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=-4.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 0C49AC07E96 for ; Thu, 15 Jul 2021 10:20:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DC6FB61360 for ; Thu, 15 Jul 2021 10:20:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241278AbhGOKXf (ORCPT ); Thu, 15 Jul 2021 06:23:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52314 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237293AbhGOKXe (ORCPT ); Thu, 15 Jul 2021 06:23:34 -0400 Received: from mail-pj1-x1032.google.com (mail-pj1-x1032.google.com [IPv6:2607:f8b0:4864:20::1032]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DC02DC06175F for ; Thu, 15 Jul 2021 03:20:40 -0700 (PDT) Received: by mail-pj1-x1032.google.com with SMTP id bt15so3550250pjb.2 for ; Thu, 15 Jul 2021 03:20:40 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:subject:to:message-id:date:user-agent:mime-version :content-transfer-encoding:content-language; bh=0c0M98GqS4QoBfMDYa+Mw0Q7vATtc9/MXR1xed72h1w=; b=FeWcPG1lAYUu3WIf0My0cXXHp16Gs9Q3sHWaTxutlzafsprsG8h4gVOQ0UUweX5VdV gTqX3rL7qKqBPbstco9HX8aHLksw35RmNhgfLP/hmdSnrwCesuDBV2Ax+LYgKvozJySQ ESN3cC5mtY9+PRLHBZcZwyIXj5Lz+S+GOPgtOTbEJqeG2cj4gkW60ZPicGw01TkPrSMX E5z5tDYTjytU0+cD5i6sylaUFk3ap1YJ0PUFYkqHEFdKsWBIBWqhHtfIvPBLC9gGg8Hb /AR9EmlULP4YWPUX1YX9mLcpMH/clry/La2LCRavG9ZxddkZlKo33mfyMYT0YA58wKXD ooqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:subject:to:message-id:date:user-agent :mime-version:content-transfer-encoding:content-language; bh=0c0M98GqS4QoBfMDYa+Mw0Q7vATtc9/MXR1xed72h1w=; b=NepZSQGo/7sIEhharQVaIzn0niphvagcN+htIJjubbGOE8Ah5S7y0zKfVnHNIUnOgW Pq9oZUBlH6VKBWKNEUbVoFDtDhuzkwKG7NMr5j2ztooGKH/QCXxNppBCK5M9IdIC9JDm XShwq5LrVSFZXfM5wepCF5PyV1JUyrmibNt9mAqmvhbMyy9feky2coTEyG+d6jWF0qE/ GDtIO2V31SGzBK3s0490daj/oI0idA8Vc+/g1GXgi+shFJ/4l+RIHbdK1/kw7uf/cS6w vu5ktpe1E1u5Qzm0FFlbkzB4QG3psihGg1sTtSAnZMByN7vVR5vLa6ob7OU6t9g977VC RsmA== X-Gm-Message-State: AOAM530bqVKMUFMuNE3EyZM5WFxCIAzxgw8WgxW0+v/QxsRllP5i4qIA 1zujOYGSx3pdlhgT9PLZeWtGnfTE6j0= X-Google-Smtp-Source: ABdhPJy2jKC1wIy3IY6eyCK9pnNyhDoZsiaiRN1V/ykXH1UDW2vRdqDFOIduaSOB8r28siVHMLekpA== X-Received: by 2002:a17:902:d50a:b029:12b:59a9:9586 with SMTP id b10-20020a170902d50ab029012b59a99586mr759156plg.62.1626344440114; Thu, 15 Jul 2021 03:20:40 -0700 (PDT) Received: from [10.162.0.18] ([45.135.186.83]) by smtp.gmail.com with ESMTPSA id p40sm6079690pfw.79.2021.07.15.03.20.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 15 Jul 2021 03:20:39 -0700 (PDT) From: Jia-Ju Bai Subject: [BUG] ALSA: sb16: possible ABBA deadlock in snd_sb_csp_stop() and snd_sb_csp_load() To: perex@perex.cz, tiwai@suse.com, alsa-devel@alsa-project.org, "linux-kernel@vger.kernel.org >> linux-kernel" Message-ID: <7b0fcdaf-cd4f-4728-2eae-48c151a92e10@gmail.com> Date: Thu, 15 Jul 2021 18:20:36 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, I find there is a possible ABBA deadlock in the SB16 driver in Linux 5.10: In snd_sb_csp_stop(): 876:     spin_lock_irqsave(&p->chip->mixer_lock, flags); 882:     spin_lock(&p->chip->reg_lock); In snd_sb_csp_load(): 614:     spin_lock_irqsave(&p->chip->reg_lock, flags); 653:     spin_lock(&p->chip->mixer_lock); When snd_sb_csp_stop() and snd_sb_csp_load() are concurrently executed, the deadlock can occur. I check the code and find a possible case of such concurrent execution: #CPU1: snd_sb16_playback_close   snd_sb16_csp_playback_close (csp->ops.csp_stop(csp))     snd_sb_csp_stop #CPU2: snd_sb_csp_ioctl   snd_sb_csp_riff_load     snd_sb_csp_load_user       snd_sb_csp_load I am not quite sure whether this possible deadlock is real and how to fix it if it is real. Any feedback would be appreciated, thanks Best wishes, Jia-Ju Bai