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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 66AF2C433F5 for ; Thu, 9 Sep 2021 05:34:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 468FB61167 for ; Thu, 9 Sep 2021 05:34:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350788AbhIIFgD (ORCPT ); Thu, 9 Sep 2021 01:36:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:58610 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350756AbhIIFgC (ORCPT ); Thu, 9 Sep 2021 01:36:02 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1977C60C3E; Thu, 9 Sep 2021 05:34:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1631165694; bh=BB6pGedXQUsrlUiMqtRcXBIqRDB0kN7zw5uwHiPQ7h8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=TS9SVYKFEA2+L5H6Nx7Yskr8YYIE0vfAnepmSDk6SOOAFqxZjv4HJflkdISwhC19a Li0q/FKG59sf+V7jRa7DyDmzCweQG83GQ7qxHt26ebnanxSZrn+9YE039XT9vSWXVL aEZwc3bEWV0851CSUUSSOefXMKHXQvn4dChoCiWU= Date: Thu, 9 Sep 2021 07:34:31 +0200 From: Greg Kroah-Hartman To: "Yu, Lang" Cc: Joe Perches , "Rafael J . Wysocki" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] sysfs: Remove page boundary align limitation on sysfs_emit and sysfs_emit_at Message-ID: References: <20210908120723.3920701-1-lang.yu@amd.com> <04b52ef5b63abf25e6d50fd5bdfa90727e100a09.camel@perches.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 09, 2021 at 05:27:49AM +0000, Yu, Lang wrote: > [AMD Official Use Only] > > > > >-----Original Message----- > >From: Joe Perches > >Sent: Thursday, September 9, 2021 1:06 PM > >To: Yu, Lang ; Greg Kroah-Hartman > >; Rafael J . Wysocki ; linux- > >kernel@vger.kernel.org > >Subject: Re: [PATCH] sysfs: Remove page boundary align limitation on sysfs_emit > >and sysfs_emit_at > > > >On Wed, 2021-09-08 at 20:07 +0800, Lang Yu wrote: > >> The key purpose of sysfs_emit and sysfs_emit_at is to ensure that no > >> overrun is done. Make them more equivalent with scnprintf. > > > >I can't think of a single reason to do this. > >sysfs_emit and sysfs_emit_at are specific to sysfs. > > > >Use of these functions outside of sysfs is not desired or supported. > > > > > Thanks for your reply. But I'm still curious why you put such a limitation. > As "Documentation/filesystems/sysfs.rst" described, we can just use > scnprintf(buf, PAGE_SIZE, "%s\n", dev->name) in show functions without > such a limitation. > > But you said that " - show() should only use sysfs_emit() or sysfs_emit_at() when formatting > the value to be returned to user space. " in Documentation/filesystems/sysfs.rst. > > Some guys just try to replace scnprintf with sysfs_emit() or sysfs_emit_at() per above documents. That is just fine in sysfs show() functions. > But sprintf and sysfs_emit/sysfs_emit_at are not totally equivalent(e.g., page boundary align). Which is good, it checks for more error conditions. I fail to understand what problem you have had with this. What sysfs file was converted and had issues? > In my opinion, we add a new api and try to replace an old api. Does we need to make it more > compatible with old api? Thanks. There is no "old api" here. People used a wide variety of different things in sysfs file show() functions, now you can just use a single one. thanks, greg k-h