[FFmpeg-devel] [PATCH 01/13] avcodec/vp9: Do not destroy uninitialized mutexes/conditions

[Steve Lhomme]

On 2021-09-02 17:34, Andreas Rheinhardt wrote:
> Also do not destroy and reinitialize mutexes and conditions when
> certain input parameters change. Given that the decoder did not
> create these variables at all during init, uninitialized mutexes
> and conditions are destroyed before the very first initialization.
> This is undefined behaviour and certain threading implementations
> like pthreadGC2 crash when it is attempted.
> 
> Fix this by initializing these objects once during init and freeing
> them in close.

Works for me.

> Reported-by: Steve Lhomme <robux4 at ycbcr.xyz>
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
> ---
>   libavcodec/vp9.c | 18 +++++++++++++-----
>   1 file changed, 13 insertions(+), 5 deletions(-)
> 
> diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
> index 874005a5ae..5c20a7ec5d 100644
> --- a/libavcodec/vp9.c
> +++ b/libavcodec/vp9.c
> @@ -43,8 +43,6 @@ static void vp9_free_entries(AVCodecContext *avctx) {
>       VP9Context *s = avctx->priv_data;
>   
>       if (avctx->active_thread_type & FF_THREAD_SLICE)  {
> -        pthread_mutex_destroy(&s->progress_mutex);
> -        pthread_cond_destroy(&s->progress_cond);
>           av_freep(&s->entries);
>       }
>   }
> @@ -66,9 +64,6 @@ static int vp9_alloc_entries(AVCodecContext *avctx, int n) {
>   
>           for (i  = 0; i < n; i++)
>               atomic_init(&s->entries[i], 0);
> -
> -        pthread_mutex_init(&s->progress_mutex, NULL);
> -        pthread_cond_init(&s->progress_cond, NULL);
>       }
>       return 0;
>   }
> @@ -1252,6 +1247,12 @@ static av_cold int vp9_decode_free(AVCodecContext *avctx)
>   
>       free_buffers(s);
>       vp9_free_entries(avctx);
> +#if HAVE_THREADS
> +    if (avctx->active_thread_type & FF_THREAD_SLICE) {
> +        pthread_mutex_destroy(&s->progress_mutex);
> +        pthread_cond_destroy(&s->progress_cond);
> +    }
> +#endif
>       av_freep(&s->td);
>       return 0;
>   }
> @@ -1797,6 +1798,13 @@ static av_cold int vp9_decode_init(AVCodecContext *avctx)
>       s->last_bpp = 0;
>       s->s.h.filter.sharpness = -1;
>   
> +#if HAVE_THREADS
> +    if (avctx->active_thread_type & FF_THREAD_SLICE) {
> +        pthread_mutex_init(&s->progress_mutex, NULL);
> +        pthread_cond_init(&s->progress_cond, NULL);
> +    }
> +#endif
> +
>       for (int i = 0; i < 3; i++) {
>           s->s.frames[i].tf.f = av_frame_alloc();
>           if (!s->s.frames[i].tf.f)
> -- 
> 2.30.2
>