github.com/flowerwrong/netstack@v0.0.0-20191009141956-e5848263af28/sleep/commit_noasm.go (about) 1 // Copyright 2018 The gVisor Authors. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 // +build !race 16 // +build !amd64 17 18 package sleep 19 20 import "sync/atomic" 21 22 // commitSleep signals to wakers that the given g is now sleeping. Wakers can 23 // then fetch it and wake it. 24 // 25 // The commit may fail if wakers have been asserted after our last check, in 26 // which case they will have set s.waitingG to zero. 27 // 28 // It is written in assembly because it is called from g0, so it doesn't have 29 // a race context. 30 func commitSleep(g uintptr, waitingG *uintptr) bool { 31 for { 32 // Check if the wait was aborted. 33 if atomic.LoadUintptr(waitingG) == 0 { 34 return false 35 } 36 37 // Try to store the G so that wakers know who to wake. 38 if atomic.CompareAndSwapUintptr(waitingG, preparingG, g) { 39 return true 40 } 41 } 42 }