From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from perceval.ideasonboard.com ([213.167.242.64]:35492 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726612AbeJHRLK (ORCPT ); Mon, 8 Oct 2018 13:11:10 -0400 Reply-To: kieran.bingham+renesas@ideasonboard.com Subject: Re: [PATCH] kbuild: fix kernel/bounds.c 'W=1' warning To: Masahiro Yamada , miguel.ojeda.sandonis@gmail.com Cc: Arnd Bergmann , Andrew Morton , Linux-Renesas , stable , Linux Kernel Mailing List , Linux Kbuild mailing list References: <20180921142234.16882-1-kieran.bingham+renesas@ideasonboard.com> <20181005083313.2088252-1-arnd@arndb.de> From: Kieran Bingham Message-ID: <5cbb504c-0506-cec8-d51b-00928cdb27fe@ideasonboard.com> Date: Mon, 8 Oct 2018 11:00:10 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 8bit Sender: linux-renesas-soc-owner@vger.kernel.org List-ID: On 06/10/18 23:06, Masahiro Yamada wrote: > On Sun, Oct 7, 2018 at 6:58 AM Masahiro Yamada > wrote: >> >> Hi Miguel, >> >> >> On Sun, Oct 7, 2018 at 6:18 AM Miguel Ojeda >> wrote: >>> >>> On Fri, Oct 5, 2018 at 10:35 AM Arnd Bergmann wrote: >>>> >>>> Building any configuration with 'make W=1' produces a warning: >>>> >>>> kernel/bounds.c:16:6: warnign: no previous prototype for 'foo' [-Wmissing-prototypes] >>>> >>>> When also passing -Werror, this prevents us from building any >>>> other files. Nobody ever calls the function, but we can't make >>>> it 'static' either since we want the compiler output. >>>> >>>> Calling it 'main' instead however avoids the warning, because gcc >>>> does not insist on having a declaration for main. >>> >>> I think marking the function as static __used should do the trick and >>> would be less confusing. >> >> >> >> >> I tried __used, but I still see the warning. >> >> >> masahiro@grover:~/ref/linux$ git diff >> diff --git a/kernel/bounds.c b/kernel/bounds.c >> index c373e88..aee0101 100644 >> --- a/kernel/bounds.c >> +++ b/kernel/bounds.c >> @@ -13,7 +13,7 @@ >> #include >> #include >> >> -void foo(void) >> +void __used foo(void) >> { >> /* The enum constants to put into include/generated/bounds.h */ >> DEFINE(NR_PAGEFLAGS, __NR_PAGEFLAGS); >> masahiro@grover:~/ref/linux$ make W=1 prepare >> CC kernel/bounds.s >> kernel/bounds.c:16:13: warning: no previous prototype for ‘foo’ >> [-Wmissing-prototypes] >> void __used foo(void) >> ^ >> CC arch/x86/kernel/asm-offsets.s > > > > Sorry, I forgot to add 'static'. > > Adding both static and __used worked for me, > and I like the idea. > Aha - I'd also tried converting to static in my earlier attempts, but didn't realise we had __used! updating as "static __used" causes the following diff: diff -Nurp bounds.s.foo bounds.s.static-used --- bounds.s.foo 2018-10-05 10:20:53.269941404 +0100 +++ bounds.s.static-used 2018-10-08 10:51:18.079309049 +0100 @@ -110,7 +110,6 @@ #NO_APP .align 2 .p2align 3,,7 - .global foo .type foo, %function foo: stp x29, x30, [sp, -16]! //,,, I'd say this is a pretty good alternative fix - however I see Arnd's version is already on it's way though akpm's tree... https://ozlabs.org/~akpm/mmots/broken-out/kbuild-fix-kernel-boundsc-w%3D1-warning.patch Anyway, as long as one of the variants gets there I'll be happy :) -- Regards Kieran