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List:       linux-kernel
Subject:    Re: [PATCH v3] tty: tty_io: remove hung_up_tty_fops
From:       Linus Torvalds <torvalds () linux-foundation ! org>
Date:       2024-04-29 15:38:28
Message-ID: CAHk-=whnQXNVwuf42Sh2ngBGhBqbJjUfq5ux6e7Si_XSPAt05A () mail ! gmail ! com
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On Mon, 29 Apr 2024 at 06:56, Marco Elver <elver@google.com> wrote:
>
> A WRITE_ONCE() / READ_ONCE() pair would do it here. What should we use instead?

Why would we annotate a "any other code generation is insane" issues at all?

When we do chained pointer loads in

    file->f_op->op()

and we say "I don't care what value I get for the middle one", I don't
see the value in annotating that at all.

There is no compiler that will sanely and validly do a pointer chain
load by *anything* but a load. And it doesn't matter to us if it then
spills and reloads, it will *STILL* be a load.

We're not talking about "extract different bits in separate
operations". We're talking about following one pointer that can point
to two separate static values.

Reality matters. A *lot* more than some "C standard" that we already
have ignored for decades because it's not strong enough.

                       Linus

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