libavcodec/frame_thread_encoder.c - manifest_repos/ffmpeg - Git at Google

 /*
  * Copyright (c) 2012 Michael Niedermayer <michaelni@gmx.at>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * FFmpeg is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with FFmpeg; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */

 #include <stdatomic.h>

 #include "frame_thread_encoder.h"

 #include "libavutil/fifo.h"
 #include "libavutil/avassert.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/opt.h"
 #include "libavutil/thread.h"
 #include "avcodec.h"
 #include "internal.h"
 #include "thread.h"

 #define MAX_THREADS 64
 #define BUFFER_SIZE (2*MAX_THREADS)

 typedef struct{
     void *indata;
     void *outdata;
     int64_t return_code;
     unsigned index;
 } Task;

 typedef struct{
     AVCodecContext *parent_avctx;
     pthread_mutex_t buffer_mutex;

     AVFifoBuffer *task_fifo;
     pthread_mutex_t task_fifo_mutex;
     pthread_cond_t task_fifo_cond;

     Task finished_tasks[BUFFER_SIZE];
     pthread_mutex_t finished_task_mutex;
     pthread_cond_t finished_task_cond;

     unsigned task_index;
     unsigned finished_task_index;

     pthread_t worker[MAX_THREADS];
     atomic_int exit;
 } ThreadContext;

 static void * attribute_align_arg worker(void *v){
     AVCodecContext *avctx = v;
     ThreadContext *c = avctx->internal->frame_thread_encoder;
     AVPacket *pkt = NULL;

     while (!atomic_load(&c->exit)) {
         int got_packet = 0, ret;
         AVFrame *frame;
         Task task;

         if(!pkt) pkt = av_packet_alloc();
         if(!pkt) continue;
         av_init_packet(pkt);

         pthread_mutex_lock(&c->task_fifo_mutex);
         while (av_fifo_size(c->task_fifo) <= 0 || atomic_load(&c->exit)) {
             if (atomic_load(&c->exit)) {
                 pthread_mutex_unlock(&c->task_fifo_mutex);
                 goto end;
             }
             pthread_cond_wait(&c->task_fifo_cond, &c->task_fifo_mutex);
         }
         av_fifo_generic_read(c->task_fifo, &task, sizeof(task), NULL);
         pthread_mutex_unlock(&c->task_fifo_mutex);
         frame = task.indata;

         ret = avctx->codec->encode2(avctx, pkt, frame, &got_packet);
         if(got_packet) {
             int ret2 = av_packet_make_refcounted(pkt);
             if (ret >= 0 && ret2 < 0)
                 ret = ret2;
             pkt->pts = pkt->dts = frame->pts;
         } else {
             pkt->data = NULL;
             pkt->size = 0;
         }
         pthread_mutex_lock(&c->buffer_mutex);
         av_frame_unref(frame);
         pthread_mutex_unlock(&c->buffer_mutex);
         av_frame_free(&frame);
         pthread_mutex_lock(&c->finished_task_mutex);
         c->finished_tasks[task.index].outdata = pkt; pkt = NULL;
         c->finished_tasks[task.index].return_code = ret;
         pthread_cond_signal(&c->finished_task_cond);
         pthread_mutex_unlock(&c->finished_task_mutex);
     }
 end:
     av_free(pkt);
     pthread_mutex_lock(&c->buffer_mutex);
     avcodec_close(avctx);
     pthread_mutex_unlock(&c->buffer_mutex);
     av_freep(&avctx);
     return NULL;
 }

 int ff_frame_thread_encoder_init(AVCodecContext *avctx, AVDictionary *options){
     int i=0;
     ThreadContext *c;


     if(   !(avctx->thread_type & FF_THREAD_FRAME)
        || !(avctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS))
         return 0;

