Re: [dpdk-dev] [PATCH] eal: fix argument to rte_bsf32_safe

[Tyler Retzlaff <roretzla@linux.microsoft.com>]

On Tue, Jul 13, 2021 at 01:12:21PM -0700, Stephen Hemminger wrote:
> The first argument to rte_bsf32_safe was incorrectly declared as
> a 64 bit value. This function only correctly handles on 32 bit values
> and the underlying function rte_bsf32 only accepts 32 bit values.
> This was introduced when the safe version was added and probably cause
> by copy/paste from the 64 bit version.

there are multiple errors in this family of functions [1] both in usage
and signatures. we previously discussed rolling all fixes up into a single
patch and announcing an api break.

a doc patch was submitted as per the process documented for breaking api
but received no replies [2]

i have a full patch that corrects the whole family if you would like to
take it instead. contact me offline if you are interested.

1. http://mails.dpdk.org/archives/dev/2021-March/201590.html
2. http://mails.dpdk.org/archives/dev/2021-March/201868.html

the change stand-alone is correct so

Acked-By: Tyler Retzlaff <roretzla@linux.microsoft.com>

> 
> The bug passed silently under the radar until some other code was
> built with -Wall and -Wextra in C++ and C++ complains about the
> missing cast.
> 
> Yes, this is a API signature change, but the original code was wrong.
> It is an inline so not an ABI change.
> 
> Fixes: 4e261f551986 ("eal: add 64-bit bsf and 32-bit safe bsf functions")
> Cc: anatoly.burakov@intel.com
> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
> ---
>  lib/eal/include/rte_common.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/eal/include/rte_common.h b/lib/eal/include/rte_common.h
> index d5a32c66a5fe..99eb5f1820ae 100644
> --- a/lib/eal/include/rte_common.h
> +++ b/lib/eal/include/rte_common.h
> @@ -623,7 +623,7 @@ rte_bsf32(uint32_t v)
>   *     Returns 0 if ``v`` was 0, otherwise returns 1.
>   */
>  static inline int
> -rte_bsf32_safe(uint64_t v, uint32_t *pos)
> +rte_bsf32_safe(uint32_t v, uint32_t *pos)
>  {
>  	if (v == 0)
>  		return 0;
> -- 
> 2.30.2