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 55AC4C43334 for ; Wed, 13 Jul 2022 05:44:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234109AbiGMFoH (ORCPT ); Wed, 13 Jul 2022 01:44:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232040AbiGMFoF (ORCPT ); Wed, 13 Jul 2022 01:44:05 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id ABC9233401 for ; Tue, 12 Jul 2022 22:44:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1657691043; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=sogOu0Je2hI8kCeSkB7cNWVEmJuAsjifkkQViIo6h78=; b=b0Z0dSW1durBSaZ7SutJDvSrLd2jeQdNNfZr2Lrc2bUy1e2tWOhqDf+KT20jXgECb16xAa oKsg1+T+oQbG9xOezZ/ybDNRmQFrKqGyxQzxtug8+HMVo7A1pJrLrbVwAwterUzOUqWqdB mCmpiloUv0O4k/N7BFWUg8smfdeI5hU= Received: from mail-pg1-f198.google.com (mail-pg1-f198.google.com [209.85.215.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-414-PrLjoZApPq6WaZ8Mk-eqnw-1; Wed, 13 Jul 2022 01:44:02 -0400 X-MC-Unique: PrLjoZApPq6WaZ8Mk-eqnw-1 Received: by mail-pg1-f198.google.com with SMTP id v202-20020a6361d3000000b0041615ebed02so3307224pgb.5 for ; Tue, 12 Jul 2022 22:44:02 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent:subject :content-language:to:cc:references:from:in-reply-to :content-transfer-encoding; bh=sogOu0Je2hI8kCeSkB7cNWVEmJuAsjifkkQViIo6h78=; b=SlUj5m7TtmU6oA7Eyh3h66H0BSkwkFJDbsmwP2cTub7vq+9ZOZysYScEyUjAj6Z8Qa 6R+bLs058DWIyecGd3OS1G/myH4fA+xgj7IFeDDOd9ym7ViSiFQNby+vBBzz91Um//L0 z+UUZfeLyG7oi3cc5o3A7LOnjobUCmbnZMrw09elubjrRIeIgxDybD+K870WyBoAgeyY E+LYlZDwDKJyG76g1V6V3DyNIuo67ARlWyXyjN//FyGHBKjhx/+qeJSNs1F5RKDKp5L2 3W1FTcWwqXz/7mpxomyB3bdYOgZ8f0b/vnvg+wmXJYf8TXBexdcLDnCF5REFneXaSIvb savA== X-Gm-Message-State: AJIora9UBoh4Q0nSmQvSrYrtJQGOQORa42U3tKH2AQUklFnu1r+0LTUt ZT3G+gfnLB2B5fIlDEyUZQjmuR7t8REtPQnabENY1UGSRKlQ6I3KS0mu4fchqQBNjrk4ZwhQQ/9 Ieqbl5Eek1qbCnuI3Ky5k+1Z7 X-Received: by 2002:a05:6a00:c95:b0:52b:e4c:19d5 with SMTP id a21-20020a056a000c9500b0052b0e4c19d5mr575691pfv.50.1657691041131; Tue, 12 Jul 2022 22:44:01 -0700 (PDT) X-Google-Smtp-Source: AGRyM1syH+1nFx4fKmmG1nejbbinYoF6wkNNQaFi8/VZ2oi6PeG4TpUQIBxAubV7u0BXIAuFc5S89Q== X-Received: by 2002:a05:6a00:c95:b0:52b:e4c:19d5 with SMTP id a21-20020a056a000c9500b0052b0e4c19d5mr575672pfv.50.1657691040884; Tue, 12 Jul 2022 22:44:00 -0700 (PDT) Received: from [10.72.12.200] ([209.132.188.80]) by smtp.gmail.com with ESMTPSA id b21-20020aa79515000000b0052ac5e304ccsm6121714pfp.194.2022.07.12.22.43.57 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 12 Jul 2022 22:44:00 -0700 (PDT) Message-ID: <1106133f-ebd4-f6a8-83ab-19e995bcdba6@redhat.com> Date: Wed, 13 Jul 2022 13:43:53 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:91.0) Gecko/20100101 Thunderbird/91.11.0 Subject: Re: [PATCH v2 1/5] vduse: Remove unnecessary spin lock protection Content-Language: en-US To: Xie Yongji , mst@redhat.com, xiaodong.liu@intel.com, maxime.coquelin@redhat.com, stefanha@redhat.com Cc: songmuchun@bytedance.com, virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org References: <20220706050503.171-1-xieyongji@bytedance.com> <20220706050503.171-2-xieyongji@bytedance.com> From: Jason Wang In-Reply-To: <20220706050503.171-2-xieyongji@bytedance.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/7/6 13:04, Xie Yongji 写道: > Taking iotlb lock to access bounce page in page fault > handler is meaningless since vduse_domain_free_bounce_pages() > would only be called during file release. > > Signed-off-by: Xie Yongji > --- > drivers/vdpa/vdpa_user/iova_domain.c | 7 ++----- > 1 file changed, 2 insertions(+), 5 deletions(-) > > diff --git a/drivers/vdpa/vdpa_user/iova_domain.c b/drivers/vdpa/vdpa_user/iova_domain.c > index 6daa3978d290..bca1f0b8850c 100644 > --- a/drivers/vdpa/vdpa_user/iova_domain.c > +++ b/drivers/vdpa/vdpa_user/iova_domain.c > @@ -211,17 +211,14 @@ static struct page * > vduse_domain_get_bounce_page(struct vduse_iova_domain *domain, u64 iova) > { > struct vduse_bounce_map *map; > - struct page *page = NULL; > + struct page *page; > > - spin_lock(&domain->iotlb_lock); > map = &domain->bounce_maps[iova >> PAGE_SHIFT]; > if (!map->bounce_page) > - goto out; > + return NULL; Interesting, I wonder why we don't serialize with vduse_domain_map_bounce_page() with iotlb_lock? Thanks > > page = map->bounce_page; > get_page(page); > -out: > - spin_unlock(&domain->iotlb_lock); > > return page; > }