d42e876164
Fixes issue on iPad Pro 10.5 (and probably other places) where threads are not properly synchronized. On x86 this data race was benign as load and store instructions are atomic, they were being atomic in practice as the program hasn't been observed to be miscompiled. Such guarantees are not made outside x86, and real problems manifested where libvpx reliably reproduced a broken bitstream for even just the initial keyframe. This was detected in WebRTC where this device started using multithreading (as its CPU count is higher than earlier devices, where the problem did not manifest as single-threading was used in practice). This issue was not detected under thread-sanitizer bots as mutexes were conditionally used under this platform to simulate the protected read and write semantics that were in practice provided on x86 platforms. This change also removes several mutexes, so encoder/decoder state is lighter-weight after this change and we do not need to initialize so many mutexes (this was done even on non-thread-sanitizer platforms where they were unused). Change-Id: If41fcb0d99944f7bbc8ec40877cdc34d672ae72a
213 lines
5.4 KiB
C
213 lines
5.4 KiB
C
/*
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* Copyright (c) 2010 The WebM project authors. All Rights Reserved.
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*
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* Use of this source code is governed by a BSD-style license
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* that can be found in the LICENSE file in the root of the source
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* tree. An additional intellectual property rights grant can be found
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* in the file PATENTS. All contributing project authors may
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* be found in the AUTHORS file in the root of the source tree.
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*/
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#ifndef VP8_COMMON_THREADING_H_
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#define VP8_COMMON_THREADING_H_
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#include "./vpx_config.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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#if CONFIG_OS_SUPPORT && CONFIG_MULTITHREAD
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/* Thread management macros */
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#if defined(_WIN32) && !HAVE_PTHREAD_H
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/* Win32 */
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#include <process.h>
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#include <windows.h>
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#if defined(__GNUC__) && \
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(__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 2))
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#define THREAD_FUNCTION \
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__attribute__((force_align_arg_pointer)) unsigned int __stdcall
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#else
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#define THREAD_FUNCTION unsigned int __stdcall
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#endif
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#define THREAD_FUNCTION_RETURN DWORD
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#define THREAD_SPECIFIC_INDEX DWORD
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#define pthread_t HANDLE
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#define pthread_attr_t DWORD
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#define pthread_detach(thread) \
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if (thread != NULL) CloseHandle(thread)
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#define thread_sleep(nms) Sleep(nms)
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#define pthread_cancel(thread) terminate_thread(thread, 0)
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#define ts_key_create(ts_key, destructor) \
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{ ts_key = TlsAlloc(); };
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#define pthread_getspecific(ts_key) TlsGetValue(ts_key)
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#define pthread_setspecific(ts_key, value) TlsSetValue(ts_key, (void *)value)
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#define pthread_self() GetCurrentThreadId()
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#elif defined(__OS2__)
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/* OS/2 */
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#define INCL_DOS
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#include <os2.h>
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#include <stdlib.h>
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#define THREAD_FUNCTION void *
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#define THREAD_FUNCTION_RETURN void *
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#define THREAD_SPECIFIC_INDEX PULONG
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#define pthread_t TID
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#define pthread_attr_t ULONG
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#define pthread_detach(thread) 0
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#define thread_sleep(nms) DosSleep(nms)
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#define pthread_cancel(thread) DosKillThread(thread)
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#define ts_key_create(ts_key, destructor) \
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DosAllocThreadLocalMemory(1, &(ts_key));
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#define pthread_getspecific(ts_key) ((void *)(*(ts_key)))
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#define pthread_setspecific(ts_key, value) (*(ts_key) = (ULONG)(value))
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#define pthread_self() _gettid()
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#else
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#ifdef __APPLE__
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#include <mach/mach_init.h>
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#include <mach/semaphore.h>
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#include <mach/task.h>
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#include <time.h>
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#include <unistd.h>
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#else
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#include <semaphore.h>
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#endif
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#include <pthread.h>
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/* pthreads */
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/* Nearly everything is already defined */
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#define THREAD_FUNCTION void *
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#define THREAD_FUNCTION_RETURN void *
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#define THREAD_SPECIFIC_INDEX pthread_key_t
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#define ts_key_create(ts_key, destructor) \
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pthread_key_create(&(ts_key), destructor);
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#endif
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/* Synchronization macros: Win32 and Pthreads */
