1 files changed, 324 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_rwlock.c b/lib/libthr/thread/thr_rwlock.c
new file mode 100644
index 0000000..397663e
--- /dev/null
+++ b/lib/libthr/thread/thr_rwlock.c
@@ -0,0 +1,324 @@
+/*-
+ * Copyright (c) 1998 Alex Nash
+ * 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 <errno.h>
+#include <limits.h>
+#include <stdlib.h>
+
+#include "namespace.h"
+#include <pthread.h>
+#include "un-namespace.h"
+#include "thr_private.h"
+
+__weak_reference(_pthread_rwlock_destroy, pthread_rwlock_destroy);
+__weak_reference(_pthread_rwlock_init, pthread_rwlock_init);
+__weak_reference(_pthread_rwlock_rdlock, pthread_rwlock_rdlock);
+__weak_reference(_pthread_rwlock_timedrdlock, pthread_rwlock_timedrdlock);
+__weak_reference(_pthread_rwlock_tryrdlock, pthread_rwlock_tryrdlock);
+__weak_reference(_pthread_rwlock_trywrlock, pthread_rwlock_trywrlock);
+__weak_reference(_pthread_rwlock_unlock, pthread_rwlock_unlock);
+__weak_reference(_pthread_rwlock_wrlock, pthread_rwlock_wrlock);
+__weak_reference(_pthread_rwlock_timedwrlock, pthread_rwlock_timedwrlock);
+
+#define CHECK_AND_INIT_RWLOCK							\
+	if (__predict_false((prwlock = (*rwlock)) <= THR_RWLOCK_DESTROYED)) {	\
+		if (prwlock == THR_RWLOCK_INITIALIZER) {			\
+			int ret;						\
+			ret = init_static(_get_curthread(), rwlock);		\
+			if (ret)						\
+				return (ret);					\
+		} else if (prwlock == THR_RWLOCK_DESTROYED) {			\
+			return (EINVAL);					\
+		}								\
+		prwlock = *rwlock;						\
+	}
+
+/*
+ * Prototypes
+ */
+
+static int
+rwlock_init(pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr __unused)
+{
+	pthread_rwlock_t prwlock;
+
+	prwlock = (pthread_rwlock_t)calloc(1, sizeof(struct pthread_rwlock));
+	if (prwlock == NULL)
+		return (ENOMEM);
+	*rwlock = prwlock;
+	return (0);
+}
+
+int
+_pthread_rwlock_destroy (pthread_rwlock_t *rwlock)
+{
+	pthread_rwlock_t prwlock;
+	int ret;
+
+	prwlock = *rwlock;
+	if (prwlock == THR_RWLOCK_INITIALIZER)
+		ret = 0;
+	else if (prwlock == THR_RWLOCK_DESTROYED)
+		ret = EINVAL;
+	else {
+		*rwlock = THR_RWLOCK_DESTROYED;
+
+		free(prwlock);
+		ret = 0;
+	}
+	return (ret);
+}
+
+static int
+init_static(struct pthread *thread, pthread_rwlock_t *rwlock)
+{
+	int ret;
+
+	THR_LOCK_ACQUIRE(thread, &_rwlock_static_lock);
+
+	if (*rwlock == THR_RWLOCK_INITIALIZER)
+		ret = rwlock_init(rwlock, NULL);
+	else
+		ret = 0;
+
+	THR_LOCK_RELEASE(thread, &_rwlock_static_lock);
+
+	return (ret);
+}
+
+int
+_pthread_rwlock_init (pthread_rwlock_t *rwlock, const pthread_rwlockattr_t *attr)
+{
+	*rwlock = NULL;
+	return (rwlock_init(rwlock, attr));
+}
+
+static int
+rwlock_rdlock_common(pthread_rwlock_t *rwlock, const struct timespec *abstime)
+{
+	struct pthread *curthread = _get_curthread();
+	pthread_rwlock_t prwlock;
+	int flags;
+	int ret;
+
+	CHECK_AND_INIT_RWLOCK
+
+	if (curthread->rdlock_count) {
+		/*
+		 * To avoid having to track all the rdlocks held by
+		 * a thread or all of the threads that hold a rdlock,
+		 * we keep a simple count of all the rdlocks held by
+		 * a thread.  If a thread holds any rdlocks it is
+		 * possible that it is attempting to take a recursive
+		 * rdlock.  If there are blocked writers and precedence
+		 * is given to them, then that would result in the thread
+		 * deadlocking.  So allowing a thread to take the rdlock
+		 * when it already has one or more rdlocks avoids the
+		 * deadlock.  I hope the reader can follow that logic ;-)
+		 */
+		flags = URWLOCK_PREFER_READER;
+	} else {
+		flags = 0;
+	}
+
+	/*
+	 * POSIX said the validity of the abstimeout parameter need
+	 * not be checked if the lock can be immediately acquired.
