/* SPDX-License-Identifier: LGPL-2.1-or-later */ /* * Copyright (C) 2019, Google Inc. * * v4l2_compat_manager.cpp - V4L2 compatibility manager */ #include "v4l2_compat_manager.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include "libcamera/internal/log.h" #include "v4l2_camera_file.h" using namespace libcamera; LOG_DEFINE_CATEGORY(V4L2Compat) namespace { template void get_symbol(T &func, const char *name) { func = reinterpret_cast(dlsym(RTLD_NEXT, name)); } } /* namespace */ V4L2CompatManager::V4L2CompatManager() : cm_(nullptr) { get_symbol(fops_.openat, "openat64"); get_symbol(fops_.dup, "dup"); get_symbol(fops_.close, "close"); get_symbol(fops_.ioctl, "ioctl"); get_symbol(fops_.mmap, "mmap64"); get_symbol(fops_.munmap, "munmap"); } V4L2CompatManager::~V4L2CompatManager() { files_.clear(); mmaps_.clear(); if (cm_) { proxies_.clear(); cm_->stop(); delete cm_; cm_ = nullptr; } } int V4L2CompatManager::start() { cm_ = new CameraManager(); int ret = cm_->start(); if (ret) { LOG(V4L2Compat, Error) << "Failed to start camera manager: " << strerror(-ret); delete cm_; cm_ = nullptr; return ret; } LOG(V4L2Compat, Debug) << "Started camera manager"; /* * For each Camera registered in the system, a V4L2CameraProxy gets * created here to wrap a camera device. */ unsigned int index = 0; for (auto &camera : cm_->cameras()) { V4L2CameraProxy *proxy = new V4L2CameraProxy(index, camera); proxies_.emplace_back(proxy); ++index; } return 0; } V4L2CompatManager *V4L2CompatManager::instance() { static V4L2CompatManager instance; return &instance; } std::shared_ptr V4L2CompatManager::cameraFile(int fd) { auto file = files_.find(fd); if (file == files_.end()) return nullptr; return file->second; } int V4L2CompatManager::getCameraIndex(int fd) { struct stat statbuf; int ret = fstat(fd, &statbuf); if (ret < 0) return -1; std::shared_ptr target = cm_->get(statbuf.st_rdev); if (!target) return -1; unsigned int index = 0; for (auto &camera : cm_->cameras()) { if (camera == target) return index; ++index; } return -1; } int V4L2CompatManager::openat(int dirfd, const char *path, int oflag, mode_t mode) { int fd = fops_.openat(dirfd, path, oflag, mode); if (fd < 0) return fd; struct stat statbuf; int ret = fstat(fd, &statbuf); if (ret < 0 || (statbuf.st_mode & S_IFMT) != S_IFCHR || major(statbuf.st_rdev) != 81) return fd; if (!cm_) start(); ret = getCameraIndex(fd); if (ret < 0) { LOG(V4L2Compat, Info) << "No camera found for " << path; return fd; } fops_.close(fd); int efd = eventfd(0, EFD_SEMAPHORE | ((oflag & O_CLOEXEC) ? EFD_CLOEXEC : 0) | ((oflag & O_NONBLOCK) ? EFD_NONBLOCK : 0)); if (efd < 0) return efd; V4L2CameraProxy *proxy = proxies_[ret].get(); files_.emplace(efd, std::make_shared(efd, oflag & O_NONBLOCK, proxy)); return efd; } int V4L2CompatManager::dup(int oldfd) { int newfd = fops_.dup(oldfd); if (newfd < 0) return newfd; auto file = files_.find(oldfd); if (file != files_.end()) files_[newfd] = file->second; return newfd; } int V4L2CompatManager::close(int fd) { auto file = files_.find(fd); if (file != files_.end()) files_.erase(file); /* We still need to close the eventfd. */ return fops_.close(fd); } void *V4L2CompatManager::mmap(void *addr, size_t length, int prot, int flags, int fd, off64_t offset) { std::shared_ptr file = cameraFile(fd); if (!file) return fops_.mmap(addr, length, prot, flags, fd, offset); void *map = file->proxy()->mmap(addr, length, prot, flags, offset); if (map == MAP_FAILED) return map; /* * Map to V4L2CameraProxy directly to prevent adding more references * to V4L2CameraFile. */ mmaps_[map] = file->proxy(); return map; } int V4L2CompatManager::munmap(void *addr, size_t length) { auto device = mmaps_.find(addr); if (device == mmaps_.end()) return fops_.munmap(addr, length); V4L2CameraProxy *proxy = device->second; int ret = proxy->munmap(addr, length); if (ret < 0) return ret; mmaps_.erase(device); return 0; } int V4L2CompatManager::ioctl(int fd, unsigned long request, void *arg) { std::shared_ptr file = cameraFile(fd); if (!file) return fops_.ioctl(fd, request, arg); return file->proxy()->ioctl(file.get(), request, arg); } /a> 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629

/* SPDX-License-Identifier: LGPL-2.1-or-later */
/*
 * Copyright (C) 2019, Google Inc.
 *
 * thread.cpp - Thread support
 */

#include "libcamera/internal/thread.h"

