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=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1,USER_IN_DEF_DKIM_WL 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 8A632C2D0C9 for ; Fri, 13 Dec 2019 02:59:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 60E2E24656 for ; Fri, 13 Dec 2019 02:59:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="mvV048o5" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731821AbfLMC7Q (ORCPT ); Thu, 12 Dec 2019 21:59:16 -0500 Received: from linux.microsoft.com ([13.77.154.182]:41646 "EHLO linux.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731465AbfLMC7Q (ORCPT ); Thu, 12 Dec 2019 21:59:16 -0500 Received: from [10.137.112.111] (unknown [131.107.147.111]) by linux.microsoft.com (Postfix) with ESMTPSA id 2DA5820B7187; Thu, 12 Dec 2019 18:59:15 -0800 (PST) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 2DA5820B7187 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1576205955; bh=qv+NmmnZ+/n9eF3FzeCcHEgZTGuVHBDcefUGSa3G2Ug=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=mvV048o53KZrnKUqBWi40AGMeYEPwiiAx3txKH0je5V8BQHmIW8UQ03ad8Z3hPAAf bUr4X2ZCRYkT0HLu0Ljs7y9O14mIukU7XyaxUCh9MiWMy6feKWF3KGqHWHRevCUYUM IyS/6OHbMg6T3Tsm9ESbrhWes2lpClPsNMtTkyxY= Subject: Re: [PATCH v3 1/2] IMA: Define workqueue for early boot "key" measurements To: Mimi Zohar , linux-integrity@vger.kernel.org Cc: eric.snowberg@oracle.com, dhowells@redhat.com, mathew.j.martineau@linux.intel.com, matthewgarrett@google.com, sashal@kernel.org, jamorris@linux.microsoft.com, linux-kernel@vger.kernel.org, keyrings@vger.kernel.org References: <20191213004250.21132-1-nramas@linux.microsoft.com> <20191213004250.21132-2-nramas@linux.microsoft.com> <1576202134.4579.189.camel@linux.ibm.com> <6e0dad33-66f9-4807-d08d-ff30396cec5e@linux.microsoft.com> <1576204377.4579.206.camel@linux.ibm.com> From: Lakshmi Ramasubramanian Message-ID: Date: Thu, 12 Dec 2019 18:59:39 -0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <1576204377.4579.206.camel@linux.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/12/2019 6:32 PM, Mimi Zohar wrote: >>> >>> Don't you need a test here, before setting ima_process_keys? >>> >>> if (ima_process_keys) >>> return; >>> >>> Mimi >> >> That check is done before the comment - at the start of >> ima_process_queued_keys(). > > The first test prevents taking the mutex unnecessarily. > > Mimi I am trying to understand your concern here. Could you please clarify? => If ima_process_keys is false -> With the mutex held, should check ima_process_keys again before setting? Let's say 2 or more threads are racing in calling ima_process_queued_keys(): The 1st one will set ima_process_keys and process queued keys. The 2nd and subsequent ones - even if they have gone past the initial check, will find an empty list of keys (the list "ima_keys") when they take the mutex. So they'll not process any keys. thanks, -lakshmi