linux-kernel - Re: [PATCH 1/2] uaccess: Simplify code pattern for masked user copies

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Message-ID: <CAHk-=wjv5x4ee-nKLfwoYwgJ9OqBkd+wqGn-dgWpHdpA2oZqqw@mail.gmail.com>
Date: Sun, 9 Feb 2025 10:46:03 -0800
From: Linus Torvalds <torvalds@...ux-foundation.org>
To: David Laight <david.laight.linux@...il.com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	Arnd Bergmann <arnd@...db.de>, Kees Cook <kees@...nel.org>
Subject: Re: [PATCH 1/2] uaccess: Simplify code pattern for masked user copies

On Sun, 9 Feb 2025 at 10:40, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> It's *really* easy to miss the "oh, that changes X" when the only
> little tiny sign of it is that "&" character inside the argument list,
> and then the *normal* mental model is that arguments are arguments
> *to* the function, not returns *from* the function.

While I'm ranting, this is just another case of "C++ really got this
very very wrong".

C++ made pass-by-reference really easy, and removed the need for even
that tiny marker in the caller.

So then you really can't even visually see that "oh, that call changes
its argument", and have to just know.

              Linus