#include <atomic>
#include <condition_variable>
#include <list>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>

#include "libcamera/internal/event_dispatcher.h"
#include "libcamera/internal/event_dispatcher_poll.h"
#include "libcamera/internal/log.h"
#include "libcamera/internal/message.h"

/**
 * \page thread Thread Support
 *
 * libcamera supports multi-threaded applications through a threading model that
 * sets precise rules to guarantee thread-safe usage of the API. Additionally,
 * libcamera makes internal use of threads, and offers APIs that simplify
 * interactions with application threads. Careful compliance with the threading
 * model will ensure avoidance of race conditions.
 *
 * Every thread created by libcamera is associated with an instance of the
 * Thread class. Those threads run an internal event loop by default to
 * dispatch events to objects. Additionally, the main thread of the application
 * (defined as the thread that calls CameraManager::start()) is also associated
 * with a Thread instance, but has no event loop accessible to libcamera. Other
 * application threads are not visible to libcamera.
 *
 * \section thread-objects Threads and Objects
 *
 * Instances of the Object class and all its derived classes are thread-aware
 * and are bound to the thread they are created in. They are said to *live* in
 * a thread, and they interact with the event loop of their thread for the
 * purpose of message passing and signal delivery. Messages posted to the
 * object with Object::postMessage() will be delivered from the event loop of
 * the thread that the object lives in. Signals delivered to the object, unless
 * explicitly connected with ConnectionTypeDirect, will also be delivered from
 * the object thread's event loop.
 *
 * All Object instances created internally by libcamera are bound to internal
 * threads. As objects interact with thread event loops for proper operation,
 * creating an Object instance in a thread that has no internal event loop (such
 * as the main application thread, or libcamera threads that have a custom main
 * loop), prevents some features of the Object class from being used. See
 * Thread::exec() for more details.
 *
 * \section thread-signals Threads and Signals
 *
 * When sent to a receiver that does not inherit from the Object class, signals
 * are delivered synchronously in the thread of the sender. When the receiver
 * inherits from the Object class, delivery is by default asynchronous if the
 * sender and receiver live in different threads. In that case, the signal is
 * posted to the receiver's message queue and will be delivered from the
 * receiver's event loop, running in the receiver's thread. This mechanism can
 * be overridden by selecting a different connection type when calling
 * Signal::connect().
 *
 * Asynchronous signal delivery is used internally in libcamera, but is also
 * available to applications if desired. To use this feature, applications
 * shall create receiver classes that inherit from the Object class, and
 * provide an event loop to the CameraManager as explained above. Note that
 * Object instances created by the application are limited to living in the
 * application's main thread. Creating Object instances from another thread of
 * an application causes undefined behaviour.
 *
 * \section thread-reentrancy Reentrancy and Thread-Safety
 *
 * Through the documentation, several terms are used to define how classes and
 * their member functions can be used from multiple threads.
 *
 * - A **reentrant** function may be called simultaneously from multiple
 *   threads if and only if each invocation uses a different instance of the
 *   class. This is the default for all member functions not explictly marked
 *   otherwise.
 *
 * - \anchor thread-safe A **thread-safe** function may be called
 *   simultaneously from multiple threads on the same instance of a class. A
 *   thread-safe function is thus reentrant. Thread-safe functions may also be
 *   called simultaneously with any other reentrant function of the same class
 *   on the same instance.
 *
 * - \anchor thread-bound A **thread-bound** function may be called only from
 *   the thread that the class instances lives in (see section \ref
 *   thread-objects). For instances of classes that do not derive from the
 *   Object class, this is the thread in which the instance was created. A
 *   thread-bound function is not thread-safe, and may or may not be reentrant.
 *
 * Neither reentrancy nor thread-safety, in this context, mean that a function
 * may be called simultaneously from the same thread, for instance from a
 * callback invoked by the function. This may deadlock and isn't allowed unless
 * separately documented.
 *
 * A class is defined as reentrant, thread-safe or thread-bound if all its
 * member functions are reentrant, thread-safe or thread-bound respectively.
 * Some member functions may additionally be documented as having additional
 * thread-related attributes.
 *
 * Most classes are reentrant but not thread-safe, as making them fully
 * thread-safe would incur locking costs considered prohibitive for the
 * expected use cases.
 */

/**
 * \file thread.h
 * \brief Thread support
 */

namespace libcamera {

LOG_DEFINE_CATEGORY(Thread)

class ThreadMain;

/**
 * \brief A queue of posted messages
 */
class MessageQueue
{
public:
	/**
	 * \brief List of queued Message instances
	 */
	std::list<std::unique_ptr<Message>> list_;
	/**
	 * \brief Protects the \ref list_
	 */
	Mutex mutex_;
};

/**
 * \brief Thread-local internal data
 */
class ThreadData
{
public:
	ThreadData()
		: thread_(nullptr), running_(false), dispatcher_(nullptr)
	{
	}

	static ThreadData *current();

private:
	friend class Thread;
	friend class ThreadMain;

	Thread *thread_;
	bool running_;
	pid_t tid_;

	Mutex mutex_;

	std::atomic<EventDispatcher *> dispatcher_;

	std::condition_variable cv_;