Adding upstream version 0.6.0.

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

include/ck_swlock.h

@@ -0,0 +1,218 @@
+/*
+ * Copyright 2014 Jaidev Sridhar.
+ * Copyright 2014 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_SWLOCK_H
+#define CK_SWLOCK_H
+
+#include <ck_elide.h>
+#include <ck_limits.h>
+#include <ck_pr.h>
+#include <ck_stdbool.h>
+#include <ck_stddef.h>
+
+struct ck_swlock {
+	uint32_t value;
+};
+typedef struct ck_swlock ck_swlock_t;
+
+#define CK_SWLOCK_INITIALIZER	{0}
+#define CK_SWLOCK_WRITER_BIT	(1UL << 31)
+#define CK_SWLOCK_LATCH_BIT	(1UL << 30)
+#define CK_SWLOCK_WRITER_MASK	(CK_SWLOCK_LATCH_BIT | CK_SWLOCK_WRITER_BIT)
+#define CK_SWLOCK_READER_MASK   (UINT32_MAX ^ CK_SWLOCK_WRITER_MASK)
+
+CK_CC_INLINE static void
+ck_swlock_init(struct ck_swlock *rw)
+{
+
+	rw->value = 0;
+	ck_pr_barrier();
+	return;
+}
+
+CK_CC_INLINE static void
+ck_swlock_write_unlock(ck_swlock_t *rw)
+{
+
+	ck_pr_fence_unlock();
+	ck_pr_and_32(&rw->value, CK_SWLOCK_READER_MASK);
+	return;
+}
+
+CK_CC_INLINE static bool
+ck_swlock_locked_writer(ck_swlock_t *rw)
+{
+	bool r;
+
+	r = ck_pr_load_32(&rw->value) & CK_SWLOCK_WRITER_BIT;
+	ck_pr_fence_acquire();
+	return r;
+}
+
+CK_CC_INLINE static void
+ck_swlock_write_downgrade(ck_swlock_t *rw)
+{
+
+	ck_pr_inc_32(&rw->value);
+	ck_swlock_write_unlock(rw);
+	return;
+}
+
+CK_CC_INLINE static bool
+ck_swlock_locked(ck_swlock_t *rw)
+{
+	bool r;
+
+	r = ck_pr_load_32(&rw->value);
+	ck_pr_fence_acquire();
+	return r;
+}
+
+CK_CC_INLINE static bool
+ck_swlock_write_trylock(ck_swlock_t *rw)
+{
+	bool r;
+
+	r = ck_pr_cas_32(&rw->value, 0, CK_SWLOCK_WRITER_BIT);
+	ck_pr_fence_lock();
+	return r;
+}
+
+CK_ELIDE_TRYLOCK_PROTOTYPE(ck_swlock_write, ck_swlock_t,
+    ck_swlock_locked, ck_swlock_write_trylock)
+
+CK_CC_INLINE static void
+ck_swlock_write_lock(ck_swlock_t *rw)
+{
+
+	ck_pr_or_32(&rw->value, CK_SWLOCK_WRITER_BIT);
+	while (ck_pr_load_32(&rw->value) & CK_SWLOCK_READER_MASK)
+		ck_pr_stall();
+
+	ck_pr_fence_lock();
+	return;
+}
+
+CK_CC_INLINE static void
+ck_swlock_write_latch(ck_swlock_t *rw)
+{
+
+	/* Publish intent to acquire lock. */
+	ck_pr_or_32(&rw->value, CK_SWLOCK_WRITER_BIT);
+
+	/* Stall until readers have seen the writer and cleared. */
+	while (ck_pr_cas_32(&rw->value, CK_SWLOCK_WRITER_BIT,
+	    CK_SWLOCK_WRITER_MASK) == false)  {
+		do {
+			ck_pr_stall();
+		} while (ck_pr_load_32(&rw->value) != CK_SWLOCK_WRITER_BIT);
+	}
+
+	ck_pr_fence_lock();
+	return;
+}
+
+CK_CC_INLINE static void
+ck_swlock_write_unlatch(ck_swlock_t *rw)
+{
+
+	ck_pr_fence_unlock();
+	ck_pr_store_32(&rw->value, 0);
+	return;
+}
+
+CK_ELIDE_PROTOTYPE(ck_swlock_write, ck_swlock_t,
+    ck_swlock_locked, ck_swlock_write_lock,
+    ck_swlock_locked_writer, ck_swlock_write_unlock)
+
+CK_ELIDE_TRYLOCK_PROTOTYPE(ck_swlock_read, ck_swlock_t,
+    ck_swlock_locked_writer, ck_swlock_read_trylock)
+
+CK_CC_INLINE static bool
+ck_swlock_read_trylock(ck_swlock_t *rw)
+{
+	uint32_t l = ck_pr_load_32(&rw->value);
+
+	if (l & CK_SWLOCK_WRITER_BIT)
+		return false;
+
+	l = ck_pr_faa_32(&rw->value, 1) & CK_SWLOCK_WRITER_MASK;
+	if (l == CK_SWLOCK_WRITER_BIT)
+		ck_pr_dec_32(&rw->value);
+
+	ck_pr_fence_lock();
+	return l == 0;
+}
+
+CK_CC_INLINE static void
+ck_swlock_read_lock(ck_swlock_t *rw)
+{
+	uint32_t l;
+
+	for (;;) {
+		while (ck_pr_load_32(&rw->value) & CK_SWLOCK_WRITER_BIT)
+			ck_pr_stall();
+
+		l = ck_pr_faa_32(&rw->value, 1) & CK_SWLOCK_WRITER_MASK;
+		if (l == 0)
+			break;
+
+		/*
+		 * If the latch bit has not been set, then the writer would
+		 * have observed the reader and will wait to completion of
+		 * read-side critical section.
+		 */
+		if (l == CK_SWLOCK_WRITER_BIT)
+			ck_pr_dec_32(&rw->value);
+	}
+
+	ck_pr_fence_lock();
+	return;
+}
+
+CK_CC_INLINE static bool
+ck_swlock_locked_reader(ck_swlock_t *rw)
+{
+
+	ck_pr_fence_load();
+	return ck_pr_load_32(&rw->value) & CK_SWLOCK_READER_MASK;
+}
+
+CK_CC_INLINE static void
+ck_swlock_read_unlock(ck_swlock_t *rw)
+{
+
+	ck_pr_fence_unlock();
+	ck_pr_dec_32(&rw->value);
+	return;
+}
+
+CK_ELIDE_PROTOTYPE(ck_swlock_read, ck_swlock_t,
+    ck_swlock_locked_writer, ck_swlock_read_lock,
+    ck_swlock_locked_reader, ck_swlock_read_unlock)
+
+#endif /* CK_SWLOCK_H */