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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C81CC433EF for ; Mon, 25 Jul 2022 09:39:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234045AbiGYJjP (ORCPT ); Mon, 25 Jul 2022 05:39:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44090 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234262AbiGYJjN (ORCPT ); Mon, 25 Jul 2022 05:39:13 -0400 Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4B124BC15 for ; Mon, 25 Jul 2022 02:39:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1658741953; x=1690277953; h=message-id:date:mime-version:cc:subject:to:references: from:in-reply-to:content-transfer-encoding; bh=FeSuo0JJdNSjMoYJ09VPheK/a4W0VdfiJn8DvjdV9n0=; b=JJ6jNQM6dt1Tvy6ap5ILbAKcqLwLdj9su1uyimaQZV9vLguncdRlNLZ6 EWUA6ro5AnI99P0v98tN52odtiXKXuUafbxkMuywmm1W27M4X1+d/JGnS M71xqUoX6iMUHXhPxja4sIJBsvH8fsJQWKQEvk8rOlImi5F6KGKVCbFbl vhlsTrUosNGIFEUblxpgUMzmtB4Xcptl2PEUxXXRH3MwqSPovInu2hgAt yk37QA9t/tnUTLmaBl7EOJYcbW8GKCycwRT/MLYiJuVWrtjAEv6DWV4Bz WXVRRBfihufmhOki4e+Y0o0Kpg0QXai0dXrdofpgwaDvJDQv5Wn6z0VoL g==; X-IronPort-AV: E=McAfee;i="6400,9594,10418"; a="287668956" X-IronPort-AV: E=Sophos;i="5.93,192,1654585200"; d="scan'208";a="287668956" Received: from fmsmga008.fm.intel.com ([10.253.24.58]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jul 2022 02:39:13 -0700 X-IronPort-AV: E=Sophos;i="5.93,192,1654585200"; d="scan'208";a="658112475" Received: from liangk-mobl.ccr.corp.intel.com (HELO [10.255.30.67]) ([10.255.30.67]) by fmsmga008-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 25 Jul 2022 02:39:11 -0700 Message-ID: Date: Mon, 25 Jul 2022 17:39:11 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Cc: baolu.lu@linux.intel.com, Joerg Roedel , Will Deacon , Robin Murphy , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 1/1] iommu/vt-d: Fix possible recursive locking in intel_iommu_init() Content-Language: en-US To: "Tian, Kevin" , "iommu@lists.linux.dev" References: <20220718235325.3952426-1-baolu.lu@linux.intel.com> <8e970367-746e-0e74-ba39-e941fdbfdab7@linux.intel.com> From: Baolu Lu In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/7/25 15:40, Tian, Kevin wrote: >> From: Baolu Lu >> Sent: Sunday, July 24, 2022 11:00 AM >> >> Hi Kevin, >> >> On 2022/7/21 15:39, Tian, Kevin wrote: >>>> From: Lu Baolu >>>> Sent: Tuesday, July 19, 2022 7:53 AM >>>> >>>> @@ -88,7 +89,8 @@ extern struct list_head dmar_drhd_units; >>>> static inline bool dmar_rcu_check(void) >>>> { >>>> return rwsem_is_locked(&dmar_global_lock) || >>>> - system_state == SYSTEM_BOOTING; >>>> + system_state == SYSTEM_BOOTING || >>>> + (IS_ENABLED(CONFIG_INTEL_IOMMU) >>>> && !intel_iommu_enabled); >>>> } >>> >>> intel_iommu_enabled is 0 if CONFIG_INTEL_IOMMU is not set. >>> >>> same for other similar checks. >> >> Sorry that I didn't get your point. If CONFIG_INTEL_IOMMU is not set, >> IS_ENABLED(CONFIG_INTEL_IOMMU) is 0. The adding check has no effect. >> Did >> I miss anything? >> > > My point was that the check on CONFIG_INTEL_IOMMU is unnecessary. Oh, if INTEL_IOMMU is not configured, the interrupt remapping could also be supported, so we still need the rcu protection. We only relax the rcu check when INTEL_IOMMU is configured, but not enabled yet. Best regards, baolu