svn commit: r262063 - in stable/8: share/man/man9 sys/kern sys/sys
Andriy Gapon
avg at FreeBSD.org
Mon Feb 17 15:24:51 UTC 2014
Author: avg
Date: Mon Feb 17 15:24:49 2014
New Revision: 262063
URL: http://svnweb.freebsd.org/changeset/base/262063
Log:
MFC r258713,262062: add taskqueue_drain_all
Modified:
stable/8/share/man/man9/Makefile
stable/8/share/man/man9/taskqueue.9
stable/8/sys/kern/subr_taskqueue.c
stable/8/sys/sys/taskqueue.h
Directory Properties:
stable/8/share/man/man9/ (props changed)
stable/8/sys/ (props changed)
stable/8/sys/kern/ (props changed)
stable/8/sys/sys/ (props changed)
Modified: stable/8/share/man/man9/Makefile
==============================================================================
--- stable/8/share/man/man9/Makefile Mon Feb 17 15:20:03 2014 (r262062)
+++ stable/8/share/man/man9/Makefile Mon Feb 17 15:24:49 2014 (r262063)
@@ -1262,19 +1262,22 @@ MLINKS+=sysctl_ctx_init.9 sysctl_ctx_ent
sysctl_ctx_init.9 sysctl_ctx_free.9
MLINKS+=taskqueue.9 TASK_INIT.9 \
taskqueue.9 TASK_INITIALIZER.9 \
+ taskqueue.9 taskqueue_block.9 \
taskqueue.9 taskqueue_create.9 \
taskqueue.9 taskqueue_create_fast.9 \
taskqueue.9 TASKQUEUE_DECLARE.9 \
taskqueue.9 TASKQUEUE_DEFINE.9 \
taskqueue.9 TASKQUEUE_DEFINE_THREAD.9 \
taskqueue.9 taskqueue_drain.9 \
+ taskqueue.9 taskqueue_drain_all.9 \
taskqueue.9 taskqueue_enqueue.9 \
taskqueue.9 taskqueue_enqueue_fast.9 \
taskqueue.9 TASKQUEUE_FAST_DEFINE.9 \
taskqueue.9 TASKQUEUE_FAST_DEFINE_THREAD.9 \
taskqueue.9 taskqueue_free.9 \
taskqueue.9 taskqueue_member.9 \
- taskqueue.9 taskqueue_run.9
+ taskqueue.9 taskqueue_run.9 \
+ taskqueue.9 taskqueue_unblock.9
MLINKS+=time.9 boottime.9 \
time.9 time_second.9 \
time.9 time_uptime.9
Modified: stable/8/share/man/man9/taskqueue.9
==============================================================================
--- stable/8/share/man/man9/taskqueue.9 Mon Feb 17 15:20:03 2014 (r262062)
+++ stable/8/share/man/man9/taskqueue.9 Mon Feb 17 15:24:49 2014 (r262063)
@@ -28,7 +28,7 @@
.\"
.\" $FreeBSD$
.\"
-.Dd August 18, 2009
+.Dd January 24, 2014
.Dt TASKQUEUE 9
.Os
.Sh NAME
@@ -69,6 +69,12 @@ struct task {
.Fn taskqueue_run_fast "struct taskqueue *queue"
.Ft void
.Fn taskqueue_drain "struct taskqueue *queue" "struct task *task"
+.Ft void
+.Fn taskqueue_drain_all "struct taskqueue *queue"
+.Ft void
+.Fn taskqueue_block "struct taskqueue *queue"
+.Ft void
+.Fn taskqueue_unblock "struct taskqueue *queue"
.Ft int
.Fn taskqueue_member "struct taskqueue *queue" "struct thread *td"
.Fn TASK_INIT "struct task *task" "int priority" "task_fn_t *func" "void *context"
@@ -176,6 +182,73 @@ function is used to wait for the task to
There is no guarantee that the task will not be
enqueued after call to
.Fn taskqueue_drain .
+If the caller wants to put the task into a known state,
+then before calling
+.Fn taskqueue_drain
+the caller should use out-of-band means to ensure that the task
+would not be enqueued.
+For example, if the task is enqueued by an interrupt filter, then
+the interrupt could be disabled.
+.Pp
+The
+.Fn taskqueue_drain_all
+function is used to wait for all pending and running tasks that
+are enqueued on the taskqueue to finish.
+The caller must arrange that the tasks are not re-enqueued.
+Note that
+.Fn taskqueue_drain_all
+currently does not handle tasks with delayed enqueueing.
