[PATCH] Remove potential reference count races.

[Nikolay Sivov]

On 10/28/2012 04:59, max at mtew.isa-geek.net wrote:
> From: Max TenEyck Woodbury <max at mtew.isa-geek.net>
>
> ---
>   dlls/gdi32/freetype.c |    4 ++--
>   1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/dlls/gdi32/freetype.c b/dlls/gdi32/freetype.c
> index 6af977c..3379c6e 100644
> --- a/dlls/gdi32/freetype.c
> +++ b/dlls/gdi32/freetype.c
> @@ -3820,7 +3820,7 @@ static struct font_mapping *map_font_file( const char *name )
>       {
>           if (mapping->dev == st.st_dev && mapping->ino == st.st_ino)
>           {
> -            mapping->refcount++;
> +            InterlockedIncrement(&mapping->refcount);
>               close( fd );
>               return mapping;
>           }
> @@ -3850,7 +3850,7 @@ error:
>   
>   static void unmap_font_file( struct font_mapping *mapping )
>   {
> -    if (!--mapping->refcount)
> +    if (!InterlockedDecrement(&mapping->refcount))
>       {
>           list_remove( &mapping->entry );
>           munmap( mapping->data, mapping->size );
How does it help exactly and what is the problem with this code?