[FFmpeg-devel] [PATCH 3/3] avutil/mem_internal: use av_max_alloc_get() in ff_fast_malloc()

[James Almer]

On 5/22/2021 7:09 PM, James Almer wrote:
> This puts ff_fast_malloc() and av_fast_malloc() in line with ff_fast_realloc()
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
> The alternative to this set would be to move av_fast_padded_malloc() from
> avcodec to avutil, and moving ff_fast_malloc() from mem_internal.h to mem.c, in
> which case it will no longer be inlined for easy use.

av_fast_padded_malloc() can't be moved since it uses 
AV_INPUT_BUFFER_PADDING_SIZE, so the only alternative is to move 
ff_fast_malloc() to mem.c, have it use max_alloc_size, and make 
av_fast_padded_malloc() call av_fast_mallocz().

If that's preferred to adding a function to get the max alloc value to 
lavu, i'll send a patchset for it.

> 
>   libavutil/mem_internal.h | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/libavutil/mem_internal.h b/libavutil/mem_internal.h
> index ee2575c85f..76277d3fe4 100644
> --- a/libavutil/mem_internal.h
> +++ b/libavutil/mem_internal.h
> @@ -24,6 +24,7 @@
>   #include "config.h"
>   
>   #include <stdint.h>
> +#include <stdatomic.h>
>   
>   #include "avassert.h"
>   #include "mem.h"
> @@ -138,14 +139,21 @@
>   
>   static inline int ff_fast_malloc(void *ptr, unsigned int *size, size_t min_size, int zero_realloc)
>   {
> +    size_t max_size;
>       void *val;
>   
> +    av_max_alloc_get(&max_size);
> +
>       memcpy(&val, ptr, sizeof(val));
>       if (min_size <= *size) {
>           av_assert0(val || !min_size);
>           return 0;
>       }
> -    min_size = FFMAX(min_size + min_size / 16 + 32, min_size);
> +    if (min_size > max_size) {
> +        *size = 0;
> +        return 1;
> +    }
> +    min_size = FFMIN(max_size, FFMAX(min_size + min_size / 16 + 32, min_size));
>       av_freep(ptr);
>       val = zero_realloc ? av_mallocz(min_size) : av_malloc(min_size);
>       memcpy(ptr, &val, sizeof(val));
>