From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757929AbcCCOZv (ORCPT ); Thu, 3 Mar 2016 09:25:51 -0500 Received: from lists.s-osg.org ([54.187.51.154]:33803 "EHLO lists.s-osg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757791AbcCCOZt (ORCPT ); Thu, 3 Mar 2016 09:25:49 -0500 Subject: Re: [PATCH v5 22/22] sound/usb: Use Media Controller API to share media resources To: Dan Carpenter References: <1456937431-3794-1-git-send-email-shuahkh@osg.samsung.com> <20160302204131.GV5273@mwanda> <56D76FBF.9050209@osg.samsung.com> <20160303103637.GW5273@mwanda> Cc: mchehab@osg.samsung.com, tiwai@suse.com, clemens@ladisch.de, hans.verkuil@cisco.com, laurent.pinchart@ideasonboard.com, sakari.ailus@linux.intel.com, javier@osg.samsung.com, pawel@osciak.com, m.szyprowski@samsung.com, kyungmin.park@samsung.com, perex@perex.cz, arnd@arndb.de, tvboxspy@gmail.com, crope@iki.fi, ruchandani.tina@gmail.com, corbet@lwn.net, chehabrafael@gmail.com, k.kozlowski@samsung.com, stefanr@s5r6.in-berlin.de, inki.dae@samsung.com, jh1009.sung@samsung.com, elfring@users.sourceforge.net, prabhakar.csengg@gmail.com, sw0312.kim@samsung.com, p.zabel@pengutronix.de, ricardo.ribalda@gmail.com, labbott@fedoraproject.org, pierre-louis.bossart@linux.intel.com, ricard.wanderlof@axis.com, julian@jusst.de, takamichiho@gmail.com, dominic.sacre@gmx.de, misterpib@gmail.com, daniel@zonque.org, gtmkramer@xs4all.nl, normalperson@yhbt.net, joe@oampo.co.uk, linuxbugs@vittgam.net, johan@oljud.se, klock.android@gmail.com, nenggun.kim@samsung.com, j.anaszewski@samsung.com, geliangtang@163.com, albert@huitsing.nl, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, alsa-devel@alsa-project.org, Shuah Khan From: Shuah Khan Organization: Samsung Open Source Group Message-ID: <56D84961.9050902@osg.samsung.com> Date: Thu, 3 Mar 2016 07:25:37 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <20160303103637.GW5273@mwanda> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/03/2016 03:36 AM, Dan Carpenter wrote: > On Wed, Mar 02, 2016 at 03:57:03PM -0700, Shuah Khan wrote: >> On 03/02/2016 01:41 PM, Dan Carpenter wrote: >>> On Wed, Mar 02, 2016 at 09:50:31AM -0700, Shuah Khan wrote: >>>> + mctl = kzalloc(sizeof(*mctl), GFP_KERNEL); >>>> + if (!mctl) >>>> + return -ENOMEM; >>>> + >>>> + mctl->media_dev = mdev; >>>> + if (stream == SNDRV_PCM_STREAM_PLAYBACK) { >>>> + intf_type = MEDIA_INTF_T_ALSA_PCM_PLAYBACK; >>>> + mctl->media_entity.function = MEDIA_ENT_F_AUDIO_PLAYBACK; >>>> + mctl->media_pad.flags = MEDIA_PAD_FL_SOURCE; >>>> + mixer_pad = 1; >>>> + } else { >>>> + intf_type = MEDIA_INTF_T_ALSA_PCM_CAPTURE; >>>> + mctl->media_entity.function = MEDIA_ENT_F_AUDIO_CAPTURE; >>>> + mctl->media_pad.flags = MEDIA_PAD_FL_SINK; >>>> + mixer_pad = 2; >>>> + } >>>> + mctl->media_entity.name = pcm->name; >>>> + media_entity_pads_init(&mctl->media_entity, 1, &mctl->media_pad); >>>> + ret = media_device_register_entity(mctl->media_dev, >>>> + &mctl->media_entity); >>>> + if (ret) >>>> + goto err1; >>> >>> Could we give this label a meaningful name instead of a number? >>> goto free_mctl; >> >> I do see other places where numbered labels are used. > > Yeah. But it's the wrong idea. If you remove a label then you have to > renumber everything. Plus it doesn't say what the goto does. > >> Names might help with code readability. >> >> register_entity_fail probably makes more sense as a >> label than free_mctl. > > A lot of people do that but the you wind up with code like: > > foo = whatever_register(); > if (!foo) > goto whatever_failed; > > if (something_else) > goto whatever_failed; > > So it doesn't make sense. Also it doesn't tell you what the goto does. > (You can already see that whatever_failed from looking at the if > statement on the line before.) This function is larger than a page so > you have to flip down to the other page to see what the goto does, then > you have to flip back and find your place again. But if the label says > what the goto does then you can just say, "Have we allocated anything > since mctl? No, then freeing mctl is the right thing." You don't need > to flip to the othe page. > Yeah. You are right about large routines and needing to check labels. I will fix it in a followup patch. thanks, -- Shuah -- Shuah Khan Sr. Linux Kernel Developer Open Source Innovation Group Samsung Research America (Silicon Valley) shuahkh@osg.samsung.com | (970) 217-8978