+.Pp
+The
+.Fn taskqueue_block
+function blocks the taskqueue.
+It prevents any enqueued but not running tasks from being executed.
+Future calls to
+.Fn taskqueue_enqueue
+will enqueue tasks, but the tasks will not be run until
+.Fn taskqueue_unblock
+is called.
+Please note that
+.Fn taskqueue_block
+does not wait for any currently running tasks to finish.
+Thus, the
+.Fn taskqueue_block
+does not provide a guarantee that
+.Fn taskqueue_run
+is not running after
+.Fn taskqueue_block
+returns, but it does provide a guarantee that
+.Fn taskqueue_run
+will not be called again
+until
+.Fn taskqueue_unblock
+is called.
+If the caller requires a guarantee that
+.Fn taskqueue_run
+is not running, then this must be arranged by the caller.
+Note that if
+.Fn taskqueue_drain
+is called on a task that is enqueued on a taskqueue that is blocked by
+.Fn taskqueue_block ,
+then
+.Fn taskqueue_drain
+can not return until the taskqueue is unblocked.
+This can result in a deadlock if the thread blocked in
+.Fn taskqueue_drain
+is the thread that is supposed to call
+.Fn taskqueue_unblock .
+Thus, use of
+.Fn taskqueue_drain
+after
+.Fn taskqueue_block
+is discouraged, because the state of the task can not be known in advance.
+The same caveat applies to
+.Fn taskqueue_drain_all .
+.Pp
+The
+.Fn taskqueue_unblock
+function unblocks the previously blocked taskqueue.
+All enqueued tasks can be run after this call.
.Pp
The
.Fn taskqueue_member
Modified: stable/8/sys/kern/subr_taskqueue.c
==============================================================================
--- stable/8/sys/kern/subr_taskqueue.c Mon Feb 17 15:20:03 2014 (r262062)
+++ stable/8/sys/kern/subr_taskqueue.c Mon Feb 17 15:24:49 2014 (r262063)
@@ -202,6 +202,15 @@ taskqueue_enqueue(struct taskqueue *queu
return 0;
}
+static void
+taskqueue_drain_running(struct taskqueue *queue)
+{
+
+ while (!TAILQ_EMPTY(&queue->tq_active))
+ TQ_SLEEP(queue, &queue->tq_active, &queue->tq_mutex,
+ PWAIT, "-", 0);
+}
+
void
taskqueue_block(struct taskqueue *queue)
{
@@ -254,6 +263,8 @@ taskqueue_run_locked(struct taskqueue *q
wakeup(task);
}
TAILQ_REMOVE(&queue->tq_active, &tb, tb_link);
+ if (TAILQ_EMPTY(&queue->tq_active))
+ wakeup(&queue->tq_active);
}
void
@@ -296,6 +307,25 @@ taskqueue_drain(struct taskqueue *queue,
}
}
+void
+taskqueue_drain_all(struct taskqueue *queue)
+{
+ struct task *task;
+
+ if (!queue->tq_spin)
+ WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
+
+ TQ_LOCK(queue);
+ task = STAILQ_LAST(&queue->tq_queue, task, ta_link);
+ if (task != NULL)
+ while (task->ta_pending != 0)
+ TQ_SLEEP(queue, task, &queue->tq_mutex, PWAIT, "-", 0);
+ taskqueue_drain_running(queue);
+ KASSERT(STAILQ_EMPTY(&queue->tq_queue),
+ ("taskqueue queue is not empty after draining"));
+ TQ_UNLOCK(queue);
+}
+
static void
taskqueue_swi_enqueue(void *context)
{
Modified: stable/8/sys/sys/taskqueue.h
==============================================================================
--- stable/8/sys/sys/taskqueue.h Mon Feb 17 15:20:03 2014 (r262062)
+++ stable/8/sys/sys/taskqueue.h Mon Feb 17 15:24:49 2014 (r262063)
@@ -55,6 +55,7 @@ int taskqueue_start_threads(struct taskq
const char *name, ...) __printflike(4, 5);
int taskqueue_enqueue(struct taskqueue *queue, struct task *task);
void taskqueue_drain(struct taskqueue *queue, struct task *task);
+void taskqueue_drain_all(struct taskqueue *queue);
void taskqueue_free(struct taskqueue *queue);
void taskqueue_run(struct taskqueue *queue);
void taskqueue_block(struct taskqueue *queue);
More information about the svn-src-stable-8
mailing list