blob: 69d1c314989173a0f279a1e47ddb86d4fc2d0099 [file] [log] [blame]
Josh Gaoc51726c2018-10-11 16:33:05 -07001/*
2 * Copyright (C) 2018 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 TRACE_TAG USB
18
19#include "sysdeps.h"
20
21#include <errno.h>
22#include <stdio.h>
23#include <stdlib.h>
24#include <string.h>
25#include <sys/ioctl.h>
26#include <sys/types.h>
27#include <unistd.h>
28
29#include <linux/usb/functionfs.h>
30#include <sys/eventfd.h>
31
32#include <array>
33#include <future>
34#include <memory>
35#include <mutex>
36#include <optional>
37#include <vector>
38
39#include <asyncio/AsyncIO.h>
40
41#include <android-base/logging.h>
42#include <android-base/macros.h>
43#include <android-base/properties.h>
44#include <android-base/thread_annotations.h>
45
46#include <adbd/usb.h>
47
48#include "adb_unique_fd.h"
49#include "adb_utils.h"
50#include "sysdeps/chrono.h"
51#include "transport.h"
52#include "types.h"
53
54using android::base::StringPrintf;
55
Josh Gaoc0b831b2019-02-13 15:27:28 -080056// We can't find out whether we have support for AIO on ffs endpoints until we submit a read.
57static std::optional<bool> gFfsAioSupported;
58
Josh Gaoc51726c2018-10-11 16:33:05 -070059static constexpr size_t kUsbReadQueueDepth = 16;
60static constexpr size_t kUsbReadSize = 16384;
61
62static constexpr size_t kUsbWriteQueueDepth = 16;
63
64static const char* to_string(enum usb_functionfs_event_type type) {
65 switch (type) {
66 case FUNCTIONFS_BIND:
67 return "FUNCTIONFS_BIND";
68 case FUNCTIONFS_UNBIND:
69 return "FUNCTIONFS_UNBIND";
70 case FUNCTIONFS_ENABLE:
71 return "FUNCTIONFS_ENABLE";
72 case FUNCTIONFS_DISABLE:
73 return "FUNCTIONFS_DISABLE";
74 case FUNCTIONFS_SETUP:
75 return "FUNCTIONFS_SETUP";
76 case FUNCTIONFS_SUSPEND:
77 return "FUNCTIONFS_SUSPEND";
78 case FUNCTIONFS_RESUME:
79 return "FUNCTIONFS_RESUME";
80 }
81}
82
83enum class TransferDirection : uint64_t {
84 READ = 0,
85 WRITE = 1,
86};
87
88struct TransferId {
89 TransferDirection direction : 1;
90 uint64_t id : 63;
91
92 TransferId() : TransferId(TransferDirection::READ, 0) {}
93
94 private:
95 TransferId(TransferDirection direction, uint64_t id) : direction(direction), id(id) {}
96
97 public:
98 explicit operator uint64_t() const {
99 uint64_t result;
100 static_assert(sizeof(*this) == sizeof(result));
101 memcpy(&result, this, sizeof(*this));
102 return result;
103 }
104
105 static TransferId read(uint64_t id) { return TransferId(TransferDirection::READ, id); }
106 static TransferId write(uint64_t id) { return TransferId(TransferDirection::WRITE, id); }
107
108 static TransferId from_value(uint64_t value) {
109 TransferId result;
110 memcpy(&result, &value, sizeof(value));
111 return result;
112 }
113};
114
115struct IoBlock {
116 bool pending;
117 struct iocb control;
118 Block payload;
119
120 TransferId id() const { return TransferId::from_value(control.aio_data); }
121};
122
123struct ScopedAioContext {
124 ScopedAioContext() = default;
125 ~ScopedAioContext() { reset(); }
126
127 ScopedAioContext(ScopedAioContext&& move) { reset(move.release()); }
128 ScopedAioContext(const ScopedAioContext& copy) = delete;
129
130 ScopedAioContext& operator=(ScopedAioContext&& move) {
131 reset(move.release());
132 return *this;
133 }
134 ScopedAioContext& operator=(const ScopedAioContext& copy) = delete;
135
136 static ScopedAioContext Create(size_t max_events) {
137 aio_context_t ctx = 0;
138 if (io_setup(max_events, &ctx) != 0) {
