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From:   Linus Torvalds <torvalds@linux-foundation.org>
Date:   Fri, 25 Mar 2022 10:29:21 -0700
Message-ID: <CAHk-=wgaxDHAhxBkU_mVE5uw5po+qvzy4jgK8Q82rgi7XqZfiA@mail.gmail.com>
Subject: Re: [GIT PULL] locking changes for v5.18
To:     Andy Shevchenko <andriy.shevchenko@intel.com>
Cc:     Borislav Petkov <bp@alien8.de>, Ingo Molnar <mingo@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Will Deacon <will@kernel.org>,
        Waiman Long <longman@redhat.com>,
        Boqun Feng <boqun.feng@gmail.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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On Fri, Mar 25, 2022 at 4:42 AM Andy Shevchenko
<andriy.shevchenko@intel.com> wrote:
>
> What about old one? I have already complained in the early discussion that
> `make W=1 ...` is broken by this change.

So that is REALLY D*MN EASY TO FIX.

If you use W=1, and don't want WERROR, then don't *do* that then.

End of story.

But that's on _you_. Not on the build system. If you use W=1 and
WERROR together, you get exactly what you asked for. It might even be
what you wanted, if you want to go through the warnings/errors as you
encounter them, instead of building everything.

And that's why I refuse to take the completely broken "strip out one
or the other automatically" change.

It's a perfectly valid combination to enable both.

But more importantly, -Werror is more important than W=1. So if
anything should be disabled, it's W=1.

Side note: that would be trivial to just have in the Kconfig files if
W=1 was just a config option.

Do something like

     config EXTRA_ERRORS
         int "Add extra compiler errors" if EXPERT
         depends on !WERROR
         range 0-2
         default 0

but note again: WERROR should be the thing that controls this and
should be on by default, not the other way around.

If you want EXTRA_ERRORS, you should not only be CONFIG_EXPERT, you
should also have to manually disable WERROR that *normal* people
should have on by default.

              Linus