From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753310AbaB0TX5 (ORCPT ); Thu, 27 Feb 2014 14:23:57 -0500 Received: from merlin.infradead.org ([205.233.59.134]:60900 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751514AbaB0TX4 (ORCPT ); Thu, 27 Feb 2014 14:23:56 -0500 Date: Thu, 27 Feb 2014 20:23:35 +0100 From: Peter Zijlstra To: Josh Triplett Cc: Rashika Kheria , linux-kernel@vger.kernel.org, Paul Mackerras , Ingo Molnar , Arnaldo Carvalho de Melo Subject: Re: [PATCH 08/46] kernel: MOve prototype declaration to header file include/linux/perf_event.h Message-ID: <20140227192335.GZ27965@twins.programming.kicks-ass.net> References: <7b4a60c74ced00e0d65c38488f20dc4bd69f0dd2.1393493276.git.rashika.kheria@gmail.com> <137eb91c7ce020384a1fb967c1c8b7eaeded21d8.1393493276.git.rashika.kheria@gmail.com> <20140227115414.GD9987@twins.programming.kicks-ass.net> <20140227155149.GB26756@thin> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20140227155149.GB26756@thin> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Feb 27, 2014 at 07:51:50AM -0800, Josh Triplett wrote: > On Thu, Feb 27, 2014 at 12:54:14PM +0100, Peter Zijlstra wrote: > > On Thu, Feb 27, 2014 at 05:02:48PM +0530, Rashika Kheria wrote: > > > Add prototype declaration of function to header file > > > include/linux/perf_event.h because it is used by more than one file. > > > > > > This eliminates the following warning in kernel/events/core.c: > > > kernel/events/core.c:3743:13: warning: no previous prototype for ‘arch_perf_update_userpage’ [-Wmissing-prototypes] > > > > # git grep arch_perf_update_userpage > > arch/x86/kernel/cpu/perf_event.c:void arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now) > > kernel/events/core.c:void __weak arch_perf_update_userpage(struct perf_event_mmap_page *userpg, u64 now) > > kernel/events/core.c: arch_perf_update_userpage(userpg, now); > > > > > > There's two definitions; one weak, and one usage site. > > > > What gives? > > There's no prototype for the function anywhere, so -Wmissing-prototypes > rightfully complains. Adding the prototype to a header included in both > source files ensures that the function signatures must match, and > eliminates the warning. Definitions don't require prior declarations. Only usage without prior definitions require them. I still don't see a problem. Seems to me you're just blindly making a stupid checker happy, just shoot it in the face.