Re: [PATCH RFC] userfaultfd: introduce UFFDIO_COPY_MODE_YOUNG

[John Hubbard <jhubbard@nvidia.com>]

On 6/14/22 11:56, Mike Rapoport wrote:
>> But, I cannot take it anymore: the list of arguments for uffd stuff is
>> crazy. I would like to collect all the possible arguments that are used for
>> uffd operation into some “struct uffd_op”.
> 
> Squashing boolean parameters into int flags will also reduce the insane
> amount of parameters. No strong feelings though.
>   

Just a quick drive-by comment about boolean arguments: they ruin the
readability of the call sites. In practice, sometimes a single boolean
argument can be OK-ish (still poor to read at the call site, but easier
to code initially), but once you get past one boolean argument in the
function, readability is hopeless:

     foo(ptr, true, false, a == b);

So if you have a choice, I implore you to prefer flags and/or enums. :)


thanks,
-- 
John Hubbard
NVIDIA