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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 39229C64EBC for ; Thu, 4 Oct 2018 05:25:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01F5820877 for ; Thu, 4 Oct 2018 05:24:59 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 01F5820877 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727167AbeJDMQ2 (ORCPT ); Thu, 4 Oct 2018 08:16:28 -0400 Received: from mx2.suse.de ([195.135.220.15]:50514 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726438AbeJDMQ2 (ORCPT ); Thu, 4 Oct 2018 08:16:28 -0400 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 99B57AF53; Thu, 4 Oct 2018 05:24:56 +0000 (UTC) Date: Thu, 04 Oct 2018 07:24:56 +0200 Message-ID: From: Takashi Iwai To: Jia-Ju Bai Cc: keescook@chromium.org, perex@perex.cz, alsa-devel@alsa-project.org, Linux Kernel Mailing List Subject: Re: [BUG] sound: pci: trident: a possible data race In-Reply-To: References: <864e211c-8be5-6a34-902a-a71f176111db@gmail.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/26 (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 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 04 Oct 2018 05:08:45 +0200, Jia-Ju Bai wrote: > > Thanks for the reply :) > > > On 2018/10/3 23:54, Takashi Iwai wrote: > > On Wed, 03 Oct 2018 14:50:25 +0200, > > Jia-Ju Bai wrote: > >> CPU0: > >> snd_trident_hw_free > >> snd_trident_free_voice > >> line 3870: spin_lock_irqsave() > >> line 3881: voice->substream = NULL; [WRITE] > >> CPU1: > >> snd_trident_interrupt > >> line 3798: snd_pcm_period_elapsed(voice->substream); [READ] > >> > >> As for voice->substream, the WRITE operation in CPU0 is performed > >> with holding a spinlock, but the READ operation in CPU1 is performed > >> without holding this spinlock, so there may exist a data race. > > Thanks for the report. > > > > The actual crash must be very unlikely, almost 0%, though. > > snd_trident_hw_free() is called always after the PCM stream gets > > stopped via trigger callback, i.e. at the moment, there is no > > corresponding interrupt is generated for that voice entry. > > How about the case that playback and capture are performed concurrently? > Namely, snd_trident_hw_free() is called for playback, and the > interrupt is generated for capture. They are different substreams, hence it won't pick up the substream object. > > And the hardware is very old, I bet only a handful people still using > > in the whole world :) > > I have this hardware, so I am the one of these handful people ;) Wow, that's fun. Then we can really fix the issue, if any. Did you actually hit any relevant bug? thanks, Takashi