linux-kernel - Re: [RFC PATCH 03/13] usb: remove the usage of the list iterator after the loop

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Message-ID: <CAHk-=wi+sjd8FT_FeJ2UOU2Ti7ws1i7hDweAW2gp8a-JpO-Tbg@mail.gmail.com>
Date:   Tue, 1 Mar 2022 12:26:16 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc:     Martin Uecker <uecker@...raz.at>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 03/13] usb: remove the usage of the list iterator
 after the loop

On Mon, Feb 28, 2022 at 5:50 AM Miguel Ojeda
<miguel.ojeda.sandonis@...il.com> wrote:
>
> But making it non-UB in the standard does not force a project to
> consider it "not an error", which is what actually matters for being
> able to use UBSan effectively or not.

Absolutely.

I think people should treat UBsan and friends a bit like "runtime lint".

"lint" traditionally doesn't necessarily check for just *incorrect* C.

It checks for things that can be confusing to humans, even if they are
100% completely conforming standard C.

Classic example: indentation. Having the wrong indentation is not in
any shape of form "undefined behavior" from a C standpoint, but it
sure is something that makes sense checking for anyway.

I think "integer overflow" should be considered the exact same thing.
It should *not* be treated as "undefined behavior", and it should not
give the compiler the option to generate code that doesn't match what
the programmer wrote.

But having a checking tool that says "This looks wrong - you just had
an integer overflow"? THAT makes 100% sense.

The C standard rules "undefined behavior" really is a problem in the standard.

                     Linus