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[src/trunk]: src Add workqueue_wait that waits for a specific work to finish
details: https://anonhg.NetBSD.org/src/rev/f8351242576c
branches: trunk
changeset: 828706:f8351242576c
user: ozaki-r <ozaki-r%NetBSD.org@localhost>
date: Thu Dec 28 07:00:52 2017 +0000
description:
Add workqueue_wait that waits for a specific work to finish
The caller must ensure that no new work is enqueued before calling
workqueue_wait. Note that Note that if the workqueue is WQ_PERCPU, the caller
can enqueue a new work to another queue other than the waiting queue.
Discussed on tech-kern@
diffstat:
share/man/man9/workqueue.9 | 21 ++++++++-
sys/kern/subr_workqueue.c | 105 ++++++++++++++++++++++++++++++++++++--------
sys/sys/workqueue.h | 3 +-
3 files changed, 107 insertions(+), 22 deletions(-)
diffs (244 lines):
diff -r 244db33d51a0 -r f8351242576c share/man/man9/workqueue.9
--- a/share/man/man9/workqueue.9 Thu Dec 28 06:13:50 2017 +0000
+++ b/share/man/man9/workqueue.9 Thu Dec 28 07:00:52 2017 +0000
@@ -1,4 +1,4 @@
-.\" $NetBSD: workqueue.9,v 1.11 2015/10/13 04:22:24 riastradh Exp $
+.\" $NetBSD: workqueue.9,v 1.12 2017/12/28 07:00:52 ozaki-r Exp $
.\"
.\" Copyright (c)2005 YAMAMOTO Takashi,
.\" All rights reserved.
@@ -25,7 +25,7 @@
.\" SUCH DAMAGE.
.\"
.\" ------------------------------------------------------------
-.Dd October 24, 2011
+.Dd December 28, 2017
.Dt WORKQUEUE 9
.Os
.\" ------------------------------------------------------------
@@ -47,6 +47,10 @@
"struct workqueue *wq" "struct work *wk" "struct cpu_info *ci"
.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
.Ft void
+.Fn workqueue_wait \
+"struct workqueue *wq" "struct work *wk"
+.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+.Ft void
.Fn workqueue_destroy \
"struct workqueue *wq"
.\" ------------------------------------------------------------
@@ -118,6 +122,19 @@
framework.
.Pp
.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
+.Fn workqueue_wait
+waits for a specified work
+.Fa wk
+on the workqueue
+.Fa wq
+to finish.
+The caller must ensure that no new work will be enqueued to the workqueue
+beforehand.
+Note that if the workqueue is
+.Dv WQ_PERCPU ,
+the caller can enqueue a new work to another queue other than the waiting queue.
+.Pp
+.\" - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
.Fn workqueue_destroy
destroys a workqueue and frees associated resources.
The caller should ensure that the workqueue has no work enqueued beforehand.
diff -r 244db33d51a0 -r f8351242576c sys/kern/subr_workqueue.c
--- a/sys/kern/subr_workqueue.c Thu Dec 28 06:13:50 2017 +0000
+++ b/sys/kern/subr_workqueue.c Thu Dec 28 07:00:52 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: subr_workqueue.c,v 1.33 2012/10/07 22:16:21 matt Exp $ */
+/* $NetBSD: subr_workqueue.c,v 1.34 2017/12/28 07:00:52 ozaki-r Exp $ */
/*-
* Copyright (c)2002, 2005, 2006, 2007 YAMAMOTO Takashi,
@@ -27,7 +27,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: subr_workqueue.c,v 1.33 2012/10/07 22:16:21 matt Exp $");
+__KERNEL_RCSID(0, "$NetBSD: subr_workqueue.c,v 1.34 2017/12/28 07:00:52 ozaki-r Exp $");
#include <sys/param.h>
#include <sys/cpu.h>
@@ -49,8 +49,10 @@
struct workqueue_queue {
kmutex_t q_mutex;
kcondvar_t q_cv;
- struct workqhead q_queue;
+ struct workqhead q_queue_pending;
+ struct workqhead q_queue_running;
lwp_t *q_worker;
+ work_impl_t *q_waiter;
};
struct workqueue {
@@ -115,24 +117,29 @@
q = workqueue_queue_lookup(wq, curlwp->l_cpu);
for (;;) {
- struct workqhead tmp;
-
/*
* we violate abstraction of SIMPLEQ.