     if(   !avctx->thread_count
        && avctx->codec_id == AV_CODEC_ID_MJPEG
        && !(avctx->flags & AV_CODEC_FLAG_QSCALE)) {
         av_log(avctx, AV_LOG_DEBUG,
                "Forcing thread count to 1 for MJPEG encoding, use -thread_type slice "
                "or a constant quantizer if you want to use multiple cpu cores\n");
         avctx->thread_count = 1;
     }
     if(   avctx->thread_count > 1
        && avctx->codec_id == AV_CODEC_ID_MJPEG
        && !(avctx->flags & AV_CODEC_FLAG_QSCALE))
         av_log(avctx, AV_LOG_WARNING,
                "MJPEG CBR encoding works badly with frame multi-threading, consider "
                "using -threads 1, -thread_type slice or a constant quantizer.\n");

     if (avctx->codec_id == AV_CODEC_ID_HUFFYUV ||
         avctx->codec_id == AV_CODEC_ID_FFVHUFF) {
         int warn = 0;
         int context_model = 0;
         AVDictionaryEntry *con = av_dict_get(options, "context", NULL, AV_DICT_MATCH_CASE);

         if (con && con->value)
             context_model = atoi(con->value);

         if (avctx->flags & AV_CODEC_FLAG_PASS1)
             warn = 1;
         else if(context_model > 0) {
             AVDictionaryEntry *t = av_dict_get(options, "non_deterministic",
                                                NULL, AV_DICT_MATCH_CASE);
             warn = !t || !t->value || !atoi(t->value) ? 1 : 0;
         }
         // huffyuv does not support these with multiple frame threads currently
         if (warn) {
             av_log(avctx, AV_LOG_WARNING,
                "Forcing thread count to 1 for huffyuv encoding with first pass or context 1\n");
             avctx->thread_count = 1;
         }
     }

     if(!avctx->thread_count) {
         avctx->thread_count = av_cpu_count();
         avctx->thread_count = FFMIN(avctx->thread_count, MAX_THREADS);
     }

     if(avctx->thread_count <= 1)
         return 0;

     if(avctx->thread_count > MAX_THREADS)
         return AVERROR(EINVAL);

     av_assert0(!avctx->internal->frame_thread_encoder);
     c = avctx->internal->frame_thread_encoder = av_mallocz(sizeof(ThreadContext));
     if(!c)
         return AVERROR(ENOMEM);

     c->parent_avctx = avctx;

     c->task_fifo = av_fifo_alloc_array(BUFFER_SIZE, sizeof(Task));
     if(!c->task_fifo)
         goto fail;

     pthread_mutex_init(&c->task_fifo_mutex, NULL);
     pthread_mutex_init(&c->finished_task_mutex, NULL);
     pthread_mutex_init(&c->buffer_mutex, NULL);
     pthread_cond_init(&c->task_fifo_cond, NULL);
     pthread_cond_init(&c->finished_task_cond, NULL);
     atomic_init(&c->exit, 0);

     for(i=0; i<avctx->thread_count ; i++){
         AVDictionary *tmp = NULL;
         int ret;
         void *tmpv;
         AVCodecContext *thread_avctx = avcodec_alloc_context3(avctx->codec);
         if(!thread_avctx)
             goto fail;
         tmpv = thread_avctx->priv_data;
         *thread_avctx = *avctx;
         ret = av_opt_copy(thread_avctx, avctx);
         if (ret < 0)
             goto fail;
         thread_avctx->priv_data = tmpv;
         thread_avctx->internal = NULL;
         if (avctx->codec->priv_class) {
             int ret = av_opt_copy(thread_avctx->priv_data, avctx->priv_data);
             if (ret < 0)
                 goto fail;
         } else if (avctx->codec->priv_data_size) {
             memcpy(thread_avctx->priv_data, avctx->priv_data, avctx->codec->priv_data_size);
         }
         thread_avctx->thread_count = 1;
         thread_avctx->active_thread_type &= ~FF_THREAD_FRAME;

         av_dict_copy(&tmp, options, 0);
         av_dict_set(&tmp, "threads", "1", 0);
         if(avcodec_open2(thread_avctx, avctx->codec, &tmp) < 0) {
             av_dict_free(&tmp);
             goto fail;
         }
         av_dict_free(&tmp);
         av_assert0(!thread_avctx->internal->frame_thread_encoder);
         thread_avctx->internal->frame_thread_encoder = c;
         if(pthread_create(&c->worker[i], NULL, worker, thread_avctx)) {
             goto fail;
         }
     }

