linux-kernel - Re: [PATCH v2] mm: kmemleak: Use address-of operator on section symbols

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Message-ID: <20200221013756.GA8323@ubuntu-m2-xlarge-x86>
Date:   Thu, 20 Feb 2020 18:37:56 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Catalin Marinas <catalin.marinas@....com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH v2] mm: kmemleak: Use address-of operator on section
 symbols

On Thu, Feb 20, 2020 at 05:35:01PM -0800, Andrew Morton wrote:
> On Wed, 19 Feb 2020 22:15:51 -0700 Nathan Chancellor <natechancellor@...il.com> wrote:
> 
> > Clang warns:
> > 
> > These are not true arrays, they are linker defined symbols, which are
> > just addresses. Using the address of operator silences the warning and
> > does not change the resulting assembly with either clang/ld.lld or
> > gcc/ld (tested with diff + objdump -Dr).
> 
> I guess you forgot to quote the clang output?

Ugh yes, sorry. I can send a v3 later  or here it is if you want to
stitch it in:

../mm/kmemleak.c:1955:28: warning: array comparison always evaluates to a constant [-Wtautological-compare]
        if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
                                  ^
../mm/kmemleak.c:1955:60: warning: array comparison always evaluates to a constant [-Wtautological-compare]
        if (__start_ro_after_init < _sdata || __end_ro_after_init > _edata)
                                                                  ^
2 warnings generated.

Cheers,
Nathan