linux-kernel - Re: [PATCH v1 1/1] x86/percpu: Cast -1 to argument type when comparing in percpu_add

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Message-ID: <CAKwvOd=m7bMWLVNRcr6BA_gBaqKmZ1NOd0=Sa5322FZZ4jAmqg@mail.gmail.com>
Date: Wed, 16 Oct 2024 10:03:10 -0700
From: Nick Desaulniers <ndesaulniers@...gle.com>
To: Dave Hansen <dave.hansen@...el.com>
Cc: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, Ingo Molnar <mingo@...nel.org>, 
	Uros Bizjak <ubizjak@...il.com>, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	llvm@...ts.linux.dev, Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>, 
	Christoph Lameter <cl@...ux.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org, 
	"H. Peter Anvin" <hpa@...or.com>, Nathan Chancellor <nathan@...nel.org>, Bill Wendling <morbo@...gle.com>, 
	Justin Stitt <justinstitt@...gle.com>
Subject: Re: [PATCH v1 1/1] x86/percpu: Cast -1 to argument type when
 comparing in percpu_add_op()

On Wed, Oct 16, 2024 at 8:45 AM Dave Hansen <dave.hansen@...el.com> wrote:
> Since I'm making comments, I would have really appreciated some extra
> info here like why you are hitting this and nobody else is.  This is bog
> standard code that everybody compiles.  Is clang use _that_ unusual?  Or
> do most clang users just ignore all the warnings?  Or are you using a
> bleeding edge version of clang that spits out new warnings that other
> clang users aren't seeing?

Note the W=1 part in the commit message.  That's the part people
generally don't test with, but the bots do.

On Thu, Sep 5, 2024 at 10:04 AM Andy Shevchenko
<andriy.shevchenko@...ux.intel.com> wrote:
>
> When percpu_add_op() is used with unsigned argument, it prevents kernel builds
> with clang, `make W=1` and CONFIG_WERROR=y:

-- 
Thanks,
~Nick Desaulniers