[Mesa-dev] [PATCH 7/7] util: Fix ralloc to use malloc instead of calloc

[Jason Ekstrand]

On Tue, Jun 14, 2016 at 7:59 AM, Juha-Pekka Heikkila <
juhapekka.heikkila at gmail.com> wrote:

> ralloc originally had had idea of using malloc but somehow
> had slipped in calloc. Without these changes rzalloc did double
> job of zeroing the memory, first calloc and then memset.
> Now change ralloc to use malloc, leave rzalloc to use calloc and
> make needed changes in ralloc functions to get things working.
>
> Signed-off-by: Juha-Pekka Heikkila <juhapekka.heikkila at gmail.com>
> ---
>  src/util/ralloc.c | 49 +++++++++++++++++++++++++++++++++----------------
>  src/util/ralloc.h |  2 +-
>  2 files changed, 34 insertions(+), 17 deletions(-)
>
> diff --git a/src/util/ralloc.c b/src/util/ralloc.c
> index 9526011..527385d 100644
> --- a/src/util/ralloc.c
> +++ b/src/util/ralloc.c
> @@ -104,25 +104,12 @@ add_child(ralloc_header *parent, ralloc_header *info)
>  void *
>  ralloc_context(const void *ctx)
>  {
> -   return ralloc_size(ctx, 0);
> +   return rzalloc_size(ctx, 0);
>  }
>
> -void *
> -ralloc_size(const void *ctx, size_t size)
> -{
> -   /* ralloc_size was originally implemented using calloc, which meant
> some
> -    * code accidentally relied on its zero filling behavior.
> -    *
> -    * TODO: Make ralloc_size not zero fill memory, and cleanup any code
> that
> -    * should instead be using rzalloc.
> -    */
> -   return rzalloc_size(ctx, size);
> -}
> -
> -void *
> -rzalloc_size(const void *ctx, size_t size)
> +static void*
> +ralloc_header_helper(const void *ctx, const void *block)
>  {
> -   void *block = calloc(1, size + sizeof(ralloc_header));
>     ralloc_header *info;
>     ralloc_header *parent;
>
> @@ -131,6 +118,12 @@ rzalloc_size(const void *ctx, size_t size)
>     info = (ralloc_header *) block;
>     parent = ctx != NULL ? get_header(ctx) : NULL;
>
> +   info->child = NULL;
> +   info->parent = NULL;
> +   info->prev = NULL;
> +   info->next = NULL;
> +   info->destructor = NULL;
> +
>     add_child(parent, info);
>
>  #ifdef DEBUG
> @@ -140,6 +133,30 @@ rzalloc_size(const void *ctx, size_t size)
>     return PTR_FROM_HEADER(info);
>  }
>
> +void *
> +ralloc_size(const void *ctx, size_t size)
> +{
> +   void *block;
> +
> +   if (size + sizeof(ralloc_header) < size )
> +      return NULL;
> +
> +   block = malloc(size + sizeof(ralloc_header));
>

One more thing that I think I'd like to see you try is to add

memset(block, 139, size + sizeof(ralloc_header));

right here and see if everything still works.  Frequently malloc will
return zerod memory and we'd like to be 100% sure that isn't a problem.
For that matter, I think it'd be good to just put that inside of a "#ifndef
NDEBUG" and leave it so that it gets tested in debug builds.


> +   return ralloc_header_helper(ctx, block);
> +}
> +
> +void *
> +rzalloc_size(const void *ctx, size_t size)
> +{
> +   void *block;
> +
> +   if (size + sizeof(ralloc_header) < size )
> +      return NULL;
> +
> +   block = calloc(1, size + sizeof(ralloc_header));
> +   return ralloc_header_helper(ctx, block);
> +}
> +
>  /* helper function - assumes ptr != NULL */
>  static void *
>  resize(void *ptr, size_t size)
> diff --git a/src/util/ralloc.h b/src/util/ralloc.h
> index 7587e11..462db7d 100644
> --- a/src/util/ralloc.h
> +++ b/src/util/ralloc.h
> @@ -430,7 +430,7 @@ private:
>                    \
>  public:                                                                  \
>     static void* operator new(size_t size, void *mem_ctx)                 \
>     {                                                                     \
> -      void *p = ralloc_size(mem_ctx, size);                              \
> +      void *p = rzalloc_size(mem_ctx, size);                             \
>        assert(p != NULL);                                                 \
>        if (!HAS_TRIVIAL_DESTRUCTOR(TYPE))                                 \
>           ralloc_set_destructor(p, _ralloc_destructor);                   \
> --
> 1.9.1
>
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