Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016 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 | |
| 17 | #define LOG_TAG "FMQ_EventFlags" |
| 18 | |
| 19 | #include <fmq/EventFlag.h> |
| 20 | #include <linux/futex.h> |
| 21 | #include <sys/mman.h> |
| 22 | #include <sys/syscall.h> |
| 23 | #include <utils/Log.h> |
| 24 | #include <new> |
| 25 | |
| 26 | namespace android { |
| 27 | namespace hardware { |
| 28 | |
| 29 | status_t EventFlag::createEventFlag(int fd, off_t offset, EventFlag** flag) { |
| 30 | if (flag == nullptr) { |
| 31 | return BAD_VALUE; |
| 32 | } |
| 33 | |
| 34 | status_t status = NO_MEMORY; |
| 35 | *flag = nullptr; |
| 36 | |
| 37 | EventFlag* evFlag = new (std::nothrow) EventFlag(fd, offset, &status); |
| 38 | if (evFlag != nullptr) { |
| 39 | if (status == NO_ERROR) { |
| 40 | *flag = evFlag; |
| 41 | } else { |
| 42 | delete evFlag; |
| 43 | } |
| 44 | } |
| 45 | |
| 46 | return status; |
| 47 | } |
| 48 | |
| 49 | status_t EventFlag::createEventFlag(std::atomic<uint32_t>* fwAddr, |
| 50 | EventFlag** flag) { |
| 51 | if (flag == nullptr) { |
| 52 | return BAD_VALUE; |
| 53 | } |
| 54 | |
| 55 | status_t status = NO_MEMORY; |
| 56 | *flag = nullptr; |
| 57 | |
| 58 | EventFlag* evFlag = new (std::nothrow) EventFlag(fwAddr, &status); |
| 59 | if (evFlag != nullptr) { |
| 60 | if (status == NO_ERROR) { |
| 61 | *flag = evFlag; |
| 62 | } else { |
| 63 | delete evFlag; |
| 64 | } |
| 65 | } |
| 66 | |
| 67 | return status; |
| 68 | } |
| 69 | |
| 70 | /* |
| 71 | * mmap memory for the futex word |
| 72 | */ |
| 73 | EventFlag::EventFlag(int fd, off_t offset, status_t* status) { |
| 74 | mEfWordPtr = static_cast<std::atomic<uint32_t>*>(mmap(NULL, |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 75 | sizeof(std::atomic<uint32_t>), |
| 76 | PROT_READ | PROT_WRITE, |
| 77 | MAP_SHARED, fd, offset)); |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 78 | mEfWordNeedsUnmapping = true; |
| 79 | if (mEfWordPtr != MAP_FAILED) { |
| 80 | *status = NO_ERROR; |
| 81 | } else { |
| 82 | *status = -errno; |
| 83 | ALOGE("Attempt to mmap event flag word failed: %s\n", strerror(errno)); |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | /* |
| 88 | * Use this constructor if we already know where the futex word for |
| 89 | * the EventFlag group lives. |
| 90 | */ |
| 91 | EventFlag::EventFlag(std::atomic<uint32_t>* fwAddr, status_t* status) { |
| 92 | *status = NO_ERROR; |
| 93 | if (fwAddr == nullptr) { |
| 94 | *status = BAD_VALUE; |
| 95 | } else { |
| 96 | mEfWordPtr = fwAddr; |
| 97 | } |
| 98 | } |
| 99 | |
| 100 | /* |
| 101 | * Set the specified bits of the futex word here and wake up any |
| 102 | * thread waiting on any of the bits. |
| 103 | */ |
| 104 | status_t EventFlag::wake(uint32_t bitmask) { |
| 105 | /* |
| 106 | * Return early if there are no set bits in bitmask. |
| 107 | */ |
| 108 | if (bitmask == 0) { |
| 109 | return NO_ERROR; |
| 110 | } |
| 111 | |
| 112 | status_t status = NO_ERROR; |
| 113 | uint32_t old = std::atomic_fetch_or(mEfWordPtr, bitmask); |
| 114 | /* |
Hridya Valsaraju | af605d4 | 2017-01-19 12:12:29 -0800 | [diff] [blame] | 115 | * No need to call FUTEX_WAKE_BITSET if there were deferred wakes |
| 116 | * already available for all set bits from bitmask. |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 117 | */ |
| 118 | if ((~old & bitmask) != 0) { |
| 119 | int ret = syscall(__NR_futex, mEfWordPtr, FUTEX_WAKE_BITSET, |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 120 | INT_MAX, NULL, NULL, bitmask); |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 121 | if (ret == -1) { |
| 122 | status = -errno; |
| 123 | ALOGE("Error in event flag wake attempt: %s\n", strerror(errno)); |
| 124 | } |
| 125 | } |
| 126 | return status; |
| 127 | } |
| 128 | |
| 129 | /* |
| 130 | * Wait for any of the bits in the bitmask to be set |
| 131 | * and return which bits caused the return. |
| 132 | */ |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 133 | status_t EventFlag::wait(uint32_t bitmask, uint32_t* efState, int64_t timeoutNanoSeconds) { |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 134 | /* |