     avctx->active_thread_type = FF_THREAD_FRAME;

     return 0;
 fail:
     avctx->thread_count = i;
     av_log(avctx, AV_LOG_ERROR, "ff_frame_thread_encoder_init failed\n");
     ff_frame_thread_encoder_free(avctx);
     return -1;
 }

 void ff_frame_thread_encoder_free(AVCodecContext *avctx){
     int i;
     ThreadContext *c= avctx->internal->frame_thread_encoder;

     pthread_mutex_lock(&c->task_fifo_mutex);
     atomic_store(&c->exit, 1);
     pthread_cond_broadcast(&c->task_fifo_cond);
     pthread_mutex_unlock(&c->task_fifo_mutex);

     for (i=0; i<avctx->thread_count; i++) {
          pthread_join(c->worker[i], NULL);
     }

     while (av_fifo_size(c->task_fifo) > 0) {
         Task task;
         AVFrame *frame;
         av_fifo_generic_read(c->task_fifo, &task, sizeof(task), NULL);
         frame = task.indata;
         av_frame_free(&frame);
         task.indata = NULL;
     }

     for (i=0; i<BUFFER_SIZE; i++) {
         if (c->finished_tasks[i].outdata != NULL) {
             AVPacket *pkt = c->finished_tasks[i].outdata;
             av_packet_free(&pkt);
             c->finished_tasks[i].outdata = NULL;
         }
     }

     pthread_mutex_destroy(&c->task_fifo_mutex);
     pthread_mutex_destroy(&c->finished_task_mutex);
     pthread_mutex_destroy(&c->buffer_mutex);
     pthread_cond_destroy(&c->task_fifo_cond);
     pthread_cond_destroy(&c->finished_task_cond);
     av_fifo_freep(&c->task_fifo);
     av_freep(&avctx->internal->frame_thread_encoder);
 }

 int ff_thread_video_encode_frame(AVCodecContext *avctx, AVPacket *pkt, const AVFrame *frame, int *got_packet_ptr){
     ThreadContext *c = avctx->internal->frame_thread_encoder;
     Task task;
     int ret;

     av_assert1(!*got_packet_ptr);

     if(frame){
         AVFrame *new = av_frame_alloc();
         if(!new)
             return AVERROR(ENOMEM);
         ret = av_frame_ref(new, frame);
         if(ret < 0) {
             av_frame_free(&new);
             return ret;
         }

         task.index = c->task_index;
         task.indata = (void*)new;
         pthread_mutex_lock(&c->task_fifo_mutex);
         av_fifo_generic_write(c->task_fifo, &task, sizeof(task), NULL);
         pthread_cond_signal(&c->task_fifo_cond);
         pthread_mutex_unlock(&c->task_fifo_mutex);

         c->task_index = (c->task_index+1) % BUFFER_SIZE;
     }

     pthread_mutex_lock(&c->finished_task_mutex);
     if (c->task_index == c->finished_task_index ||
         (frame && !c->finished_tasks[c->finished_task_index].outdata &&
          (c->task_index - c->finished_task_index) % BUFFER_SIZE <= avctx->thread_count)) {
             pthread_mutex_unlock(&c->finished_task_mutex);
             return 0;
         }

     while (!c->finished_tasks[c->finished_task_index].outdata) {
         pthread_cond_wait(&c->finished_task_cond, &c->finished_task_mutex);
     }
     task = c->finished_tasks[c->finished_task_index];
     *pkt = *(AVPacket*)(task.outdata);
     if(pkt->data)
         *got_packet_ptr = 1;
     av_freep(&c->finished_tasks[c->finished_task_index].outdata);
     c->finished_task_index = (c->finished_task_index+1) % BUFFER_SIZE;
     pthread_mutex_unlock(&c->finished_task_mutex);

     return task.return_code;
 }
	/*
	* Copyright (c) 2012 Michael Niedermayer <michaelni@gmx.at>
	*
	* This file is part of FFmpeg.
	*
	* FFmpeg is free software; you can redistribute it and/or
	* modify it under the terms of the GNU Lesser General Public
	* License as published by the Free Software Foundation; either
	* version 2.1 of the License, or (at your option) any later version.
	*
	* FFmpeg is distributed in the hope that it will be useful,
	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* Lesser General Public License for more details.
	*
	* You should have received a copy of the GNU Lesser General Public
	* License along with FFmpeg; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	#include <stdatomic.h>

