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=-10.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 A1414C49361 for ; Fri, 18 Jun 2021 01:53:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D56C610A7 for ; Fri, 18 Jun 2021 01:53:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233577AbhFRBz3 (ORCPT ); Thu, 17 Jun 2021 21:55:29 -0400 Received: from mga07.intel.com ([134.134.136.100]:26655 "EHLO mga07.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230211AbhFRBz1 (ORCPT ); Thu, 17 Jun 2021 21:55:27 -0400 IronPort-SDR: fw1zNkt50bmiJR4APLQY6qLvaqHBaUyebh142HBugncQuw+pkYY2A29mFXhWoIoZWQhinRVrhX bp+Q+a7URkhg== X-IronPort-AV: E=McAfee;i="6200,9189,10018"; a="270328631" X-IronPort-AV: E=Sophos;i="5.83,281,1616482800"; d="scan'208";a="270328631" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Jun 2021 18:53:18 -0700 IronPort-SDR: Q5vu6PcEGBkldERazoleVuGDdZijSRvTVciKwDk0WAnv8lUAoPMVEHc8AnTcAQzhMepbLoAcKJ DIMIojw+Gw+g== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.83,281,1616482800"; d="scan'208";a="472612920" Received: from allen-box.sh.intel.com (HELO [10.239.159.118]) ([10.239.159.118]) by fmsmga004.fm.intel.com with ESMTP; 17 Jun 2021 18:53:16 -0700 Cc: baolu.lu@linux.intel.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linuxarm@huawei.com, thunder.leizhen@huawei.com, chenxiang66@hisilicon.com, linux-doc@vger.kernel.org Subject: Re: [PATCH v13 6/6] iommu: Remove mode argument from iommu_set_dma_strict() To: Robin Murphy , John Garry , joro@8bytes.org, will@kernel.org, dwmw2@infradead.org, corbet@lwn.net References: <1623841437-211832-1-git-send-email-john.garry@huawei.com> <1623841437-211832-7-git-send-email-john.garry@huawei.com> <7d0fb0e2-4671-16db-6963-b0493d7a549b@arm.com> From: Lu Baolu Message-ID: Date: Fri, 18 Jun 2021 09:51:48 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: <7d0fb0e2-4671-16db-6963-b0493d7a549b@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Robin, On 6/18/21 2:56 AM, Robin Murphy wrote: >>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c >>> index 60b1ec42e73b..ff221d3ddcbc 100644 >>> --- a/drivers/iommu/iommu.c >>> +++ b/drivers/iommu/iommu.c >>> @@ -349,10 +349,9 @@ static int __init iommu_dma_setup(char *str) >>>   } >>>   early_param("iommu.strict", iommu_dma_setup); >>> -void iommu_set_dma_strict(bool strict) >>> +void iommu_set_dma_strict(void) >>>   { >>> -    if (strict || !(iommu_cmd_line & IOMMU_CMD_LINE_STRICT)) >>> -        iommu_dma_strict = strict; >>> +    iommu_dma_strict = true; >> >> Sorry, I still can't get how iommu.strict kernel option works. >> >> static int __init iommu_dma_setup(char *str) >> { >>          int ret = kstrtobool(str, &iommu_dma_strict); > > Note that this is the bit that does the real work - if the argument > parses OK then iommu_dma_strict is reassigned with the appropriate > value. The iommu_cmd_line stuff is a bit of additional bookkeeping, > basically just so we can see whether default values have been overridden. Ah, get it. Thanks a lot. I missed this part and naively thought it just converts a string to integer. Best regards, baolu