linux-kernel - [PATCH 3.16 013/158] iommu/vt-d: Defer domain removal if device is assigned to a driver

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Message-Id: <20140915192543.280737055@linuxfoundation.org>
Date:	Mon, 15 Sep 2014 12:24:12 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Jiang Liu <jiang.liu@...ux.intel.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Joerg Roedel <jroedel@...e.de>
Subject: [PATCH 3.16 013/158] iommu/vt-d: Defer domain removal if device is assigned to a driver

3.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Joerg Roedel <jroedel@...e.de>

commit e7f9fa5498d91fcdc63d93007ba43f36b1a30538 upstream.

When the BUS_NOTIFY_DEL_DEVICE event is received the device
might still be attached to a driver. In this case the domain
can't be released as the mappings might still be in use.

Defer the domain removal in this case until we receivce the
BUS_NOTIFY_UNBOUND_DRIVER event.

Cc: Jiang Liu <jiang.liu@...ux.intel.com>
Cc: David Woodhouse <dwmw2@...radead.org>
Signed-off-by: Joerg Roedel <jroedel@...e.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/iommu/intel-iommu.c |    8 ++++++++
 1 file changed, 8 insertions(+)

--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -3891,6 +3891,14 @@ static int device_notifier(struct notifi
 	    action != BUS_NOTIFY_DEL_DEVICE)
 		return 0;
 
+	/*
+	 * If the device is still attached to a device driver we can't
+	 * tear down the domain yet as DMA mappings may still be in use.
+	 * Wait for the BUS_NOTIFY_UNBOUND_DRIVER event to do that.
+	 */
+	if (action == BUS_NOTIFY_DEL_DEVICE && dev->driver != NULL)
+		return 0;
+
 	domain = find_domain(dev);
 	if (!domain)
 		return 0;


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