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lavc/h264: don't touch H264Context->ref_count[] during MB decoding. 

The variable is copied to subsequent threads at the same time, so this
may cause wrong ref_count[] values to be copied to subsequent threads.

This bug was found using TSAN and Helgrind.

Original patch by Ronald, adapted with a local_ref_count by Clément,
following the suggestion of Michael Niedermayer.

Signed-off-by: Clément Bœsch <clement.boesch@smartjog.com>
tags/n1.1
Ronald S. Bultje Clément Bœsch 13 years ago
parent
5cdd3b995c
commit
2e59210edf
2 changed files with 28 additions and 40 deletions
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  1. +15
    -21
      libavcodec/h264_cabac.c
  2. +13
    -19
      libavcodec/h264_cavlc.c

+ 15
- 21
libavcodec/h264_cabac.c View File

@@ -1864,6 +1864,7 @@ int ff_h264_decode_mb_cabac(H264Context *h) {
int dct8x8_allowed= h->pps.transform_8x8_mode;
int decode_chroma = h->sps.chroma_format_idc == 1 || h->sps.chroma_format_idc == 2;
const int pixel_shift = h->pixel_shift;
unsigned local_ref_count[2];

mb_xy = h->mb_xy = s->mb_x + s->mb_y*s->mb_stride;

@@ -2004,10 +2005,8 @@ decode_intra_mb:
return 0;
}

if(MB_MBAFF){
h->ref_count[0] <<= 1;
h->ref_count[1] <<= 1;
}
local_ref_count[0] = h->ref_count[0] << MB_MBAFF;
local_ref_count[1] = h->ref_count[1] << MB_MBAFF;

fill_decode_caches(h, mb_type);

@@ -2077,10 +2076,10 @@ decode_intra_mb:
for( i = 0; i < 4; i++ ) {
if(IS_DIRECT(h->sub_mb_type[i])) continue;
if(IS_DIR(h->sub_mb_type[i], 0, list)){
if( h->ref_count[list] > 1 ){
if (local_ref_count[list] > 1) {
ref[list][i] = decode_cabac_mb_ref( h, list, 4*i );
if(ref[list][i] >= (unsigned)h->ref_count[list]){
av_log(s->avctx, AV_LOG_ERROR, "Reference %d >= %d\n", ref[list][i], h->ref_count[list]);
if (ref[list][i] >= (unsigned)local_ref_count[list]) {
av_log(s->avctx, AV_LOG_ERROR, "Reference %d >= %d\n", ref[list][i], local_ref_count[list]);
return -1;
}
}else
@@ -2163,10 +2162,10 @@ decode_intra_mb:
for(list=0; list<h->list_count; list++){
if(IS_DIR(mb_type, 0, list)){
int ref;
if(h->ref_count[list] > 1){
if (local_ref_count[list] > 1) {
ref= decode_cabac_mb_ref(h, list, 0);
if(ref >= (unsigned)h->ref_count[list]){
av_log(s->avctx, AV_LOG_ERROR, "Reference %d >= %d\n", ref, h->ref_count[list]);
if (ref >= (unsigned)local_ref_count[list]) {
av_log(s->avctx, AV_LOG_ERROR, "Reference %d >= %d\n", ref, local_ref_count[list]);
return -1;
}
}else
@@ -2191,10 +2190,10 @@ decode_intra_mb:
for(i=0; i<2; i++){
if(IS_DIR(mb_type, i, list)){
int ref;
if(h->ref_count[list] > 1){
if (local_ref_count[list] > 1) {
ref= decode_cabac_mb_ref( h, list, 8*i );
if(ref >= (unsigned)h->ref_count[list]){
av_log(s->avctx, AV_LOG_ERROR, "Reference %d >= %d\n", ref, h->ref_count[list]);
if (ref >= (unsigned)local_ref_count[list]) {
av_log(s->avctx, AV_LOG_ERROR, "Reference %d >= %d\n", ref, local_ref_count[list]);
return -1;
}
}else
@@ -2226,10 +2225,10 @@ decode_intra_mb:
for(i=0; i<2; i++){
if(IS_DIR(mb_type, i, list)){ //FIXME optimize
int ref;
if(h->ref_count[list] > 1){
if (local_ref_count[list] > 1) {
ref= decode_cabac_mb_ref( h, list, 4*i );
if(ref >= (unsigned)h->ref_count[list]){
av_log(s->avctx, AV_LOG_ERROR, "Reference %d >= %d\n", ref, h->ref_count[list]);
if (ref >= (unsigned)local_ref_count[list]) {
av_log(s->avctx, AV_LOG_ERROR, "Reference %d >= %d\n", ref, local_ref_count[list]);
return -1;
}
}else
@@ -2402,10 +2401,5 @@ decode_intra_mb:
s->current_picture.f.qscale_table[mb_xy] = s->qscale;
write_back_non_zero_count(h);