139 PLOG(FATAL) << "failed to create aio_context_t";
140 }
141 ScopedAioContext result;
142 result.reset(ctx);
143 return result;
144 }
145
146 aio_context_t release() {
147 aio_context_t result = context_;
148 context_ = 0;
149 return result;
150 }
151
152 void reset(aio_context_t new_context = 0) {
153 if (context_ != 0) {
154 io_destroy(context_);
155 }
156
157 context_ = new_context;
158 }
159
160 aio_context_t get() { return context_; }
161
162 private:
163 aio_context_t context_ = 0;
164};
165
166struct UsbFfsConnection : public Connection {
167 UsbFfsConnection(unique_fd control, unique_fd read, unique_fd write,
168 std::promise<void> destruction_notifier)
169 : stopped_(false),
170 destruction_notifier_(std::move(destruction_notifier)),
171 control_fd_(std::move(control)),
172 read_fd_(std::move(read)),
173 write_fd_(std::move(write)) {
174 LOG(INFO) << "UsbFfsConnection constructed";
Josh Gaoc0b831b2019-02-13 15:27:28 -0800175 worker_event_fd_.reset(eventfd(0, EFD_CLOEXEC));
176 if (worker_event_fd_ == -1) {
177 PLOG(FATAL) << "failed to create eventfd";
178 }
179
180 monitor_event_fd_.reset(eventfd(0, EFD_CLOEXEC));
181 if (monitor_event_fd_ == -1) {
Josh Gaoc51726c2018-10-11 16:33:05 -0700182 PLOG(FATAL) << "failed to create eventfd";
183 }
184
185 aio_context_ = ScopedAioContext::Create(kUsbReadQueueDepth + kUsbWriteQueueDepth);
186 }
187
188 ~UsbFfsConnection() {
189 LOG(INFO) << "UsbFfsConnection being destroyed";
190 Stop();
191 monitor_thread_.join();
Josh Gaoc0b831b2019-02-13 15:27:28 -0800192
193 // We need to explicitly close our file descriptors before we notify our destruction,
194 // because the thread listening on the future will immediately try to reopen the endpoint.
195 control_fd_.reset();
196 read_fd_.reset();
197 write_fd_.reset();
198
Josh Gaoc51726c2018-10-11 16:33:05 -0700199 destruction_notifier_.set_value();
200 }
201
202 virtual bool Write(std::unique_ptr<apacket> packet) override final {
203 LOG(DEBUG) << "USB write: " << dump_header(&packet->msg);
204 Block header(sizeof(packet->msg));
205 memcpy(header.data(), &packet->msg, sizeof(packet->msg));
206
207 std::lock_guard<std::mutex> lock(write_mutex_);
208 write_requests_.push_back(CreateWriteBlock(std::move(header), next_write_id_++));
209 if (!packet->payload.empty()) {
210 write_requests_.push_back(
211 CreateWriteBlock(std::move(packet->payload), next_write_id_++));
212 }
213 SubmitWrites();
214 return true;
215 }
216
217 virtual void Start() override final { StartMonitor(); }
218
219 virtual void Stop() override final {
220 if (stopped_.exchange(true)) {
221 return;
222 }
223 stopped_ = true;
224 uint64_t notify = 1;
Josh Gaoc0b831b2019-02-13 15:27:28 -0800225 ssize_t rc = adb_write(worker_event_fd_.get(), &notify, sizeof(notify));
Josh Gaoc51726c2018-10-11 16:33:05 -0700226 if (rc < 0) {
Josh Gaoc0b831b2019-02-13 15:27:28 -0800227 PLOG(FATAL) << "failed to notify worker eventfd to stop UsbFfsConnection";
Josh Gaoc51726c2018-10-11 16:33:05 -0700228 }
229 CHECK_EQ(static_cast<size_t>(rc), sizeof(notify));
Josh Gaoc0b831b2019-02-13 15:27:28 -0800230
231 rc = adb_write(monitor_event_fd_.get(), &notify, sizeof(notify));
232 if (rc < 0) {
233 PLOG(FATAL) << "failed to notify monitor eventfd to stop UsbFfsConnection";
234 }
235
236 CHECK_EQ(static_cast<size_t>(rc), sizeof(notify));
Josh Gaoc51726c2018-10-11 16:33:05 -0700237 }
238
239 private:
240 void StartMonitor() {
241 // This is a bit of a mess.
