From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 912B7C43381 for ; Thu, 7 Mar 2019 10:06:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0435A20835 for ; Thu, 7 Mar 2019 10:06:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726337AbfCGKGJ (ORCPT ); Thu, 7 Mar 2019 05:06:09 -0500 Received: from mx2.suse.de ([195.135.220.15]:42162 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726127AbfCGKGJ (ORCPT ); Thu, 7 Mar 2019 05:06:09 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 7F271ACC6; Thu, 7 Mar 2019 10:06:07 +0000 (UTC) Received: by unicorn.suse.cz (Postfix, from userid 1000) id 4AC60E1175; Thu, 7 Mar 2019 11:06:05 +0100 (CET) Date: Thu, 7 Mar 2019 11:06:05 +0100 From: Michal Kubecek To: Arnd Bergmann Cc: "David S. Miller" , Florian Fainelli , Jakub Kicinski , Jiri Pirko , Nick Desaulniers , Kees Cook , Wenwen Wang , Ilya Lesokhin , Pablo Neira Ayuso , Edward Cree , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] ethtool: reduce stack usage with clang Message-ID: <20190307100605.GA20309@unicorn.suse.cz> References: <20190307093408.3425010-1-arnd@arndb.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190307093408.3425010-1-arnd@arndb.de> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 07, 2019 at 10:33:35AM +0100, Arnd Bergmann wrote: > clang inlines the dev_ethtool() more aggressively than gcc does, leading > to a larger amount of used stack space: > > net/core/ethtool.c:2536:24: error: stack frame size of 1216 bytes in function 'dev_ethtool' [-Werror,-Wframe-larger-than=] > > Marking the sub-functions that require the most stack space as > noinline_for_stack gives us reasonable behavior on all compilers. > > Signed-off-by: Arnd Bergmann > --- > net/core/ethtool.c | 18 ++++++++++-------- > 1 file changed, 10 insertions(+), 8 deletions(-) > > diff --git a/net/core/ethtool.c b/net/core/ethtool.c > index d4918ffddda8..fcbed78172a0 100644 > --- a/net/core/ethtool.c > +++ b/net/core/ethtool.c ... > @@ -2533,7 +2535,7 @@ static int ethtool_set_fecparam(struct net_device *dev, void __user *useraddr) > > /* The main entry point in this file. Called from net/core/dev_ioctl.c */ > > -int dev_ethtool(struct net *net, struct ifreq *ifr) > +int noinline_for_stack dev_ethtool(struct net *net, struct ifreq *ifr) > { > struct net_device *dev = __dev_get_by_name(net, ifr->ifr_name); > void __user *useraddr = ifr->ifr_data; Is this part really needed? AFAICS dev_ethtool() is only called from dev_ioctl() which is in a different compilation unit so that dev_ethtool() won't be inlined anyway. Michal Kubecek