freebsd-dev/sys/kern/subr_taskqueue.c
Andriy Gapon 706b0d31bb taskqueue: drop unused tq_name field
tq_name was used write-only and besides it was just a pointer, so it
could point to some garbage in a temporary buffer that's gone.
This change shouldn't change KPI/KBI as struct taskqueue is private to
subr_taskqueue.c.
If we find a need for tq_name it can be resurrected at any moment.
taskqueue_create() interface is preserved for this purpose.

Suggested by:	jhb
MFC after:	10 days
2010-11-23 14:30:22 +00:00

486 lines
11 KiB
C

/*-
* 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/interrupt.h>
#include <sys/kernel.h>
#include <sys/kthread.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/sched.h>
#include <sys/taskqueue.h>
#include <sys/unistd.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 taskqueue {
STAILQ_HEAD(, task) tq_queue;
taskqueue_enqueue_fn tq_enqueue;
void *tq_context;
TAILQ_HEAD(, taskqueue_busy) tq_active;
struct mtx tq_mutex;
struct thread **tq_threads;
int tq_tcount;
int tq_spin;
int tq_flags;
};
#define TQ_FLAGS_ACTIVE (1 << 0)
#define TQ_FLAGS_BLOCKED (1 << 1)
#define TQ_FLAGS_PENDING (1 << 2)
#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_UNLOCK(tq) \
do { \
if ((tq)->tq_spin) \
mtx_unlock_spin(&(tq)->tq_mutex); \
else \
mtx_unlock(&(tq)->tq_mutex); \
} while (0)
static __inline int
TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
int t)
{
if (tq->tq_spin)
return (msleep_spin(p, m, wm, t));
return (msleep(p, m, pri, wm, t));
}
static struct taskqueue *
_taskqueue_create(const char *name __unused, int mflags,
taskqueue_enqueue_fn enqueue, void *context,
int mtxflags, const char *mtxname)
{
struct taskqueue *queue;
queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags | M_ZERO);
if (!queue)
return NULL;
STAILQ_INIT(&queue->tq_queue);
TAILQ_INIT(&queue->tq_active);
queue->tq_enqueue = enqueue;
queue->tq_context = context;
queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
queue->tq_flags |= TQ_FLAGS_ACTIVE;
mtx_init(&queue->tq_mutex, mtxname, 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, "taskqueue");
}
/*
* Signal a taskqueue thread to terminate.
*/
static void
taskqueue_terminate(struct thread **pp, struct taskqueue *tq)
{
while (tq->tq_tcount > 0) {
wakeup(tq);
TQ_SLEEP(tq, pp, &tq->tq_mutex, PWAIT, "taskqueue_destroy", 0);
}
}
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?"));
mtx_destroy(&queue->tq_mutex);
free(queue->tq_threads, M_TASKQUEUE);
free(queue, M_TASKQUEUE);
}
int
taskqueue_enqueue(struct taskqueue *queue, struct task *task)
{
struct task *ins;
struct task *prev;
TQ_LOCK(queue);
/*
* Count multiple enqueues.
*/
if (task->ta_pending) {
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_BLOCKED) == 0)
queue->tq_enqueue(queue->tq_context);
else
queue->tq_flags |= TQ_FLAGS_PENDING;
TQ_UNLOCK(queue);
return 0;
}
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 (queue->tq_flags & TQ_FLAGS_PENDING) {
queue->tq_flags &= ~TQ_FLAGS_PENDING;
queue->tq_enqueue(queue->tq_context);
}
TQ_UNLOCK(queue);
}
static void
taskqueue_run_locked(struct taskqueue *queue)
{
struct taskqueue_busy tb;
struct task *task;
int pending;
mtx_assert(&queue->tq_mutex, MA_OWNED);
tb.tb_running = NULL;
TAILQ_INSERT_TAIL(&queue->tq_active, &tb, tb_link);
while (STAILQ_FIRST(&queue->tq_queue)) {
/*
* Carefully remove the first task from the queue and
* zero its pending count.
*/
task = STAILQ_FIRST(&queue->tq_queue);
STAILQ_REMOVE_HEAD(&queue->tq_queue, ta_link);
pending = task->ta_pending;
task->ta_pending = 0;
tb.tb_running = task;
TQ_UNLOCK(queue);
task->ta_func(task->ta_context, pending);
TQ_LOCK(queue);
tb.tb_running = NULL;
wakeup(task);
}
TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
}
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;
mtx_assert(&queue->tq_mutex, MA_OWNED);
TAILQ_FOREACH(tb, &queue->tq_active, tb_link) {
if (tb->tb_running == task)
return (1);
}
return (0);
}
int
taskqueue_cancel(struct taskqueue *queue, struct task *task, u_int *pendp)
