[FFmpeg-devel] [PATCH] [Trac ticket #3194] libavcodec/utils: Statically initialize global mutexes to avoid a leak.

[Hendrik Leppkes]

On Sun, Dec 15, 2013 at 12:17 PM, Tomer Barletz <barletz at gmail.com> wrote:
> ---
>  libavcodec/utils.c | 25 +++++++------------------
>  1 file changed, 7 insertions(+), 18 deletions(-)
>
> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
> index 73370fe..0653acc 100644
> --- a/libavcodec/utils.c
> +++ b/libavcodec/utils.c
> @@ -74,20 +74,6 @@ static int default_lockmgr_cb(void **arg, enum AVLockOp op)
>      case AV_LOCK_CREATE:
>          return 0;
>      case AV_LOCK_OBTAIN:
> -        if (!*mutex) {
> -            pthread_mutex_t *tmp = av_malloc(sizeof(pthread_mutex_t));
> -            if (!tmp)
> -                return AVERROR(ENOMEM);
> -            if ((err = pthread_mutex_init(tmp, NULL))) {
> -                av_free(tmp);
> -                return AVERROR(err);
> -            }
> -            if (avpriv_atomic_ptr_cas(mutex, NULL, tmp)) {
> -                pthread_mutex_destroy(tmp);
> -                av_free(tmp);
> -            }
> -        }
> -
>          if ((err = pthread_mutex_lock(*mutex)))
>              return AVERROR(err);
>
> @@ -100,8 +86,7 @@ static int default_lockmgr_cb(void **arg, enum AVLockOp op)
>      case AV_LOCK_DESTROY:
>          if (*mutex)
>              pthread_mutex_destroy(*mutex);
> -        av_free(*mutex);
> -        avpriv_atomic_ptr_cas(mutex, *mutex, NULL);
> +
>          return 0;
>      }
>      return 1;
> @@ -114,8 +99,12 @@ static int (*lockmgr_cb)(void **mutex, enum AVLockOp op) = NULL;
>
>  volatile int ff_avcodec_locked;
>  static int volatile entangled_thread_counter = 0;
> -static void *codec_mutex;
> -static void *avformat_mutex;
> +
> +static pthread_mutex_t codec_mutex_real = PTHREAD_MUTEX_INITIALIZER;
> +static void *codec_mutex = &codec_mutex_real;
> +
> +static pthread_mutex_t avformat_mutex_real = PTHREAD_MUTEX_INITIALIZER;
> +static void *avformat_mutex = &avformat_mutex_real;
>
>  #if FF_API_FAST_MALLOC && CONFIG_SHARED && HAVE_SYMVER
>  FF_SYMVER(void*, av_fast_realloc, (void *ptr, unsigned int *size, size_t min_size), "LIBAVCODEC_55")

Static initialization doesn't work with the w32threads compat wrapper,
and as such, this patch would break this use-case.