linux-kernel - Re: C aggregate passing (Rust kernel policy)

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Message-ID: <CAHk-=whEkEsGHWBMZ17v5=sq1uRe6g-BRHy5xNZK-2JBKRs=_A@mail.gmail.com>
Date: Wed, 26 Feb 2025 15:16:54 -0800
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: Kent Overstreet <kent.overstreet@...ux.dev>
Cc: Martin Uecker <uecker@...raz.at>, Ralf Jung <post@...fj.de>, 
	"Paul E. McKenney" <paulmck@...nel.org>, Alice Ryhl <aliceryhl@...gle.com>, 
	Ventura Jack <venturajack85@...il.com>, Gary Guo <gary@...yguo.net>, airlied@...il.com, 
	boqun.feng@...il.com, david.laight.linux@...il.com, ej@...i.de, 
	gregkh@...uxfoundation.org, hch@...radead.org, hpa@...or.com, 
	ksummit@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	miguel.ojeda.sandonis@...il.com, rust-for-linux@...r.kernel.org
Subject: Re: C aggregate passing (Rust kernel policy)

On Wed, 26 Feb 2025 at 14:27, Kent Overstreet <kent.overstreet@...ux.dev> wrote:
>
> This is another one that's entirely eliminated due to W^X references.

Are you saying rust cannot have global flags?

That seems unlikely. And broken if so.

> IOW: if you're writing code where rematerializing reads is even a
> _concern_ in Rust, then you had to drop to unsafe {} to do it - and your
> code is broken, and yes it will have UB.

If you need to drop to unsafe mode just to read a global flag that may
be set concurrently, you're doing something wrong as a language
designer.

And if your language then rematerializes reads, the language is shit.

Really.

             Linus