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/* $OpenBSD: kern_task.c,v 1.15 2015/11/19 13:19:24 dlg Exp $ */
/*
* Copyright (c) 2013 David Gwynne <dlg@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/kthread.h>
#include <sys/task.h>
#define TASK_ONQUEUE 1
struct taskq {
enum {
TQ_S_CREATED,
TQ_S_RUNNING,
TQ_S_DESTROYED
} tq_state;
unsigned int tq_running;
unsigned int tq_nthreads;
unsigned int tq_flags;
const char *tq_name;
struct mutex tq_mtx;
TAILQ_HEAD(, task) tq_worklist;
};
struct taskq taskq_sys = {
TQ_S_CREATED,
0,
1,
0,
"systq",
MUTEX_INITIALIZER(IPL_HIGH),
TAILQ_HEAD_INITIALIZER(taskq_sys.tq_worklist)
};
struct taskq taskq_sys_mp = {
TQ_S_CREATED,
0,
1,
TASKQ_MPSAFE,
"systqmp",
MUTEX_INITIALIZER(IPL_HIGH),
TAILQ_HEAD_INITIALIZER(taskq_sys_mp.tq_worklist)
};
typedef int (*sleepfn)(const volatile void *, struct mutex *, int,
const char *, int);
struct taskq *const systq = &taskq_sys;
struct taskq *const systqmp = &taskq_sys_mp;
void taskq_init(void); /* called in init_main.c */
void taskq_create_thread(void *);
int taskq_sleep(const volatile void *, struct mutex *, int,
const char *, int);
int taskq_next_work(struct taskq *, struct task *, sleepfn);
void taskq_thread(void *);
void
taskq_init(void)
{
kthread_create_deferred(taskq_create_thread, systq);
kthread_create_deferred(taskq_create_thread, systqmp);
}
struct taskq *
taskq_create(const char *name, unsigned int nthreads, int ipl,
unsigned int flags)
{
struct taskq *tq;
tq = malloc(sizeof(*tq), M_DEVBUF, M_WAITOK);
if (tq == NULL)
return (NULL);
tq->tq_state = TQ_S_CREATED;
tq->tq_running = 0;
tq->tq_nthreads = nthreads;
tq->tq_name = name;
tq->tq_flags = flags;
mtx_init(&tq->tq_mtx, ipl);
TAILQ_INIT(&tq->tq_worklist);
/* try to create a thread to guarantee that tasks will be serviced */
kthread_create_deferred(taskq_create_thread, tq);
return (tq);
}
void
taskq_destroy(struct taskq *tq)
{
mtx_enter(&tq->tq_mtx);
switch (tq->tq_state) {
case TQ_S_CREATED:
/* tq is still referenced by taskq_create_thread */
tq->tq_state = TQ_S_DESTROYED;
mtx_leave(&tq->tq_mtx);
return;
case TQ_S_RUNNING:
tq->tq_state = TQ_S_DESTROYED;
break;
default:
panic("unexpected %s tq state %u", tq->tq_name, tq->tq_state);
}
while (tq->tq_running > 0) {
wakeup(tq);
msleep(&tq->tq_running, &tq->tq_mtx, PWAIT, "tqdestroy", 0);
}
mtx_leave(&tq->tq_mtx);
free(tq, M_DEVBUF, sizeof(*tq));
}
void
taskq_create_thread(void *arg)
{
struct taskq *tq = arg;
int rv;
mtx_enter(&tq->tq_mtx);
switch (tq->tq_state) {
case TQ_S_DESTROYED:
mtx_leave(&tq->tq_mtx);
free(tq, M_DEVBUF, sizeof(*tq));
return;
case TQ_S_CREATED:
tq->tq_state = TQ_S_RUNNING;
break;
default:
panic("unexpected %s tq state %d", tq->tq_name, tq->tq_state);
}
do {
tq->tq_running++;
