Re: C aggregate passing (Rust kernel policy)

[Linus Torvalds]

On Wed, 26 Feb 2025 at 15:27, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> My point is that the compiler is free to turn that into:
>
>         r = READ_ONCE(global);
>         if (r > 1000)
>                 goto out;
>         x = r;
>
> and not change the expected result.

Yes.

It is safe to *combine* reads - it's what the CPU will effectively do
anyway (modulo MMIO, which as mentioned is why volatile is so special
and so different).

It's just not safe to split them.

        Linus