From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753650AbbBTDeh (ORCPT ); Thu, 19 Feb 2015 22:34:37 -0500 Received: from ozlabs.org ([103.22.144.67]:48987 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752314AbbBTDef (ORCPT ); Thu, 19 Feb 2015 22:34:35 -0500 Message-ID: <1424403272.26444.1.camel@ellerman.id.au> Subject: Re: [PATCH 4/4] powerpc/mpic: remove unused functions From: Michael Ellerman To: Arseny Solokha Cc: Benjamin Herrenschmidt , Paul Mackerras , Scott Wood , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Date: Fri, 20 Feb 2015 14:34:32 +1100 In-Reply-To: <87d256kry8.fsf@KB00016249.iskra.kb> References: <1424084188-17097-1-git-send-email-asolokha@kb.kras.ru> <1424084188-17097-5-git-send-email-asolokha@kb.kras.ru> <1424307520.22020.5.camel@ellerman.id.au> <87d256kry8.fsf@KB00016249.iskra.kb> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7-0ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2015-02-19 at 19:26 +0700, Arseny Solokha wrote: > > On Mon, 2015-02-16 at 17:56 +0700, Arseny Solokha wrote: > >> Drop unused fsl_mpic_primary_get_version(), mpic_set_clk_ratio(), > >> mpic_set_serial_int(). > > > > I'm always happy to remove unused code, but the interesting question is why are > > they unused? Please tell me in the changelog. > > To being able to give a definitive answer, it's necessary to understand > the intentions of original developers of these pieces. I just can tell > these functions have no users and trivial grepping easily proves it; > I've got the impression they are here only for the sake of > implementation completeness. Yeah OK. I didn't expect you to read the minds of the developers who wrote the code :) > Two machines at hands, e300 and e500 based, boot and run without > regressions on my workload with this series applied. The removed code > seems also been rarely touched, so it seems the series is safe at least > in general. But I can't obviously express any strong point in support of > the series, so it's completely OK to leave things as is. OK that's a good data point. > + fsl_mpic_primary_get_version() is just a safe wrapper around > fsl_mpic_get_version() for SMP configurations. While the latter is > called explicitly for handling PIC initialization and setting up error > interrupt vector depending on PIC hardware version, the former isn't > used for anything. > > + As for mpic_set_clk_ratio() and mpic_set_serial_int(), they both > are almost nine years old[1] but still have no chance to be called even > from out-of-tree modules because they both are __init and of course > aren't exported. Non-demanded functionality? > > Of course I'll include the last two paragraphs into the V2 patch > description if the explanation is convincing enough and you ACK it. If > the patch is safe it's also necessary to extend it a bit, making its > second part actually a complete revert of [1]. > > [1] https://lists.ozlabs.org/pipermail/linuxppc-dev/2006-June/023867.html That is more like what I was looking for. If I just get a patch saying "removed unused foo()", I have to go and dig and find out: - was it recently added and will be used soon? - is it ancient and never used, if so can we work out why, ie. feature X never landed so this code is no longer needed. - is it old code that *was* used but isn't now because commit ... removed the last user. - is it code that *should* be used, but isn't for some odd reason? So if you can provide that sort of detail for me, that really adds value to the patch. Otherwise the patch is basically just a TODO for me, to go and work out why the code is unused. cheers