From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on archive.lwn.net X-Spam-Level: X-Spam-Status: No, score=-6.0 required=5.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=unavailable autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by archive.lwn.net (Postfix) with ESMTP id E12307D04D for ; Thu, 14 Feb 2019 11:26:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727678AbfBNL0X (ORCPT ); Thu, 14 Feb 2019 06:26:23 -0500 Received: from www.osadl.org ([62.245.132.105]:37553 "EHLO www.osadl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727097AbfBNL0X (ORCPT ); Thu, 14 Feb 2019 06:26:23 -0500 Received: from debian01.hofrr.at (178.115.242.59.static.drei.at [178.115.242.59]) by www.osadl.org (8.13.8/8.13.8/OSADL-2007092901) with ESMTP id x1EBQ7jh020439; Thu, 14 Feb 2019 12:26:07 +0100 From: Nicholas Mc Guire To: Jonathan Corbet Cc: Greg Kroah-Hartman , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, Nicholas Mc Guire Subject: [PATCH RFC] sysfs.txt: add note on available attribute macros Date: Thu, 14 Feb 2019 12:21:50 +0100 Message-Id: <1550143310-17463-1-git-send-email-hofrat@osadl.org> X-Mailer: git-send-email 2.1.4 Sender: linux-doc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-doc@vger.kernel.org The common cases of attributes should probably be using the __ATTR_XXX macros to make code more concise and readable but the current sysfs.txt does not point developers to those convenience macros. Further there is no note in sysfs.txt currently explaining why trying to set a sysfs file to mode 0666 will fail. Signed-off-by: Nicholas Mc Guire --- Note quite sure if this is the right place to place the note on mode 0666 but it should be somewhere as any attempt to set 0666 will be reverted to 0664. Documentation/filesystems/sysfs.txt | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/Documentation/filesystems/sysfs.txt b/Documentation/filesystems/sysfs.txt index 41411b0..c246142 100644 --- a/Documentation/filesystems/sysfs.txt +++ b/Documentation/filesystems/sysfs.txt @@ -116,6 +116,22 @@ static struct device_attribute dev_attr_foo = { .store = store_foo, }; +Note as stated in include/linux/kernel.h "OTHER_WRITABLE? Generally +considered a bad idea." so trying to set a sysfs file writable for +everyone will fail reverting to mode 0664. + +For this common cases sysfs.h provides convenience macros to +make defining attributes easier as well as making code more +concise and readable. The above case could be shortened to: + +static struct device_attribute dev_attr_foo = __ATTR_RW(foo); + +the list of helpers available is: +__ATTR_RO(name): same as above with mode 0444 +__ATTR_WO(name): same as above with mode 0200 +__ATTR_RO_MODE(name, mode): allowing to pass in a specific mode +__ATTR_RW(name): setting mode to 0644 +__ATTR_NULL: which sets the name to NULL Subsystem-Specific Callbacks ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -- 2.1.4