TASKQUEUE(9): Use FreeBSD implementation

5 files changed, 514 insertions, 353 deletions

diff --git a/Makefile b/Makefile
index 2d7d113f..11f44de2 100644
--- a/Makefile
+++ b/Makefile
@@ -83,7 +83,6 @@ LIB_C_FILES += rtemsbsd/rtems/rtems-bsd-syscall-api.c
 LIB_C_FILES += rtemsbsd/rtems/rtems-bsd-sysctlbyname.c
 LIB_C_FILES += rtemsbsd/rtems/rtems-bsd-sysctl.c
 LIB_C_FILES += rtemsbsd/rtems/rtems-bsd-sysctlnametomib.c
-LIB_C_FILES += rtemsbsd/rtems/rtems-bsd-taskqueue.c
 LIB_C_FILES += rtemsbsd/rtems/rtems-bsd-thread.c
 LIB_C_FILES += rtemsbsd/rtems/rtems-bsd-timesupport.c
 LIB_C_FILES += rtemsbsd/rtems/rtems-kvm.c
@@ -144,6 +143,7 @@ LIB_C_FILES += freebsd/sys/kern/subr_kobj.c
 LIB_C_FILES += freebsd/sys/kern/subr_module.c
 LIB_C_FILES += freebsd/sys/kern/subr_rman.c
 LIB_C_FILES += freebsd/sys/kern/subr_sbuf.c
+LIB_C_FILES += freebsd/sys/kern/subr_taskqueue.c
 LIB_C_FILES += freebsd/sys/kern/subr_unit.c
 LIB_C_FILES += freebsd/sys/kern/sys_generic.c
 LIB_C_FILES += freebsd/sys/kern/uipc_accf.c
diff --git a/freebsd-to-rtems.py b/freebsd-to-rtems.py
index ebb1c1e9..953bb6d9 100755
--- a/freebsd-to-rtems.py
+++ b/freebsd-to-rtems.py
@@ -640,7 +640,6 @@ rtems.addRTEMSSourceFiles(
 		'rtems/rtems-bsd-sysctlbyname.c',
 		'rtems/rtems-bsd-sysctl.c',
 		'rtems/rtems-bsd-sysctlnametomib.c',
-		'rtems/rtems-bsd-taskqueue.c',
 		'rtems/rtems-bsd-thread.c',
 		'rtems/rtems-bsd-timesupport.c',
 		'rtems/rtems-kvm.c',
@@ -804,6 +803,7 @@ base.addSourceFiles(
 		'sys/kern/subr_module.c',
 		'sys/kern/subr_rman.c',
 		'sys/kern/subr_sbuf.c',
+		'sys/kern/subr_taskqueue.c',
 		'sys/kern/subr_unit.c',
 		'sys/kern/sys_generic.c',
 		'sys/kern/uipc_accf.c',
@@ -1175,7 +1175,6 @@ devNet.addSourceFiles(
 devNic = Module('dev_nic')
 devNic.addHeaderFiles(
 	[
-	#	'sys/taskqueue.h',
 		'sys/sys/pciio.h',
 		'sys/dev/random/randomdev_soft.h',
 		'sys/sys/eventvar.h',
diff --git a/freebsd/sys/kern/subr_taskqueue.c b/freebsd/sys/kern/subr_taskqueue.c
new file mode 100644
index 00000000..bbfe69e4
--- /dev/null
+++ b/freebsd/sys/kern/subr_taskqueue.c
@@ -0,0 +1,509 @@
+#include <machine/rtems-bsd-config.h>
+
+/*-
+ * 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 <rtems/bsd/sys/param.h>
+#include <sys/systm.h>
+#include <sys/bus.h>
+#include <sys/interrupt.h>
+#include <sys/kernel.h>
+#include <sys/kthread.h>
+#include <rtems/bsd/sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mutex.h>
+#include <sys/proc.h>
+#include <sys/sched.h>
+#include <sys/taskqueue.h>
+#include <rtems/bsd/sys/unistd.h>
+#include <machine/stdarg.h>
+
+static MALLOC_DEFINE(M_TASKQUEUE, "taskqueue", "Task Queues");
+#ifndef __rtems__
+static void	*taskqueue_giant_ih;
+#endif /* __rtems__ */
+static void	*taskqueue_ih;
+
+struct taskqueue_busy {
+	struct task	*tb_running;
+	TAILQ_ENTRY(taskqueue_busy) tb_link;
+};
+
+struct taskqueue {
+	STAILQ_HEAD(, task)	tq_queue;
+	const char		*tq_name;
+	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;
+#ifndef __rtems__
+	int			tq_spin;
+#endif /* __rtems__ */
+	int			tq_flags;
+};
+
+#define	TQ_FLAGS_ACTIVE		(1 << 0)
+#define	TQ_FLAGS_BLOCKED	(1 << 1)
+#define	TQ_FLAGS_PENDING	(1 << 2)
+
+static void	taskqueue_run_locked(struct taskqueue *);
+
+static __inline void
+TQ_LOCK(struct taskqueue *tq)
+{
+#ifndef __rtems__
+	if (tq->tq_spin)
+		mtx_lock_spin(&tq->tq_mutex);
+	else
