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Exercise greater care in acquiring and releasing work.

This commit is contained in:
riastradh 2018-08-27 14:59:20 +00:00
parent 2e56c8b44a
commit 7d2f7a0702
1 changed files with 39 additions and 8 deletions
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47
sys/external/bsd/common/linux/linux_work.c vendored
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@ -1,4 +1,4 @@
/* $NetBSD: linux_work.c,v 1.16 2018/08/27 14:58:57 riastradh Exp $ */
/* $NetBSD: linux_work.c,v 1.17 2018/08/27 14:59:20 riastradh Exp $ */
/*-
* Copyright (c) 2018 The NetBSD Foundation, Inc.
@ -30,7 +30,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: linux_work.c,v 1.16 2018/08/27 14:58:57 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: linux_work.c,v 1.17 2018/08/27 14:59:20 riastradh Exp $");
#include <sys/types.h>
#include <sys/atomic.h>
@ -60,6 +60,11 @@ struct workqueue_struct {
static void __dead linux_workqueue_thread(void *);
static void linux_workqueue_timeout(void *);
static struct workqueue_struct *
acquire_work(struct work_struct *,
struct workqueue_struct *);
static void release_work(struct work_struct *,
struct workqueue_struct *);
static void queue_delayed_work_anew(struct workqueue_struct *,
struct delayed_work *, unsigned long);
@ -238,7 +243,7 @@ linux_workqueue_thread(void *cookie)
if (wq->wq_requeued)
wq->wq_requeued = false;
else
work->work_queue = NULL;
release_work(work, wq);
wq->wq_current_work = NULL;
cv_broadcast(&wq->wq_cv);
}
@ -278,6 +283,7 @@ linux_workqueue_timeout(void *cookie)
dw->dw_state = DELAYED_WORK_IDLE;
callout_destroy(&dw->dw_callout);
TAILQ_REMOVE(&wq->wq_delayed, dw, dw_entry);
release_work(&dw->work, wq);
break;
default:
panic("delayed work callout in bad state: %p", dw);
@ -316,6 +322,33 @@ INIT_WORK(struct work_struct *work, void (*fn)(struct work_struct *))
work->func = fn;
}
static struct workqueue_struct *
acquire_work(struct work_struct *work, struct workqueue_struct *wq)
{
struct workqueue_struct *wq0;
KASSERT(mutex_owned(&wq->wq_lock));
wq0 = atomic_cas_ptr(&work->work_queue, NULL, wq);
if (wq0 == NULL) {
membar_enter();
KASSERT(work->work_queue == wq);
}
return wq0;
}
static void
release_work(struct work_struct *work, struct workqueue_struct *wq)
{
KASSERT(work->work_queue == wq);
KASSERT(mutex_owned(&wq->wq_lock));
membar_exit();
work->work_queue = NULL;
}
bool
schedule_work(struct work_struct *work)
{
@ -332,8 +365,7 @@ queue_work(struct workqueue_struct *wq, struct work_struct *work)
KASSERT(wq != NULL);
mutex_enter(&wq->wq_lock);
if (__predict_true((wq0 = atomic_cas_ptr(&work->work_queue, NULL, wq))
== NULL)) {
if (__predict_true((wq0 = acquire_work(work, wq)) == NULL)) {
TAILQ_INSERT_TAIL(&wq->wq_queue, work, work_entry);
newly_queued = true;
} else {
@ -462,8 +494,7 @@ queue_delayed_work(struct workqueue_struct *wq, struct delayed_work *dw,
bool newly_queued;
mutex_enter(&wq->wq_lock);
if (__predict_true((wq0 = atomic_cas_ptr(&dw->work.work_queue, NULL,
wq)) == NULL)) {
if (__predict_true((wq0 = acquire_work(&dw->work, wq)) == NULL)) {
KASSERT(dw->dw_state == DELAYED_WORK_IDLE);
queue_delayed_work_anew(wq, dw, ticks);
newly_queued = true;
@ -484,7 +515,7 @@ mod_delayed_work(struct workqueue_struct *wq, struct delayed_work *dw,
bool timer_modified;
mutex_enter(&wq->wq_lock);
if ((wq0 = atomic_cas_ptr(&dw->work.work_queue, NULL, wq)) == NULL) {
if ((wq0 = acquire_work(&dw->work, wq)) == NULL) {
KASSERT(dw->dw_state == DELAYED_WORK_IDLE);
queue_delayed_work_anew(wq, dw, ticks);
timer_modified = false;