Adding upstream version 0.6.0.

Signed-off-by: Daniel Baumann <daniel@debian.org>
2025-02-09 07:35:45 +01:00 · 2025-02-09 07:35:45 +01:00 · 7f70a05c55
commit 7f70a05c55
parent c49a9029dc
465 changed files with 60158 additions and 0 deletions
--- a/include/spinlock/mcs.h
+++ b/include/spinlock/mcs.h
@ -0,0 +1,155 @@
+/*
+ * 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_MCS_H
+#define CK_SPINLOCK_MCS_H
+
+#include <ck_cc.h>
+#include <ck_pr.h>
+#include <ck_stdbool.h>
+#include <ck_stddef.h>
+
+#ifndef CK_F_SPINLOCK_MCS
+#define CK_F_SPINLOCK_MCS
+
+struct ck_spinlock_mcs {
+	unsigned int locked;
+	struct ck_spinlock_mcs *next;
+};
+typedef struct ck_spinlock_mcs * ck_spinlock_mcs_t;
+typedef struct ck_spinlock_mcs ck_spinlock_mcs_context_t;
+
+#define CK_SPINLOCK_MCS_INITIALIZER	    (NULL)
+
+CK_CC_INLINE static void
+ck_spinlock_mcs_init(struct ck_spinlock_mcs **queue)
+{
+
+	*queue = NULL;
+	ck_pr_barrier();
+	return;
+}
+
+CK_CC_INLINE static bool
+ck_spinlock_mcs_trylock(struct ck_spinlock_mcs **queue,
+    struct ck_spinlock_mcs *node)
+{
+	bool r;
+
+	node->locked = true;
+	node->next = NULL;
+	ck_pr_fence_store_atomic();
+
+	r = ck_pr_cas_ptr(queue, NULL, node);
+	ck_pr_fence_lock();
+	return r;
+}
+
+CK_CC_INLINE static bool
+ck_spinlock_mcs_locked(struct ck_spinlock_mcs **queue)
+{
+	bool r;
+
+	r = ck_pr_load_ptr(queue) != NULL;
+	ck_pr_fence_acquire();
+	return r;
+}
+
+CK_CC_INLINE static void
+ck_spinlock_mcs_lock(struct ck_spinlock_mcs **queue,
+    struct ck_spinlock_mcs *node)
+{
+	struct ck_spinlock_mcs *previous;
+
+	/*
+	 * In the case that there is a successor, let them know they must
+	 * wait for us to unlock.
+	 */
+	node->locked = true;
+	node->next = NULL;
+	ck_pr_fence_store_atomic();
+
+	/*
+	 * Swap current tail with current lock request. If the swap operation
+	 * returns NULL, it means the queue was empty. If the queue was empty,
+	 * then the operation is complete.
+	 */
+	previous = ck_pr_fas_ptr(queue, node);
+	if (previous != NULL) {
+		/*
+		 * Let the previous lock holder know that we are waiting on
+		 * them.
+		 */
+		ck_pr_store_ptr(&previous->next, node);
+		while (ck_pr_load_uint(&node->locked) == true)
+			ck_pr_stall();
+	}
+
+	ck_pr_fence_lock();
+	return;
+}
+
+CK_CC_INLINE static void
+ck_spinlock_mcs_unlock(struct ck_spinlock_mcs **queue,
+    struct ck_spinlock_mcs *node)
+{
+	struct ck_spinlock_mcs *next;
+
+	ck_pr_fence_unlock();
+
+	next = ck_pr_load_ptr(&node->next);
+	if (next == NULL) {
+		/*
+		 * If there is no request following us then it is a possibilty
+		 * that we are the current tail. In this case, we may just
+		 * mark the spinlock queue as empty.
+		 */
+		if (ck_pr_load_ptr(queue) == node &&
+		    ck_pr_cas_ptr(queue, node, NULL) == true) {
+			return;
+		}
+
+		/*
+		 * If the node is not the current tail then a lock operation
+		 * is in-progress. In this case, busy-wait until the queue is
+		 * in a consistent state to wake up the incoming lock
+		 * request.
+		 */
+		for (;;) {
+			next = ck_pr_load_ptr(&node->next);
+			if (next != NULL)
+				break;
+
+			ck_pr_stall();
+		}
+	}
+
+	/* Allow the next lock operation to complete. */
+	ck_pr_store_uint(&next->locked, false);
+	return;
+}
+#endif /* CK_F_SPINLOCK_MCS */
+#endif /* CK_SPINLOCK_MCS_H */