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=-4.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 EAE2CC2D0A8 for ; Mon, 28 Sep 2020 12:25:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABA532083B for ; Mon, 28 Sep 2020 12:25:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601295957; bh=wVrs+3kytjBZohn7BTL2U88iwkha6UbOsn4DCBgdtK0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=JFJu5StOdK4vW9vObqgWovgwZnDf2OQLbUOoO4jjnfY4PQDuOViht8bj5E6kuxUIh /yk4JSJNWxk5dALEepiwVrKmSuN5L/KkUwD65iQh+aiAtBwMrRyRws+b/x1HLSIf1P 93rpWyFmIUstp7zQ3UYuaY51eQS6kgYsKXHOiGy0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726573AbgI1MZ4 (ORCPT ); Mon, 28 Sep 2020 08:25:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:57264 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726442AbgI1MZ4 (ORCPT ); Mon, 28 Sep 2020 08:25:56 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8638C207E8; Mon, 28 Sep 2020 12:25:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601295955; bh=wVrs+3kytjBZohn7BTL2U88iwkha6UbOsn4DCBgdtK0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EB+Oa95iV1npMb0/iwRazczbrwezIYljsx+rtwNmKiGkdgkovVWks8EaIIA4E47NT 3SUEdo7tmd/utx0m3zdlztaHKbGlZvBBK9H/iWj/5Q9Ev08hGMAnpkZ0o/FAsTVgpw IHXoBZtGXWQkv6l0/Kv12svaLSlasuMxnuPH5dq8= Date: Mon, 28 Sep 2020 14:26:02 +0200 From: Greg Kroah-Hartman To: Shuo A Liu Cc: linux-kernel@vger.kernel.org, x86@kernel.org, "H . Peter Anvin" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Sean Christopherson , Yu Wang , Reinette Chatre , Zhi Wang , Zhenyu Wang Subject: Re: [PATCH v4 06/17] virt: acrn: Introduce VM management interfaces Message-ID: <20200928122602.GB682772@kroah.com> References: <20200922114311.38804-1-shuo.a.liu@intel.com> <20200922114311.38804-7-shuo.a.liu@intel.com> <20200927104702.GE88650@kroah.com> <20200928035030.GD1057@shuo-intel.sh.intel.com> <20200928052516.GD767987@kroah.com> <20200928062934.GF1057@shuo-intel.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200928062934.GF1057@shuo-intel.sh.intel.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 28, 2020 at 02:29:34PM +0800, Shuo A Liu wrote: > On Mon 28.Sep'20 at 7:25:16 +0200, Greg Kroah-Hartman wrote: > > On Mon, Sep 28, 2020 at 11:50:30AM +0800, Shuo A Liu wrote: > > > > > + write_lock_bh(&acrn_vm_list_lock); > > > > > + list_add(&vm->list, &acrn_vm_list); > > > > > + write_unlock_bh(&acrn_vm_list_lock); > > > > > > > > Why are the _bh() variants being used here? > > > > > > > > You are only accessing this list from userspace context in this patch. > > > > > > > > Heck, you aren't even reading from the list, only writing to it... > > > > > > acrn_vm_list is read in a tasklet which dispatch I/O requests and is wrote > > > in VM creation ioctl. Use the rwlock mechanism to protect it. > > > The reading operation is introduced in the following patches of this > > > series. So i keep the lock type at the moment of introduction. > > > > Ok, but think about someone trying to review this code. Does this lock > > actually make sense here? No, it does not. How am I supposed to know > > to look at future patches to determine that it changes location and > > usage to require this? > > OK. May i know how to handle such kind of code submission? Or which way > following do you prefer? > 1) Use a mutex lock here, then change it to rwlock in a later patch > of this series. Wouldn't this make more sense if you had to read these one after another? > 2) Add more comments in changelog about the lock. (Now, there is > comment around the acrn_vm_list_lock) It's hard to verify a comment's statement without digging through other patches in the series, right? You want the reviewer to just trust you? :) Again, what would _YOU_ want to see if you had to review this? > > That's just not fair, would you want to review something like this? > > > > And a HUGE meta-comment, again, why am I the only one reviewing this > > stuff? Why do you have a ton of Intel people on the Cc: yet it is, once > > again, my job to do this? > > The patchset has been reviewed in Intel's internal mailist several > rounds and got Reviewed-by: before send out. That's why i Cced many > Intel people as well. Then why didn't any of those intel people on the cc: actually review it after you have sent it out? Why is it only me? Do I need to wait longer for them to get to this? I'll gladly do so next time... > This patchset is all about a common driver for the ACRN hypervisor > support. I put the code in drivers/virt/ and found you are one of the > maintainer of vboxguest driver which is in the same subdirectory. I > thought you should be the right person to be Cced when i submitted this > series. I am, I'm not complaining about that. I'm complaining that it seems to be _only_ me reviewing this here, and not any of the people you are cc:ing from intel. Most of those people should be giving you this same type of review comments and not forcing an external person to do so, right? > Certainly, any comments are welcome. And really appreciate your review > and help. I have little experience to submit a new driver to the > community, my apologies if thing goes wrong. You didn't do anything wrong, I'm arguing about the larger meta-issue I have right now with Intel and the lack of reviews that seems to happen from other Intel people on their co-workers patches. Anyway, you are doing fine, it's an iterative process, hopefully you can also review other people's patches in this area that are being posted as well. thanks, greg k-h