[dev.garbage] Merge remote-tracking branch 'origin/master' into HEAD

Change-Id: I282fd9ce9db435dfd35e882a9502ab1abc185297

1 files changed, 5 insertions, 2 deletions

diff --git a/src/runtime/lfstack.go b/src/runtime/lfstack.go
index ea640eb12f..db54ecb05e 100644
--- a/src/runtime/lfstack.go
+++ b/src/runtime/lfstack.go
@@ -3,6 +3,9 @@
 // license that can be found in the LICENSE file.
 
 // Lock-free stack.
+// Initialize head to 0, compare with 0 to test for emptiness.
+// The stack does not keep pointers to nodes,
+// so they can be garbage collected if there are no other pointers to nodes.
 // The following code runs only on g0 stack.
 
 package runtime
@@ -15,7 +18,7 @@ import (
 func lfstackpush(head *uint64, node *lfnode) {
 	node.pushcnt++
 	new := lfstackPack(node, node.pushcnt)
-	if node1, _ := lfstackUnpack(new); node1 != node {
+	if node1 := lfstackUnpack(new); node1 != node {
 		print("runtime: lfstackpush invalid packing: node=", node, " cnt=", hex(node.pushcnt), " packed=", hex(new), " -> node=", node1, "\n")
 		throw("lfstackpush")
 	}
@@ -34,7 +37,7 @@ func lfstackpop(head *uint64) unsafe.Pointer {
 		if old == 0 {
 			return nil
 		}
-		node, _ := lfstackUnpack(old)
+		node := lfstackUnpack(old)
 		next := atomic.Load64(&node.next)
 		if atomic.Cas64(head, old, next) {
 			return unsafe.Pointer(node)