242 // It's possible for io_submit to end up blocking, if we call it as the endpoint
243 // becomes disabled. Work around this by having a monitor thread to listen for functionfs
244 // lifecycle events. If we notice an error condition (either we've become disabled, or we
245 // were never enabled in the first place), we send interruption signals to the worker thread
246 // until it dies, and then report failure to the transport via HandleError, which will
247 // eventually result in the transport being destroyed, which will result in UsbFfsConnection
248 // being destroyed, which unblocks the open thread and restarts this entire process.
249 static constexpr int kInterruptionSignal = SIGUSR1;
250 static std::once_flag handler_once;
251 std::call_once(handler_once, []() { signal(kInterruptionSignal, [](int) {}); });
252
253 monitor_thread_ = std::thread([this]() {
254 adb_thread_setname("UsbFfs-monitor");
255
256 bool bound = false;
257 bool started = false;
258 bool running = true;
259 while (running) {
Josh Gaoc0b831b2019-02-13 15:27:28 -0800260 int timeout = -1;
Josh Gaoc51726c2018-10-11 16:33:05 -0700261 if (!bound || !started) {
Josh Gaoc0b831b2019-02-13 15:27:28 -0800262 timeout = 5000 /*ms*/;
263 }
264
265 adb_pollfd pfd[2] = {
266 { .fd = control_fd_.get(), .events = POLLIN, .revents = 0 },
267 { .fd = monitor_event_fd_.get(), .events = POLLIN, .revents = 0 },
268 };
269 int rc = TEMP_FAILURE_RETRY(adb_poll(pfd, 2, timeout));
270 if (rc == -1) {
271 PLOG(FATAL) << "poll on USB control fd failed";
272 } else if (rc == 0) {
273 // Something in the kernel presumably went wrong.
274 // Close our endpoints, wait for a bit, and then try again.
275 aio_context_.reset();
276 read_fd_.reset();
277 write_fd_.reset();
278 control_fd_.reset();
279 std::this_thread::sleep_for(5s);
280 HandleError("didn't receive FUNCTIONFS_ENABLE, retrying");
281 return;
282 }
283
284 if (pfd[1].revents) {
285 // We were told to die.
286 break;
Josh Gaoc51726c2018-10-11 16:33:05 -0700287 }
288
289 struct usb_functionfs_event event;
290 if (TEMP_FAILURE_RETRY(adb_read(control_fd_.get(), &event, sizeof(event))) !=
291 sizeof(event)) {
292 PLOG(FATAL) << "failed to read functionfs event";
293 }
294
295 LOG(INFO) << "USB event: "
296 << to_string(static_cast<usb_functionfs_event_type>(event.type));
297
298 switch (event.type) {
299 case FUNCTIONFS_BIND:
300 CHECK(!started) << "received FUNCTIONFS_ENABLE while already bound?";
301 bound = true;
302 break;
303
304 case FUNCTIONFS_ENABLE:
305 CHECK(!started) << "received FUNCTIONFS_ENABLE while already running?";
306 started = true;
307 StartWorker();
308 break;
309
310 case FUNCTIONFS_DISABLE:
311 running = false;
312 break;
313 }
314 }
315
316 pthread_t worker_thread_handle = worker_thread_.native_handle();
317 while (true) {
318 int rc = pthread_kill(worker_thread_handle, kInterruptionSignal);
319 if (rc != 0) {
320 LOG(ERROR) << "failed to send interruption signal to worker: " << strerror(rc);
321 break;
322 }
323
324 std::this_thread::sleep_for(100ms);
325
326 rc = pthread_kill(worker_thread_handle, 0);
327 if (rc == 0) {
328 continue;
329 } else if (rc == ESRCH) {
330 break;
331 } else {
332 LOG(ERROR) << "failed to send interruption signal to worker: " << strerror(rc);
333 }
334 }
335
336 worker_thread_.join();
337
338 aio_context_.reset();
339 read_fd_.reset();
340 write_fd_.reset();
341 });
342 }
343
344 void StartWorker() {
345 worker_thread_ = std::thread([this]() {
346 adb_thread_setname("UsbFfs-worker");
347 for (size_t i = 0; i < kUsbReadQueueDepth; ++i) {
348 read_requests_[i] = CreateReadBlock(next_read_id_++);
Josh Gaoc0b831b2019-02-13 15:27:28 -0800349 if (!SubmitRead(&read_requests_[i])) {
350 return;
351 }
Josh Gaoc51726c2018-10-11 16:33:05 -0700352 }
353