mtx_leave(&tq->tq_mtx);
rv = kthread_create(taskq_thread, tq, NULL, tq->tq_name);
mtx_enter(&tq->tq_mtx);
if (rv != 0) {
printf("unable to create thread for \"%s\" taskq\n",
tq->tq_name);
tq->tq_running--;
/* could have been destroyed during kthread_create */
if (tq->tq_state == TQ_S_DESTROYED &&
tq->tq_running == 0)
wakeup_one(&tq->tq_running);
break;
}
} while (tq->tq_running < tq->tq_nthreads);
mtx_leave(&tq->tq_mtx);
}
void
task_set(struct task *t, void (*fn)(void *), void *arg)
{
t->t_func = fn;
t->t_arg = arg;
t->t_flags = 0;
}
int
task_add(struct taskq *tq, struct task *w)
{
int rv = 0;
if (ISSET(w->t_flags, TASK_ONQUEUE))
return (0);
mtx_enter(&tq->tq_mtx);
if (!ISSET(w->t_flags, TASK_ONQUEUE)) {
rv = 1;
SET(w->t_flags, TASK_ONQUEUE);
TAILQ_INSERT_TAIL(&tq->tq_worklist, w, t_entry);
}
mtx_leave(&tq->tq_mtx);
if (rv)
wakeup_one(tq);
return (rv);
}
int
task_del(struct taskq *tq, struct task *w)
{
int rv = 0;
if (!ISSET(w->t_flags, TASK_ONQUEUE))
return (0);
mtx_enter(&tq->tq_mtx);
if (ISSET(w->t_flags, TASK_ONQUEUE)) {
rv = 1;
CLR(w->t_flags, TASK_ONQUEUE);
TAILQ_REMOVE(&tq->tq_worklist, w, t_entry);
}
mtx_leave(&tq->tq_mtx);
return (rv);
}
int
taskq_sleep(const volatile void *ident, struct mutex *mtx, int priority,
const char *wmesg, int tmo)
{
u_int *flags = &curproc->p_flag;
int rv;
atomic_clearbits_int(flags, P_CANTSLEEP);
rv = msleep(ident, mtx, priority, wmesg, tmo);
atomic_setbits_int(flags, P_CANTSLEEP);
return (tmo);
}
int
taskq_next_work(struct taskq *tq, struct task *work, sleepfn tqsleep)
{
struct task *next;
mtx_enter(&tq->tq_mtx);
while ((next = TAILQ_FIRST(&tq->tq_worklist)) == NULL) {
if (tq->tq_state != TQ_S_RUNNING) {
mtx_leave(&tq->tq_mtx);
return (0);
}
tqsleep(tq, &tq->tq_mtx, PWAIT, "bored", 0);
}
TAILQ_REMOVE(&tq->tq_worklist, next, t_entry);
CLR(next->t_flags, TASK_ONQUEUE);
*work = *next; /* copy to caller to avoid races */
next = TAILQ_FIRST(&tq->tq_worklist);
mtx_leave(&tq->tq_mtx);
if (next != NULL && tq->tq_nthreads > 1)
wakeup_one(tq);
return (1);
}
void
taskq_thread(void *xtq)
{
sleepfn tqsleep = msleep;
struct taskq *tq = xtq;
struct task work;
int last;
if (ISSET(tq->tq_flags, TASKQ_MPSAFE))
KERNEL_UNLOCK();
if (ISSET(tq->tq_flags, TASKQ_CANTSLEEP)) {
tqsleep = taskq_sleep;
atomic_setbits_int(&curproc->p_flag, P_CANTSLEEP);
}
while (taskq_next_work(tq, &work, tqsleep)) {
(*work.t_func)(work.t_arg);
sched_pause();
}
mtx_enter(&tq->tq_mtx);
last = (--tq->tq_running == 0);
mtx_leave(&tq->tq_mtx);
if (ISSET(tq->tq_flags, TASKQ_MPSAFE))
KERNEL_LOCK();
if (ISSET(tq->tq_flags, TASKQ_CANTSLEEP))
atomic_clearbits_int(&curproc->p_flag, P_CANTSLEEP);
if (last)
wakeup_one(&tq->tq_running);
kthread_exit(0);
}
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