+#endif /* __rtems__ */
+		mtx_lock(&tq->tq_mutex);
+}
+
+static __inline void
+TQ_UNLOCK(struct taskqueue *tq)
+{
+#ifndef __rtems__
+	if (tq->tq_spin)
+		mtx_unlock_spin(&tq->tq_mutex);
+	else
+#endif /* __rtems__ */
+		mtx_unlock(&tq->tq_mutex);
+}
+
+static __inline int
+TQ_SLEEP(struct taskqueue *tq, void *p, struct mtx *m, int pri, const char *wm,
+    int t)
+{
+#ifndef __rtems__
+	if (tq->tq_spin)
+		return (msleep_spin(p, m, wm, t));
+#endif /* __rtems__ */
+	return (msleep(p, m, pri, wm, t));
+}
+
+static struct taskqueue *
+_taskqueue_create(const char *name, 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_name = name;
+	queue->tq_enqueue = enqueue;
+	queue->tq_context = context;
+#ifndef __rtems__
+	queue->tq_spin = (mtxflags & MTX_SPIN) != 0;
+#else /* __rtems__ */
+	/*
+	 * FIXME: Here is a potential performance optimization.  Maybe also an
+	 * issue for correctness.
+	 */
+#endif /* __rtems__ */
+	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_run_locked(queue);
+	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);
+}
+
+void
+taskqueue_drain(struct taskqueue *queue, struct task *task)
+{
+#ifndef __rtems__
+	if (queue->tq_spin) {		/* XXX */
+		mtx_lock_spin(&queue->tq_mutex);
+		while (task->ta_pending != 0 || task_is_running(queue, task))
+			msleep_spin(task, &queue->tq_mutex, "-", 0);
+		mtx_unlock_spin(&queue->tq_mutex);
+	} else {
+#endif /* __rtems__ */
+		WITNESS_WARN(WARN_GIANTOK | WARN_SLEEPOK, NULL, __func__);
+
+		mtx_lock(&queue->tq_mutex);
+		while (task->ta_pending != 0 || task_is_running(queue, task))
+			msleep(task, &queue->tq_mutex, PWAIT, "-", 0);
+		mtx_unlock(&queue->tq_mutex);
+#ifndef __rtems__
+	}
+#endif /* __rtems__ */
+}
+
+static void
+taskqueue_swi_enqueue(void *context)
+{
+	swi_sched(taskqueue_ih, 0);
+}
+
+static void
+taskqueue_swi_run(void *dummy)
+{
+	taskqueue_run(taskqueue_swi);
+}
+
+#ifndef __rtems__
+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);
+}
+#endif /* __rtems__ */
+
+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++;
+	}
+#ifndef __rtems__
+	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);
+	}
+#else /* __rtems__ */
+	(void) td;
+#endif /* __rtems__ */
+
+	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);
+	}
+
+	/* 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)); 
+
+#ifndef __rtems__
+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)); 
+#endif /* __rtems__ */
+
+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);
+}
diff --git a/libbsd.txt b/libbsd.txt
index 65b1dbc7..caacf1ee 100644
--- a/libbsd.txt
+++ b/libbsd.txt
@@ -92,7 +92,9 @@ the current Git submodule commit is this
 * get_cyclecount(): The implementation is a security problem.
 
 * What to do with the priority parameter present in the FreeBSD synchronization
-  primitives?
+  primitives and the thread creation functions?
+
+* TASKQUEUE(9): Support spin mutexes.
 
 * ZONE(9): Review allocator lock usage in rtems-bsd-chunk.c.
 
diff --git a/rtemsbsd/rtems/rtems-bsd-taskqueue.c b/rtemsbsd/rtems/rtems-bsd-taskqueue.c
deleted file mode 100644
index 58959df2..00000000
--- a/rtemsbsd/rtems/rtems-bsd-taskqueue.c
+++ /dev/null
@@ -1,349 +0,0 @@
-/**
- * @file
- *
- * @ingroup rtems_bsd_rtems
- *
- * @brief TODO.
- */
-
-/*
- * COPYRIGHT (c) 2012.
- * On-Line Applications Research Corporation (OAR).
