Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751483AbWLRRsP (ORCPT ); Mon, 18 Dec 2006 12:48:15 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751520AbWLRRsO (ORCPT ); Mon, 18 Dec 2006 12:48:14 -0500 Received: from nic.NetDirect.CA ([216.16.235.2]:56319 "EHLO rubicon.netdirect.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751483AbWLRRsO (ORCPT ); Mon, 18 Dec 2006 12:48:14 -0500 X-Originating-Ip: 24.148.236.183 Date: Mon, 18 Dec 2006 12:43:35 -0500 (EST) From: "Robert P. J. Day" X-X-Sender: rpjday@localhost.localdomain To: Linux kernel mailing list cc: Andrew Morton Subject: [PATCH] Add a new section to CodingStyle, promoting include/linux/kernel.h. Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Net-Direct-Inc-MailScanner-Information: Please contact the ISP for more information X-Net-Direct-Inc-MailScanner: Found to be clean X-Net-Direct-Inc-MailScanner-SpamCheck: not spam, SpamAssassin (not cached, score=-16.8, required 5, ALL_TRUSTED -1.80, BAYES_00 -15.00) X-Net-Direct-Inc-MailScanner-From: rpjday@mindspring.com Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1790 Lines: 52 Add a new section to the CodingStyle file, encouraging people not to re-invent available kernel macros such as ARRAY_SIZE(), FIELD_SIZEOF(), min() and max(), among others. Signed-off-by: Robert P. J. Day --- NOTE: at the moment, there is not a single invocation of the FIELD_SIZEOF() macro anywhere in the entire source tree, so if someone had a hankering to rename it to something more catchy, now would be a good time and i can always resubmit the patch i sent in yesterday. diff --git a/Documentation/CodingStyle b/Documentation/CodingStyle index 0ad6dcb..a736333 100644 --- a/Documentation/CodingStyle +++ b/Documentation/CodingStyle @@ -682,6 +682,24 @@ result. Typical examples would be functions that return pointers; they use NULL or the ERR_PTR mechanism to report failure. + Chapter 17: Don't re-invent the kernel macros + +The header file include/linux/kernel.h contains a number of macros that +you should use, rather than explicitly coding some variant of them yourself. +For example, if you need to calculate the length of an array, take advantage +of the macro + + #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0])) + +Similarly, if you need to calculate the size of some structure member, use + + #define FIELD_SIZEOF(t, f) (sizeof(((t*)0)->f)) + +There are also min() and max() macros that do strict type checking if you +need them. Feel free to peruse that header file to see what else is already +defined that you shouldn't reproduce in your code. + + Appendix I: References - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/