354 while (!stopped_) {
355 uint64_t dummy;
Josh Gaoc0b831b2019-02-13 15:27:28 -0800356 ssize_t rc = adb_read(worker_event_fd_.get(), &dummy, sizeof(dummy));
Josh Gaoc51726c2018-10-11 16:33:05 -0700357 if (rc == -1) {
358 PLOG(FATAL) << "failed to read from eventfd";
359 } else if (rc == 0) {
360 LOG(FATAL) << "hit EOF on eventfd";
361 }
362
363 WaitForEvents();
364 }
365 });
366 }
367
368 void PrepareReadBlock(IoBlock* block, uint64_t id) {
369 block->pending = false;
370 block->payload.resize(kUsbReadSize);
371 block->control.aio_data = static_cast<uint64_t>(TransferId::read(id));
372 block->control.aio_buf = reinterpret_cast<uintptr_t>(block->payload.data());
373 block->control.aio_nbytes = block->payload.size();
374 }
375
376 IoBlock CreateReadBlock(uint64_t id) {
377 IoBlock block;
378 PrepareReadBlock(&block, id);
379 block.control.aio_rw_flags = 0;
380 block.control.aio_lio_opcode = IOCB_CMD_PREAD;
381 block.control.aio_reqprio = 0;
382 block.control.aio_fildes = read_fd_.get();
383 block.control.aio_offset = 0;
384 block.control.aio_flags = IOCB_FLAG_RESFD;
Josh Gaoc0b831b2019-02-13 15:27:28 -0800385 block.control.aio_resfd = worker_event_fd_.get();
Josh Gaoc51726c2018-10-11 16:33:05 -0700386 return block;
387 }
388
389 void WaitForEvents() {
390 static constexpr size_t kMaxEvents = kUsbReadQueueDepth + kUsbWriteQueueDepth;
391 struct io_event events[kMaxEvents];
392 struct timespec timeout = {.tv_sec = 0, .tv_nsec = 0};
393 int rc = io_getevents(aio_context_.get(), 0, kMaxEvents, events, &timeout);
394 if (rc == -1) {
395 HandleError(StringPrintf("io_getevents failed while reading: %s", strerror(errno)));
396 return;
397 }
398
399 for (int event_idx = 0; event_idx < rc; ++event_idx) {
400 auto& event = events[event_idx];
401 TransferId id = TransferId::from_value(event.data);
402
403 if (event.res < 0) {
404 std::string error =
405 StringPrintf("%s %" PRIu64 " failed with error %s",
406 id.direction == TransferDirection::READ ? "read" : "write",
407 id.id, strerror(-event.res));
408 HandleError(error);
409 return;
410 }
411
412 if (id.direction == TransferDirection::READ) {
413 HandleRead(id, event.res);
414 } else {
415 HandleWrite(id);
416 }
417 }
418 }
419
420 void HandleRead(TransferId id, int64_t size) {
421 uint64_t read_idx = id.id % kUsbReadQueueDepth;
422 IoBlock* block = &read_requests_[read_idx];
423 block->pending = false;
424 block->payload.resize(size);
425
426 // Notification for completed reads can be received out of order.
427 if (block->id().id != needed_read_id_) {
428 LOG(VERBOSE) << "read " << block->id().id << " completed while waiting for "
429 << needed_read_id_;
430 return;
431 }
432
433 for (uint64_t id = needed_read_id_;; ++id) {
434 size_t read_idx = id % kUsbReadQueueDepth;
435 IoBlock* current_block = &read_requests_[read_idx];
436 if (current_block->pending) {
437 break;
438 }
439 ProcessRead(current_block);
440 ++needed_read_id_;
441 }
442 }
443
444 void ProcessRead(IoBlock* block) {
445 if (!block->payload.empty()) {
446 if (!incoming_header_.has_value()) {
447 CHECK_EQ(sizeof(amessage), block->payload.size());
448 amessage msg;
449 memcpy(&msg, block->payload.data(), sizeof(amessage));
450 LOG(DEBUG) << "USB read:" << dump_header(&msg);
451 incoming_header_ = msg;
452 } else {
453 size_t bytes_left = incoming_header_->data_length - incoming_payload_.size();
454 Block payload = std::move(block->payload);
455 CHECK_LE(payload.size(), bytes_left);
456 incoming_payload_.append(std::make_unique<Block>(std::move(payload)));
457 }
458
459 if (incoming_header_->data_length == incoming_payload_.size()) {
460 auto packet = std::make_unique<apacket>();
461 packet->msg = *incoming_header_;
462
463 // TODO: Make apacket contain an IOVector so we don't have to coalesce.
