Merge 216da0b7 (automated)

1 files changed, 42 insertions, 0 deletions

diff --git a/pkg/sleep/commit_noasm.go b/pkg/sleep/commit_noasm.go
new file mode 100644
index 000000000..686b1da3d
--- /dev/null
+++ b/pkg/sleep/commit_noasm.go
@@ -0,0 +1,42 @@
+// Copyright 2018 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !race
+// +build !amd64
+
+package sleep
+
+import "sync/atomic"
+
+// commitSleep signals to wakers that the given g is now sleeping. Wakers can
+// then fetch it and wake it.
+//
+// The commit may fail if wakers have been asserted after our last check, in
+// which case they will have set s.waitingG to zero.
+//
+// It is written in assembly because it is called from g0, so it doesn't have
+// a race context.
+func commitSleep(g uintptr, waitingG *uintptr) bool {
+	for {
+		// Check if the wait was aborted.
+		if atomic.LoadUintptr(waitingG) == 0 {
+			return false
+		}
+
+		// Try to store the G so that wakers know who to wake.
+		if atomic.CompareAndSwapUintptr(waitingG, preparingG, g) {
+			return true
+		}
+	}
+}