Add taskqueue system for easy-to-use SWIs among other things.

Reviewed by: arch

1 files changed, 203 insertions, 0 deletions

diff --git a/sys/kern/subr_taskqueue.c b/sys/kern/subr_taskqueue.c
new file mode 100644
index 0000000..ab47b4f
--- /dev/null
+++ b/sys/kern/subr_taskqueue.c
@@ -0,0 +1,203 @@
+/*-
+ * 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.
+ *
+ *	$FreeBSD$
+ */
+
+#include <sys/param.h>
+#include <sys/queue.h>
+#include <sys/systm.h>
+#include <sys/kernel.h>
+#include <sys/taskqueue.h>
+#include <sys/interrupt.h>
+#include <sys/malloc.h>
+#include <machine/ipl.h>
+
+MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
+
+static STAILQ_HEAD(taskqueue_list, taskqueue) taskqueue_queues;
+
+struct taskqueue {
+	STAILQ_ENTRY(taskqueue)	tq_link;
+	STAILQ_HEAD(, task)	tq_queue;
+	const char		*tq_name;
+	taskqueue_enqueue_fn	tq_enqueue;
+	void			*tq_context;
+	int			tq_draining;
+};
+
+struct taskqueue *
+taskqueue_create(const char *name, int mflags,
+		 taskqueue_enqueue_fn enqueue, void *context)
+{
+	struct taskqueue *queue;
+	static int once = 1;
+	int s;
+
+	queue = malloc(sizeof(struct taskqueue), M_TASKQUEUE, mflags);
+	if (!queue)
+		return 0;
+	STAILQ_INIT(&queue->tq_queue);
+	queue->tq_name = name;
+	queue->tq_enqueue = enqueue;
+	queue->tq_context = context;
+	queue->tq_draining = 0;
+
+	s = splhigh();
+	if (once) {
+		STAILQ_INIT(&taskqueue_queues);
+		once = 0;
+	}
+	STAILQ_INSERT_TAIL(&taskqueue_queues, queue, tq_link);
+	splx(s);
+
+	return queue;
+}
+
+void
+taskqueue_free(struct taskqueue *queue)
+{
+	int s = splhigh();
+	queue->tq_draining = 1;
+	splx(s);
+
+	taskqueue_run(queue);
+
+	s = splhigh();
+	STAILQ_REMOVE(&taskqueue_queues, queue, taskqueue, tq_link);
+	splx(s);
+
+	free(queue, M_TASKQUEUE);
+}
+
+struct taskqueue *
+taskqueue_find(const char *name)
+{
+	struct taskqueue *queue;
+	int s;
+
+	s = splhigh();
+	STAILQ_FOREACH(queue, &taskqueue_queues, tq_link)
+		if (!strcmp(queue->tq_name, name)) {
+			splx(s);
+			return queue;
+		}
+	splx(s);
+	return 0;
+}
+
+int
+taskqueue_enqueue(struct taskqueue *queue, struct task *task)
+{
+	struct task *ins;
+	struct task *prev;
+
+	int s = splhigh();
+
+	/*
+	 * Don't allow new tasks on a queue which is being freed.
+	 */
+	if (queue->tq_draining) {
+		splx(s);
+		return EPIPE;
+	}
+
+	/*
+	 * Count multiple enqueues.
+	 */
+	if (task->ta_pending) {
+		task->ta_pending++;
+		splx(s);
+		return 0;
+	}
+
+	/*
+	 * Optimise the case when all tasks have the same priority.
+	 */
+	prev = STAILQ_LAST(&queue->tq_queue);
+	if (!prev || prev->ta_priority >= task->ta_priority) {
+		STAILQ_INSERT_TAIL(&queue->tq_queue, task, ta_link);
+	} else {
+		prev = 0;
+		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_enqueue)
+		queue->tq_enqueue(queue->tq_context);
+
+	splx(s);
+
+	return 0;
+}
+
+void
+taskqueue_run(struct taskqueue *queue)
+{
+	int s;
+	struct task *task;
+	int pending;
+
+	s = splhigh();
+	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;
+		splx(s);
+
+		task->ta_func(task->ta_context, pending);
+
+		s = splhigh();
+	}
+	splx(s);
+}
+
+static void
+taskqueue_swi_enqueue(void *context)
+{
+	setsofttq();
+}
+
+static void
+taskqueue_swi_run(void)
+{
+	taskqueue_run(taskqueue_swi);
+}
+
+TASKQUEUE_DEFINE(swi, taskqueue_swi_enqueue, 0,
+		 register_swi(SWI_TQ, taskqueue_swi_run));