- * 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 <rtems.h>
-#include <rtems/error.h>
-#include <machine/rtems-bsd-taskqueue.h>
-
-/*
-#define STATIC static
-*/
-#undef  DEBUG
-
-#ifdef DEBUG
-#include <stdio.h>
-#ifndef STATIC
-#define STATIC
-#endif
-#else
-#ifndef STATIC
-#define STATIC static
-#endif
-#endif
-
-#define TQ_WAKE_EVENT RTEMS_EVENT_0
-
-/* This implementation is extremely simple; we assume
- * that all taskqueues (and as a matter of fact there is
- * only a single one) are manipulated with the rtems
- * bsdnet semaphore held. I.e.,
- *   taskqueue_enqueue()
- *   taskqueue_drain()
- *   etc.
- * are called from an environment that holds the
- * bsdnet semaphore.
- * Likewise, the thread that works the taskqueue
- * holds the semaphore while doing so.
- *
- */
-
-/* use single-linked list; 'drain' which would benefit from
- * double-linked list is seldom used and performance doesn't
- * matter much there. OTOH, the frequent case of working
- * the list + enqueueing is more efficient for the single-linked
- * list.
-struct task {
-	struct task *ta_next;
-	int		     ta_pending;
-	int		     ta_priority;
-	task_fn      ta_fn;
-	void        *ta_fn_arg;
-};
- */
-
-struct taskqueue {
-	struct task anchor;
-	struct task *tail;
-	tq_enq_fn   enq_fn;
-	void       *enq_fn_arg;
-	rtems_id    tid;
-};
-
-
-STATIC struct taskqueue the_taskqueue = {
-	{ 0, 0, 0, 0, 0 },
-	&the_taskqueue.anchor,
-	taskqueue_thread_enqueue,
-	&taskqueue_fast,
-	0
-};
-
-struct taskqueue *taskqueue_fast = &the_taskqueue;
-struct taskqueue *taskqueue_swi = NULL;
-
-struct taskqueue *
-taskqueue_create(const char *name, int mflags, tq_enq_fn enq_fn, void *arg)
-{
-	if ( enq_fn != taskqueue_thread_enqueue )
-		rtems_panic("rtems_taskqueue: attempt to create non-standard TQ; implementation needs to be modified\n");
-	return &the_taskqueue;
-}
-
-struct taskqueue *
-taskqueue_create_fast(const char *name, int mflags, tq_enq_fn enq_fn, void *arg)
-{
-	return taskqueue_create(name, mflags, enq_fn, arg);
-}
-
-/* taskqueue_enqueue must be allowed from an ISR;
- * hence, all critical list manipulation must lock out
- * interrupts...
- */
-int
-taskqueue_enqueue(struct taskqueue *tq, struct task *ta)
-{
-rtems_interrupt_level l;
-
-rtems_interrupt_disable(l);
-	if ( 0 == ta->ta_pending ++ ) {
-		/* hook into list */
-		ta->ta_next       = 0;
-		tq->tail->ta_next = ta;
-		tq->tail          = ta;
-	}
-	tq->enq_fn(tq->enq_fn_arg);
-rtems_interrupt_enable(l);
-	return 0;
-}
-
-int
-taskqueue_enqueue_fast(struct taskqueue *queue, struct task *task)
-{
-  return taskqueue_enqueue(queue, task);
-}
-
-void
-taskqueue_thread_enqueue(void *ctxt)
-{
-int                   dopost;
-/* pointer-to-pointer is what bsd provides; we currently
- * follow the scheme even we don't directly use the argument
- * passed to taskqueue_create...
- */
-struct taskqueue *tq = *(struct taskqueue **)ctxt;
-	/* If this is the first entry on the list then the
-	 * task needs to be notified...
-	 */
-	dopost = ( tq->anchor.ta_next == tq->tail && 1 == tq->tail->ta_pending );
-
-	if ( dopost )
-		rtems_event_send(tq->tid, TQ_WAKE_EVENT);
-}
-
-/* Returns 0 on success */
-int
-taskqueue_start_threads(struct taskqueue **ptq, int count, int prio, const char *fmt, ...)
-{
-	if ( count != 1 )
-		rtems_panic("rtems_taskqueue: taskqueue_start_threads cannot currently deal with count != 1\n");
-	
-	/* Do (non thread-safe) lazy init as a fallback */
-	if ( ! the_taskqueue.tid )
-		rtems_taskqueue_initialize();
-	return 0;
-}
-
-void
-taskqueue_drain(struct taskqueue *tq, struct task *ta)
-{
-rtems_interrupt_level l;
-struct task *p, *q;
-int    i;
-
-	/* find predecessor; searching the list should be
-	 * safe; an ISR might append a new record to the tail
-	 * while we are working but that should be OK.