if(MB_MBAFF){
h->ref_count[0] >>= 1;
h->ref_count[1] >>= 1;
}

return 0;
}

+ 13
- 19
libavcodec/h264_cavlc.c View File

@@ -700,6 +700,7 @@ int ff_h264_decode_mb_cavlc(H264Context *h){
int dct8x8_allowed= h->pps.transform_8x8_mode;
int decode_chroma = h->sps.chroma_format_idc == 1 || h->sps.chroma_format_idc == 2;
const int pixel_shift = h->pixel_shift;
unsigned local_ref_count[2];

mb_xy = h->mb_xy = s->mb_x + s->mb_y*s->mb_stride;

@@ -785,10 +786,8 @@ decode_intra_mb:
return 0;
}

if(MB_MBAFF){
h->ref_count[0] <<= 1;
h->ref_count[1] <<= 1;
}
local_ref_count[0] = h->ref_count[0] << MB_MBAFF;
local_ref_count[1] = h->ref_count[1] << MB_MBAFF;

fill_decode_neighbors(h, mb_type);
fill_decode_caches(h, mb_type);
@@ -869,7 +868,7 @@ decode_intra_mb:
}

for(list=0; list<h->list_count; list++){
int ref_count= IS_REF0(mb_type) ? 1 : h->ref_count[list];
int ref_count= IS_REF0(mb_type) ? 1 : local_ref_count[list];
for(i=0; i<4; i++){
if(IS_DIRECT(h->sub_mb_type[i])) continue;
if(IS_DIR(h->sub_mb_type[i], 0, list)){
@@ -949,13 +948,13 @@ decode_intra_mb:
for(list=0; list<h->list_count; list++){
unsigned int val;
if(IS_DIR(mb_type, 0, list)){
if(h->ref_count[list]==1){
if(local_ref_count[list]==1){
val= 0;
}else if(h->ref_count[list]==2){
}else if(local_ref_count[list]==2){
val= get_bits1(&s->gb)^1;
}else{
val= get_ue_golomb_31(&s->gb);
if(val >= h->ref_count[list]){
if(val >= local_ref_count[list]){
av_log(h->s.avctx, AV_LOG_ERROR, "ref %u overflow\n", val);
return -1;
}
@@ -979,13 +978,13 @@ decode_intra_mb:
for(i=0; i<2; i++){
unsigned int val;
if(IS_DIR(mb_type, i, list)){
if(h->ref_count[list] == 1){
if(local_ref_count[list] == 1){
val= 0;
}else if(h->ref_count[list] == 2){
}else if(local_ref_count[list] == 2){
val= get_bits1(&s->gb)^1;
}else{
val= get_ue_golomb_31(&s->gb);
if(val >= h->ref_count[list]){
if(val >= local_ref_count[list]){
av_log(h->s.avctx, AV_LOG_ERROR, "ref %u overflow\n", val);
return -1;
}
@@ -1016,13 +1015,13 @@ decode_intra_mb:
for(i=0; i<2; i++){
unsigned int val;
if(IS_DIR(mb_type, i, list)){ //FIXME optimize
if(h->ref_count[list]==1){
if(local_ref_count[list]==1){
val= 0;
}else if(h->ref_count[list]==2){
}else if(local_ref_count[list]==2){
val= get_bits1(&s->gb)^1;
}else{
val= get_ue_golomb_31(&s->gb);
if(val >= h->ref_count[list]){
if(val >= local_ref_count[list]){
av_log(h->s.avctx, AV_LOG_ERROR, "ref %u overflow\n", val);
return -1;
}
@@ -1162,10 +1161,5 @@ decode_intra_mb:
s->current_picture.f.qscale_table[mb_xy] = s->qscale;
write_back_non_zero_count(h);

if(MB_MBAFF){
h->ref_count[0] >>= 1;
h->ref_count[1] >>= 1;
}

return 0;
}

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