linux-kernel - Re: [PATCH] zlib: define get_unaligned16() only when used

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Message-ID: <20201124115058.GA32060@infradead.org>
Date:   Tue, 24 Nov 2020 11:50:58 +0000
From:   Christoph Hellwig <hch@...radead.org>
To:     Jann Horn <jannh@...gle.com>
Cc:     Lukas Bulwahn <lukas.bulwahn@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Arnd Bergmann <arnd@...db.de>, Tom Rix <trix@...hat.com>,
        Nathan Chancellor <natechancellor@...il.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        kernel-janitors@...r.kernel.org,
        kernel list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] zlib: define get_unaligned16() only when used

On Tue, Nov 24, 2020 at 12:08:40PM +0100, Jann Horn wrote:
> > Since commit acaab7335bd6 ("lib/zlib: remove outdated and incorrect
> > pre-increment optimization"), get_unaligned16() is only used when
> > !CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS.
> >
> > Hence, make CC=clang W=1 warns:
> >
> >   lib/zlib_inflate/inffast.c:20:1:
> >     warning: unused function 'get_unaligned16' [-Wunused-function]
> >
> > Define get_unaligned16() only when it is actually used.
> >
> > Signed-off-by: Lukas Bulwahn <lukas.bulwahn@...il.com>
> 
> AFAICS a nicer option would be to "#include <asm/unaligned.h>" and
> then use "get_unaligned", which should automatically do the right
> thing everywhere and remove the need for defining get_unaligned16()
> and checking CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS entirely?

Yes, that is the right thing to do.