Received: by 2002:a05:6358:3188:b0:123:57c1:9b43 with SMTP id q8csp1184717rwd; Thu, 15 Jun 2023 07:24:00 -0700 (PDT) X-Google-Smtp-Source: ACHHUZ4TZsnEHSsLKGCzb8vEYe4UYQAGOeCHhCiFNc+IJQ9+ypXWvSD/LNaZ/UBo8o8N0dmHP7eX X-Received: by 2002:a05:6808:1cc:b0:39a:a62c:51f2 with SMTP id x12-20020a05680801cc00b0039aa62c51f2mr13569913oic.43.1686839039791; Thu, 15 Jun 2023 07:23:59 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1686839039; cv=none; d=google.com; s=arc-20160816; b=BykOvEqAOAiGXSvkYqAwK2cnggow4nGut+u4aWyVrX+6g22b1+qZ0bQEvV4XKpsiWN e+eQUCUsrnV+RJcYZ/n5lkWGsDkhdJMkia6Dh0P85r3E5rQJzk99S9HJeffuE+uv7jrp YcHSVOfrcpr4jMmxOo5VKbS1PXpIT8sXcV++gBzy7jo7/s21JqHKcF9i491YIhBagrYz K9G18hekjXPgIdImWqCFPDOYxTZNfSy1GPSzsSEQ6yhORIIxN7Va8i1AOdkBAEp3nqNy zdyMt+rtZGodODNarMKMeZIRNgvh+8GLVl8JZRlTk9iFRBHFcfv8RWNzCykWIGSNm+UM iMgw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from :dkim-signature; bh=AjGNsoyoK5D+RJq6nyibBF7s8NAROrXXFDradtiR7EE=; b=R0F/D3CltjCHkRgW/u7oQqvlRC3vejF/Hv8NqKDK1oll4pZYkFWJKnpIzgC3CijaNr cv6Qmo44M/kI0BAcxomnA+ObQxUT4dRoXJjvcjalYPJgiMcRSHyrxXg/PCEXWCBe58sY XsvBWUvhEnwOQ9Nos76LakQB0fW1MsjeseFj9h8E9em01yCgNkMFxMi9+XtlMs3DJfef AzwJv1xb4yWyBhZqnVg/WhgY9suNDA7uylRkeOrx5+Vit2O/5wrMVOg8edT1mzuKZJiH kDRcRBFGJgoagJ0dDP6mlD052z4XQ6Gbyot2xwkDRhFjwf/yMp91YjfvhBeF4idvFY39 yKLA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@cirrus.com header.s=PODMain02222019 header.b=cToN3yGL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=cirrus.com Return-Path: Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id w15-20020a637b0f000000b0054fef6280d1si1964618pgc.745.2023.06.15.07.23.46; Thu, 15 Jun 2023 07:23:59 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@cirrus.com header.s=PODMain02222019 header.b=cToN3yGL; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=cirrus.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344947AbjFOOND (ORCPT + 99 others); Thu, 15 Jun 2023 10:13:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42214 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344910AbjFOOMr (ORCPT ); Thu, 15 Jun 2023 10:12:47 -0400 Received: from mx0b-001ae601.pphosted.com (mx0a-001ae601.pphosted.com [67.231.149.25]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3277C2683 for ; Thu, 15 Jun 2023 07:12:46 -0700 (PDT) Received: from pps.filterd (m0077473.ppops.net [127.0.0.1]) by mx0a-001ae601.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 35FE4O1N019435; Thu, 15 Jun 2023 09:12:10 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cirrus.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=PODMain02222019; bh=AjGNsoyoK5D+RJq6nyibBF7s8NAROrXXFDradtiR7EE=; b=cToN3yGLlHYejStDOuS6sTL8/BmqCwQuEn+N30FJvc6ckt8QbzGmjLMQsmFk7smlBEQN 07TOSvGxCBrZwfrC7pCLx5OrnHF7Ow6LDkPOlL8lqzXfAxoCZHFlAOj01kPWqzbYpu7z UdpNQ0YiybPlYaDcE3xKKouYzRPZRc9OEeiTR9cNGM6PGvAVq3PWa8N3WUQkqTVglY0j D8PK+/yDt6eYhepp20pkcAQzvdWFtQy+TPly0IoDDTqaOUmSFdVvezj96XoYwmkTDFS7 mg7JYQXvg3ZyJtZTHlZSwmUMI+RT5IuXKbztpvbC9k0jnXQ/72BEgMPScmGScdxaMqlk fA== Received: from ediex02.ad.cirrus.com ([84.19.233.68]) by mx0a-001ae601.pphosted.com (PPS) with ESMTPS id 3r4pk0d8fp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 15 Jun 2023 09:12:10 -0500 Received: from ediex02.ad.cirrus.com (198.61.84.81) by ediex02.ad.cirrus.com (198.61.84.81) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.26; Thu, 15 Jun 2023 15:12:08 +0100 Received: from ediswmail.ad.cirrus.com (198.61.86.93) by anon-ediex02.ad.cirrus.com (198.61.84.81) with