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From: Joerg Roedel <jroedel@suse.de>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	David Woodhouse <dwmw2@infradead.org>,
	Jiang Liu <jiang.liu@linux.intel.com>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	Myron Stowe <mstowe@redhat.com>
Subject: Re: [PATCH 2/2] iommu/vt-d: Only remove domain when device is removed
Date: Thu, 6 Nov 2014 13:54:05 +0100	[thread overview]
Message-ID: <20141106125405.GI8354@suse.de> (raw)
In-Reply-To: <1415117537.27420.428.camel@ul30vt.home>

Hi Alex,

On Tue, Nov 04, 2014 at 09:12:17AM -0700, Alex Williamson wrote:
> I haven't tested it, but I'm concerned whether this has introduced a
> domain leak.  If we think about the case of unbinding a device from a
> host driver and attaching it to a domain through the IOMMU API, I think
> we used to count on this path to call domain_exit(), which made the
> domain_context_mapped() in intel_iommu_attach_device() "unlikely".  With
> this change, isn't the test in intel_iommu_attach_device() now neither
> likely nor unlikely and we're only removing the dev_info from the domain
> and not destroying the domain itself?  Thanks,

As I see it, there is no leak. The DMA-API domains are kept in the
device_domain_list and re-used when the device driver re-attaches. But
your are right that the unlikely in intel_iommu_attach_device() isn't
true anymore. We could probably remove it.


	Joerg


WARNING: multiple messages have this Message-ID (diff)
From: Joerg Roedel <jroedel-l3A5Bk7waGM@public.gmane.org>
To: Alex Williamson
	<alex.williamson-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
Cc: Greg Kroah-Hartman
	<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org,
	Myron Stowe <mstowe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	David Woodhouse <dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	Jiang Liu <jiang.liu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
Subject: Re: [PATCH 2/2] iommu/vt-d: Only remove domain when device is removed
Date: Thu, 6 Nov 2014 13:54:05 +0100	[thread overview]
Message-ID: <20141106125405.GI8354@suse.de> (raw)
In-Reply-To: <1415117537.27420.428.camel-85EaTFmN5p//9pzu0YdTqQ@public.gmane.org>

Hi Alex,

On Tue, Nov 04, 2014 at 09:12:17AM -0700, Alex Williamson wrote:
> I haven't tested it, but I'm concerned whether this has introduced a
> domain leak.  If we think about the case of unbinding a device from a
> host driver and attaching it to a domain through the IOMMU API, I think
> we used to count on this path to call domain_exit(), which made the
> domain_context_mapped() in intel_iommu_attach_device() "unlikely".  With
> this change, isn't the test in intel_iommu_attach_device() now neither
> likely nor unlikely and we're only removing the dev_info from the domain
> and not destroying the domain itself?  Thanks,

As I see it, there is no leak. The DMA-API domains are kept in the
device_domain_list and re-used when the device driver re-attaches. But
your are right that the unlikely in intel_iommu_attach_device() isn't
true anymore. We could probably remove it.


	Joerg

  reply	other threads:[~2014-11-06 12:54 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-30 11:02 [PATCH 0/2] iommu/vt-d: Keep RMRR mappings around on driver unbind Joerg Roedel
2014-09-30 11:02 ` Joerg Roedel
2014-09-30 11:02 ` [PATCH 1/2] driver core: Add BUS_NOTIFY_REMOVED_DEVICE event Joerg Roedel
2014-09-30 11:02   ` Joerg Roedel
2014-09-30 11:02 ` [PATCH 2/2] iommu/vt-d: Only remove domain when device is removed Joerg Roedel
2014-09-30 11:02   ` Joerg Roedel
2014-11-04 16:12   ` Alex Williamson
2014-11-04 16:12     ` Alex Williamson
2014-11-06 12:54     ` Joerg Roedel [this message]
2014-11-06 12:54       ` Joerg Roedel
2014-11-06 16:16       ` Alex Williamson
2014-11-06 16:16         ` Alex Williamson
2014-11-06 16:43         ` Alex Williamson
2014-11-06 16:43           ` Alex Williamson
2014-12-09 12:15         ` Joerg Roedel
2014-12-09 12:15           ` Joerg Roedel
2014-12-11 16:35           ` Jerry Hoemann
2014-12-11 16:35             ` Jerry Hoemann
2014-12-12 15:56             ` Joerg Roedel
2014-12-12 15:56               ` Joerg Roedel
2014-10-01 22:35 ` [PATCH 0/2] iommu/vt-d: Keep RMRR mappings around on driver unbind Greg Kroah-Hartman
2014-10-01 22:35   ` Greg Kroah-Hartman
2014-10-02  9:20   ` Joerg Roedel
2014-10-02  9:20     ` Joerg Roedel
2014-10-02  0:30 ` Jerry Hoemann
2014-10-02  0:30   ` Jerry Hoemann

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