[vlc-devel] [PATCH 3/3] dec: lock p_vout/p_aout when read from the DecoderThread

[Thomas Guillem]

On Thu, May 17, 2018, at 14:36, Thomas Guillem wrote:
> Since these variables can be written from any thread from format_update()
> callbacks.
> ---
>  src/input/decoder.c | 59 +++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 49 insertions(+), 10 deletions(-)
> 
> diff --git a/src/input/decoder.c b/src/input/decoder.c
> index 1fdc4fb7ed..e8e4c109ef 100644
> --- a/src/input/decoder.c
> +++ b/src/input/decoder.c
> @@ -103,10 +103,11 @@ struct decoder_owner
>      vlc_cond_t  wait_fifo; /* TODO: merge with wait_acknowledge */
>      vlc_cond_t  wait_timed;
>  
> -    /* -- These variables need locking on write(only) -- */
> +    /* These variables are written from the format_update() callbacks threads.
> +     * They need locking when they are read from the DecoderThread (use
> +     * dec_get_aout()/dec_get_vout() helpers). */
>      audio_output_t *p_aout;
> -
> -    vout_thread_t   *p_vout;
> +    vout_thread_t  *p_vout;
>  
>      /* -- Theses variables need locking on read *and* write -- */
>      /* Preroll */
> @@ -158,6 +159,24 @@ static inline struct decoder_owner 
> *dec_get_owner( decoder_t *p_dec )
>      return container_of( p_dec, struct decoder_owner, dec );
>  }
>  
> +static audio_output_t *dec_get_aout( decoder_t *p_dec )
> +{
> +    struct decoder_owner *p_owner = dec_get_owner( p_dec );
> +    vlc_mutex_lock( &p_owner->lock );
> +    audio_output_t *p_aout = p_owner->p_aout ? 
> vlc_object_hold( p_owner->p_aout ) : NULL;
> +    vlc_mutex_unlock( &p_owner->lock );
> +    return p_aout;
> +}
> +
> +static vout_thread_t *dec_get_vout( decoder_t *p_dec )
> +{
> +    struct decoder_owner *p_owner = dec_get_owner( p_dec );
> +    vlc_mutex_lock( &p_owner->lock );
> +    vout_thread_t *p_vout = p_owner->p_vout ? vlc_object_hold( p_owner-
> >p_vout ) : NULL;
> +    vlc_mutex_unlock( &p_owner->lock );
> +    return p_vout;
> +}
> +
>  /**
>   * Load a decoder module
>   */
> @@ -238,15 +257,17 @@ static int ReloadDecoder( decoder_t *p_dec, bool 
> b_packetizer,
>      if( reload == RELOAD_DECODER_AOUT )
>      {
>          assert( p_owner->fmt.i_cat == AUDIO_ES );
> -        audio_output_t *p_aout = p_owner->p_aout;
>  
>          vlc_mutex_lock( &p_owner->lock );
> +        audio_output_t *p_aout = p_owner->p_aout ? 
> vlc_object_hold( p_owner->p_aout ) : NULL;

No needed since the module is unloaded here.

>          p_owner->p_aout = NULL;
>          vlc_mutex_unlock( &p_owner->lock );
> +
>          if( p_aout )
>          {
>              aout_DecDelete( p_aout );
>              input_resource_PutAout( p_owner->p_resource, p_aout );
> +            vlc_object_release( p_aout );
>          }
>      }
>  
> @@ -1538,13 +1559,25 @@ static void *DecoderThread( void *p_data )
>              switch( p_dec->fmt_out.i_cat )
>              {
>                  case VIDEO_ES:
> -                    if( p_owner->p_vout != NULL )
> -                        vout_ChangePause( p_owner->p_vout, paused, date );
> +                {
> +                    vout_thread_t *p_vout = dec_get_vout( p_dec );
> +                    if( p_vout != NULL )
> +                    {
> +                        vout_ChangePause( p_vout, paused, date );
> +                        vlc_object_release( p_vout );
> +                    }
>                      break;
> +                }
>                  case AUDIO_ES:
> -                    if( p_owner->p_aout != NULL )
> -                        aout_DecChangePause( p_owner->p_aout, paused, date );
> +                {
> +                    audio_output_t *p_aout = dec_get_aout( p_dec );
> +                    if( p_aout != NULL )
> +                    {
> +                        aout_DecChangePause( p_aout, paused, date );
> +                        vlc_object_release( p_aout );
> +                    }
>                      break;
> +                }
>                  case SPU_ES:
>                      break;
>                  default:
> @@ -1569,9 +1602,15 @@ static void *DecoderThread( void *p_data )
>                  case VIDEO_ES:
>                      break;
>                  case AUDIO_ES:
> -                    if( p_owner->p_aout != NULL )
> -                        aout_DecChangeRate( p_owner->p_aout, rate );
> +                {
> +                    audio_output_t *p_aout = dec_get_aout( p_dec );
> +                    if( p_aout != NULL )
> +                    {
> +                        aout_DecChangeRate( p_aout, rate );
> +                        vlc_object_release( p_aout );
> +                    }
>                      break;
> +                }
>                  case SPU_ES:
>                      break;
>                  default:
> -- 
> 2.17.0
> 
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