From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp09.au.ibm.com (e23smtp09.au.ibm.com [202.81.31.142]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp09.au.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 785E32C007B for ; Mon, 19 Aug 2013 11:55:45 +1000 (EST) Received: from /spool/local by e23smtp09.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 19 Aug 2013 22:50:09 +1000 Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [9.190.235.152]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 692202BB0052 for ; Mon, 19 Aug 2013 11:55:40 +1000 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r7J1daYI58261604 for ; Mon, 19 Aug 2013 11:39:36 +1000 Received: from d23av01.au.ibm.com (localhost [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id r7J1tddE024778 for ; Mon, 19 Aug 2013 11:55:39 +1000 Date: Mon, 19 Aug 2013 09:55:38 +0800 From: Wei Yang To: Alexey Kardashevskiy Subject: Re: [PATCH 2/2] powerpc/iommu: check dev->iommu_group before remove a device from iommu_group Message-ID: <20130819015538.GB8342@weiyang.vnet.ibm.com> References: <1376647687-20550-1-git-send-email-weiyang@linux.vnet.ibm.com> <1376647687-20550-3-git-send-email-weiyang@linux.vnet.ibm.com> <520DFBC8.4040509@ozlabs.ru> <20130819012945.GA8342@weiyang.vnet.ibm.com> <52117765.7010205@ozlabs.ru> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <52117765.7010205@ozlabs.ru> Cc: paulus@au1.ibm.com, benh@au1.ibm.com, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Reply-To: Wei Yang List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, Aug 19, 2013 at 11:39:49AM +1000, Alexey Kardashevskiy wrote: >On 08/19/2013 11:29 AM, Wei Yang wrote: >> On Fri, Aug 16, 2013 at 08:15:36PM +1000, Alexey Kardashevskiy wrote: >>> On 08/16/2013 08:08 PM, Wei Yang wrote: >>>> --- >>>> arch/powerpc/kernel/iommu.c | 3 ++- >>>> 1 files changed, 2 insertions(+), 1 deletions(-) >>>> >>>> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c >>>> index b20ff17..5abf7c3 100644 >>>> --- a/arch/powerpc/kernel/iommu.c >>>> +++ b/arch/powerpc/kernel/iommu.c >>>> @@ -1149,7 +1149,8 @@ static int iommu_bus_notifier(struct notifier_block *nb, >>>> case BUS_NOTIFY_ADD_DEVICE: >>>> return iommu_add_device(dev); >>>> case BUS_NOTIFY_DEL_DEVICE: >>>> - iommu_del_device(dev); >>>> + if (dev->iommu_group) >>>> + iommu_del_device(dev); >>>> return 0; >>>> default: >>>> return 0; >>>> >>> >>> This one seems redundant, no? >> >> Sorry for the late. >> >> Yes, these two patches have the same purpose to guard the system, while in two >> different places. One is in powernv platform, the other is in the generic iommu >> driver. >> >> The one in powernv platform is used to correct the original logic. >> >> The one in generic iommu driver is to keep system safe in case other platform to >> call iommu_group_remove_device() without the check. > > >But I am moving bus notifier to powernv code (posted a patch last week, >otherwise Freescale's IOMMU conflicted) so this won't be the case. Yes, I see the patch. This means other platforms, besides powernv, will check the dev->iommu_group before remove the device? This would be a convention? If this is the case, the second patch is enough. We don't need to check it in generic iommu driver. Since I am not very familiar with the code convention, I post these two patches together. This doesn't mean I need to push both of them. Your comments are welcome, lets me understand which one is more suitable in this case. > > > >-- >Alexey -- Richard Yang Help you, Help me