From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wm1-f65.google.com ([209.85.128.65]:36156 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727399AbfJKPnP (ORCPT ); Fri, 11 Oct 2019 11:43:15 -0400 Received: by mail-wm1-f65.google.com with SMTP id m18so10688631wmc.1 for ; Fri, 11 Oct 2019 08:43:14 -0700 (PDT) Date: Fri, 11 Oct 2019 16:43:11 +0100 From: Matthias Maennich Subject: Re: [PATCH 4/4] export: avoid code duplication in include/linux/export.h Message-ID: <20191011154311.GA192647@google.com> References: <20191010151443.7399-1-maennich@google.com> <20191010151443.7399-5-maennich@google.com> <20191011153127.GA1283883@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: <20191011153127.GA1283883@kroah.com> Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, kernel-team@android.com, Jessica Yu , Masahiro Yamada , Martijn Coenen , Lucas De Marchi , Shaun Ruffell , Will Deacon , linux-kbuild@vger.kernel.org, linux-modules@vger.kernel.org, Rasmus Villemoes On Fri, Oct 11, 2019 at 05:31:27PM +0200, Greg Kroah-Hartman wrote: >On Thu, Oct 10, 2019 at 04:14:43PM +0100, Matthias Maennich wrote: >> Now that the namespace value is not part of the __ksymtab entry name >> anymore, we can simplify the implementation of EXPORT_SYMBOL*. By >> allowing the empty string "" to represent 'no namespace', we can unify >> the implementation and drop a lot redundant code. That increases >> readability and maintainability. >> >> As Masahiro pointed out earlier, >> "The drawback of this change is, it grows the code size. When the symbol >> has no namespace, sym->namespace was previously NULL, but it is now am >> empty string "". So, it increases 1 byte for every no namespace >> EXPORT_SYMBOL. A typical kernel configuration has 10K exported symbols, >> so it increases 10KB in rough estimation." > >10Kb of non-swapable memory isn't good. But if you care about that, you >can get it back with the option to compile away any non-used symbols, >and that shouldn't be affected by this change, right? Rasmus suggested to put the 'aMS' flags on the __ksymtab_strings section to mitigate this: https://lore.kernel.org/lkml/f2e28d6b-77c5-5fe2-0bc4-b24955de9954@rasmusvillemoes.dk/ I was not yet able to properly test this, so I did not include it in this series. As I said in the cover letter, this 4th patch might be optional for 5.4. So, we could defer it to a later time when we have addressed that properly. Cheers, Matthias > >That being said, the code is a lot cleaner, so I have no objection to >it. > >Reviewed-by: Greg Kroah-Hartman