Re: Rust kernel policy

Steven Rostedt
2025-02-19T16:33:08Z

On Wed, 19 Feb 2025 17:15:43 +0100
Willy Tarreau <w@1wt.eu> wrote:

> Yeah absolutely. However I remember having faced code in the past where
> developers had abused this "unlock on return" concept resulting in locks
> lazily being kept way too long after an operation. I don't think this
> will happen in the kernel thanks to reviews, but typically all the stuff
> that's done after a locked retrieval was done normally is down outside
> of the lock, while here for the sake of not dealing with unlocks, quite
> a few lines were still covered by the lock for no purpose. Anyway
> there's no perfect solution.

This was one of my concerns, and it does creep up slightly (even in my own
use cases where I implemented them!).

But we should be encouraging the use of:

scoped_guard(mutex)(&my_mutex) {
/* Do the work needed for for my_mutex */
}

Which does work out very well. And the fact that the code guarded by the
mutex is now also indented, it makes it easier to review.

-- Steve