Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753861Ab3HSBzq (ORCPT ); Sun, 18 Aug 2013 21:55:46 -0400 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:58620 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751500Ab3HSBzo (ORCPT ); Sun, 18 Aug 2013 21:55:44 -0400 Date: Mon, 19 Aug 2013 09:55:38 +0800 From: Wei Yang To: Alexey Kardashevskiy Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, benh@au1.ibm.com, paulus@au1.ibm.com 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> Reply-To: Wei Yang 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 Content-Disposition: inline In-Reply-To: <52117765.7010205@ozlabs.ru> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-MML: No X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13081901-1618-0000-0000-00000479489F Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2265 Lines: 68 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/