Re: [GIT PULL] Please pull hmm changes

[Linus Torvalds <torvalds@linux-foundation.org>]

On Wed, Dec 18, 2019 at 6:59 AM Jason Gunthorpe <jgg@mellanox.com> wrote:
>
> Do you think calling it 'mmn_subscriptions' is clear?

Why do you want that "mmn"?

Guys, the "mmn" part is clear from the _context_. The function name is

When the function name is something like "mmu_interval_read_begin()",
and the filename is "mm/mmu_notifier.c", you do NOT NEED silly
prefixes like "mmn" for local variables.

They add NOTHING.

And they make the code an illegible mess.

Yes, global function names need to be unique, and if they aren't
really core, they want some prefix that explains the context, because
global functions are called from _outside_ the context that explains
them.

But if it's a "struct mmu_interval_notifier" pointer, and it's inside
a file that is all about these pointers, it shouldn't be called
"mmn_xyz".  That's not a name. That's line noise.

So call it a "notifier". Maybe even an "interval_notifier" if you
don't mind the typing. Name it by something _descriptive_. And if you
want.

And "subscriptions" is a lovely name. What does the "mmn" buy you?

Just to clarify: the names I really hated were the local variable
names (and the argument names) that were all entirely within the
context of mm/mmu_notifier.c. Calling something "mmn_mm" is a random
jumble of letters that looks more like you're humming than you're
speaking.

Don't mumble. Speak _clearly_.

The other side of "short names" is that some non-local conventions
exist because they are _so_ global. So if it's just a mm pointer, call
it "mm". We do have some very core concepts in the kernel that
permeate _everything_, and those core things we tend to have very
short names for. So whenever you're working with VM code, you'll see
lots of small names like "mm", "vma", "pte" etc. They aren't exactly
clear, but they are _globally_ something you read and learn when you
work on the Linux VM code.

That's very diofferent from "mmn" - the "mmn" thing isn't some global
shorthand, it is just a local abomination.

So "notifier_mm" makes sense - it's the mm for a notifier. But
"mmn_notifier" does not, because "mmn" only makes sense in a local
context, and in that local context it's not any new information at
all.

See the difference? Two shorthands, but one makes sense and adds
information, while the other is just unnecessary and pointless and
doesn't add anything at all.

                Linus