| 135 | * Return early if there are no set bits in bitmask. |
| 136 | */ |
| 137 | if (bitmask == 0 || efState == nullptr) { |
| 138 | return BAD_VALUE; |
| 139 | } |
| 140 | |
| 141 | status_t status = NO_ERROR; |
| 142 | uint32_t old = std::atomic_fetch_and(mEfWordPtr, ~bitmask); |
| 143 | uint32_t setBits = old & bitmask; |
| 144 | /* |
| 145 | * If there was a deferred wake available, no need to call FUTEX_WAIT_BITSET. |
| 146 | */ |
| 147 | if (setBits != 0) { |
| 148 | *efState = setBits; |
| 149 | return status; |
| 150 | } |
| 151 | |
| 152 | uint32_t efWord = old & ~bitmask; |
| 153 | /* |
| 154 | * The syscall will put the thread to sleep only |
| 155 | * if the futex word still contains the expected |
| 156 | * value i.e. efWord. If the futex word contents have |
Andreas Huber | 3c2dcb1 | 2017-01-11 12:40:22 -0800 | [diff] [blame] | 157 | * changed, it fails with the error EAGAIN; If a timeout |
| 158 | * is specified and exceeded the syscall fails with ETIMEDOUT. |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 159 | */ |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 160 | int ret = 0; |
| 161 | if (timeoutNanoSeconds) { |
| 162 | struct timespec waitTimeAbsolute; |
| 163 | addNanosecondsToCurrentTime(timeoutNanoSeconds, &waitTimeAbsolute); |
| 164 | |
| 165 | ret = syscall(__NR_futex, mEfWordPtr, FUTEX_WAIT_BITSET, |
| 166 | efWord, &waitTimeAbsolute, NULL, bitmask); |
| 167 | } else { |
| 168 | ret = syscall(__NR_futex, mEfWordPtr, FUTEX_WAIT_BITSET, efWord, NULL, NULL, bitmask); |
| 169 | } |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 170 | if (ret == -1) { |
| 171 | status = -errno; |
Andreas Huber | 3c2dcb1 | 2017-01-11 12:40:22 -0800 | [diff] [blame] | 172 | if (status != -EAGAIN && status != -ETIMEDOUT) { |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 173 | ALOGE("Event flag wait was unsuccessful: %s\n", strerror(errno)); |
| 174 | } |
| 175 | *efState = 0; |
| 176 | } else { |
Hridya Valsaraju | 92b79dc | 2016-12-19 14:57:44 -0800 | [diff] [blame] | 177 | old = std::atomic_fetch_and(mEfWordPtr, ~bitmask); |
| 178 | *efState = old & bitmask; |
Hridya Valsaraju | 77c8aba | 2017-03-03 07:57:37 -0800 | [diff] [blame^] | 179 | |
| 180 | if (*efState == 0) { |
| 181 | /* Return -EINTR for a spurious wakeup */ |
| 182 | status = -EINTR; |
| 183 | } |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 184 | } |
| 185 | return status; |
| 186 | } |
| 187 | |
| 188 | status_t EventFlag::unmapEventFlagWord(std::atomic<uint32_t>* efWordPtr, |
| 189 | bool* efWordNeedsUnmapping) { |
| 190 | status_t status = NO_ERROR; |
| 191 | if (*efWordNeedsUnmapping) { |
| 192 | int ret = munmap(efWordPtr, sizeof(std::atomic<uint32_t>)); |
| 193 | if (ret != 0) { |
| 194 | status = -errno; |
| 195 | ALOGE("Error in deleting event flag group: %s\n", strerror(errno)); |
| 196 | } |
| 197 | *efWordNeedsUnmapping = false; |
| 198 | } |
| 199 | return status; |
| 200 | } |
| 201 | |
| 202 | status_t EventFlag::deleteEventFlag(EventFlag** evFlag) { |
| 203 | if (evFlag == nullptr || *evFlag == nullptr) { |
| 204 | return BAD_VALUE; |
| 205 | } |
| 206 | |
| 207 | status_t status = unmapEventFlagWord((*evFlag)->mEfWordPtr, |
| 208 | &(*evFlag)->mEfWordNeedsUnmapping); |
| 209 | delete *evFlag; |
| 210 | *evFlag = nullptr; |
| 211 | |
| 212 | return status; |
| 213 | } |
| 214 | |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 215 | void EventFlag::addNanosecondsToCurrentTime(int64_t nanoSeconds, struct timespec* waitTime) { |
| 216 | static constexpr int64_t kNanosPerSecond = 1000000000; |
| 217 | |
| 218 | clock_gettime(CLOCK_MONOTONIC, waitTime); |
| 219 | waitTime->tv_sec += nanoSeconds / kNanosPerSecond; |
| 220 | waitTime->tv_nsec += nanoSeconds % kNanosPerSecond; |
| 221 | |
| 222 | if (waitTime->tv_nsec >= kNanosPerSecond) { |
| 223 | waitTime->tv_sec++; |
| 224 | waitTime->tv_nsec -= kNanosPerSecond; |
| 225 | } |
| 226 | } |
| 227 | |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 228 | EventFlag::~EventFlag() { |
| 229 | unmapEventFlagWord(mEfWordPtr, &mEfWordNeedsUnmapping); |
| 230 | } |
| 231 | |
| 232 | } // namespace hardware |
| 233 | } // namespace android |