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lavc/pthread_frame: avoid leaving stale hwaccel state in worker threads 

This state is not refcounted, so make sure it always has a well-defined
owner.

Remove the block added in 091341f2ab, as
this commit also solves that issue in a more general way.

(cherry picked from commit cc867f2c09)
Signed-off-by: Anton Khirnov <anton@khirnov.net>
(cherry picked from commit 35aa7e70e7)
Signed-off-by: Anton Khirnov <anton@khirnov.net>
(cherry picked from commit 3bc28e9d1a)
Signed-off-by: Anton Khirnov <anton@khirnov.net>
(cherry picked from commit d4b7b3c03e)
This commit is contained in:
Anton Khirnov 2022-09-02 22:21:27 +02:00 committed by James Almer
parent cda5d4698c
commit 031c9601d0
1 changed files with 35 additions and 11 deletions
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46
libavcodec/pthread_frame.c
View File

@ -135,6 +135,12 @@ typedef struct FrameThreadContext {
* Set for the first N packets, where N is the number of threads.
* While it is set, ff_thread_en/decode_frame won't return any results.
*/
/* hwaccel state is temporarily stored here in order to transfer its ownership
* to the next decoding thread without the need for extra synchronization */
const AVHWAccel *stash_hwaccel;
void *stash_hwaccel_context;
void *stash_hwaccel_priv;
} FrameThreadContext;
#define THREAD_SAFE_CALLBACKS(avctx) \
@ -211,9 +217,17 @@ static attribute_align_arg void *frame_worker_thread(void *arg)
ff_thread_finish_setup(avctx);
if (p->hwaccel_serializing) {
/* wipe hwaccel state to avoid stale pointers lying around;
* the state was transferred to FrameThreadContext in
* ff_thread_finish_setup(), so nothing is leaked */
avctx->hwaccel = NULL;
avctx->hwaccel_context = NULL;
avctx->internal->hwaccel_priv_data = NULL;
p->hwaccel_serializing = 0;
pthread_mutex_unlock(&p->parent->hwaccel_mutex);
}
av_assert0(!avctx->hwaccel);
if (p->async_serializing) {
p->async_serializing = 0;
@ -275,14 +289,10 @@ static int update_context_from_thread(AVCodecContext *dst, AVCodecContext *src,
dst->color_range = src->color_range;
dst->chroma_sample_location = src->chroma_sample_location;
dst->hwaccel = src->hwaccel;
dst->hwaccel_context = src->hwaccel_context;
dst->channels = src->channels;
dst->sample_rate = src->sample_rate;
dst->sample_fmt = src->sample_fmt;
dst->channel_layout = src->channel_layout;
dst->internal->hwaccel_priv_data = src->internal->hwaccel_priv_data;
if (!!dst->hw_frames_ctx != !!src->hw_frames_ctx ||
(dst->hw_frames_ctx && dst->hw_frames_ctx->data != src->hw_frames_ctx->data)) {
@ -426,6 +436,12 @@ static int submit_packet(PerThreadContext *p, AVCodecContext *user_avctx,
pthread_mutex_unlock(&p->mutex);
return err;
}
/* transfer hwaccel state stashed from previous thread, if any */
av_assert0(!p->avctx->hwaccel);
FFSWAP(const AVHWAccel*, p->avctx->hwaccel, fctx->stash_hwaccel);
FFSWAP(void*, p->avctx->hwaccel_context, fctx->stash_hwaccel_context);
FFSWAP(void*, p->avctx->internal->hwaccel_priv_data, fctx->stash_hwaccel_priv);
}
av_packet_unref(&p->avpkt);
@ -627,6 +643,14 @@ void ff_thread_finish_setup(AVCodecContext *avctx) {
async_lock(p->parent);
}
/* save hwaccel state for passing to the next thread;
* this is done here so that this worker thread can wipe its own hwaccel
* state after decoding, without requiring synchronization */
av_assert0(!p->parent->stash_hwaccel);
p->parent->stash_hwaccel = avctx->hwaccel;
p->parent->stash_hwaccel_context = avctx->hwaccel_context;
p->parent->stash_hwaccel_priv = avctx->internal->hwaccel_priv_data;
pthread_mutex_lock(&p->progress_mutex);
if(atomic_load(&p->state) == STATE_SETUP_FINISHED){
av_log(avctx, AV_LOG_WARNING, "Multiple ff_thread_finish_setup() calls\n");
@ -668,13 +692,6 @@ void ff_frame_thread_free(AVCodecContext *avctx, int thread_count)
park_frame_worker_threads(fctx, thread_count);
if (fctx->prev_thread && avctx->internal->hwaccel_priv_data !=
fctx->prev_thread->avctx->internal->hwaccel_priv_data) {
if (update_context_from_thread(avctx, fctx->prev_thread->avctx, 1) < 0) {
av_log(avctx, AV_LOG_ERROR, "Failed to update user thread.\n");
}
}
if (fctx->prev_thread && fctx->prev_thread != fctx->threads)
if (update_context_from_thread(fctx->threads->avctx, fctx->prev_thread->avctx, 0) < 0) {
av_log(avctx, AV_LOG_ERROR, "Final thread update failed\n");
@ -738,6 +755,13 @@ void ff_frame_thread_free(AVCodecContext *avctx, int thread_count)
pthread_mutex_destroy(&fctx->async_mutex);
pthread_cond_destroy(&fctx->async_cond);
/* if we have stashed hwaccel state, move it to the user-facing context,
* so it will be freed in avcodec_close() */
av_assert0(!avctx->hwaccel);
FFSWAP(const AVHWAccel*, avctx->hwaccel, fctx->stash_hwaccel);
FFSWAP(void*, avctx->hwaccel_context, fctx->stash_hwaccel_context);
FFSWAP(void*, avctx->internal->hwaccel_priv_data, fctx->stash_hwaccel_priv);
av_freep(&avctx->internal->thread_ctx);
if (avctx->priv_data && avctx->codec && avctx->codec->priv_class)