464 packet->payload = incoming_payload_.coalesce();
465 read_callback_(this, std::move(packet));
466
467 incoming_header_.reset();
468 incoming_payload_.clear();
469 }
470 }
471
472 PrepareReadBlock(block, block->id().id + kUsbReadQueueDepth);
473 SubmitRead(block);
474 }
475
Josh Gaoc0b831b2019-02-13 15:27:28 -0800476 bool SubmitRead(IoBlock* block) {
Josh Gaoc51726c2018-10-11 16:33:05 -0700477 block->pending = true;
478 struct iocb* iocb = &block->control;
479 if (io_submit(aio_context_.get(), 1, &iocb) != 1) {
Josh Gaoc0b831b2019-02-13 15:27:28 -0800480 if (errno == EINVAL && !gFfsAioSupported.has_value()) {
481 HandleError("failed to submit first read, AIO on FFS not supported");
482 gFfsAioSupported = false;
483 return false;
484 }
485
Josh Gaoc51726c2018-10-11 16:33:05 -0700486 HandleError(StringPrintf("failed to submit read: %s", strerror(errno)));
Josh Gaoc0b831b2019-02-13 15:27:28 -0800487 return false;
Josh Gaoc51726c2018-10-11 16:33:05 -0700488 }
Josh Gaoc0b831b2019-02-13 15:27:28 -0800489
490 gFfsAioSupported = true;
491 return true;
Josh Gaoc51726c2018-10-11 16:33:05 -0700492 }
493
494 void HandleWrite(TransferId id) {
495 std::lock_guard<std::mutex> lock(write_mutex_);
496 auto it =
497 std::find_if(write_requests_.begin(), write_requests_.end(), [id](const auto& req) {
498 return static_cast<uint64_t>(req->id()) == static_cast<uint64_t>(id);
499 });
500 CHECK(it != write_requests_.end());
501
502 write_requests_.erase(it);
503 size_t outstanding_writes = --writes_submitted_;
504 LOG(DEBUG) << "USB write: reaped, down to " << outstanding_writes;
505
506 SubmitWrites();
507 }
508
509 std::unique_ptr<IoBlock> CreateWriteBlock(Block payload, uint64_t id) {
510 auto block = std::make_unique<IoBlock>();
511 block->payload = std::move(payload);
512 block->control.aio_data = static_cast<uint64_t>(TransferId::write(id));
513 block->control.aio_rw_flags = 0;
514 block->control.aio_lio_opcode = IOCB_CMD_PWRITE;
515 block->control.aio_reqprio = 0;
516 block->control.aio_fildes = write_fd_.get();
517 block->control.aio_buf = reinterpret_cast<uintptr_t>(block->payload.data());
518 block->control.aio_nbytes = block->payload.size();
519 block->control.aio_offset = 0;
520 block->control.aio_flags = IOCB_FLAG_RESFD;
Josh Gaoc0b831b2019-02-13 15:27:28 -0800521 block->control.aio_resfd = worker_event_fd_.get();
Josh Gaoc51726c2018-10-11 16:33:05 -0700522 return block;
523 }
524
525 void SubmitWrites() REQUIRES(write_mutex_) {
526 if (writes_submitted_ == kUsbWriteQueueDepth) {
527 return;
528 }
529
530 ssize_t writes_to_submit = std::min(kUsbWriteQueueDepth - writes_submitted_,
531 write_requests_.size() - writes_submitted_);
532 CHECK_GE(writes_to_submit, 0);
533 if (writes_to_submit == 0) {
534 return;
535 }
536
537 struct iocb* iocbs[kUsbWriteQueueDepth];
538 for (int i = 0; i < writes_to_submit; ++i) {
539 CHECK(!write_requests_[writes_submitted_ + i]->pending);
540 write_requests_[writes_submitted_ + i]->pending = true;
541 iocbs[i] = &write_requests_[writes_submitted_ + i]->control;
542 LOG(VERBOSE) << "submitting write_request " << static_cast<void*>(iocbs[i]);
543 }
544
