[PATCH i-g-t] lib/igt_core: Use suffix for casting to long to avoid overflow

[Kamil Konieczny]

Hi Zbigniew,
On 2024-12-17 at 11:58:07 +0100, Zbigniew Kempczyński wrote:

please improve subject, imho better something like:

Avoid overflow in micro/nano-seconds calculations
or
Fix overflow in micro/nano-seconds calculations

or propose yourself one line description.

> Multiplication without using casting to long (long) for at least
> one argument in expression may cause overflow especially when we're
> using this for calculating timeouts in nanoseconds precision.
> 
> Ensure we're picking valid ul/ull suffix for base definitions for
> all dependents.
> 
> Reported-by: Ilia Levi <ilia.levi at intel.com>
> Closes: https://gitlab.freedesktop.org/drm/igt-gpu-tools/-/issues/163
> 

I agree here with Lucas, remove this empty line.

> Signed-off-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>
> Cc: Lucas De Marchi <lucas.demarchi at intel.com>
> Cc: Ilia Levi <ilia.levi at intel.com>
> ---
>  lib/igt_core.h | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/lib/igt_core.h b/lib/igt_core.h
> index 90f57402f0..1b6e70182b 100644
> --- a/lib/igt_core.h
> +++ b/lib/igt_core.h
> @@ -1517,11 +1517,17 @@ void igt_kmsg(const char *format, ...);
>  #define le32_to_cpu(x)  (x)
>  #endif
>  
> -#define MSEC_PER_SEC (1000u)
> +#if __WORDSIZE == 64

I am not sure if this is defined on all platforms where igt
is compiled, on musl and on non-Linux like FreeBSD,
why not make #ifndef/#define/#endif for __WORDSIZE ?

BTW is it just sizeof(1ul) == 8 ?

With this fixed and subject improved
Reviewed-by: Kamil Konieczny <kamil.konieczny at linux.intel.com>

Regards,
Kamil

> +#define MSEC_PER_SEC (1000ul)
> +#define USEC_PER_MSEC (1000ul)
> +#else
> +#define MSEC_PER_SEC (1000ull)
> +#define USEC_PER_MSEC (1000ull)
> +#endif
> +
>  #define USEC_PER_SEC (1000u * MSEC_PER_SEC)
>  #define USEC_PER_DECISEC (100u * MSEC_PER_SEC)
>  #define NSEC_PER_SEC (1000u * USEC_PER_SEC)
> -#define USEC_PER_MSEC (1000u)
>  #define NSEC_PER_MSEC (1000u * USEC_PER_MSEC)
>  
>  #define for_if(expr__) if (!(expr__)) {} else
> -- 
> 2.34.1
>