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 1D218C43334 for ; Wed, 13 Jul 2022 10:39:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236007AbiGMKjU (ORCPT ); Wed, 13 Jul 2022 06:39:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236140AbiGMKjR (ORCPT ); Wed, 13 Jul 2022 06:39:17 -0400 Received: from mail-ej1-x630.google.com (mail-ej1-x630.google.com [IPv6:2a00:1450:4864:20::630]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3AA5FFD218 for ; Wed, 13 Jul 2022 03:39:16 -0700 (PDT) Received: by mail-ej1-x630.google.com with SMTP id dn9so19080071ejc.7 for ; Wed, 13 Jul 2022 03:39:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=QIHulqJCI6QS+uVnMeeckx+ivdKRcKJrp3Fznv1diRA=; b=b39JIh5Sn80p9Cwg5CczCcll9xxOtCpwBU8EkcKlvxasF1TGM7spzJvVWQIH3+MQN2 NkjNvqVpZ6lve4jSZ83utKSYsP8h1Olo2uWm3y55yvlLvz50se+/MKxCEgjSKbAWzuY6 OO+AzyW2wsKjAogwRcyLpW6pMmZ8xiM6MTwpBFR4HhU8YkIyNa5hW0xgAZdhIXKMg5qN qnT6kms49QQxRLNzRngFZIs8CEYQfdhG/h15zgWFt77g6ENFq56QyKyg0g0ggEIPcmcc eptKoheTXinZKNx6tbzOdabE1KS7Im2Pje8bRQLy9zCCL62Tkejy15eidgr7QS92QLC9 HhAw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=QIHulqJCI6QS+uVnMeeckx+ivdKRcKJrp3Fznv1diRA=; b=7SLuYba5iHQvh/HHHaA5snB+HxUmZCAbMqOLFFLvlxjWJwnSiDj6ILcdopj9Eq7QLD AP02QtZY/5AISHWP6GQ1cDAWSj3hZ++2eW41aC4ZpmXG8EWII/y/PUJDmaoT4yIlXur2 F2VYzte6zaDSolTsZVK4OWCdBAvhKM9c4bQYf3OQe7NeuhWICDsxAj7IlA1SjTOZgoCC PEXGY9jgXn/54GgVne4/z1rvJuLELBfjgNvk9LYJsBRgnn9HcjfT1fDuWJN9CFCzfAMI 1HGjulLs65M8JeJ5veVXoTS8wgc/jvK2M4WyeMQhMjvvs5geEYA9MQAQ6R3l7ClgPxMk JSlA== X-Gm-Message-State: AJIora8W2kdQTpsqHr6QA6hIXvfKGICpPNywoXVSIFc3AIr6NJwY/++P Z21yU3CVbbV/pAKi9+BaZPi1smQow1OFWXkswGJc X-Google-Smtp-Source: AGRyM1tg7nAPmOCQxALFa3BTiCVyybPUfjZcPF2mOe+x/k9WKNSd7G90DvHc7x20Dc3t7OOY9yRx2gGpj+toZuzXBVA= X-Received: by 2002:a17:907:a056:b0:72b:1964:fbcc with SMTP id gz22-20020a170907a05600b0072b1964fbccmr2820402ejc.489.1657708754817; Wed, 13 Jul 2022 03:39:14 -0700 (PDT) MIME-Version: 1.0 References: <20220706050503.171-1-xieyongji@bytedance.com> <20220706050503.171-2-xieyongji@bytedance.com> <20220713015352-mutt-send-email-mst@kernel.org> In-Reply-To: <20220713015352-mutt-send-email-mst@kernel.org> From: Yongji Xie Date: Wed, 13 Jul 2022 18:39:04 +0800 Message-ID: Subject: Re: [PATCH v2 1/5] vduse: Remove unnecessary spin lock protection To: "Michael S. Tsirkin" Cc: Jason Wang , Liu Xiaodong , Maxime Coquelin , Stefan Hajnoczi , songmuchun@bytedance.com, virtualization , linux-kernel Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 13, 2022 at 1:57 PM Michael S. Tsirkin wrote: > > On Wed, Jul 06, 2022 at 01:04:59PM +0800, Xie Yongji wrote: > > 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 > > vduse_domain_free_bounce_pages is not the > only one taking this lock. Yes, but only vduse_domain_free_bounce_pages() is to protect domain->bounce_maps with this lock. In other places, the lock is used to protect the domain->iotlb. > This commit log needs more > analysis documenting all points of access to bounce_maps > and why vduse_domain_get_bounce_page and file > release are the only two. > OK, I will explain that we actually protect two different variables (domain->bounce_maps and domain->iotlb) with one lock. Thanks, Yongji