Adding upstream version 0.6.0.

Signed-off-by: Daniel Baumann <daniel@debian.org>

include/spinlock/clh.h

@@ -0,0 +1,122 @@
+/*
+ * Copyright 2010-2015 Samy Al Bahra.
+ * 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.
+ */
+
+#ifndef CK_SPINLOCK_CLH_H
+#define CK_SPINLOCK_CLH_H
+
+#include <ck_cc.h>
+#include <ck_limits.h>
+#include <ck_pr.h>
+#include <ck_stdbool.h>
+#include <ck_stddef.h>
+
+#ifndef CK_F_SPINLOCK_CLH
+#define CK_F_SPINLOCK_CLH
+
+struct ck_spinlock_clh {
+	unsigned int wait;
+	struct ck_spinlock_clh *previous;
+};
+typedef struct ck_spinlock_clh ck_spinlock_clh_t;
+
+CK_CC_INLINE static void
+ck_spinlock_clh_init(struct ck_spinlock_clh **lock, struct ck_spinlock_clh *unowned)
+{
+
+	unowned->previous = NULL;
+	unowned->wait = false;
+	*lock = unowned;
+	ck_pr_barrier();
+	return;
+}
+
+CK_CC_INLINE static bool
+ck_spinlock_clh_locked(struct ck_spinlock_clh **queue)
+{
+	struct ck_spinlock_clh *head;
+	bool r;
+
+	head = ck_pr_load_ptr(queue);
+	r = ck_pr_load_uint(&head->wait);
+	ck_pr_fence_acquire();
+	return r;
+}
+
+CK_CC_INLINE static void
+ck_spinlock_clh_lock(struct ck_spinlock_clh **queue, struct ck_spinlock_clh *thread)
+{
+	struct ck_spinlock_clh *previous;
+
+	/* Indicate to the next thread on queue that they will have to block. */
+	thread->wait = true;
+	ck_pr_fence_store_atomic();
+
+	/*
+	 * Mark current request as last request. Save reference to previous
+	 * request.
+	 */
+	previous = ck_pr_fas_ptr(queue, thread);
+	thread->previous = previous;
+
+	/* Wait until previous thread is done with lock. */
+	ck_pr_fence_load();
+	while (ck_pr_load_uint(&previous->wait) == true)
+		ck_pr_stall();
+
+	ck_pr_fence_lock();
+	return;
+}
+
+CK_CC_INLINE static void
+ck_spinlock_clh_unlock(struct ck_spinlock_clh **thread)
+{
+	struct ck_spinlock_clh *previous;
+
+	/*
+	 * If there are waiters, they are spinning on the current node wait
+	 * flag. The flag is cleared so that the successor may complete an
+	 * acquisition. If the caller is pre-empted then the predecessor field
+	 * may be updated by a successor's lock operation. In order to avoid
+	 * this, save a copy of the predecessor before setting the flag.
+	 */
+	previous = thread[0]->previous;
+
+	/*
+	 * We have to pay this cost anyways, use it as a compiler barrier too.
+	 */
+	ck_pr_fence_unlock();
+	ck_pr_store_uint(&(*thread)->wait, false);
+
+	/*
+	 * Predecessor is guaranteed not to be spinning on previous request,
+	 * so update caller to use previous structure. This allows successor
+	 * all the time in the world to successfully read updated wait flag.
+	 */
+	*thread = previous;
+	return;
+}
+#endif /* CK_F_SPINLOCK_CLH */
+#endif /* CK_SPINLOCK_CLH_H */