Re: [PATCH v1 1/1] treewide: Align match_string() with sysfs_match_string()

[Yury Norov]

On Mon, Jun 10, 2024 at 10:08:00AM +0200, Linus Walleij wrote:
> On Tue, Jun 4, 2024 at 9:46 AM Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> wrote:
> 
> [Maybe slightly off-topic, ranty]
> 
> > Why do we think it's a good idea to increase and normalize the use of
> > double-underscore function names across the kernel, like
> > __match_string() in this case? It should mean "reserved for the
> > implementation, not to be called directly".
> >
> > If it's to be used directly, it should be named accordingly, right?
> 
> It's a huge mess. "__" prefix is just so ambiguous I think it just
> shouldn't be used or prolifierated, and it usually breaks Rusty Russells
> API rules times over.
> 
> Consider __set_bit() from <linux/bitops.h>, used all over the place,
> in contrast with set_bit() for example, what does "__" represent in
> this context that makes __set_bit() different from set_bit()?
> 
> It means "non-atomic"...
> 
> How does a random contributor know this?
> 
> Yeah, you guess it. By the token of "everybody knows that".
> (Grep, google, repeat for the number of contributors to the kernel.)
> 
> I was considering to send a script to Torvalds to just change all
> this to set_bit_nonatomic() (etc) but was hesitating because that
> makes the name unambiguous but long. I think I stayed off it
> because changing stuff like that all over the place creates churn
> and churn is bad.

Hi Linus,

I think about renaming set_bit() stuff for atomicity at least twice
a year. But it would be over 15000 renames for set and clear_bit only:

yury:linux$ git grep -w -E "set_bit|clear_bit"|wc -l
12972
yury:linux$ git grep -w -E "__set_bit|__clear_bit"|wc -l
2914

Anyways, if someone is brave enough to do that... The main problem is
that set_bit() is heavily abused because people don't bother putting
the '__' thing, which leads to using atomic helpers where non-atomic
versions are enough. 

So the right path for renaming would be:

s/set_bit/atomic_set_bit
s/__set_bit/nonatomic_set_bit
/* Wait for a full release cycle or two to let people get used, then */
#define set_bit nonatomic_set_bit

Thanks,
Yury

PS. Had to drop all maillists except for LKML and some random victims
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