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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,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 6BD72C63777 for ; Thu, 26 Nov 2020 08:59:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 11C1C20B80 for ; Thu, 26 Nov 2020 08:59:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="PSNCdCVQ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389106AbgKZI7O (ORCPT ); Thu, 26 Nov 2020 03:59:14 -0500 Received: from mail.kernel.org ([198.145.29.99]:57618 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729672AbgKZI7N (ORCPT ); Thu, 26 Nov 2020 03:59:13 -0500 Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (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 2BBEC20B1F; Thu, 26 Nov 2020 08:59:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1606381153; bh=3Z7eRBn4dS+xir49QzOYa87bW7pn9PHPlCT+5gQc7Og=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=PSNCdCVQz1MyuMUhKyU2c1gKbWizEfuomF+7Qezcb4C2PGrhqfIdaty8QHPV2jQrU 5H7dE01Wxra89dScVelDQTIPKy0J6SjOvPV5vJT/sode7QxQw+QnkctQn2Iz6lrvwm IXbYN5r4CrtuZe4lmNuv5hRHehQvpFc6OtEGM/6E= Date: Thu, 26 Nov 2020 08:59:08 +0000 From: Will Deacon To: Yang Yingliang Cc: Lu Baolu , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] iommu: fix return error code in iommu_probe_device() Message-ID: <20201126085908.GC17797@willie-the-truck> References: <20201117025238.3425422-1-yangyingliang@huawei.com> <835ab066-b6b8-a211-4941-c01781031de8@linux.intel.com> <454f5e3e-c380-e8a5-9283-3f7578eb601e@huawei.com> <20201117224102.GD524@willie-the-truck> <78bee047-ab33-4d81-6f77-af4c5b6e8aaa@huawei.com> <20201125113545.GA15451@willie-the-truck> <9e7481f4-e55e-6c7a-dde9-62912c6e5eb4@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9e7481f4-e55e-6c7a-dde9-62912c6e5eb4@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Nov 26, 2020 at 10:29:57AM +0800, Yang Yingliang wrote: > > On 2020/11/25 19:35, Will Deacon wrote: > > On Wed, Nov 25, 2020 at 09:54:34AM +0800, Yang Yingliang wrote: > > > On 2020/11/18 6:41, Will Deacon wrote: > > > > On Tue, Nov 17, 2020 at 07:11:28PM +0800, Yang Yingliang wrote: > > > > > On 2020/11/17 17:40, Lu Baolu wrote: > > > > > > On 2020/11/17 10:52, Yang Yingliang wrote: > > > > > > > If iommu_group_get() failed, it need return error code > > > > > > > in iommu_probe_device(). > > > > > > > > > > > > > > Fixes: cf193888bfbd ("iommu: Move new probe_device path...") > > > > > > > Reported-by: Hulk Robot > > > > > > > Signed-off-by: Yang Yingliang > > > > > > > --- > > > > > > >   drivers/iommu/iommu.c | 4 +++- > > > > > > >   1 file changed, 3 insertions(+), 1 deletion(-) > > > > > > > > > > > > > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > > > > > > > index b53446bb8c6b..6f4a32df90f6 100644 > > > > > > > --- a/drivers/iommu/iommu.c > > > > > > > +++ b/drivers/iommu/iommu.c > > > > > > > @@ -253,8 +253,10 @@ int iommu_probe_device(struct device *dev) > > > > > > >           goto err_out; > > > > > > >         group = iommu_group_get(dev); > > > > > > > -    if (!group) > > > > > > > +    if (!group) { > > > > > > > +        ret = -ENODEV; > > > > > > Can you please explain why you use -ENODEV here? > > > > > Before 79659190ee97 ("iommu: Don't take group reference in > > > > > iommu_alloc_default_domain()"), in > > > > > > > > > > iommu_alloc_default_domain(), if group is NULL, it will return -ENODEV. > > > > Hmm. While I think the patch is ok, I'm not sure it qualifies as a fix. > > > > Has iommu_probe_device() ever propagated this error? The commit you > > > > identify in the 'Fixes:' tag doesn't seem to change this afaict. > > > I think after this commit 439945e74a4b ("iommu: Move default domain > > > allocation to iommu_probe_device()"), > > That SHA doesn't exist in my tree (maybe you mean 6e1aa2049154?). But even > > then, I'm not sure 6e1aa2049154 is actually broken if you look at the > > interaction with group creation in __iommu_probe_device(). > > > > In fact, isn't that the case in mainline too? If __iommu_probe_device() > > returns 0, then we _know_ a group exists and so iommu_group_get() will > > succeed. I'm still happy with the patch in case this changes in future, > > but it doesn't appear to be fixing anything. Do you agree? > > Yes, I look into the __iommu_probe_device(), if it can't get group, it will > return error > > first.  Do I need send a v2 without the fix tag ? Yes, I think that would be fine, and perhaps update the commit message to make it clear that this is purely cosmetic. Will