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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=unavailable 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 4CF87C4CEC7 for ; Sat, 14 Sep 2019 07:50:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2E5392081B for ; Sat, 14 Sep 2019 07:50:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727236AbfINHuZ (ORCPT ); Sat, 14 Sep 2019 03:50:25 -0400 Received: from ms.lwn.net ([45.79.88.28]:35640 "EHLO ms.lwn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726622AbfINHuZ (ORCPT ); Sat, 14 Sep 2019 03:50:25 -0400 Received: from localhost.localdomain (localhost [127.0.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ms.lwn.net (Postfix) with ESMTPSA id 9E15E378; Sat, 14 Sep 2019 07:50:22 +0000 (UTC) Date: Sat, 14 Sep 2019 01:50:18 -0600 From: Jonathan Corbet To: =?UTF-8?B?QW5kcsOp?= Almeida Cc: linux-block@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, axboe@kernel.dk, kernel@collabora.com, krisman@collabora.com Subject: Re: [PATCH v2 4/4] coding-style: add explanation about pr_fmt macro Message-ID: <20190914015018.4fa90f28@lwn.net> In-Reply-To: <20190913220300.422869-5-andrealmeid@collabora.com> References: <20190913220300.422869-1-andrealmeid@collabora.com> <20190913220300.422869-5-andrealmeid@collabora.com> Organization: LWN.net X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Fri, 13 Sep 2019 19:03:00 -0300 André Almeida wrote: > The pr_fmt macro is useful to format log messages printed by pr_XXXX() > functions. Add text to explain the purpose of it, how to use and an > example. So I've finally had a chance to take a real look at this... > diff --git a/Documentation/process/coding-style.rst b/Documentation/process/coding-style.rst > index f4a2198187f9..1a33a933fbd3 100644 > --- a/Documentation/process/coding-style.rst > +++ b/Documentation/process/coding-style.rst > @@ -819,7 +819,15 @@ which you should use to make sure messages are matched to the right device > and driver, and are tagged with the right level: dev_err(), dev_warn(), > dev_info(), and so forth. For messages that aren't associated with a > particular device, defines pr_notice(), pr_info(), > -pr_warn(), pr_err(), etc. > +pr_warn(), pr_err(), etc. It's possible to format pr_XXX() messages using the > +macro pr_fmt() to prevent rewriting the style of messages. It should be > +defined before ``#include ``, to avoid compiler warning about > +redefinitions, or just use ``#undef pr_fmt``. This is particularly useful for > +adding the name of the module at the beginning of the message, for instance: > + > +.. code-block:: c > + > + #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt Honestly, I think that this is out of scope for a document on coding style. That document is already far too long for most people to read, I don't think we should load it down with more stuff that isn't directly style related. That said, the information can be useful. I wanted to say that it should go with the documentation of the pr_* macros but ... well ... um ... we don't seem to have a whole lot of that. Figures. I suspect this is more than you wanted to sign up for, but...IMO, the right thing to do is to fill printk.h with a nice set of kerneldoc comments describing how this stuff should be used, then to pull that information into the core-api manual, somewhere near our extensive discussion of printk formats. It's amazing that we lack docs for something so basic. Thanks, jon