RE: [PATCH] eal: fix pointer add/sub macros for large offsets values

[Konstantin Ananyev <konstantin.ananyev@huawei.com>]

> The macros for adding or subtracting from pointers cast the pointer type
> to uintptr_t before doing the arithmetic. However, for 32-bit builds, if
> the value being added or subtracted is larger than uintptr_t, then we
> get errors when casting back to "void *" type.

But probably error here in such case is a good thing, as it flags an overflow?
Can't user explicitly convert x then to 32-bit type, if that was an intention?

> We fix this by casting
> the result to uintptr_t before casting to pointer.
> 
> Fixes: af75078fece3 ("first public release")
> Cc: stable@dpdk.org
> 
> Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
>  lib/eal/include/rte_common.h | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
> index f872d3eabb..c17f50e2fd 100644
> --- a/lib/eal/include/rte_common.h
> +++ b/lib/eal/include/rte_common.h
> @@ -572,12 +572,12 @@ static void __attribute__((destructor(RTE_PRIO(prio)),
> used)) func(void)
>  /**
>   * add a byte-value offset to a pointer
>   */
> -#define RTE_PTR_ADD(ptr, x) ((void*)((uintptr_t)(ptr) + (x)))
> +#define RTE_PTR_ADD(ptr, x) ((void *)(uintptr_t)((uintptr_t)(ptr) + (x)))
> 
>  /**
>   * subtract a byte-value offset from a pointer
>   */
> -#define RTE_PTR_SUB(ptr, x) ((void *)((uintptr_t)(ptr) - (x)))
> +#define RTE_PTR_SUB(ptr, x) ((void *)(uintptr_t)((uintptr_t)(ptr) - (x)))
> 
>  /**
>   * get the difference between two pointer values, i.e. how far apart
> --
> 2.53.0