1 files changed, 261 insertions, 0 deletions

diff --git a/zfs/lib/libspl/taskq.c b/zfs/lib/libspl/taskq.c
new file mode 100644
index 000000000..93acdcf8e
--- /dev/null
+++ b/zfs/lib/libspl/taskq.c
@@ -0,0 +1,261 @@
+/*
+ * CDDL HEADER START
+ *
+ * The contents of this file are subject to the terms of the
+ * Common Development and Distribution License (the "License").
+ * You may not use this file except in compliance with the License.
+ *
+ * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
+ * or http://www.opensolaris.org/os/licensing.
+ * See the License for the specific language governing permissions
+ * and limitations under the License.
+ *
+ * When distributing Covered Code, include this CDDL HEADER in each
+ * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
+ * If applicable, add the following below this CDDL HEADER, with the
+ * fields enclosed by brackets "[]" replaced with your own identifying
+ * information: Portions Copyright [yyyy] [name of copyright owner]
+ *
+ * CDDL HEADER END
+ */
+/*
+ * Copyright 2008 Sun Microsystems, Inc.  All rights reserved.
+ * Use is subject to license terms.
+ */
+
+#include <sys/zfs_context.h>
+
+int taskq_now;
+taskq_t *system_taskq;
+
+typedef struct task {
+	struct task	*task_next;
+	struct task	*task_prev;
+	task_func_t	*task_func;
+	void		*task_arg;
+} task_t;
+
+#define	TASKQ_ACTIVE	0x00010000
+
+struct taskq {
+	kmutex_t	tq_lock;
+	krwlock_t	tq_threadlock;
+	kcondvar_t	tq_dispatch_cv;
+	kcondvar_t	tq_wait_cv;
+	thread_t	*tq_threadlist;
+	int		tq_flags;
+	int		tq_active;
+	int		tq_nthreads;
+	int		tq_nalloc;
+	int		tq_minalloc;
+	int		tq_maxalloc;
+	task_t		*tq_freelist;
+	task_t		tq_task;
+};
+
+static task_t *
+task_alloc(taskq_t *tq, int tqflags)
+{
+	task_t *t;
+
+	if ((t = tq->tq_freelist) != NULL && tq->tq_nalloc >= tq->tq_minalloc) {
+		tq->tq_freelist = t->task_next;
+	} else {
+		mutex_exit(&tq->tq_lock);
+		if (tq->tq_nalloc >= tq->tq_maxalloc) {
+			if (!(tqflags & KM_SLEEP)) {
+				mutex_enter(&tq->tq_lock);
+				return (NULL);
+			}
+			/*
+			 * We don't want to exceed tq_maxalloc, but we can't
+			 * wait for other tasks to complete (and thus free up
+			 * task structures) without risking deadlock with
+			 * the caller.  So, we just delay for one second
+			 * to throttle the allocation rate.
+			 */
+			delay(hz);
+		}
+		t = kmem_alloc(sizeof (task_t), tqflags);
+		mutex_enter(&tq->tq_lock);
+		if (t != NULL)
+			tq->tq_nalloc++;
+	}
+	return (t);
+}
+
+static void
+task_free(taskq_t *tq, task_t *t)
+{
+	if (tq->tq_nalloc <= tq->tq_minalloc) {
+		t->task_next = tq->tq_freelist;
+		tq->tq_freelist = t;
+	} else {
+		tq->tq_nalloc--;
+		mutex_exit(&tq->tq_lock);
+		kmem_free(t, sizeof (task_t));
+		mutex_enter(&tq->tq_lock);
+	}
+}
+
+taskqid_t
+taskq_dispatch(taskq_t *tq, task_func_t func, void *arg, uint_t tqflags)
+{
+	task_t *t;
+
+	if (taskq_now) {
+		func(arg);
+		return (1);
+	}
+
+	mutex_enter(&tq->tq_lock);
+	ASSERT(tq->tq_flags & TASKQ_ACTIVE);
+	if ((t = task_alloc(tq, tqflags)) == NULL) {
+		mutex_exit(&tq->tq_lock);
+		return (0);
+	}
+	t->task_next = &tq->tq_task;
+	t->task_prev = tq->tq_task.task_prev;
+	t->task_next->task_prev = t;
+	t->task_prev->task_next = t;
+	t->task_func = func;