	#include "frame_thread_encoder.h"

	#include "libavutil/fifo.h"
	#include "libavutil/avassert.h"
	#include "libavutil/imgutils.h"
	#include "libavutil/opt.h"
	#include "libavutil/thread.h"
	#include "avcodec.h"
	#include "internal.h"
	#include "thread.h"

	#define MAX_THREADS 64
	#define BUFFER_SIZE (2*MAX_THREADS)

	typedef struct{
	void *indata;
	void *outdata;
	int64_t return_code;
	unsigned index;
	} Task;

	typedef struct{
	AVCodecContext *parent_avctx;
	pthread_mutex_t buffer_mutex;

	AVFifoBuffer *task_fifo;
	pthread_mutex_t task_fifo_mutex;
	pthread_cond_t task_fifo_cond;

	Task finished_tasks[BUFFER_SIZE];
	pthread_mutex_t finished_task_mutex;
	pthread_cond_t finished_task_cond;

	unsigned task_index;
	unsigned finished_task_index;

	pthread_t worker[MAX_THREADS];
	atomic_int exit;
	} ThreadContext;

	static void * attribute_align_arg worker(void *v){
	AVCodecContext *avctx = v;
	ThreadContext *c = avctx->internal->frame_thread_encoder;
	AVPacket *pkt = NULL;

	while (!atomic_load(&c->exit)) {
	int got_packet = 0, ret;
	AVFrame *frame;
	Task task;

	if(!pkt) pkt = av_packet_alloc();
	if(!pkt) continue;
	av_init_packet(pkt);

	pthread_mutex_lock(&c->task_fifo_mutex);
	while (av_fifo_size(c->task_fifo) <= 0 \|\| atomic_load(&c->exit)) {
	if (atomic_load(&c->exit)) {
	pthread_mutex_unlock(&c->task_fifo_mutex);
	goto end;
	}
	pthread_cond_wait(&c->task_fifo_cond, &c->task_fifo_mutex);
	}
	av_fifo_generic_read(c->task_fifo, &task, sizeof(task), NULL);
	pthread_mutex_unlock(&c->task_fifo_mutex);
	frame = task.indata;

	ret = avctx->codec->encode2(avctx, pkt, frame, &got_packet);
	if(got_packet) {
	int ret2 = av_packet_make_refcounted(pkt);
	if (ret >= 0 && ret2 < 0)
	ret = ret2;
	pkt->pts = pkt->dts = frame->pts;
	} else {
	pkt->data = NULL;
	pkt->size = 0;
	}
	pthread_mutex_lock(&c->buffer_mutex);
	av_frame_unref(frame);
	pthread_mutex_unlock(&c->buffer_mutex);
	av_frame_free(&frame);
	pthread_mutex_lock(&c->finished_task_mutex);
	c->finished_tasks[task.index].outdata = pkt; pkt = NULL;
	c->finished_tasks[task.index].return_code = ret;
	pthread_cond_signal(&c->finished_task_cond);
	pthread_mutex_unlock(&c->finished_task_mutex);
	}
	end:
	av_free(pkt);
	pthread_mutex_lock(&c->buffer_mutex);
	avcodec_close(avctx);
	pthread_mutex_unlock(&c->buffer_mutex);
	av_freep(&avctx);
	return NULL;
	}

	int ff_frame_thread_encoder_init(AVCodecContext avctx, AVDictionary options){
	int i=0;
	ThreadContext *c;


	if( !(avctx->thread_type & FF_THREAD_FRAME)
	\|\| !(avctx->codec->capabilities & AV_CODEC_CAP_FRAME_THREADS))
	return 0;

