Re: Buggy __free(kfree) usage pattern already in tree

[Linus Torvalds]

On Fri, 15 Sept 2023 at 14:32, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
>
> It also got me thinking about named_guard() for the myriad of
> conditional locks we have.
>
>         named_guard(try_mutex, foo_guard)(&foo->lock);
>         if (foo_guard) {
>                 // we got the lock, do our thing
>         }

Hmm. It looks ugly to me. I really hate the "named_guard" thing. One
of the reasons I liked the guard/scoped_guard() macros was because how
it created _anonymous_ guards, and made it completely unnecessary to
make up a pointless name.

If trylock ends up being a common pattern, I think we should strive to
make it a lot easier to use.

Can we make it act like "scoped_guard()", except the lock function is
fundamentally conditional?

Call it "cond_guard()", and make the syntax otherwise be the same as
"scoped_guard()", iow, using a unique ID for the guard name.

So

        cond_guard(try_mutex)(&foo->lock) {
                .. this is the "we got the lock" region ..
        }

would I think be a much better syntax.

Could we live with that?

               Linus