-	 */
-	for ( p = &tq->anchor; (q = p->ta_next); p=q ) {
-		if ( q == ta ) {
-		rtems_interrupt_disable(l);
-			/* found; do work */
-			/* remember 'pending' count and extract */
-			i              = ta->ta_pending;
-			ta->ta_pending = 0;
-			p->ta_next     = ta->ta_next;
-			ta->ta_next    = 0;
-			/* adjust tail */
-			if ( tq->tail == q )
-				tq->tail = p;
-		rtems_interrupt_enable(l);
-			for ( ; i>0; i-- ) {
-				ta->ta_fn(ta->ta_fn_arg, i);
-			}
-			return;
-		}
-	}
-}
-
-/* work the task queue and return
- * nonzero if the list is not empty
- * (which means that some callback has
- * rescheduled itself)
- */
-static void *
-taskqueue_work(struct taskqueue *tq)
-{
-rtems_interrupt_level l;
-struct task   *p, *q;
-task_fn        f;
-void        *arg;
-int            i;
-
-/* work off a temporary list in case any callback reschedules
- * itself or if new tasks are queued from an ISR.
- */
-rtems_interrupt_disable(l);
-	p = tq->anchor.ta_next;
-
-	tq->anchor.ta_next = 0;
-	tq->tail           = &tq->anchor;
-rtems_interrupt_enable(l);
-
-	while ( (q=p) ) {
-	rtems_interrupt_disable(l);
-		i = q->ta_pending;
-		q->ta_pending = 0;
-		/* extract */
-		p          = q->ta_next;
-		q->ta_next = 0;
-		f          = q->ta_fn;
-		arg        = q->ta_fn_arg;
-	rtems_interrupt_enable(l);
-		for ( ; i>0; i-- ) {
-			f(arg, i);
-		}
-	}
-	return tq->anchor.ta_next;
-}
-
-void
-taskqueue_free(struct taskqueue *tq)
-{
-	taskqueue_work(tq);
-}
-
-static void
-taskqueueDoWork(void *arg)
-{
-struct taskqueue *tq = arg;
-rtems_event_set  evs;
-rtems_status_code sc;
-	while ( 1 ) {
-		sc = rtems_event_receive(TQ_WAKE_EVENT, RTEMS_EVENT_ANY | RTEMS_WAIT, RTEMS_NO_TIMEOUT, &evs);
-		if ( RTEMS_SUCCESSFUL != sc ) {
-			rtems_error(sc,"rtems_taskqueue: taskqueueDoWork() unable to receive wakup event\n");
-			rtems_panic("Can't proceed\n");
-		}
-		if ( taskqueue_work(tq) ) {
-#if 0
-			/* chance to reschedule */
-			rtems_bsdnet_semaphore_release();
-			rtems_task_wake_after(0);
-			rtems_bsdnet_semaphore_obtain();
-#else
-			/* hopefully, releasing the semaphore (as part of bsdnet_event_receive)
-			 * and obtaining the event (which has been posted already)
-			 * yields the CPU if necessary...
-			 */
-#endif
-		}
-	}
-}
-
-#ifdef DEBUG
-struct task_dbg {
-	struct task t;
-	char        *nm;
-};
-
-struct task_dbg taskA = {
-	{0},
-	"taskA"
-};
-
-struct task_dbg taskB = {
-	{0},
-	"taskB"
-};
-
-struct task_dbg taskC = {
-	{0},
-	"taskC"
-};
-
-static void the_task_fn(void *arg, int pending)
-{
-struct task_dbg *td = arg;
-	printf("%s (pending: %i)\n", td->nm, pending);
-	/* Test rescheduling */
-	if ( pending > 3 )
-		taskqueue_enqueue(&the_taskqueue,&td->t);
-}
-
-void taskqueue_dump()
-{
-struct task *p;
-	printf("Anchor %p, Tail %p\n", &the_taskqueue.anchor, the_taskqueue.tail);
-	for ( p = the_taskqueue.anchor.ta_next; p; p=p->ta_next ) {
-		printf("%p: (pending %2i, next %p)\n",
-			p, p->ta_pending, p->ta_next);
-	}
-}
-#endif
-
-rtems_id
-rtems_taskqueue_initialize()
-{
-#ifdef DEBUG
-	TASK_INIT( &taskA.t, 0, the_task_fn, &taskA );
-	TASK_INIT( &taskB.t, 0, the_task_fn, &taskB );
-	TASK_INIT( &taskC.t, 0, the_task_fn, &taskC );
-#endif
-	if ( ! the_taskqueue.tid )
-		the_taskqueue.tid = rtems_bsdnet_newproc("tskq", 10000, taskqueueDoWork, &the_taskqueue);
-	return the_taskqueue.tid;
-}
-
-#ifdef DEBUG
-void
-_cexpModuleInitialize(void *u)
-{
-	rtems_bsdnet_initialize_network();
-	the_taskqueue.tid = rtems_taskqueue_initialize();
-}
-#endif