	if( !avctx->thread_count
	&& avctx->codec_id == AV_CODEC_ID_MJPEG
	&& !(avctx->flags & AV_CODEC_FLAG_QSCALE)) {
	av_log(avctx, AV_LOG_DEBUG,
	"Forcing thread count to 1 for MJPEG encoding, use -thread_type slice "
	"or a constant quantizer if you want to use multiple cpu cores\n");
	avctx->thread_count = 1;
	}
	if( avctx->thread_count > 1
	&& avctx->codec_id == AV_CODEC_ID_MJPEG
	&& !(avctx->flags & AV_CODEC_FLAG_QSCALE))
	av_log(avctx, AV_LOG_WARNING,
	"MJPEG CBR encoding works badly with frame multi-threading, consider "
	"using -threads 1, -thread_type slice or a constant quantizer.\n");

	if (avctx->codec_id == AV_CODEC_ID_HUFFYUV \|\|
	avctx->codec_id == AV_CODEC_ID_FFVHUFF) {
	int warn = 0;
	int context_model = 0;
	AVDictionaryEntry *con = av_dict_get(options, "context", NULL, AV_DICT_MATCH_CASE);

	if (con && con->value)
	context_model = atoi(con->value);

	if (avctx->flags & AV_CODEC_FLAG_PASS1)
	warn = 1;
	else if(context_model > 0) {
	AVDictionaryEntry *t = av_dict_get(options, "non_deterministic",
	NULL, AV_DICT_MATCH_CASE);
	warn = !t \|\| !t->value \|\| !atoi(t->value) ? 1 : 0;
	}
	// huffyuv does not support these with multiple frame threads currently
	if (warn) {
	av_log(avctx, AV_LOG_WARNING,
	"Forcing thread count to 1 for huffyuv encoding with first pass or context 1\n");
	avctx->thread_count = 1;
	}
	}

	if(!avctx->thread_count) {
	avctx->thread_count = av_cpu_count();
	avctx->thread_count = FFMIN(avctx->thread_count, MAX_THREADS);
	}

	if(avctx->thread_count <= 1)
	return 0;

	if(avctx->thread_count > MAX_THREADS)
	return AVERROR(EINVAL);

	av_assert0(!avctx->internal->frame_thread_encoder);
	c = avctx->internal->frame_thread_encoder = av_mallocz(sizeof(ThreadContext));
	if(!c)
	return AVERROR(ENOMEM);

	c->parent_avctx = avctx;

	c->task_fifo = av_fifo_alloc_array(BUFFER_SIZE, sizeof(Task));
	if(!c->task_fifo)
	goto fail;

	pthread_mutex_init(&c->task_fifo_mutex, NULL);
	pthread_mutex_init(&c->finished_task_mutex, NULL);
	pthread_mutex_init(&c->buffer_mutex, NULL);
	pthread_cond_init(&c->task_fifo_cond, NULL);
	pthread_cond_init(&c->finished_task_cond, NULL);
	atomic_init(&c->exit, 0);

	for(i=0; i<avctx->thread_count ; i++){
	AVDictionary *tmp = NULL;
	int ret;
	void *tmpv;
	AVCodecContext *thread_avctx = avcodec_alloc_context3(avctx->codec);
	if(!thread_avctx)
	goto fail;
	tmpv = thread_avctx->priv_data;
	thread_avctx = avctx;
	ret = av_opt_copy(thread_avctx, avctx);
	if (ret < 0)
	goto fail;
	thread_avctx->priv_data = tmpv;
	thread_avctx->internal = NULL;
	if (avctx->codec->priv_class) {
	int ret = av_opt_copy(thread_avctx->priv_data, avctx->priv_data);
	if (ret < 0)
	goto fail;
	} else if (avctx->codec->priv_data_size) {
	memcpy(thread_avctx->priv_data, avctx->priv_data, avctx->codec->priv_data_size);
	}
	thread_avctx->thread_count = 1;
	thread_avctx->active_thread_type &= ~FF_THREAD_FRAME;

