[FFmpeg-devel] [PATCH 1/3] avcodec/mlp: Make initializing CRCs thread-safe

[Jai Luthra]

LGTM

On Tue, Nov 24, 2020, at 1:29 AM, Andreas Rheinhardt wrote:
> Andreas Rheinhardt:
> > Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> > ---
> >  libavcodec/mlp.c | 17 ++++++++++-------
> >  1 file changed, 10 insertions(+), 7 deletions(-)
> > 
> > diff --git a/libavcodec/mlp.c b/libavcodec/mlp.c
> > index ddbab60c4e..74363c3b95 100644
> > --- a/libavcodec/mlp.c
> > +++ b/libavcodec/mlp.c
> > @@ -23,6 +23,7 @@
> >  
> >  #include "libavutil/crc.h"
> >  #include "libavutil/intreadwrite.h"
> > +#include "libavutil/thread.h"
> >  #include "mlp.h"
> >  
> >  const uint8_t ff_mlp_huffman_tables[3][18][2] = {
> > @@ -62,7 +63,6 @@ const uint64_t ff_mlp_channel_layouts[12] = {
> >      AV_CH_LAYOUT_4POINT1, AV_CH_LAYOUT_5POINT1_BACK, 0,
> >  };
> >  
> > -static int crc_init = 0;
> >  #if CONFIG_SMALL
> >  #define CRC_TABLE_SIZE 257
> >  #else
> > @@ -72,14 +72,17 @@ static AVCRC crc_63[CRC_TABLE_SIZE];
> >  static AVCRC crc_1D[CRC_TABLE_SIZE];
> >  static AVCRC crc_2D[CRC_TABLE_SIZE];
> >  
> > +static av_cold void mlp_init_crc(void)
> > +{
> > +    av_crc_init(crc_63, 0,  8,   0x63, sizeof(crc_63));
> > +    av_crc_init(crc_1D, 0,  8,   0x1D, sizeof(crc_1D));
> > +    av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D));
> > +}
> > +
> >  av_cold void ff_mlp_init_crc(void)
> >  {
> > -    if (!crc_init) {
> > -        av_crc_init(crc_63, 0,  8,   0x63, sizeof(crc_63));
> > -        av_crc_init(crc_1D, 0,  8,   0x1D, sizeof(crc_1D));
> > -        av_crc_init(crc_2D, 0, 16, 0x002D, sizeof(crc_2D));
> > -        crc_init = 1;
> > -    }
> > +    static AVOnce init_static_once = AV_ONCE_INIT;
> > +    ff_thread_once(&init_static_once, mlp_init_crc);
> >  }
> >  
> >  uint16_t ff_mlp_checksum16(const uint8_t *buf, unsigned int buf_size)
> > 
> Will apply this patchset tomorrow unless there are objections.
> 
> - Andreas
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