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 | |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 19 | #include <linux/futex.h> |
Dan Albert | 06c7a6f | 2017-10-11 12:44:12 -0700 | [diff] [blame] | 20 | #include <string.h> |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 21 | #include <sys/mman.h> |
| 22 | #include <sys/syscall.h> |
Steven Moreland | 26531e0 | 2017-04-13 18:20:19 -0700 | [diff] [blame] | 23 | #include <unistd.h> |
Dan Albert | 06c7a6f | 2017-10-11 12:44:12 -0700 | [diff] [blame] | 24 | |
| 25 | #include <new> |
| 26 | |
| 27 | #include <fmq/EventFlag.h> |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 28 | #include <utils/Log.h> |
Hridya Valsaraju | f542b5a | 2017-03-21 11:33:33 -0700 | [diff] [blame] | 29 | #include <utils/SystemClock.h> |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 30 | |
| 31 | namespace android { |
| 32 | namespace hardware { |
| 33 | |
| 34 | status_t EventFlag::createEventFlag(int fd, off_t offset, EventFlag** flag) { |
| 35 | if (flag == nullptr) { |
| 36 | return BAD_VALUE; |
| 37 | } |
| 38 | |
| 39 | status_t status = NO_MEMORY; |
| 40 | *flag = nullptr; |
| 41 | |
| 42 | EventFlag* evFlag = new (std::nothrow) EventFlag(fd, offset, &status); |
| 43 | if (evFlag != nullptr) { |
| 44 | if (status == NO_ERROR) { |
| 45 | *flag = evFlag; |
| 46 | } else { |
| 47 | delete evFlag; |
| 48 | } |
| 49 | } |
| 50 | |
| 51 | return status; |
| 52 | } |
| 53 | |
| 54 | status_t EventFlag::createEventFlag(std::atomic<uint32_t>* fwAddr, |
| 55 | EventFlag** flag) { |
| 56 | if (flag == nullptr) { |
| 57 | return BAD_VALUE; |
| 58 | } |
| 59 | |
| 60 | status_t status = NO_MEMORY; |
| 61 | *flag = nullptr; |
| 62 | |
| 63 | EventFlag* evFlag = new (std::nothrow) EventFlag(fwAddr, &status); |
| 64 | if (evFlag != nullptr) { |
| 65 | if (status == NO_ERROR) { |
| 66 | *flag = evFlag; |
| 67 | } else { |
| 68 | delete evFlag; |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | return status; |
| 73 | } |
| 74 | |
| 75 | /* |
| 76 | * mmap memory for the futex word |
| 77 | */ |
| 78 | EventFlag::EventFlag(int fd, off_t offset, status_t* status) { |
| 79 | mEfWordPtr = static_cast<std::atomic<uint32_t>*>(mmap(NULL, |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 80 | sizeof(std::atomic<uint32_t>), |
| 81 | PROT_READ | PROT_WRITE, |
| 82 | MAP_SHARED, fd, offset)); |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 83 | mEfWordNeedsUnmapping = true; |
| 84 | if (mEfWordPtr != MAP_FAILED) { |
| 85 | *status = NO_ERROR; |
| 86 | } else { |
| 87 | *status = -errno; |
| 88 | ALOGE("Attempt to mmap event flag word failed: %s\n", strerror(errno)); |
| 89 | } |
| 90 | } |
| 91 | |
| 92 | /* |
| 93 | * Use this constructor if we already know where the futex word for |
| 94 | * the EventFlag group lives. |
| 95 | */ |
| 96 | EventFlag::EventFlag(std::atomic<uint32_t>* fwAddr, status_t* status) { |
| 97 | *status = NO_ERROR; |
| 98 | if (fwAddr == nullptr) { |
| 99 | *status = BAD_VALUE; |
| 100 | } else { |
| 101 | mEfWordPtr = fwAddr; |
| 102 | } |
| 103 | } |
| 104 | |
| 105 | /* |
| 106 | * Set the specified bits of the futex word here and wake up any |
| 107 | * thread waiting on any of the bits. |
| 108 | */ |
| 109 | status_t EventFlag::wake(uint32_t bitmask) { |
| 110 | /* |
| 111 | * Return early if there are no set bits in bitmask. |
| 112 | */ |
| 113 | if (bitmask == 0) { |
| 114 | return NO_ERROR; |
| 115 | } |
| 116 | |
