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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY 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 2913DC4338F for ; Wed, 11 Aug 2021 04:07:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 034B260720 for ; Wed, 11 Aug 2021 04:07:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229926AbhHKEHf (ORCPT ); Wed, 11 Aug 2021 00:07:35 -0400 Received: from smtprelay0095.hostedemail.com ([216.40.44.95]:34382 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S229554AbhHKEHe (ORCPT ); Wed, 11 Aug 2021 00:07:34 -0400 Received: from omf11.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay07.hostedemail.com (Postfix) with ESMTP id B2245181CC1B7; Wed, 11 Aug 2021 04:07:09 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: joe@perches.com) by omf11.hostedemail.com (Postfix) with ESMTPA id B927C20A296; Wed, 11 Aug 2021 04:07:08 +0000 (UTC) Message-ID: Subject: Re: [PATCH] netlink: NL_SET_ERR_MSG - remove local static array From: Joe Perches To: Jakub Kicinski Cc: netdev , Johannes Berg , Jonathan Toppins , LKML Date: Tue, 10 Aug 2021 21:07:07 -0700 In-Reply-To: <20210810133058.0c7f0736@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> References: <1f99c69f4e640accaf7459065e6625e73ec0f8d4.camel@perches.com> <20210810133058.0c7f0736@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.40.0-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspamout04 X-Rspamd-Queue-Id: B927C20A296 X-Stat-Signature: erbj8ue88trry6nswhxoahbaokjr61fi X-Session-Marker: 6A6F6540706572636865732E636F6D X-Session-ID: U2FsdGVkX1+6DgYlB/FaT7vkiYsQX+R3g2pF1EQooxU= X-HE-Tag: 1628654828-659544 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 2021-08-10 at 13:30 -0700, Jakub Kicinski wrote: > On Mon, 09 Aug 2021 10:04:00 -0700 Joe Perches wrote: > > The want was to have some separate object section for netlink messages > > so all netlink messages could be specifically listed by some tool but > > the effect is duplicating static const char arrays in the object code. > > > > It seems unused presently so change the macro to avoid the local static > > declarations until such time as these actually are wanted and used. > > > > This reduces object size ~8KB in an x86-64 defconfig without modules. [] > > diff --git a/include/linux/netlink.h b/include/linux/netlink.h [] > > @@ -89,13 +89,12 @@ struct netlink_ext_ack { > >   * to the lack of an output buffer.) > >   */ > >  #define NL_SET_ERR_MSG(extack, msg) do { \ > > - static const char __msg[] = msg; \ > >   struct netlink_ext_ack *__extack = (extack); \ > >   \ > > - do_trace_netlink_extack(__msg); \ > > + do_trace_netlink_extack(msg); \ > >   \ > >   if (__extack) \ > > - __extack->_msg = __msg; \ > > + __extack->_msg = msg; \ > >  } while (0) > > But you've made us evaluate msg multiple times now. > Given extack is carefully evaluated only once this stands out. msg is always a const char array so no evaluation is done. It's just a pointer. In fact, this could either become a static inline or a simple function call to reduce object size even further. For instance: $ size vmlinux.o.nl_func.* text data bss dec hex filename 19974564 3457991 741312 24173867 170dd2b vmlinux.o.nl_func.new 19992097 3457967 741312 24191376 1712190 vmlinux.o.nl_func.old --- include/linux/netlink.h | 29 ++++++++++------------------- net/netlink/af_netlink.c | 13 +++++++++++++ 2 files changed, 23 insertions(+), 19 deletions(-) diff --git a/include/linux/netlink.h b/include/linux/netlink.h index 61b1c7fcc401e..fe80c2704cc23 100644 --- a/include/linux/netlink.h +++ b/include/linux/netlink.h @@ -82,21 +82,16 @@ struct netlink_ext_ack { u8 cookie_len; }; +void netlink_set_err_msg(struct netlink_ext_ack *extack, const char *msg); /* Always use this macro, this allows later putting the * message into a separate section or such for things * like translation or listing all possible messages. * Currently string formatting is not supported (due * to the lack of an output buffer.) */ -#define NL_SET_ERR_MSG(extack, msg) do { \ - static const char __msg[] = msg; \ - struct netlink_ext_ack *__extack = (extack); \ - \ - do_trace_netlink_extack(__msg); \ - \ - if (__extack) \ - __extack->_msg = __msg; \ -} while (0) + +#define NL_SET_ERR_MSG(extack, msg) \ + netlink_set_err_msg(extack, msg) #define NL_SET_ERR_MSG_MOD(extack, msg) \ NL_SET_ERR_MSG((extack), KBUILD_MODNAME ": " msg) @@ -110,16 +105,12 @@ struct netlink_ext_ack { #define NL_SET_BAD_ATTR(extack, attr) NL_SET_BAD_ATTR_POLICY(extack, attr, NULL) -#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) do { \ - static const char __msg[] = msg; \ - struct netlink_ext_ack *__extack = (extack); \ - \ - do_trace_netlink_extack(__msg); \ - \ - if (__extack) { \ - __extack->_msg = __msg; \ - __extack->bad_attr = (attr); \ - __extack->policy = (pol); \ +#define NL_SET_ERR_MSG_ATTR_POL(extack, attr, pol, msg) \ +do { \ + netlink_set_err_msg(extack, msg); \ + if (extack) { \ + extack->bad_attr = (attr); \ + extack->policy = (pol); \ } \ } while (0) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 24b7cf447bc55..b6d035f0d343b 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2561,6 +2561,19 @@ int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 portid, } EXPORT_SYMBOL(nlmsg_notify); +/** + * nl_set_err_msg - + */ + +void netlink_set_err_msg(struct netlink_ext_ack *extack, const char *msg) +{ + do_trace_netlink_extack(msg); + + if (extack) + extack->_msg = msg; +} +EXPORT_SYMBOL(netlink_set_err_msg); + #ifdef CONFIG_PROC_FS struct nl_seq_iter { struct seq_net_private p;