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#if defined(_WIN32) && !HAVE_PTHREAD_H
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#define sem_t HANDLE
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#define pause(voidpara) __asm PAUSE
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#define sem_init(sem, sem_attr1, sem_init_value) \
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(int)((*sem = CreateSemaphore(NULL, 0, 32768, NULL)) == NULL)
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#define sem_wait(sem) \
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(int)(WAIT_OBJECT_0 != WaitForSingleObject(*sem, INFINITE))
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#define sem_post(sem) ReleaseSemaphore(*sem, 1, NULL)
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#define sem_destroy(sem) \
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if (*sem) ((int)(CloseHandle(*sem)) == TRUE)
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#define thread_sleep(nms) Sleep(nms)
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#elif defined(__OS2__)
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typedef struct {
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HEV event;
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HMTX wait_mutex;
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HMTX count_mutex;
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int count;
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} sem_t;
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static inline int sem_init(sem_t *sem, int pshared, unsigned int value) {
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DosCreateEventSem(NULL, &sem->event, pshared ? DC_SEM_SHARED : 0,
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value > 0 ? TRUE : FALSE);
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DosCreateMutexSem(NULL, &sem->wait_mutex, 0, FALSE);
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DosCreateMutexSem(NULL, &sem->count_mutex, 0, FALSE);
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sem->count = value;
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return 0;
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}
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static inline int sem_wait(sem_t *sem) {
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DosRequestMutexSem(sem->wait_mutex, -1);
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DosWaitEventSem(sem->event, -1);
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DosRequestMutexSem(sem->count_mutex, -1);
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sem->count--;
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if (sem->count == 0) {
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ULONG post_count;
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DosResetEventSem(sem->event, &post_count);
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}
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DosReleaseMutexSem(sem->count_mutex);
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DosReleaseMutexSem(sem->wait_mutex);
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return 0;
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}
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static inline int sem_post(sem_t *sem) {
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DosRequestMutexSem(sem->count_mutex, -1);
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if (sem->count < 32768) {
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sem->count++;
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DosPostEventSem(sem->event);
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}
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DosReleaseMutexSem(sem->count_mutex);
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return 0;
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}
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static inline int sem_destroy(sem_t *sem) {
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DosCloseEventSem(sem->event);
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DosCloseMutexSem(sem->wait_mutex);
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DosCloseMutexSem(sem->count_mutex);
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return 0;
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}
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#define thread_sleep(nms) DosSleep(nms)
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#else
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#ifdef __APPLE__
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#define sem_t semaphore_t
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#define sem_init(X, Y, Z) \
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semaphore_create(mach_task_self(), X, SYNC_POLICY_FIFO, Z)
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#define sem_wait(sem) (semaphore_wait(*sem))
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#define sem_post(sem) semaphore_signal(*sem)
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#define sem_destroy(sem) semaphore_destroy(mach_task_self(), *sem)
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#define thread_sleep(nms)
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/* { struct timespec ts;ts.tv_sec=0; ts.tv_nsec =
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1000*nms;nanosleep(&ts, NULL);} */
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#else
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#include <unistd.h>
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#include <sched.h>
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#define thread_sleep(nms) sched_yield();
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/* {struct timespec ts;ts.tv_sec=0;
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ts.tv_nsec = 1000*nms;nanosleep(&ts, NULL);} */
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#endif
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/* Not Windows. Assume pthreads */
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#endif
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#if ARCH_X86 || ARCH_X86_64
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#include "vpx_ports/x86.h"
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#else
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#define x86_pause_hint()
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#endif
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#include "vpx_util/vpx_thread.h"
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#include "vpx_util/vpx_atomics.h"
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static INLINE void vp8_atomic_spin_wait(
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int mb_col, const vpx_atomic_int *last_row_current_mb_col,
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const int nsync) {
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while (mb_col > (vpx_atomic_load_acquire(last_row_current_mb_col) - nsync)) {
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x86_pause_hint();
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thread_sleep(0);
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}
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}
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#endif /* CONFIG_OS_SUPPORT && CONFIG_MULTITHREAD */
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#ifdef __cplusplus
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} // extern "C"
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#endif
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#endif // VP8_COMMON_THREADING_H_
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