| 117 | status_t status = NO_ERROR; |
| 118 | uint32_t old = std::atomic_fetch_or(mEfWordPtr, bitmask); |
| 119 | /* |
Hridya Valsaraju | af605d4 | 2017-01-19 12:12:29 -0800 | [diff] [blame] | 120 | * No need to call FUTEX_WAKE_BITSET if there were deferred wakes |
| 121 | * already available for all set bits from bitmask. |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 122 | */ |
| 123 | if ((~old & bitmask) != 0) { |
| 124 | int ret = syscall(__NR_futex, mEfWordPtr, FUTEX_WAKE_BITSET, |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 125 | INT_MAX, NULL, NULL, bitmask); |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 126 | if (ret == -1) { |
| 127 | status = -errno; |
| 128 | ALOGE("Error in event flag wake attempt: %s\n", strerror(errno)); |
| 129 | } |
| 130 | } |
| 131 | return status; |
| 132 | } |
| 133 | |
| 134 | /* |
| 135 | * Wait for any of the bits in the bitmask to be set |
| 136 | * and return which bits caused the return. |
| 137 | */ |
Hridya Valsaraju | f542b5a | 2017-03-21 11:33:33 -0700 | [diff] [blame] | 138 | status_t EventFlag::waitHelper(uint32_t bitmask, uint32_t* efState, int64_t timeoutNanoSeconds) { |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 139 | /* |
| 140 | * Return early if there are no set bits in bitmask. |
| 141 | */ |
| 142 | if (bitmask == 0 || efState == nullptr) { |
| 143 | return BAD_VALUE; |
| 144 | } |
| 145 | |
| 146 | status_t status = NO_ERROR; |
| 147 | uint32_t old = std::atomic_fetch_and(mEfWordPtr, ~bitmask); |
| 148 | uint32_t setBits = old & bitmask; |
| 149 | /* |
| 150 | * If there was a deferred wake available, no need to call FUTEX_WAIT_BITSET. |
| 151 | */ |
| 152 | if (setBits != 0) { |
| 153 | *efState = setBits; |
| 154 | return status; |
| 155 | } |
| 156 | |
| 157 | uint32_t efWord = old & ~bitmask; |
| 158 | /* |
| 159 | * The syscall will put the thread to sleep only |
| 160 | * if the futex word still contains the expected |
| 161 | * value i.e. efWord. If the futex word contents have |
Andreas Huber | 3c2dcb1 | 2017-01-11 12:40:22 -0800 | [diff] [blame] | 162 | * changed, it fails with the error EAGAIN; If a timeout |
| 163 | * is specified and exceeded the syscall fails with ETIMEDOUT. |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 164 | */ |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 165 | int ret = 0; |
| 166 | if (timeoutNanoSeconds) { |
| 167 | struct timespec waitTimeAbsolute; |
| 168 | addNanosecondsToCurrentTime(timeoutNanoSeconds, &waitTimeAbsolute); |
| 169 | |
| 170 | ret = syscall(__NR_futex, mEfWordPtr, FUTEX_WAIT_BITSET, |
| 171 | efWord, &waitTimeAbsolute, NULL, bitmask); |
| 172 | } else { |
| 173 | ret = syscall(__NR_futex, mEfWordPtr, FUTEX_WAIT_BITSET, efWord, NULL, NULL, bitmask); |
| 174 | } |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 175 | if (ret == -1) { |
| 176 | status = -errno; |
Andreas Huber | 3c2dcb1 | 2017-01-11 12:40:22 -0800 | [diff] [blame] | 177 | if (status != -EAGAIN && status != -ETIMEDOUT) { |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 178 | ALOGE("Event flag wait was unsuccessful: %s\n", strerror(errno)); |
| 179 | } |
| 180 | *efState = 0; |
| 181 | } else { |
Hridya Valsaraju | 92b79dc | 2016-12-19 14:57:44 -0800 | [diff] [blame] | 182 | old = std::atomic_fetch_and(mEfWordPtr, ~bitmask); |
| 183 | *efState = old & bitmask; |
Hridya Valsaraju | 77c8aba | 2017-03-03 07:57:37 -0800 | [diff] [blame] | 184 | |
| 185 | if (*efState == 0) { |