Microsoft SMTP Server id 15.2.1118.26 via Frontend Transport; Thu, 15 Jun 2023 15:12:08 +0100 Received: from edi-sw-dsktp-006.ad.cirrus.com (edi-sw-dsktp-006.ad.cirrus.com [198.90.251.127]) by ediswmail.ad.cirrus.com (Postfix) with ESMTP id 28DAB11DC; Thu, 15 Jun 2023 14:12:08 +0000 (UTC) From: Richard Fitzgerald To: , , CC: , , , Richard Fitzgerald Subject: [PATCH 2/2] soundwire: stream: Make master_list ordered to prevent deadlocks Date: Thu, 15 Jun 2023 15:12:08 +0100 Message-ID: <20230615141208.679011-2-rf@opensource.cirrus.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20230615141208.679011-1-rf@opensource.cirrus.com> References: <20230615141208.679011-1-rf@opensource.cirrus.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Proofpoint-ORIG-GUID: mnNUJZBw1Evo7A57D6VUzeGSGj1bzS74 X-Proofpoint-GUID: mnNUJZBw1Evo7A57D6VUzeGSGj1bzS74 X-Proofpoint-Spam-Reason: safe X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Always add buses to the stream->master_list in a fixed order. The unique bus->id is used to order the adding of buses to the list. This prevents lockdep asserts and possible deadlocks on streams that have multiple buses. sdw_acquire_bus_lock() takes bus_lock in the order that buses are listed in stream->master_list. do_bank_switch() takes all the msg_lock in the same order. To prevent a lockdep assert, and a possible real deadlock, the relative order of taking these mutexes must always be the same. For example, if a stream takes the mutexes in the order (bus0, bus1) lockdep will assert if another stream takes them in the order (bus1, bus0). More complex relative ordering will also assert, for example if two streams take (bus0, bus1) and (bus1, bus2), then a third stream takes (bus2, bus0). Previously sdw_stream_add_master() simply added the given bus to the end of the list, requiring the caller to guarantee that buses are added in a fixed order. This isn't reasonable or necessary - it's an internal implementation detail that should not be exposed by the API. It doesn't really make sense when there could be multiple independent calling drivers, to say "you must add your buses in the same order as a different driver, that you don't know about, added them". Signed-off-by: Richard Fitzgerald --- drivers/soundwire/stream.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c index 93baca08a0de..d77a8a0d42c8 100644 --- a/drivers/soundwire/stream.c +++ b/drivers/soundwire/stream.c @@ -1150,7 +1150,8 @@ static struct sdw_master_runtime *sdw_master_rt_alloc(struct sdw_bus *bus, struct sdw_stream_runtime *stream) { - struct sdw_master_runtime *m_rt; + struct sdw_master_runtime *m_rt, *walk_m_rt; + struct list_head *insert_after; m_rt = kzalloc(sizeof(*m_rt), GFP_KERNEL); if (!m_rt) @@ -1159,7 +1160,20 @@ static struct sdw_master_runtime /* Initialization of Master runtime handle */ INIT_LIST_HEAD(&m_rt->port_list); INIT_LIST_HEAD(&m_rt->slave_rt_list); - list_add_tail(&m_rt->stream_node, &stream->master_list); + + /* + * Add in order of bus id so that when taking the bus_lock + * of multiple buses they will always be taken in the same + * order to prevent a mutex deadlock. + */ + insert_after = &stream->master_list; + list_for_each_entry_reverse(walk_m_rt, &stream->master_list, stream_node) { + if (walk_m_rt->bus->id < bus->id) { + insert_after = &walk_m_rt->stream_node; + break; + } + } + list_add(&m_rt->stream_node, insert_after); list_add_tail(&m_rt->bus_node, &bus->m_rt_list); -- 2.30.2