On 28 November 2017 at 01:26, Michael Niedermayer <mich...@niedermayer.cc>
wrote:
> On Mon, Nov 27, 2017 at 04:30:18AM +0000, Rostislav Pehlivanov wrote:
> > Signed-off-by: Rostislav Pehlivanov <atomnu...@gmail.com>
> > ---
> > libavcodec/parser.c | 14 ++++++++------
> > 1 file changed, 8 insertions(+), 6 deletions(-)
> >
> > diff --git a/libavcodec/parser.c b/libavcodec/parser.c
> > index 670680ea7c..baf1de4d88 100644
> > --- a/libavcodec/parser.c
> > +++ b/libavcodec/parser.c
> > @@ -23,30 +23,32 @@
> > #include <inttypes.h>
> > #include <stdint.h>
> > #include <string.h>
> > +#include <stdatomic.h>
> >
> > #include "libavutil/avassert.h"
> > -#include "libavutil/atomic.h"
> > #include "libavutil/internal.h"
> > #include "libavutil/mem.h"
> >
> > #include "internal.h"
> > #include "parser.h"
> >
> > -static AVCodecParser *av_first_parser = NULL;
> > +static _Atomic(AVCodecParser *)av_first_parser = NULL;
>
> This doesnt build here
>
> libavcodec/parser.c:35:8: warning: return type defaults to ‘int’ [enabled
> by default]
> static _Atomic(AVCodecParser *)av_first_parser = NULL;
> ^
> libavcodec/parser.c: In function ‘_Atomic’:
> libavcodec/parser.c:35:32: error: expected declaration specifiers before
> ‘av_first_parser’
> static _Atomic(AVCodecParser *)av_first_parser = NULL;
> ^
> libavcodec/parser.c:38:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or
> ‘__attribute__’ before ‘{’ token
> {
> ^
> libavcodec/parser.c:46:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or
> ‘__attribute__’ before ‘{’ token
> {
> ^
> libavcodec/parser.c:55:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or ‘__a
>
>
> [...]
> --
> Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Observe your enemies, for they first find out your faults. -- Antisthenes
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel@ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>
>
Does the attached patch work?
From b9ed59e9aff4a0fcc40f444f307c87acad55e139 Mon Sep 17 00:00:00 2001
From: Rostislav Pehlivanov <atomnu...@gmail.com>
Date: Mon, 27 Nov 2017 01:56:41 +0000
Subject: [PATCH v2 1/2] lavc/parser: use C11 atomics
Signed-off-by: Rostislav Pehlivanov <atomnu...@gmail.com>
---
libavcodec/parser.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/libavcodec/parser.c b/libavcodec/parser.c
index 670680ea7c..d6df62bf70 100644
--- a/libavcodec/parser.c
+++ b/libavcodec/parser.c
@@ -23,30 +23,32 @@
#include <inttypes.h>
#include <stdint.h>
#include <string.h>
+#include <stdatomic.h>
#include "libavutil/avassert.h"
-#include "libavutil/atomic.h"
#include "libavutil/internal.h"
#include "libavutil/mem.h"
#include "internal.h"
#include "parser.h"
-static AVCodecParser *av_first_parser = NULL;
+static _Atomic(AVCodecParser *) av_first_parser = NULL;
AVCodecParser *av_parser_next(const AVCodecParser *p)
{
if (p)
return p->next;
else
- return av_first_parser;
+ return atomic_load(&av_first_parser);
}
void av_register_codec_parser(AVCodecParser *parser)
{
+ AVCodecParser *old_parser;
do {
- parser->next = av_first_parser;
- } while (parser->next != avpriv_atomic_ptr_cas((void * volatile *)&av_first_parser, parser->next, parser));
+ parser->next = old_parser = atomic_load(&av_first_parser);
+ atomic_compare_exchange_strong(&av_first_parser, &old_parser, parser);
+ } while (parser->next != old_parser);
}
AVCodecParserContext *av_parser_init(int codec_id)
@@ -58,7 +60,7 @@ AVCodecParserContext *av_parser_init(int codec_id)
if (codec_id == AV_CODEC_ID_NONE)
return NULL;
- for (parser = av_first_parser; parser; parser = parser->next) {
+ for (parser = atomic_load(&av_first_parser); parser; parser = parser->next) {
if (parser->codec_ids[0] == codec_id ||
parser->codec_ids[1] == codec_id ||
parser->codec_ids[2] == codec_id ||
--
2.15.1.424.g9478a66081
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