Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S933520AbcKOPLg (ORCPT <rfc822;w@1wt.eu>);
        Tue, 15 Nov 2016 10:11:36 -0500
Received: from hqemgate14.nvidia.com ([216.228.121.143]:8706 "EHLO
        hqemgate14.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1752020AbcKOPLd (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Tue, 15 Nov 2016 10:11:33 -0500
X-PGP-Universal: processed;
        by hqnvupgp07.nvidia.com on Mon, 14 Nov 2016 19:10:35 -0800
Subject: Re: [PATCH v12 11/22] vfio iommu: Add blocking notifier to notify
 DMA_UNMAP
To: Alex Williamson <alex.williamson@redhat.com>
References: <1479138156-28905-1-git-send-email-kwankhede@nvidia.com>
 <1479138156-28905-12-git-send-email-kwankhede@nvidia.com>
 <20161114165844.52537988@t450s.home>
CC: <pbonzini@redhat.com>, <kraxel@redhat.com>, <cjia@nvidia.com>,
        <qemu-devel@nongnu.org>, <kvm@vger.kernel.org>, <kevin.tian@intel.com>,
        <jike.song@intel.com>, <bjsdjshi@linux.vnet.ibm.com>,
        <linux-kernel@vger.kernel.org>
X-Nvconfidentiality: public
From: Kirti Wankhede <kwankhede@nvidia.com>
Message-ID: <2015af0a-cd66-8092-b075-10a1b434d35c@nvidia.com>
Date: Tue, 15 Nov 2016 20:41:26 +0530
MIME-Version: 1.0
In-Reply-To: <20161114165844.52537988@t450s.home>
X-Originating-IP: [10.24.216.210]
X-ClientProxiedBy: DRHKMAIL103.nvidia.com (10.25.59.17) To
 bgmail102.nvidia.com (10.25.59.11)
Content-Type: text/plain; charset="windows-1252"
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 983
Lines: 32


>> @@ -854,15 +857,29 @@ static int vfio_dma_do_unmap(struct vfio_iommu *iommu,
>>  		if (dma->task->mm != current->mm)
>>  			break;
>>  		unmapped += dma->size;
>> +
>> +		mutex_unlock(&iommu->lock);
>> +		if (iommu->external_domain && !RB_EMPTY_ROOT(&dma->pfn_list)) {
>> +			struct vfio_iommu_type1_dma_unmap nb_unmap;
>> +
>> +			nb_unmap.iova = dma->iova;
>> +			nb_unmap.size = dma->size;
>> +			blocking_notifier_call_chain(&iommu->notifier,
>> +						    VFIO_IOMMU_NOTIFY_DMA_UNMAP,
>> +						    &nb_unmap);
>> +
>> +			if (WARN_ON(!RB_EMPTY_ROOT(&dma->pfn_list)))
>> +				goto unmap_exit;
>> +		}
>> +		mutex_lock(&iommu->lock);
> 
> Why are the mutexes pushed out so far, we are referencing way too much
> stuff outside of the mutex here.  The notifier head has its own
> semaphore, so we should be able to squeeze the mutex opening to just
> around the notifier call, in which case we only worry about the iommu
> itself going way.
> 

Right. Updating.

Thanks,
Kirti