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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 C461CC4741F for ; Sun, 1 Nov 2020 21:04:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9BE2D2224F for ; Sun, 1 Nov 2020 21:04:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727279AbgKAVEk (ORCPT ); Sun, 1 Nov 2020 16:04:40 -0500 Received: from smtprelay0117.hostedemail.com ([216.40.44.117]:52056 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727004AbgKAVEk (ORCPT ); Sun, 1 Nov 2020 16:04:40 -0500 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay03.hostedemail.com (Postfix) with ESMTP id 2B96E837F24A; Sun, 1 Nov 2020 21:04:39 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: fork10_3615e0f272aa X-Filterd-Recvd-Size: 2699 Received: from XPS-9350.home (unknown [47.151.133.149]) (Authenticated sender: joe@perches.com) by omf01.hostedemail.com (Postfix) with ESMTPA; Sun, 1 Nov 2020 21:04:37 +0000 (UTC) Message-ID: <616b92af9378e9f9697555074bba1e377450477f.camel@perches.com> Subject: Re: [PATCH 4/5] mm: shmem: Convert shmem_enabled_show to use sysfs_emit_at From: Joe Perches To: Matthew Wilcox Cc: Hugh Dickins , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Date: Sun, 01 Nov 2020 13:04:35 -0800 In-Reply-To: <20201101204834.GF27442@casper.infradead.org> References: <20201101204834.GF27442@casper.infradead.org> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.38.1-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 2020-11-01 at 20:48 +0000, Matthew Wilcox wrote: > On Sun, Nov 01, 2020 at 12:12:51PM -0800, Joe Perches wrote: > > @@ -4024,7 +4024,7 @@ int __init shmem_init(void) > >   > > > >  #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && defined(CONFIG_SYSFS) > >  static ssize_t shmem_enabled_show(struct kobject *kobj, > > - struct kobj_attribute *attr, char *buf) > > + struct kobj_attribute *attr, char *buf) > >  { > >   static const int values[] = { > >   SHMEM_HUGE_ALWAYS, > > Why? why what? > > @@ -4034,16 +4034,19 @@ static ssize_t shmem_enabled_show(struct kobject *kobj, > >   SHMEM_HUGE_DENY, > >   SHMEM_HUGE_FORCE, > >   }; > > - int i, count; > > - > > - for (i = 0, count = 0; i < ARRAY_SIZE(values); i++) { > > - const char *fmt = shmem_huge == values[i] ? "[%s] " : "%s "; > > + int len = 0; > > + int i; > > Better: > int i, len = 0; I generally disagree as I think it better to have each declaration on an individual line. > > - count += sprintf(buf + count, fmt, > > - shmem_format_huge(values[i])); > > + for (i = 0; i < ARRAY_SIZE(values); i++) { > > + len += sysfs_emit_at(buf, len, > > + shmem_huge == values[i] ? "%s[%s]" : "%s%s", > > + i ? " " : "", > > + shmem_format_huge(values[i])); > > This is ... complicated. I thought the point of doing all the sysfs_emit > stuff was to simplify things. The removal of fmt allows the format and argument to be __printf verified. Indirected formats do not generally allow that. And using sysfs_emit is not really intended to simplify output code, it's used to make sure there isn't a overflow of the PAGE_SIZE output buf when using sprintf/snprintf.