diff options
Diffstat (limited to 'pkg/sleep/commit_noasm.go')
-rw-r--r-- | pkg/sleep/commit_noasm.go | 42 |
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 + } + } +} |