{
u_int pending;
int error;
TQ_LOCK(queue);
if ((pending = task->ta_pending) > 0)
STAILQ_REMOVE(&queue->tq_queue, task, task, ta_link);
task->ta_pending = 0;
error = task_is_running(queue, task) ? EBUSY : 0;
TQ_UNLOCK(queue);
if (pendp != NULL)
*pendp = pending;
return (error);
}
void
taskqueue_drain(struct taskqueue *queue, struct task *task)
{
if (!queue->tq_spin)
WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
TQ_LOCK(queue);
while (task->ta_pending != 0 || task_is_running(queue, task))
TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
TQ_UNLOCK(queue);
}
static void
taskqueue_swi_enqueue(void *context)
{
swi_sched(taskqueue_ih, 0);
}
static void
taskqueue_swi_run(void *dummy)
{
taskqueue_run(taskqueue_swi);
}
static void
taskqueue_swi_giant_enqueue(void *context)
{
swi_sched(taskqueue_giant_ih, 0);
}
static void
taskqueue_swi_giant_run(void *dummy)
{
taskqueue_run(taskqueue_swi_giant);
}
int
taskqueue_start_threads(struct taskqueue **tqp, int count, int pri,
const char *name, ...)
{
va_list ap;
struct thread *td;
struct taskqueue *tq;
int i, error;
char ktname[MAXCOMLEN + 1];
if (count <= 0)
return (EINVAL);
tq = *tqp;
va_start(ap, name);
vsnprintf(ktname, sizeof(ktname), name, ap);
va_end(ap);
tq->tq_threads = malloc(sizeof(struct thread *) * count, M_TASKQUEUE,
M_NOWAIT | M_ZERO);
if (tq->tq_threads == NULL) {
printf("%s: no memory for %s threads\n", __func__, ktname);
return (ENOMEM);
}
for (i = 0; i < count; i++) {
if (count == 1)
error = kthread_add(taskqueue_thread_loop, tqp, NULL,
&tq->tq_threads[i], RFSTOPPED, 0, "%s", ktname);
else
error = kthread_add(taskqueue_thread_loop, tqp, NULL,
&tq->tq_threads[i], RFSTOPPED, 0,
"%s_%d", ktname, i);
if (error) {
/* should be ok to continue, taskqueue_free will dtrt */
printf("%s: kthread_add(%s): error %d", __func__,
ktname, error);
tq->tq_threads[i] = NULL; /* paranoid */
} else
tq->tq_tcount++;
}
for (i = 0; i < count; i++) {
if (tq->tq_threads[i] == NULL)
continue;
td = tq->tq_threads[i];
thread_lock(td);
sched_prio(td, pri);
sched_add(td, SRQ_BORING);
thread_unlock(td);
}
return (0);
}
void
taskqueue_thread_loop(void *arg)
{
struct taskqueue **tqp, *tq;
tqp = arg;
tq = *tqp;
TQ_LOCK(tq);
while ((tq->tq_flags & TQ_FLAGS_ACTIVE) != 0) {
taskqueue_run_locked(tq);
/*
* Because taskqueue_run() can drop tq_mutex, we need to
* check if the TQ_FLAGS_ACTIVE flag wasn't removed in the
* meantime, which means we missed a wakeup.
*/
if ((tq->tq_flags & TQ_FLAGS_ACTIVE) == 0)
break;
TQ_SLEEP(tq, tq, &tq->tq_mutex, 0, "-", 0);
}
taskqueue_run_locked(tq);
/* rendezvous with thread that asked us to terminate */
tq->tq_tcount--;
wakeup_one(tq->tq_threads);
TQ_UNLOCK(tq);
kthread_exit();
}
void
taskqueue_thread_enqueue(void *context)
{
struct taskqueue **tqp, *tq;
tqp = context;
tq = *tqp;
mtx_assert(&tq->tq_mutex, MA_OWNED);
wakeup_one(tq);
}
TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, NULL,
swi_add(NULL, "task queue", taskqueue_swi_run, NULL, SWI_TQ,
INTR_MPSAFE, &taskqueue_ih));
TASKQUEUE_DEFINE(swi_giant, taskqueue_swi_giant_enqueue, NULL,
swi_add(NULL, "Giant taskq", taskqueue_swi_giant_run,
NULL, SWI_TQ_GIANT, 0, &taskqueue_giant_ih));
TASKQUEUE_DEFINE_THREAD(thread);
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");
}
/* NB: for backwards compatibility */
int
taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
{
return taskqueue_enqueue(queue, task);
}
static void *taskqueue_fast_ih;
static void
taskqueue_fast_enqueue(void *context)
{
swi_sched(taskqueue_fast_ih, 0);
}
static void
taskqueue_fast_run(void *dummy)
{
taskqueue_run(taskqueue_fast);
}
TASKQUEUE_FAST_DEFINE(fast, taskqueue_fast_enqueue, NULL,
swi_add(NULL, "Fast task queue", taskqueue_fast_run, NULL,
SWI_TQ_FAST, INTR_MPSAFE, &taskqueue_fast_ih));
int
taskqueue_member(struct taskqueue *queue, struct thread *td)
{
int i, j, ret = 0;
TQ_LOCK(queue);
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;
}
TQ_UNLOCK(queue);
return (ret);
}