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=-17.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 5E7A7C4338F for ; Tue, 17 Aug 2021 11:54:07 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 072A761008 for ; Tue, 17 Aug 2021 11:54:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 072A761008 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id C6260402D2; Tue, 17 Aug 2021 11:54:06 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id JTwDP-d4qgKv; Tue, 17 Aug 2021 11:54:02 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by smtp2.osuosl.org (Postfix) with ESMTPS id 7879340018; Tue, 17 Aug 2021 11:54:02 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 490F1C0010; Tue, 17 Aug 2021 11:54:02 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [IPv6:2605:bc80:3010::133]) by lists.linuxfoundation.org (Postfix) with ESMTP id 6DE5DC000E for ; Tue, 17 Aug 2021 11:54:01 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 4A8444018A for ; Tue, 17 Aug 2021 11:54:01 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id pkPsv0W2d5ZF for ; Tue, 17 Aug 2021 11:53:58 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by smtp2.osuosl.org (Postfix) with ESMTPS id 524B040018 for ; Tue, 17 Aug 2021 11:53:58 +0000 (UTC) Received: from fraeml744-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4GpqD04WDBz6BGJN; Tue, 17 Aug 2021 19:53:04 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml744-chm.china.huawei.com (10.206.15.225) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.8; Tue, 17 Aug 2021 13:53:53 +0200 Received: from [10.202.227.179] (10.202.227.179) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Tue, 17 Aug 2021 12:53:53 +0100 Subject: Re: [PATCH] iommu/arm-smmu-v3: Stop pre-zeroing batch commands in arm_smmu_atc_inv_master() To: Zhen Lei , Will Deacon , Robin Murphy , Joerg Roedel , linux-arm-kernel , iommu , References: <20210817113411.1962-1-thunder.leizhen@huawei.com> From: John Garry Message-ID: <23f1cc66-2172-9534-53ef-3d9b2db26bda@huawei.com> Date: Tue, 17 Aug 2021 12:53:52 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.1 MIME-Version: 1.0 In-Reply-To: <20210817113411.1962-1-thunder.leizhen@huawei.com> Content-Language: en-US X-Originating-IP: [10.202.227.179] X-ClientProxiedBy: lhreml702-chm.china.huawei.com (10.201.108.51) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On 17/08/2021 12:34, Zhen Lei wrote: > Pre-zeroing the batched commands structure is inefficient, as individual > commands are zeroed later in arm_smmu_cmdq_build_cmd(). Therefore, only > the member 'num' needs to be initialized to 0. > > Signed-off-by: Zhen Lei Reviewed-by: John Garry > --- > drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > index 50a9db5bac466c7..e6882ae81fd08f6 100644 > --- a/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > +++ b/drivers/iommu/arm/arm-smmu-v3/arm-smmu-v3.c > @@ -1776,10 +1776,11 @@ static int arm_smmu_atc_inv_master(struct arm_smmu_master *master) > { > int i; > struct arm_smmu_cmdq_ent cmd; > - struct arm_smmu_cmdq_batch cmds = {}; > + struct arm_smmu_cmdq_batch cmds; > > arm_smmu_atc_inv_to_cmd(0, 0, 0, &cmd); > > + cmds.num = 0; We prob should have added a comment why we do this (and at the other sites). I think Robin said something similar in another patch. > for (i = 0; i < master->num_streams; i++) { > cmd.atc.sid = master->streams[i].id; > arm_smmu_cmdq_batch_add(master->smmu, &cmds, &cmd); > _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu