1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 #include "common/vsoc/shm/lock.h" 17 18 #include "common/vsoc/lib/compat.h" 19 #include "common/vsoc/lib/single_sided_signal.h" 20 21 namespace vsoc { 22 namespace layout { 23 24 void GuestLock::Lock() { 25 uint32_t tid = gettid(); 26 uint32_t expected_value; 27 uint32_t* uaddr = reinterpret_cast<uint32_t*>(&lock_uint32_); 28 29 while (1) { 30 if (TryLock(tid, &expected_value)) { 31 return; 32 } 33 SingleSidedSignal::AwaitSignal(expected_value, uaddr); 34 } 35 } 36 37 void GuestLock::Unlock() { 38 Sides sides_to_signal = UnlockCommon(gettid()); 39 if (sides_to_signal != Sides::NoSides) { 40 SingleSidedSignal::Signal(&lock_uint32_); 41 } 42 } 43 44 bool GuestLock::Recover() { 45 return RecoverSingleSided(); 46 } 47 48 } // namespace layout 49 } // namespace vsoc 50
