Add code to support pthread spin lock.

Reviewed by: deischen

1 files changed, 154 insertions, 0 deletions

diff --git a/lib/libpthread/thread/thr_pspinlock.c b/lib/libpthread/thread/thr_pspinlock.c
new file mode 100644
index 0000000..de26750
--- /dev/null
+++ b/lib/libpthread/thread/thr_pspinlock.c
@@ -0,0 +1,154 @@
+/*-
+ * Copyright (c) 2003 David Xu <davidxu@freebsd.org>
+ * 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 <stdlib.h>
+#include <pthread.h>
+#include <atomic_ops.h>
+#include "thr_private.h"
+
+#define SPIN_COUNT 10000
+
+int
+pthread_spin_init(pthread_spinlock_t *lock, int pshared)
+{
+	struct pthread_spinlock	*lck;
+	int ret;
+
+	if (lock == NULL || pshared != PTHREAD_PROCESS_PRIVATE)
+		ret = EINVAL;
+	else if ((lck = malloc(sizeof(struct pthread_spinlock))) == NULL)
+		ret = ENOMEM;
+	else {
+		lck->s_lock = 0;
+		lck->s_owner= NULL;
+		*lock = lck;
+		ret = 0;
+	}
+
+	return (ret);
+}
+
+int
+pthread_spin_destroy(pthread_spinlock_t *lock)
+{
+	int ret;
+
+	if (lock == NULL || *lock == NULL)
+		ret = EINVAL;
+	else if ((*lock)->s_owner != NULL)
+		ret = EBUSY;
+	else {
+		free(*lock);
+		*lock = NULL;
+		ret = 0;
+	}
+
+	return (ret);
+}
+
+int
+pthread_spin_trylock(pthread_spinlock_t *lock)
+{
+	struct pthread_spinlock	*lck;
+	struct pthread *self = _pthread_self();
+	int oldval, ret;
+
+	if (lock == NULL || (lck = *lock) == NULL)
+		ret = EINVAL;
+	else if (lck->s_owner == self)
+		ret = EDEADLK;
+	else if (lck->s_lock != 0)
+		ret = EBUSY;
+	else {
+		atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
+		if (oldval)
+			ret = EBUSY;
+		else {
+			lck->s_owner = _pthread_self();
+			ret = 0;
+		}
+	}
+	return (ret);
+}
+
+int
+pthread_spin_lock(pthread_spinlock_t *lock)
+{
+	struct pthread_spinlock	*lck;
+	struct pthread *self = _pthread_self();
+	int count, oldval, ret;
+
+	if (lock == NULL || (lck = *lock) == NULL)
+		ret = EINVAL;
+	else if (lck->s_owner == self)
+		ret = EDEADLK;
+	else {
+		do {
+			count = SPIN_COUNT;
+			while (lck->s_lock) {
+#ifdef __i386__
+				/* tell cpu we are spinning */
+				__asm __volatile("pause");
+#endif
+				if (--count <= 0) {
+					count = SPIN_COUNT;
+					_pthread_yield();
+				}
+			}
+			atomic_swap_int((int *)&(lck)->s_lock, 1, &oldval);
+		} while (oldval);
+
+		lck->s_owner = self;
+		ret = 0;
+	}
+
+	return (ret);
+}
+
+int
+pthread_spin_unlock(pthread_spinlock_t *lock)
+{
+	struct pthread_spinlock	*lck;
+	int ret;
+
+	if (lock == NULL || (lck = *lock) == NULL)
+		ret = EINVAL;
+	else {
+		if (lck->s_owner != _pthread_self())
+			ret = EPERM;
+		else {
+			lck->s_owner = NULL;
+			atomic_swap_int((int *)&lck->s_lock, 0, &ret);
+			ret = 0;
+		}
+	}
+
+	return (ret);
+}
+