545 int rc = io_submit(aio_context_.get(), writes_to_submit, iocbs);
546 if (rc == -1) {
547 HandleError(StringPrintf("failed to submit write requests: %s", strerror(errno)));
548 return;
549 } else if (rc != writes_to_submit) {
550 LOG(FATAL) << "failed to submit all writes: wanted to submit " << writes_to_submit
551 << ", actually submitted " << rc;
552 }
553
554 writes_submitted_ += rc;
555 }
556
557 void HandleError(const std::string& error) {
558 std::call_once(error_flag_, [&]() {
559 error_callback_(this, error);
560 if (!stopped_) {
561 Stop();
562 }
563 });
564 }
565
566 std::thread monitor_thread_;
567 std::thread worker_thread_;
568
569 std::atomic<bool> stopped_;
570 std::promise<void> destruction_notifier_;
571 std::once_flag error_flag_;
572
Josh Gaoc0b831b2019-02-13 15:27:28 -0800573 unique_fd worker_event_fd_;
574 unique_fd monitor_event_fd_;
Josh Gaoc51726c2018-10-11 16:33:05 -0700575
576 ScopedAioContext aio_context_;
577 unique_fd control_fd_;
578 unique_fd read_fd_;
579 unique_fd write_fd_;
580
581 std::optional<amessage> incoming_header_;
582 IOVector incoming_payload_;
583
584 std::array<IoBlock, kUsbReadQueueDepth> read_requests_;
585 IOVector read_data_;
586
587 // ID of the next request that we're going to send out.
588 size_t next_read_id_ = 0;
589
590 // ID of the next packet we're waiting for.
591 size_t needed_read_id_ = 0;
592
593 std::mutex write_mutex_;
594 std::deque<std::unique_ptr<IoBlock>> write_requests_ GUARDED_BY(write_mutex_);
595 size_t next_write_id_ GUARDED_BY(write_mutex_) = 0;
596 size_t writes_submitted_ GUARDED_BY(write_mutex_) = 0;
597};
598
Josh Gaoc0b831b2019-02-13 15:27:28 -0800599void usb_init_legacy();
600
Josh Gaoc51726c2018-10-11 16:33:05 -0700601static void usb_ffs_open_thread() {
602 adb_thread_setname("usb ffs open");
603
604 while (true) {
Josh Gaoc0b831b2019-02-13 15:27:28 -0800605 if (gFfsAioSupported.has_value() && !gFfsAioSupported.value()) {
606 LOG(INFO) << "failed to use nonblocking ffs, falling back to legacy";
607 return usb_init_legacy();
608 }
609
Josh Gaoc51726c2018-10-11 16:33:05 -0700610 unique_fd control;
611 unique_fd bulk_out;
612 unique_fd bulk_in;
613 if (!open_functionfs(&control, &bulk_out, &bulk_in)) {
614 std::this_thread::sleep_for(1s);
615 continue;
616 }
617
618 atransport* transport = new atransport();
619 transport->serial = "UsbFfs";
620 std::promise<void> destruction_notifier;
621 std::future<void> future = destruction_notifier.get_future();
622 transport->SetConnection(std::make_unique<UsbFfsConnection>(
623 std::move(control), std::move(bulk_out), std::move(bulk_in),
624 std::move(destruction_notifier)));
625 register_transport(transport);
626 future.wait();
627 }
628}
629
Josh Gaoc51726c2018-10-11 16:33:05 -0700630void usb_init() {
Josh Gao02e94a42019-02-28 07:26:20 +0000631 bool use_nonblocking = android::base::GetBoolProperty("persist.adb.nonblocking_ffs", true);
632 if (use_nonblocking) {
Josh Gao0d780392019-02-26 22:10:33 +0000633 std::thread(usb_ffs_open_thread).detach();
Josh Gao02e94a42019-02-28 07:26:20 +0000634 } else {
635 usb_init_legacy();
Josh Gaoc51726c2018-10-11 16:33:05 -0700636 }
637}