1 files changed, 44 insertions, 0 deletions
diff --git a/src/runtime/lfstack.go b/src/runtime/lfstack.go
new file mode 100644
index 000000000..8a36a67b3
--- /dev/null
+++ b/src/runtime/lfstack.go
@@ -0,0 +1,44 @@
+// Copyright 2012 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Lock-free stack.
+// The following code runs only on g0 stack.
+
+package runtime
+
+import "unsafe"
+
+func lfstackpush(head *uint64, node *lfnode) {
+	node.pushcnt++
+	new := lfstackPack(node, node.pushcnt)
+	if node1, _ := lfstackUnpack(new); node1 != node {
+		println("runtime: lfstackpush invalid packing: node=", node, " cnt=", hex(node.pushcnt), " packed=", hex(new), " -> node=", node1, "\n")
+		gothrow("lfstackpush")
+	}
+	for {
+		old := atomicload64(head)
+		node.next, _ = lfstackUnpack(old)
+		if cas64(head, old, new) {
+			break
+		}
+	}
+}
+
+func lfstackpop(head *uint64) unsafe.Pointer {
+	for {
+		old := atomicload64(head)
+		if old == 0 {
+			return nil
+		}
+		node, _ := lfstackUnpack(old)
+		node2 := (*lfnode)(atomicloadp(unsafe.Pointer(&node.next)))
+		new := uint64(0)
+		if node2 != nil {
+			new = lfstackPack(node2, node2.pushcnt)
+		}
+		if cas64(head, old, new) {
+			return unsafe.Pointer(node)
+		}
+	}
+}