wake_up(&tq->tq_work_waitq);
	254	out:
	255	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	256	RETURN(rc);
	257	}
	258	EXPORT_SYMBOL(__taskq_dispatch);
	259
	260	/* NOTE: Must be called with tq->tq_lock held */
	261	static taskqid_t
	262	taskq_lowest_id(taskq_t *tq)
	263	{
	264	taskqid_t lowest_id = ~0;
	265	spl_task_t *t;
	266	ENTRY;
	267
	268	ASSERT(tq);
	269	ASSERT(spin_is_locked(&tq->tq_lock));
	270
	271	list_for_each_entry(t, &tq->tq_pend_list, t_list)
	272	if (t->t_id < lowest_id)
	273	lowest_id = t->t_id;
	274
	275	list_for_each_entry(t, &tq->tq_work_list, t_list)
	276	if (t->t_id < lowest_id)
	277	lowest_id = t->t_id;
	278
	279	RETURN(lowest_id);
	280	}
	281
	282	static int
	283	taskq_thread(void *args)
	284	{
	285	DECLARE_WAITQUEUE(wait, current);
	286	sigset_t blocked;
	287	taskqid_t id;
	288	taskq_t *tq = args;
	289	spl_task_t *t;
	290	ENTRY;
	291
	292	ASSERT(tq);
	293	current->flags \|= PF_NOFREEZE;
	294
	295	sigfillset(&blocked);
	296	sigprocmask(SIG_BLOCK, &blocked, NULL);
	297	flush_signals(current);
	298
	299	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	300	tq->tq_nthreads++;
	301	wake_up(&tq->tq_wait_waitq);
	302	set_current_state(TASK_INTERRUPTIBLE);
	303
	304	while (!kthread_should_stop()) {
	305
	306	add_wait_queue(&tq->tq_work_waitq, &wait);
	307	if (list_empty(&tq->tq_pend_list)) {
	308	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	309	schedule();
	310	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	311	} else {
	312	__set_current_state(TASK_RUNNING);
	313	}
	314
	315	remove_wait_queue(&tq->tq_work_waitq, &wait);
	316	if (!list_empty(&tq->tq_pend_list)) {
	317	t = list_entry(tq->tq_pend_list.next, spl_task_t, t_list);
	318	list_del_init(&t->t_list);
	319	list_add_tail(&t->t_list, &tq->tq_work_list);
	320	tq->tq_nactive++;
	321	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	322
	323	/* Perform the requested task */
	324	t->t_func(t->t_arg);
	325
	326	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	327	tq->tq_nactive--;
	328	id = t->t_id;
	329	task_done(tq, t);
	330
	331	/* Update the lowest remaining taskqid yet to run */
	332	if (tq->tq_lowest_id == id) {
	333	tq->tq_lowest_id = taskq_lowest_id(tq);
	334	ASSERT(tq->tq_lowest_id > id);
	335	}
	336
	337	wake_up_all(&tq->tq_wait_waitq);
	338	}
	339
	340	set_current_state(TASK_INTERRUPTIBLE);
	341
	342	}
	343
	344	__set_current_state(TASK_RUNNING);
	345	tq->tq_nthreads--;
	346	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	347
	348	RETURN(0);
	349	}
	350
	351	taskq_t *
	352	__taskq_create(const char *name, int nthreads, pri_t pri,
	353	int minalloc, int maxalloc, uint_t flags)
	354	{
	355	taskq_t *tq;
	356	struct task_struct *t;
	357	int rc = 0, i, j = 0;
	358	ENTRY;
	359
	360	ASSERT(name != NULL);
	361	ASSERT(pri <= maxclsyspri);
	362	ASSERT(minalloc >= 0);
	363	ASSERT(maxalloc <= INT_MAX);
