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=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 62CADC43331 for ; Tue, 12 Nov 2019 07:32:53 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5984F214E0 for ; Tue, 12 Nov 2019 07:32:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=alsa-project.org header.i=@alsa-project.org header.b="Ci9hjqUC" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5984F214E0 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=alsa-devel-bounces@alsa-project.org Received: from alsa1.perex.cz (alsa1.perex.cz [207.180.221.201]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa0.perex.cz (Postfix) with ESMTPS id EA6F21607; Tue, 12 Nov 2019 08:31:59 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa0.perex.cz EA6F21607 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=alsa-project.org; s=default; t=1573543970; bh=08uD+IAJaqf+7epXQAYNWwbO2xuQxmOZx1Gx42Pvej8=; h=Date:From:To:In-Reply-To:References:Cc:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From; b=Ci9hjqUCoLEDmV2sKcGFeK/aFCFCJmtOcwI3I/EWdyArdpjgDeyckdUCSx2rlsyg8 EZh7R3EmAIGrerj+0i+r3Wq/FZK4lhAKznuOkErx2uA/LuCZBt2IEpYjYUZx91CtsD eWoZwOAzvQP2L+X0QSt2HiHYrpJahRDyZtoM4RLM= Received: from alsa1.perex.cz (localhost.localdomain [127.0.0.1]) by alsa1.perex.cz (Postfix) with ESMTP id 554C0F8044C; Tue, 12 Nov 2019 08:31:59 +0100 (CET) Received: by alsa1.perex.cz (Postfix, from userid 50401) id 6786BF80483; Tue, 12 Nov 2019 08:31:57 +0100 (CET) Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by alsa1.perex.cz (Postfix) with ESMTPS id ED022F80144 for ; Tue, 12 Nov 2019 08:31:53 +0100 (CET) DKIM-Filter: OpenDKIM Filter v2.11.0 alsa1.perex.cz ED022F80144 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id A7193B1A8; Tue, 12 Nov 2019 07:31:52 +0000 (UTC) Date: Tue, 12 Nov 2019 08:31:52 +0100 Message-ID: From: Takashi Iwai To: Henry Lin In-Reply-To: <20191112065108.7766-1-henryl@nvidia.com> References: <20191112065108.7766-1-henryl@nvidia.com> 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") Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Takashi Iwai , Richard Fontana , Thomas Gleixner , Allison Randal Subject: Re: [alsa-devel] [PATCH] usb-audio: not submit urb for stopped endpoint X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: alsa-devel-bounces@alsa-project.org Sender: "Alsa-devel" On Tue, 12 Nov 2019 07:51:06 +0100, Henry Lin wrote: > > While output urb's snd_complete_urb() is executing, calling > prepare_outbound_urb() may cause endpoint stopped before > prepare_outbound_urb() returns and result in next urb submitted > to stopped endpoint. usb-audio driver cannot re-use it afterwards as > the urb is still hold by usb stack. > > This change checks EP_FLAG_RUNNING flag after prepare_outbound_urb() again > to let snd_complete_urb() know the endpoint already stopped and does not > submit next urb. OK, this part looks good and understandable. > We observed two scenario have this issue: > 1. While executing snd_complete_urb() to complete an output urb, calling > prepare_outbound_urb() let deactive_urbs() get called to unlink all > active urbs. > > [ 268.097066] [] deactivate_urbs+0xd4/0x108 > [ 268.102633] [] snd_usb_endpoint_stop+0x30/0x58 > [ 268.108636] [] snd_usb_substream_playback_trigger+0xa4/0xf4 > [ 268.115765] [] snd_pcm_do_stop+0x4c/0x58 > [ 268.121245] [] snd_pcm_action_single+0x40/0x88 > [ 268.127245] [] snd_pcm_action+0x30/0xf0 > [ 268.132632] [] snd_pcm_stop+0x24/0x2c > [ 268.137851] [] xrun+0x60/0x6c > [ 268.142374] [] snd_pcm_update_state+0xa8/0x10c > [ 268.148374] [] snd_pcm_update_hw_ptr0+0x328/0x344 > [ 268.154635] [] snd_pcm_period_elapsed+0x98/0xb0 > [ 268.160723] [] prepare_playback_urb+0x46c/0x488 > [ 268.166810] [] prepare_outbound_urb+0x60/0x1d4 > [ 268.172805] [] snd_complete_urb+0x244/0x264 > [ 268.178548] [] __usb_hcd_giveback_urb+0x94/0x104 > [ 268.184721] [] usb_hcd_giveback_urb+0x3c/0x114 > [ 268.190724] [] handle_tx_event+0x1304/0x1434 > [ 268.196552] [] xhci_handle_event+0x5dc/0x788 > [ 268.202378] [] xhci_irq+0x178/0x280 > > 2. Userspace application stops playback from sound subsystem with below > call stack: > > [ 28.506477] CPU: 5 PID: 1274 Comm: AudioOut_25 Not tainted 4.4.38-tegra #31 > [ 28.513430] Hardware name: quill (DT) > [ 28.517085] Call trace: > [ 28.519531] [] dump_backtrace+0x0/0xf8 > [ 28.524837] [] show_stack+0x14/0x1c > [ 28.529885] [] dump_stack+0xac/0xe0 > [ 28.534931] [] deactivate_urbs+0x148/0x180 > [ 28.540578] [] snd_usb_endpoint_stop+0x30/0x58 > [ 28.546571] [] snd_usb_substream_playback_trigger+0xa4/0xf4 > [ 28.553699] [] snd_pcm_do_stop+0x4c/0x58 > [ 28.559179] [] snd_pcm_action_single+0x40/0x88 > [ 28.565178] [] snd_pcm_action+0x30/0xf0 > [ 28.570568] [] snd_pcm_drop+0xac/0x140 > [ 28.575873] [] snd_pcm_release_substream+0x28/0xb0 > [ 28.582212] [] snd_pcm_release+0x3c/0x98 > [ 28.587686] [] __fput+0xe0/0x1ac > [ 28.592469] [] ____fput+0xc/0x14 > [ 28.597253] [] task_work_run+0xa0/0xc0 > [ 28.602558] [] do_notify_resume+0x48/0x60 > [ 28.608123] [] work_pending+0x1c/0x20 > > In the call path, snd_pcm_stream spinlock has been acquired in > snd_pcm_drop(). If an output urb is completed between the spinlock > acquired and deactivate_urbs() clears EP_FLAG_RUNNING for the endpoint, > its executing of snd_complete_urb() will be blocked for acquiring > snd_pcm_stream spinlock in snd_pcm_period_elapsed() until the lock is > released in snd_pcm_drop(). When snd_complete_urb() continues, all jobs > for deactivate_urbs() are finished. ... but this part is unclear to me. Do you mean that we have a deadlock in these two concurrent calls without your patch? Thanks! Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@alsa-project.org https://mailman.alsa-project.org/mailman/listinfo/alsa-devel