Re: [PATCH v7 06/19] xen/bitops: put __ffs() into linux compatible header

[Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>]

Hi Oleksii,

On 4/3/24 5:19 AM, Oleksii Kurochko wrote:
> The mentioned macros exist only because of Linux compatible purpose.
> 
> The patch defines __ffs() in terms of Xen bitops and it is safe
> to define in this way ( as __ffs() - 1 ) as considering that __ffs()
> was defined as __builtin_ctzl(x), which has undefined behavior when x=0,
> so it is assumed that such cases are not encountered in the current code.
> 
> To not include <xen/linux-compat.h> to Xen library files __ffs() and __ffz()
> were defined locally in find-next-bit.c.
> 
> Except __ffs() usage in find-next-bit.c only one usage of __ffs() leave
> in smmu-v3.c. It seems that it __ffs can be changed to ffsl(x)-1 in
> this file, but to keep smmu-v3.c looks close to linux it was deciced just
> to define __ffs() in xen/linux-compat.h and include it in smmu-v3.c
> 
> Signed-off-by: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>

For the PPC part:
Acked-by: Shawn Anastasio <sanastasio@xxxxxxxxxxxxxxxxxxxxx>

Thanks,
Shawn