*/
-#if defined(DIAGNOSTIC)
- tmp.sqh_last = (void *)POISON;
-#endif /* defined(DIAGNOSTIC) */
+ mutex_enter(&q->q_mutex);
+ while (SIMPLEQ_EMPTY(&q->q_queue_pending))
+ cv_wait(&q->q_cv, &q->q_mutex);
+ KASSERT(SIMPLEQ_EMPTY(&q->q_queue_running));
+ q->q_queue_running.sqh_first =
+ q->q_queue_pending.sqh_first; /* XXX */
+ SIMPLEQ_INIT(&q->q_queue_pending);
+ mutex_exit(&q->q_mutex);
+
+ workqueue_runlist(wq, &q->q_queue_running);
mutex_enter(&q->q_mutex);
- while (SIMPLEQ_EMPTY(&q->q_queue))
- cv_wait(&q->q_cv, &q->q_mutex);
- tmp.sqh_first = q->q_queue.sqh_first; /* XXX */
- SIMPLEQ_INIT(&q->q_queue);
+ KASSERT(!SIMPLEQ_EMPTY(&q->q_queue_running));
+ SIMPLEQ_INIT(&q->q_queue_running);
+ if (__predict_false(q->q_waiter != NULL)) {
+ /* Wake up workqueue_wait */
+ cv_signal(&q->q_cv);
+ }
mutex_exit(&q->q_mutex);
-
- workqueue_runlist(wq, &tmp);
}
}
@@ -159,7 +166,8 @@
mutex_init(&q->q_mutex, MUTEX_DEFAULT, ipl);
cv_init(&q->q_cv, wq->wq_name);
- SIMPLEQ_INIT(&q->q_queue);
+ SIMPLEQ_INIT(&q->q_queue_pending);
+ SIMPLEQ_INIT(&q->q_queue_running);
ktf = ((wq->wq_flags & WQ_MPSAFE) != 0 ? KTHREAD_MPSAFE : 0);
if (wq->wq_prio < PRI_KERNEL)
ktf |= KTHREAD_TS;
@@ -194,7 +202,7 @@
*/
KASSERT(q->q_worker == curlwp);
- KASSERT(SIMPLEQ_EMPTY(&q->q_queue));
+ KASSERT(SIMPLEQ_EMPTY(&q->q_queue_pending));
mutex_enter(&q->q_mutex);
q->q_worker = NULL;
cv_signal(&q->q_cv);
@@ -210,10 +218,10 @@
KASSERT(wq->wq_func == workqueue_exit);
wqe.wqe_q = q;
- KASSERT(SIMPLEQ_EMPTY(&q->q_queue));
+ KASSERT(SIMPLEQ_EMPTY(&q->q_queue_pending));
KASSERT(q->q_worker != NULL);
mutex_enter(&q->q_mutex);
- SIMPLEQ_INSERT_TAIL(&q->q_queue, &wqe.wqe_wk, wk_entry);
+ SIMPLEQ_INSERT_TAIL(&q->q_queue_pending, &wqe.wqe_wk, wk_entry);
cv_signal(&q->q_cv);
while (q->q_worker != NULL) {
cv_wait(&q->q_cv, &q->q_mutex);
@@ -271,6 +279,64 @@
return error;
}
+static bool
+workqueue_q_wait(struct workqueue_queue *q, work_impl_t *wk_target)
+{
+ work_impl_t *wk;
+ bool found = false;
+
+ mutex_enter(&q->q_mutex);
+ again:
+ SIMPLEQ_FOREACH(wk, &q->q_queue_pending, wk_entry) {
+ if (wk == wk_target)
+ goto found;
+ }
+ SIMPLEQ_FOREACH(wk, &q->q_queue_running, wk_entry) {
+ if (wk == wk_target)
+ goto found;
+ }
+ found:
+ if (wk != NULL) {
+ found = true;
+ KASSERT(q->q_waiter == NULL);
+ q->q_waiter = wk;
+ cv_wait(&q->q_cv, &q->q_mutex);
+ goto again;
+ }
+ if (q->q_waiter != NULL)
+ q->q_waiter = NULL;
+ mutex_exit(&q->q_mutex);
+
+ return found;
+}
+
+/*
+ * Wait for a specified work to finish. The caller must ensure that no new
+ * work will be enqueued before calling workqueue_wait. Note that if the
+ * workqueue is WQ_PERCPU, the caller can enqueue a new work to another queue
+ * other than the waiting queue.
+ */
+void
+workqueue_wait(struct workqueue *wq, struct work *wk)
+{
+ struct workqueue_queue *q;
+ bool found;
+
+ if (ISSET(wq->wq_flags, WQ_PERCPU)) {
+ struct cpu_info *ci;
+ CPU_INFO_ITERATOR cii;
+ for (CPU_INFO_FOREACH(cii, ci)) {
+ q = workqueue_queue_lookup(wq, ci);
+ found = workqueue_q_wait(q, (work_impl_t *)wk);
+ if (found)
+ break;
+ }
+ } else {
+ q = workqueue_queue_lookup(wq, NULL);
+ (void) workqueue_q_wait(q, (work_impl_t *)wk);
+ }
+}
+
void
workqueue_destroy(struct workqueue *wq)
{
@@ -298,7 +364,8 @@
q = workqueue_queue_lookup(wq, ci);
mutex_enter(&q->q_mutex);
- SIMPLEQ_INSERT_TAIL(&q->q_queue, wk, wk_entry);
+ KASSERT(q->q_waiter == NULL);
+ SIMPLEQ_INSERT_TAIL(&q->q_queue_pending, wk, wk_entry);
cv_signal(&q->q_cv);
mutex_exit(&q->q_mutex);
}
diff -r 244db33d51a0 -r f8351242576c sys/sys/workqueue.h
--- a/sys/sys/workqueue.h Thu Dec 28 06:13:50 2017 +0000
+++ b/sys/sys/workqueue.h Thu Dec 28 07:00:52 2017 +0000
@@ -1,4 +1,4 @@
-/* $NetBSD: workqueue.h,v 1.9 2007/10/19 12:16:48 ad Exp $ */
+/* $NetBSD: workqueue.h,v 1.10 2017/12/28 07:00:52 ozaki-r Exp $ */
/*-
* Copyright (c)2002, 2005 YAMAMOTO Takashi,
@@ -51,6 +51,7 @@
int workqueue_create(struct workqueue **, const char *,
void (*)(struct work *, void *), void *, pri_t, int, int);
void workqueue_destroy(struct workqueue *);
+void workqueue_wait(struct workqueue *, struct work *);
void workqueue_enqueue(struct workqueue *, struct work *, struct cpu_info *);
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