From 2e664b9c1e73c80aab91070c1eb7676f04bdd12d Mon Sep 17 00:00:00 2001 From: "Ronald S. Bultje" Date: Thu, 6 Apr 2017 13:58:59 -0400 Subject: [PATCH] pthread_frame: make accesses to debug field be protected by owner lock. The av_log() is done outside the lock, but this way the accesses to the field (reads and writes) are always protected by a mutex. The av_log() is not run inside the lock context because it may involve user callbacks and doing that in performance-sensitive code is probably not a good idea. This should fix occasional tsan warnings when running fate-h264, like: WARNING: ThreadSanitizer: data race (pid=10916) Write of size 4 at 0x7d64000174fc by main thread (mutexes: write M2313): #0 update_context_from_user src/libavcodec/pthread_frame.c:335 (ffmpeg+0x000000df7b06) [..] Previous read of size 4 at 0x7d64000174fc by thread T1 (mutexes: write M2311): #0 ff_thread_await_progress src/libavcodec/pthread_frame.c:592 (ffmpeg+0x000000df8b3e) --- libavcodec/pthread_frame.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/libavcodec/pthread_frame.c b/libavcodec/pthread_frame.c index aaf576d63c..46c6292253 100644 --- a/libavcodec/pthread_frame.c +++ b/libavcodec/pthread_frame.c @@ -566,12 +566,11 @@ void ff_thread_report_progress(ThreadFrame *f, int n, int field) p = f->owner[field]->internal->thread_ctx; + pthread_mutex_lock(&p->progress_mutex); if (f->owner[field]->debug&FF_DEBUG_THREADS) av_log(f->owner[field], AV_LOG_DEBUG, "%p finished %d field %d\n", progress, n, field); - pthread_mutex_lock(&p->progress_mutex); - atomic_store_explicit(&progress[field], n, memory_order_release); pthread_cond_broadcast(&p->progress_cond); @@ -589,11 +588,10 @@ void ff_thread_await_progress(ThreadFrame *f, int n, int field) p = f->owner[field]->internal->thread_ctx; + pthread_mutex_lock(&p->progress_mutex); if (f->owner[field]->debug&FF_DEBUG_THREADS) av_log(f->owner[field], AV_LOG_DEBUG, "thread awaiting %d field %d from %p\n", n, field, progress); - - pthread_mutex_lock(&p->progress_mutex); while (atomic_load_explicit(&progress[field], memory_order_relaxed) < n) pthread_cond_wait(&p->progress_cond, &p->progress_mutex); pthread_mutex_unlock(&p->progress_mutex);