	av_dict_copy(&tmp, options, 0);
	av_dict_set(&tmp, "threads", "1", 0);
	if(avcodec_open2(thread_avctx, avctx->codec, &tmp) < 0) {
	av_dict_free(&tmp);
	goto fail;
	}
	av_dict_free(&tmp);
	av_assert0(!thread_avctx->internal->frame_thread_encoder);
	thread_avctx->internal->frame_thread_encoder = c;
	if(pthread_create(&c->worker[i], NULL, worker, thread_avctx)) {
	goto fail;
	}
	}

	avctx->active_thread_type = FF_THREAD_FRAME;

	return 0;
	fail:
	avctx->thread_count = i;
	av_log(avctx, AV_LOG_ERROR, "ff_frame_thread_encoder_init failed\n");
	ff_frame_thread_encoder_free(avctx);
	return -1;
	}

	void ff_frame_thread_encoder_free(AVCodecContext *avctx){
	int i;
	ThreadContext *c= avctx->internal->frame_thread_encoder;

	pthread_mutex_lock(&c->task_fifo_mutex);
	atomic_store(&c->exit, 1);
	pthread_cond_broadcast(&c->task_fifo_cond);
	pthread_mutex_unlock(&c->task_fifo_mutex);

	for (i=0; i<avctx->thread_count; i++) {
	pthread_join(c->worker[i], NULL);
	}

	while (av_fifo_size(c->task_fifo) > 0) {
	Task task;
	AVFrame *frame;
	av_fifo_generic_read(c->task_fifo, &task, sizeof(task), NULL);
	frame = task.indata;
	av_frame_free(&frame);
	task.indata = NULL;
	}

	for (i=0; i<BUFFER_SIZE; i++) {
	if (c->finished_tasks[i].outdata != NULL) {
	AVPacket *pkt = c->finished_tasks[i].outdata;
	av_packet_free(&pkt);
	c->finished_tasks[i].outdata = NULL;
	}
	}

	pthread_mutex_destroy(&c->task_fifo_mutex);
	pthread_mutex_destroy(&c->finished_task_mutex);
	pthread_mutex_destroy(&c->buffer_mutex);
	pthread_cond_destroy(&c->task_fifo_cond);
	pthread_cond_destroy(&c->finished_task_cond);
	av_fifo_freep(&c->task_fifo);
	av_freep(&avctx->internal->frame_thread_encoder);
	}

	int ff_thread_video_encode_frame(AVCodecContext avctx, AVPacket pkt, const AVFrame frame, int got_packet_ptr){
	ThreadContext *c = avctx->internal->frame_thread_encoder;
	Task task;
	int ret;

	av_assert1(!*got_packet_ptr);

	if(frame){
	AVFrame *new = av_frame_alloc();
	if(!new)
	return AVERROR(ENOMEM);
	ret = av_frame_ref(new, frame);
	if(ret < 0) {
	av_frame_free(&new);
	return ret;
	}

	task.index = c->task_index;
	task.indata = (void*)new;
	pthread_mutex_lock(&c->task_fifo_mutex);
	av_fifo_generic_write(c->task_fifo, &task, sizeof(task), NULL);
	pthread_cond_signal(&c->task_fifo_cond);
	pthread_mutex_unlock(&c->task_fifo_mutex);

	c->task_index = (c->task_index+1) % BUFFER_SIZE;
	}

	pthread_mutex_lock(&c->finished_task_mutex);
	if (c->task_index == c->finished_task_index \|\|
	(frame && !c->finished_tasks[c->finished_task_index].outdata &&
	(c->task_index - c->finished_task_index) % BUFFER_SIZE <= avctx->thread_count)) {
	pthread_mutex_unlock(&c->finished_task_mutex);
	return 0;
	}

	while (!c->finished_tasks[c->finished_task_index].outdata) {
	pthread_cond_wait(&c->finished_task_cond, &c->finished_task_mutex);
	}
	task = c->finished_tasks[c->finished_task_index];
	pkt = (AVPacket*)(task.outdata);
	if(pkt->data)
	*got_packet_ptr = 1;
	av_freep(&c->finished_tasks[c->finished_task_index].outdata);
	c->finished_task_index = (c->finished_task_index+1) % BUFFER_SIZE;
	pthread_mutex_unlock(&c->finished_task_mutex);

	return task.return_code;
	}