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Code Issues Releases Activity

avcodec/snow: Use ff_thread_once() in ff_snow_common_init()

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ff_snow_common_init() currently initializes static data every time it is
invoked; given that both the Snow encoder and decoder have the
FF_CODEC_CAP_INIT_THREADSAFE flag set, this can lead to data races (and
therefore undefined behaviour) even though all threads write the same
values. This commit fixes this by using ff_thread_once() for the
initializations.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
This commit is contained in:
Andreas Rheinhardt 2020-12-02 00:10:13 +01:00
parent bdfe51b44f
commit 6a94afbd5b
1 changed files with 13 additions and 5 deletions
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18
libavcodec/snow.c
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@ -21,6 +21,7 @@
#include "libavutil/intmath.h" #include "libavutil/intmath.h"
#include "libavutil/log.h" #include "libavutil/log.h"
#include "libavutil/opt.h" #include "libavutil/opt.h"
#include "libavutil/thread.h"
#include "avcodec.h" #include "avcodec.h"
#include "me_cmp.h" #include "me_cmp.h"
#include "snow_dwt.h" #include "snow_dwt.h"
@ -427,10 +428,19 @@ mca( 8, 0,8)
mca( 0, 8,8) mca( 0, 8,8)
mca( 8, 8,8) mca( 8, 8,8)
static av_cold void snow_static_init(void)
{
for (int i = 0; i < MAX_REF_FRAMES; i++)
for (int j = 0; j < MAX_REF_FRAMES; j++)
ff_scale_mv_ref[i][j] = 256 * (i + 1) / (j + 1);
init_qexp();
}
av_cold int ff_snow_common_init(AVCodecContext *avctx){ av_cold int ff_snow_common_init(AVCodecContext *avctx){
static AVOnce init_static_once = AV_ONCE_INIT;
SnowContext *s = avctx->priv_data; SnowContext *s = avctx->priv_data;
int width, height; int width, height;
int i, j; int i;
s->avctx= avctx; s->avctx= avctx;
s->max_ref_frames=1; //just make sure it's not an invalid value in case of no initial keyframe s->max_ref_frames=1; //just make sure it's not an invalid value in case of no initial keyframe
@ -480,8 +490,6 @@ av_cold int ff_snow_common_init(AVCodecContext *avctx){
mcfh(0, 8) mcfh(0, 8)
mcfh(8, 8) mcfh(8, 8)
init_qexp();
// dec += FFMAX(s->chroma_h_shift, s->chroma_v_shift); // dec += FFMAX(s->chroma_h_shift, s->chroma_v_shift);
width= s->avctx->width; width= s->avctx->width;
@ -495,8 +503,6 @@ av_cold int ff_snow_common_init(AVCodecContext *avctx){
return AVERROR(ENOMEM); return AVERROR(ENOMEM);
for(i=0; i<MAX_REF_FRAMES; i++) { for(i=0; i<MAX_REF_FRAMES; i++) {
for(j=0; j<MAX_REF_FRAMES; j++)
ff_scale_mv_ref[i][j] = 256*(i+1)/(j+1);
s->last_picture[i] = av_frame_alloc(); s->last_picture[i] = av_frame_alloc();
if (!s->last_picture[i]) if (!s->last_picture[i])
return AVERROR(ENOMEM); return AVERROR(ENOMEM);
@ -507,6 +513,8 @@ av_cold int ff_snow_common_init(AVCodecContext *avctx){
if (!s->mconly_picture || !s->current_picture) if (!s->mconly_picture || !s->current_picture)
return AVERROR(ENOMEM); return AVERROR(ENOMEM);
ff_thread_once(&init_static_once, snow_static_init);
return 0; return 0;
} }