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| author | Nuo Mi <nuomi2021@gmail.com> | 2024-09-24 22:16:57 +0800 |
|---|---|---|
| committer | Nuo Mi <nuomi2021@gmail.com> | 2024-10-04 21:58:42 +0800 |
| commit | 40a14ef970f7210c64ccfc5625871ef577f3e3a3 (patch) | |
| tree | dff8a86c9dcef84c906a139403ee91a3335f2305 /libavcodec | |
| parent | 8446e27bf3b6d9be9dd151399d6739d8e1e910d4 (diff) | |
| download | ffmpeg-40a14ef970f7210c64ccfc5625871ef577f3e3a3.tar.gz | |
avcodec/executor: remove unused ready callback
Due to the nature of multithreading, using a "ready check" mechanism may introduce a deadlock. For example:
Suppose all tasks have been submitted to the executor, and the last thread checks the entire list and finds
no ready tasks. It then goes to sleep, waiting for a new task. However, for some multithreading-related reason,
a task becomes ready after the check. Since no other thread is aware of this and no new tasks are being added to
the executor, a deadlock occurs.
In VVC, this function is unnecessary because we use a scoreboard. All tasks submitted to the executor are ready tasks.
Diffstat (limited to 'libavcodec')
| -rw-r--r-- | libavcodec/executor.c | 6 | ||||
| -rw-r--r-- | libavcodec/executor.h | 3 | ||||
| -rw-r--r-- | libavcodec/vvc/thread.c | 8 |
3 files changed, 2 insertions, 15 deletions
diff --git a/libavcodec/executor.c b/libavcodec/executor.c index 574c5c7be7..21ebad3def 100644 --- a/libavcodec/executor.c +++ b/libavcodec/executor.c @@ -79,10 +79,8 @@ static void add_task(FFTask **prev, FFTask *t) static int run_one_task(FFExecutor *e, void *lc) { FFTaskCallbacks *cb = &e->cb; - FFTask **prev; + FFTask **prev = &e->tasks; - for (prev = &e->tasks; *prev && !cb->ready(*prev, cb->user_data); prev = &(*prev)->next) - /* nothing */; if (*prev) { FFTask *t = remove_task(prev, *prev); if (e->thread_count > 0) @@ -143,7 +141,7 @@ FFExecutor* ff_executor_alloc(const FFTaskCallbacks *cb, int thread_count) { FFExecutor *e; int has_lock = 0, has_cond = 0; - if (!cb || !cb->user_data || !cb->ready || !cb->run || !cb->priority_higher) + if (!cb || !cb->user_data || !cb->run || !cb->priority_higher) return NULL; e = av_mallocz(sizeof(*e)); diff --git a/libavcodec/executor.h b/libavcodec/executor.h index 2d02734ad6..51763ec25e 100644 --- a/libavcodec/executor.h +++ b/libavcodec/executor.h @@ -42,9 +42,6 @@ typedef struct FFTaskCallbacks { // return 1 if a's priority > b's priority int (*priority_higher)(const FFTask *a, const FFTask *b); - // task is ready for run - int (*ready)(const FFTask *t, void *user_data); - // run the task int (*run)(FFTask *t, void *local_context, void *user_data); } FFTaskCallbacks; diff --git a/libavcodec/vvc/thread.c b/libavcodec/vvc/thread.c index e6907fd764..a8c19b17cf 100644 --- a/libavcodec/vvc/thread.c +++ b/libavcodec/vvc/thread.c @@ -372,13 +372,6 @@ static int task_is_stage_ready(VVCTask *t, int add) return task_has_target_score(t, stage, score); } -static int task_ready(const FFTask *_t, void *user_data) -{ - VVCTask *t = (VVCTask*)_t; - - return task_is_stage_ready(t, 0); -} - #define CHECK(a, b) \ do { \ if ((a) != (b)) \ @@ -689,7 +682,6 @@ FFExecutor* ff_vvc_executor_alloc(VVCContext *s, const int thread_count) s, sizeof(VVCLocalContext), task_priority_higher, - task_ready, task_run, }; return ff_executor_alloc(&callbacks, thread_count); |