+	t->task_arg = arg;
+	cv_signal(&tq->tq_dispatch_cv);
+	mutex_exit(&tq->tq_lock);
+	return (1);
+}
+
+void
+taskq_wait(taskq_t *tq)
+{
+	mutex_enter(&tq->tq_lock);
+	while (tq->tq_task.task_next != &tq->tq_task || tq->tq_active != 0)
+		cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
+	mutex_exit(&tq->tq_lock);
+}
+
+static void *
+taskq_thread(void *arg)
+{
+	taskq_t *tq = arg;
+	task_t *t;
+
+	mutex_enter(&tq->tq_lock);
+	while (tq->tq_flags & TASKQ_ACTIVE) {
+		if ((t = tq->tq_task.task_next) == &tq->tq_task) {
+			if (--tq->tq_active == 0)
+				cv_broadcast(&tq->tq_wait_cv);
+			cv_wait(&tq->tq_dispatch_cv, &tq->tq_lock);
+			tq->tq_active++;
+			continue;
+		}
+		t->task_prev->task_next = t->task_next;
+		t->task_next->task_prev = t->task_prev;
+		mutex_exit(&tq->tq_lock);
+
+		rw_enter(&tq->tq_threadlock, RW_READER);
+		t->task_func(t->task_arg);
+		rw_exit(&tq->tq_threadlock);
+
+		mutex_enter(&tq->tq_lock);
+		task_free(tq, t);
+	}
+	tq->tq_nthreads--;
+	cv_broadcast(&tq->tq_wait_cv);
+	mutex_exit(&tq->tq_lock);
+	return (NULL);
+}
+
+/*ARGSUSED*/
+taskq_t *
+taskq_create(const char *name, int nthreads, pri_t pri,
+	int minalloc, int maxalloc, uint_t flags)
+{
+	taskq_t *tq = kmem_zalloc(sizeof (taskq_t), KM_SLEEP);
+	int t;
+
+	rw_init(&tq->tq_threadlock, NULL, RW_DEFAULT, NULL);
+	mutex_init(&tq->tq_lock, NULL, MUTEX_DEFAULT, NULL);
+	cv_init(&tq->tq_dispatch_cv, NULL, CV_DEFAULT, NULL);
+	cv_init(&tq->tq_wait_cv, NULL, CV_DEFAULT, NULL);
+	tq->tq_flags = flags | TASKQ_ACTIVE;
+	tq->tq_active = nthreads;
+	tq->tq_nthreads = nthreads;
+	tq->tq_minalloc = minalloc;
+	tq->tq_maxalloc = maxalloc;
+	tq->tq_task.task_next = &tq->tq_task;
+	tq->tq_task.task_prev = &tq->tq_task;
+	tq->tq_threadlist = kmem_alloc(nthreads * sizeof (thread_t), KM_SLEEP);
+
+	if (flags & TASKQ_PREPOPULATE) {
+		mutex_enter(&tq->tq_lock);
+		while (minalloc-- > 0)
+			task_free(tq, task_alloc(tq, KM_SLEEP));
+		mutex_exit(&tq->tq_lock);
+	}
+
+	for (t = 0; t < nthreads; t++)
+		(void) thr_create(0, 0, taskq_thread,
+		    tq, THR_BOUND, &tq->tq_threadlist[t]);
+
+	return (tq);
+}
+
+void
+taskq_destroy(taskq_t *tq)
+{
+	int t;
+	int nthreads = tq->tq_nthreads;
+
+	taskq_wait(tq);
+
+	mutex_enter(&tq->tq_lock);
+
+	tq->tq_flags &= ~TASKQ_ACTIVE;
+	cv_broadcast(&tq->tq_dispatch_cv);
+
+	while (tq->tq_nthreads != 0)
+		cv_wait(&tq->tq_wait_cv, &tq->tq_lock);
+
+	tq->tq_minalloc = 0;
+	while (tq->tq_nalloc != 0) {
+		ASSERT(tq->tq_freelist != NULL);
+		task_free(tq, task_alloc(tq, KM_SLEEP));
+	}
+
+	mutex_exit(&tq->tq_lock);
+
+	for (t = 0; t < nthreads; t++)
+		(void) thr_join(tq->tq_threadlist[t], NULL, NULL);
+
+	kmem_free(tq->tq_threadlist, nthreads * sizeof (thread_t));
+
+	rw_destroy(&tq->tq_threadlock);
+	mutex_destroy(&tq->tq_lock);
+	cv_destroy(&tq->tq_dispatch_cv);
+	cv_destroy(&tq->tq_wait_cv);
+
+	kmem_free(tq, sizeof (taskq_t));
+}
+
+int
+taskq_member(taskq_t *tq, void *t)
+{
+	int i;
+
+	if (taskq_now)
+		return (1);
+
+	for (i = 0; i < tq->tq_nthreads; i++)
+		if (tq->tq_threadlist[i] == (thread_t)(uintptr_t)t)
+			return (1);
+
+	return (0);
+}
+
+void
+system_taskq_init(void)
+{
+	system_taskq = taskq_create("system_taskq", 64, minclsyspri, 4, 512,
+	    TASKQ_DYNAMIC | TASKQ_PREPOPULATE);
+}