[FFmpeg-devel] [PATCH 1/3] avutil/mem: make max_alloc_size an atomic type

[Anton Khirnov]

Quoting James Almer (2021-05-23 00:09:02)
> This is in preparation for the following commit.
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>  libavutil/mem.c | 17 +++++++++++------
>  1 file changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/libavutil/mem.c b/libavutil/mem.c
> index fa227f5e12..c12c24aa90 100644
> --- a/libavutil/mem.c
> +++ b/libavutil/mem.c
> @@ -31,6 +31,7 @@
>  #include <limits.h>
>  #include <stdint.h>
>  #include <stdlib.h>
> +#include <stdatomic.h>
>  #include <string.h>
>  #if HAVE_MALLOC_H
>  #include <malloc.h>
> @@ -68,17 +69,17 @@ void  free(void *ptr);
>   * dynamic libraries and remove -Wl,-Bsymbolic from the linker flags.
>   * Note that this will cost performance. */
>  
> -static size_t max_alloc_size= INT_MAX;
> +static atomic_size_t max_alloc_size = ATOMIC_VAR_INIT(INT_MAX);
>  
>  void av_max_alloc(size_t max){
> -    max_alloc_size = max;
> +    atomic_store_explicit(&max_alloc_size, max, memory_order_relaxed);

Any specific reason for using a non-default memory order?
AFAIK it is recommended by the spec authors to use default (sequentially
consistent) operations unless there is a very good reason to do
something else.

-- 
Anton Khirnov