+	 */
+	ret = _thr_rwlock_tryrdlock(&prwlock->lock, flags);
+	if (ret == 0) {
+		curthread->rdlock_count++;
+		return (ret);
+	}
+
+	if (__predict_false(abstime && 
+		(abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0)))
+		return (EINVAL);
+
+	for (;;) {
+		/* goto kernel and lock it */
+		ret = __thr_rwlock_rdlock(&prwlock->lock, flags, abstime);
+		if (ret != EINTR)
+			break;
+
+		/* if interrupted, try to lock it in userland again. */
+		if (_thr_rwlock_tryrdlock(&prwlock->lock, flags) == 0) {
+			ret = 0;
+			break;
+		}
+	}
+	if (ret == 0)
+		curthread->rdlock_count++;
+	return (ret);
+}
+
+int
+_pthread_rwlock_rdlock (pthread_rwlock_t *rwlock)
+{
+	return (rwlock_rdlock_common(rwlock, NULL));
+}
+
+int
+_pthread_rwlock_timedrdlock (pthread_rwlock_t *rwlock,
+	 const struct timespec *abstime)
+{
+	return (rwlock_rdlock_common(rwlock, abstime));
+}
+
+int
+_pthread_rwlock_tryrdlock (pthread_rwlock_t *rwlock)
+{
+	struct pthread *curthread = _get_curthread();
+	pthread_rwlock_t prwlock;
+	int flags;
+	int ret;
+
+	CHECK_AND_INIT_RWLOCK
+
+	if (curthread->rdlock_count) {
+		/*
+		 * To avoid having to track all the rdlocks held by
+		 * a thread or all of the threads that hold a rdlock,
+		 * we keep a simple count of all the rdlocks held by
+		 * a thread.  If a thread holds any rdlocks it is
+		 * possible that it is attempting to take a recursive
+		 * rdlock.  If there are blocked writers and precedence
+		 * is given to them, then that would result in the thread
+		 * deadlocking.  So allowing a thread to take the rdlock
+		 * when it already has one or more rdlocks avoids the
+		 * deadlock.  I hope the reader can follow that logic ;-)
+		 */
+		flags = URWLOCK_PREFER_READER;
+	} else {
+		flags = 0;
+	}
+
+	ret = _thr_rwlock_tryrdlock(&prwlock->lock, flags);
+	if (ret == 0)
+		curthread->rdlock_count++;
+	return (ret);
+}
+
+int
+_pthread_rwlock_trywrlock (pthread_rwlock_t *rwlock)
+{
+	struct pthread *curthread = _get_curthread();
+	pthread_rwlock_t prwlock;
+	int ret;
+
+	CHECK_AND_INIT_RWLOCK
+
+	ret = _thr_rwlock_trywrlock(&prwlock->lock);
+	if (ret == 0)
+		prwlock->owner = curthread;
+	return (ret);
+}
+
+static int
+rwlock_wrlock_common (pthread_rwlock_t *rwlock, const struct timespec *abstime)
+{
+	struct pthread *curthread = _get_curthread();
+	pthread_rwlock_t prwlock;
+	int ret;
+
+	CHECK_AND_INIT_RWLOCK
+
+	/*
+	 * POSIX said the validity of the abstimeout parameter need
+	 * not be checked if the lock can be immediately acquired.
+	 */
+	ret = _thr_rwlock_trywrlock(&prwlock->lock);
+	if (ret == 0) {
+		prwlock->owner = curthread;
+		return (ret);
+	}
+
+	if (__predict_false(abstime && 
+		(abstime->tv_nsec >= 1000000000 || abstime->tv_nsec < 0)))
+		return (EINVAL);
+
+	for (;;) {
+		/* goto kernel and lock it */
+		ret = __thr_rwlock_wrlock(&prwlock->lock, abstime);
+		if (ret == 0) {
+			prwlock->owner = curthread;
+			break;
+		}
+
+		if (ret != EINTR)
+			break;
+
+		/* if interrupted, try to lock it in userland again. */
+		if (_thr_rwlock_trywrlock(&prwlock->lock) == 0) {
+			ret = 0;
+			prwlock->owner = curthread;
+			break;
+		}
+	}
+	return (ret);
+}
+
+int
+_pthread_rwlock_wrlock (pthread_rwlock_t *rwlock)
+{
+	return (rwlock_wrlock_common (rwlock, NULL));
+}
+
+int
+_pthread_rwlock_timedwrlock (pthread_rwlock_t *rwlock,
+    const struct timespec *abstime)
+{
+	return (rwlock_wrlock_common (rwlock, abstime));
+}
+
+int
+_pthread_rwlock_unlock (pthread_rwlock_t *rwlock)
+{
+	struct pthread *curthread = _get_curthread();
+	pthread_rwlock_t prwlock;
+	int ret;
+	int32_t state;
+
+	prwlock = *rwlock;
+
+	if (__predict_false(prwlock <= THR_RWLOCK_DESTROYED))
+		return (EINVAL);
+
+	state = prwlock->lock.rw_state;
+	if (state & URWLOCK_WRITE_OWNER) {
+		if (__predict_false(prwlock->owner != curthread))
+			return (EPERM);
+		prwlock->owner = NULL;
+	}
+
+	ret = _thr_rwlock_unlock(&prwlock->lock);
+	if (ret == 0 && (state & URWLOCK_WRITE_OWNER) == 0)
+		curthread->rdlock_count--;
+
+	return (ret);
+}