[vlc-devel] [PATCH 1/2] decoder: lock vout_thread_started when written

[Rémi Denis-Courmont]

Le perjantaina 26. kesäkuuta 2020, 14.26.01 EEST Thomas Guillem a écrit :
> This variable is written from the ModuleThread or from the DecoderThread
> when the module is unloaded. The lock need to be held when this variable is
> written, since the DecoderThread read it with the lock held.

Well maybe, but the boolean presumably needs to be consistent with the 
underlying state it describes, and that's not the case with the naive locking 
below.

This looks like replacing a memory race with a functional race.

> ---
>  src/input/decoder.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/src/input/decoder.c b/src/input/decoder.c
> index 0c216bfca49..dd901f77b0c 100644
> --- a/src/input/decoder.c
> +++ b/src/input/decoder.c
> @@ -479,7 +479,9 @@ static int ModuleThread_UpdateVideoFormat( decoder_t
> *p_dec, vlc_video_context * res = input_resource_StartVout(
> p_owner->p_resource, vctx, &cfg); if (res == 0)
>      {
> +        vlc_mutex_lock( &p_owner->lock );
>          p_owner->vout_thread_started = true;
> +        vlc_mutex_unlock( &p_owner->lock );
>          decoder_Notify(p_owner, on_vout_started, p_vout, vout_order);
>      }
>      return res;


-- 
Rémi Denis-Courmont
http://www.remlab.net/