| 186 | /* Return -EINTR for a spurious wakeup */ |
| 187 | status = -EINTR; |
| 188 | } |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 189 | } |
| 190 | return status; |
| 191 | } |
| 192 | |
Hridya Valsaraju | f542b5a | 2017-03-21 11:33:33 -0700 | [diff] [blame] | 193 | /* |
| 194 | * Wait for any of the bits in the bitmask to be set |
| 195 | * and return which bits caused the return. If 'retry' |
| 196 | * is true, wait again on a spurious wake-up. |
| 197 | */ |
| 198 | status_t EventFlag::wait(uint32_t bitmask, |
| 199 | uint32_t* efState, |
| 200 | int64_t timeoutNanoSeconds, |
| 201 | bool retry) { |
| 202 | if (!retry) { |
| 203 | return waitHelper(bitmask, efState, timeoutNanoSeconds); |
| 204 | } |
| 205 | |
| 206 | bool shouldTimeOut = timeoutNanoSeconds != 0; |
| 207 | int64_t prevTimeNs = shouldTimeOut ? android::elapsedRealtimeNano() : 0; |
| 208 | status_t status; |
| 209 | while (true) { |
| 210 | if (shouldTimeOut) { |
| 211 | int64_t currentTimeNs = android::elapsedRealtimeNano(); |
| 212 | /* |
| 213 | * Decrement TimeOutNanos to account for the time taken to complete the last |
| 214 | * iteration of the while loop. |
| 215 | */ |
| 216 | timeoutNanoSeconds -= currentTimeNs - prevTimeNs; |
| 217 | prevTimeNs = currentTimeNs; |
| 218 | if (timeoutNanoSeconds <= 0) { |
| 219 | status = -ETIMEDOUT; |
| 220 | *efState = 0; |
| 221 | break; |
| 222 | } |
| 223 | } |
| 224 | |
| 225 | status = waitHelper(bitmask, efState, timeoutNanoSeconds); |
| 226 | if ((status != -EAGAIN) && (status != -EINTR)) { |
| 227 | break; |
| 228 | } |
| 229 | } |
| 230 | return status; |
| 231 | } |
| 232 | |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 233 | status_t EventFlag::unmapEventFlagWord(std::atomic<uint32_t>* efWordPtr, |
| 234 | bool* efWordNeedsUnmapping) { |
| 235 | status_t status = NO_ERROR; |
| 236 | if (*efWordNeedsUnmapping) { |
| 237 | int ret = munmap(efWordPtr, sizeof(std::atomic<uint32_t>)); |
| 238 | if (ret != 0) { |
| 239 | status = -errno; |
| 240 | ALOGE("Error in deleting event flag group: %s\n", strerror(errno)); |
| 241 | } |
| 242 | *efWordNeedsUnmapping = false; |
| 243 | } |
| 244 | return status; |
| 245 | } |
| 246 | |
| 247 | status_t EventFlag::deleteEventFlag(EventFlag** evFlag) { |
| 248 | if (evFlag == nullptr || *evFlag == nullptr) { |
| 249 | return BAD_VALUE; |
| 250 | } |
| 251 | |
| 252 | status_t status = unmapEventFlagWord((*evFlag)->mEfWordPtr, |
| 253 | &(*evFlag)->mEfWordNeedsUnmapping); |
| 254 | delete *evFlag; |
| 255 | *evFlag = nullptr; |
| 256 | |
| 257 | return status; |
| 258 | } |
| 259 | |
Hridya Valsaraju | 10f59dc | 2016-12-20 12:50:44 -0800 | [diff] [blame] | 260 | void EventFlag::addNanosecondsToCurrentTime(int64_t nanoSeconds, struct timespec* waitTime) { |
| 261 | static constexpr int64_t kNanosPerSecond = 1000000000; |
| 262 | |
| 263 | clock_gettime(CLOCK_MONOTONIC, waitTime); |
| 264 | waitTime->tv_sec += nanoSeconds / kNanosPerSecond; |
| 265 | waitTime->tv_nsec += nanoSeconds % kNanosPerSecond; |
| 266 | |
| 267 | if (waitTime->tv_nsec >= kNanosPerSecond) { |
| 268 | waitTime->tv_sec++; |
| 269 | waitTime->tv_nsec -= kNanosPerSecond; |
| 270 | } |
| 271 | } |
| 272 | |
Hridya Valsaraju | 8b0d5a5 | 2016-12-16 10:29:03 -0800 | [diff] [blame] | 273 | EventFlag::~EventFlag() { |
| 274 | unmapEventFlagWord(mEfWordPtr, &mEfWordNeedsUnmapping); |
| 275 | } |
| 276 | |
| 277 | } // namespace hardware |
| 278 | } // namespace android |