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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 8587EC433ED for ; Mon, 17 May 2021 15:07:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 63B9A6101B for ; Mon, 17 May 2021 15:07:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242917AbhEQPIe (ORCPT ); Mon, 17 May 2021 11:08:34 -0400 Received: from mx2.suse.de ([195.135.220.15]:40716 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241870AbhEQO6q (ORCPT ); Mon, 17 May 2021 10:58:46 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id C7A49AC46; Mon, 17 May 2021 14:57:28 +0000 (UTC) Date: Mon, 17 May 2021 16:57:28 +0200 Message-ID: From: Takashi Iwai To: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Jaroslav Kysela , Takashi Iwai , Greg Kroah-Hartman , Oliver Neukum , Vasily Khoruzhick , alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] sound: line6: Fix race condition in line6_probe In-Reply-To: <20210517144811.GA54892@hyeyoo> References: <20210517132725.GA50495@hyeyoo> <20210517144811.GA54892@hyeyoo> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI/1.14.6 (Maruoka) FLIM/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL/10.8 Emacs/25.3 (x86_64-suse-linux-gnu) MULE/6.0 (HANACHIRUSATO) MIME-Version: 1.0 (generated by SEMI 1.14.6 - "Maruoka") Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 17 May 2021 16:48:11 +0200, Hyeonggon Yoo wrote: > > On Mon, May 17, 2021 at 03:43:24PM +0200, Takashi Iwai wrote: > > The actually needed initialization is > > line6_init_mid() call, and this can be fixed by moving to the > > appropriate place instead of inside each private_init callback. > > Oh, I missed it! there was another caller of line6_init_midi. > your fix seems promising to me. it's putting line6_init_midi > to the right place. > > by the way looking at code, I think this driver needs some > refactoring... it doesn't handle exceptions well. Yes, there can be likely a few other holes in this driver, but for fixing them, we'd need an actual test device. The initialization procedure of this device seems complex (multi-staged) and very sensitive. Takashi > > Thanks, > > Hyeonggon > > --- > > diff --git a/sound/usb/line6/driver.c b/sound/usb/line6/driver.c > > index a030dd65eb28..9602929b7de9 100644 > > --- a/sound/usb/line6/driver.c > > +++ b/sound/usb/line6/driver.c > > @@ -699,6 +699,10 @@ static int line6_init_cap_control(struct usb_line6 *line6) > > line6->buffer_message = kmalloc(LINE6_MIDI_MESSAGE_MAXLEN, GFP_KERNEL); > > if (!line6->buffer_message) > > return -ENOMEM; > > + > > + ret = line6_init_midi(line6); > > + if (ret < 0) > > + return ret; > > } else { > > ret = line6_hwdep_init(line6); > > if (ret < 0) > > diff --git a/sound/usb/line6/pod.c b/sound/usb/line6/pod.c > > index cd44cb5f1310..16e644330c4d 100644 > > --- a/sound/usb/line6/pod.c > > +++ b/sound/usb/line6/pod.c > > @@ -376,11 +376,6 @@ static int pod_init(struct usb_line6 *line6, > > if (err < 0) > > return err; > > > > - /* initialize MIDI subsystem: */ > > - err = line6_init_midi(line6); > > - if (err < 0) > > - return err; > > - > > /* initialize PCM subsystem: */ > > err = line6_init_pcm(line6, &pod_pcm_properties); > > if (err < 0) > > diff --git a/sound/usb/line6/variax.c b/sound/usb/line6/variax.c > > index ed158f04de80..1376fc405c7f 100644 > > --- a/sound/usb/line6/variax.c > > +++ b/sound/usb/line6/variax.c > > @@ -172,11 +172,6 @@ static int variax_init(struct usb_line6 *line6, > > if (variax->buffer_activate == NULL) > > return -ENOMEM; > > > > - /* initialize MIDI subsystem: */ > > - err = line6_init_midi(&variax->line6); > > - if (err < 0) > > - return err; > > - > > /* initiate startup procedure: */ > > schedule_delayed_work(&line6->startup_work, > > msecs_to_jiffies(VARIAX_STARTUP_DELAY1)); >