svn commit: r344758 - in head/sys/fs: nfs nfsserver

[Cy Schubert]

On March 4, 2019 6:30:21 AM PST, Konstantin Belousov <kostikbel at gmail.com> wrote:
>On Mon, Mar 04, 2019 at 01:31:37PM +0000, Edward Napierala wrote:
>> pon., 4 mar 2019 o 13:20 Konstantin Belousov <kostikbel at gmail.com>
>napisał(a):
>> > > +     p = curthread;
>> > Why do you name it 'p', which is typical for process, and not 'td',
>you are
>> > changing most of the code anyway.
>> 
>> To keep the diff size smaller.  You're right, this touches a lot of
>stuff,
>> but most of those added lines are temporary anyway - they will be
>> removed later, when the td is pushed down even more.
>But if you create code churn, doing it only half way is worse.
>
>> 
>> > Also I am curious why. It is certainly fine to remove td when it is
>used
>> > as a formal placeholder argument only. But when the first action in
>the
>> > function is evaluation of curthread() it becomes less obvious.
>> 
>> Again, many/most of those are temporary.  I'm trying to push td down
>> in small steps, "layer by layer", so it's easy to review.
>> 
>> > curthread() become very cheap on modern amd64, I am not so sure
>about
>> > older machines or non-x86 cases.
>> 
>> The main reason is readability.  Right now there's no easy way to
>tell whether
>> a function can be passed any td, or if it must be curthread.
>I must admit that this is the weirdnest argument against 'td' that I
>ever
>heard.  I saw more or less reasonable argumentation
>- that using less arguments make one more register for argument passing
>  (amd64 has 6 input arg regs),
>- that less arguments make smaller call code.
>But trust me, in all cases where function can take td != curthread, it
>is
>either obvious or well-known for anybody who works with that code.
>
>Before you start doing a lot of small changes (AKA continous churn)
>please formulate your goals and get some public feedback.  My immediate
>question that I want answered before you ever start touching the code,
>is what you plan to do with
>	sys_syscall(struct thread *td, uap)

Agreed on all points. At the very least this group of commits should be reviewed on phabricator.

Can we back all these commits out until there is a proper review, please?

-- 
Pardon the typos and autocorrect, small keyboard in use.
Cheers,
Cy Schubert <Cy.Schubert at cschubert.com>
FreeBSD UNIX: <cy at FreeBSD.org> Web: http://www.FreeBSD.org

	The need of the many outweighs the greed of the few.