	364	ASSERT(!(flags & (TASKQ_CPR_SAFE \| TASKQ_DYNAMIC))); /* Unsupported */
	365
	366	tq = kmem_alloc(sizeof(*tq), KM_SLEEP);
	367	if (tq == NULL)
	368	RETURN(NULL);
	369
	370	tq->tq_threads = kmem_alloc(nthreads * sizeof(t), KM_SLEEP);
	371	if (tq->tq_threads == NULL) {
	372	kmem_free(tq, sizeof(*tq));
	373	RETURN(NULL);
	374	}
	375
	376	spin_lock_init(&tq->tq_lock);
	377	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	378	tq->tq_name = name;
	379	tq->tq_nactive = 0;
	380	tq->tq_nthreads = 0;
	381	tq->tq_pri = pri;
	382	tq->tq_minalloc = minalloc;
	383	tq->tq_maxalloc = maxalloc;
	384	tq->tq_nalloc = 0;
	385	tq->tq_flags = (flags \| TQ_ACTIVE);
	386	tq->tq_next_id = 1;
	387	tq->tq_lowest_id = 1;
	388	INIT_LIST_HEAD(&tq->tq_free_list);
	389	INIT_LIST_HEAD(&tq->tq_work_list);
	390	INIT_LIST_HEAD(&tq->tq_pend_list);
	391	init_waitqueue_head(&tq->tq_work_waitq);
	392	init_waitqueue_head(&tq->tq_wait_waitq);
	393
	394	if (flags & TASKQ_PREPOPULATE)
	395	for (i = 0; i < minalloc; i++)
	396	task_done(tq, task_alloc(tq, TQ_SLEEP \| TQ_NEW));
	397
	398	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	399
	400	for (i = 0; i < nthreads; i++) {
	401	t = kthread_create(taskq_thread, tq, "%s/%d", name, i);
	402	if (t) {
	403	tq->tq_threads[i] = t;
	404	kthread_bind(t, i % num_online_cpus());
	405	set_user_nice(t, PRIO_TO_NICE(pri));
	406	wake_up_process(t);
	407	j++;
	408	} else {
	409	tq->tq_threads[i] = NULL;
	410	rc = 1;
	411	}
	412	}
	413
	414	/* Wait for all threads to be started before potential destroy */
	415	wait_event(tq->tq_wait_waitq, tq->tq_nthreads == j);
	416
	417	if (rc) {
	418	__taskq_destroy(tq);
	419	tq = NULL;
	420	}
	421
	422	RETURN(tq);
	423	}
	424	EXPORT_SYMBOL(__taskq_create);
	425
	426	void
	427	__taskq_destroy(taskq_t *tq)
	428	{
	429	spl_task_t *t;
	430	int i, nthreads;
	431	ENTRY;
	432
	433	ASSERT(tq);
	434	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	435	tq->tq_flags &= ~TQ_ACTIVE;
	436	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	437
	438	/* TQ_ACTIVE cleared prevents new tasks being added to pending */
	439	__taskq_wait(tq);
	440
	441	nthreads = tq->tq_nthreads;
	442	for (i = 0; i < nthreads; i++)
	443	if (tq->tq_threads[i])
	444	kthread_stop(tq->tq_threads[i]);
	445
	446	spin_lock_irqsave(&tq->tq_lock, tq->tq_lock_flags);
	447
	448	while (!list_empty(&tq->tq_free_list)) {
	449	t = list_entry(tq->tq_free_list.next, spl_task_t, t_list);
	450	list_del_init(&t->t_list);
	451	task_free(tq, t);
	452	}
	453
	454	ASSERT(tq->tq_nthreads == 0);
	455	ASSERT(tq->tq_nalloc == 0);
	456	ASSERT(list_empty(&tq->tq_free_list));
	457	ASSERT(list_empty(&tq->tq_work_list));
	458	ASSERT(list_empty(&tq->tq_pend_list));
	459
	460	spin_unlock_irqrestore(&tq->tq_lock, tq->tq_lock_flags);
	461	kmem_free(tq->tq_threads, nthreads * sizeof(spl_task_t *));
	462	kmem_free(tq, sizeof(taskq_t));
	463
	464	EXIT;
	465	}
	466	EXPORT_SYMBOL(__taskq_destroy);