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authorLinus Torvalds <torvalds@linux-foundation.org>2013-07-31 17:53:38 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-31 17:53:38 -0700
commit3df765fc65354b73cdbba1a862a69dec79934633 (patch)
tree4cf2cb641c01a82ebd9ead05c772783196226432
parent19788a900803138a4c7c997eb5e9c27f9d17667e (diff)
parentd24cdbfd28b7e0ffecb1e281d73e73c03a57f734 (diff)
Merge tag 'vfio-v3.11-rc4' of git://github.com/awilliam/linux-vfio
Pull vfio fixes from Alex Williamson: "misc fixes around overreacting to bus notifier events and a locking fix for a corner case blocked remove" * tag 'vfio-v3.11-rc4' of git://github.com/awilliam/linux-vfio: vfio-pci: Avoid deadlock on remove vfio: Ignore sprurious notifies vfio: Don't overreact to DEL_DEVICE
-rw-r--r--drivers/vfio/pci/vfio_pci.c23
-rw-r--r--drivers/vfio/vfio.c37
2 files changed, 31 insertions, 29 deletions
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index c5179e269df6..cef6002acbd4 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -137,8 +137,27 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev)
*/
pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE);
- if (vdev->reset_works)
- __pci_reset_function(pdev);
+ /*
+ * Careful, device_lock may already be held. This is the case if
+ * a driver unbind is blocked. Try to get the locks ourselves to
+ * prevent a deadlock.
+ */
+ if (vdev->reset_works) {
+ bool reset_done = false;
+
+ if (pci_cfg_access_trylock(pdev)) {
+ if (device_trylock(&pdev->dev)) {
+ __pci_reset_function_locked(pdev);
+ reset_done = true;
+ device_unlock(&pdev->dev);
+ }
+ pci_cfg_access_unlock(pdev);
+ }
+
+ if (!reset_done)
+ pr_warn("%s: Unable to acquire locks for reset of %s\n",
+ __func__, dev_name(&pdev->dev));
+ }
pci_restore_state(pdev);
}
diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
index c488da5db7c7..842f4507883e 100644
--- a/drivers/vfio/vfio.c
+++ b/drivers/vfio/vfio.c
@@ -494,27 +494,6 @@ static int vfio_group_nb_add_dev(struct vfio_group *group, struct device *dev)
return 0;
}
-static int vfio_group_nb_del_dev(struct vfio_group *group, struct device *dev)
-{
- struct vfio_device *device;
-
- /*
- * Expect to fall out here. If a device was in use, it would
- * have been bound to a vfio sub-driver, which would have blocked
- * in .remove at vfio_del_group_dev. Sanity check that we no
- * longer track the device, so it's safe to remove.
- */
- device = vfio_group_get_device(group, dev);
- if (likely(!device))
- return 0;
-
- WARN("Device %s removed from live group %d!\n", dev_name(dev),
- iommu_group_id(group->iommu_group));
-
- vfio_device_put(device);
- return 0;
-}
-
static int vfio_group_nb_verify(struct vfio_group *group, struct device *dev)
{
/* We don't care what happens when the group isn't in use */
@@ -531,13 +510,11 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
struct device *dev = data;
/*
- * Need to go through a group_lock lookup to get a reference or
- * we risk racing a group being removed. Leave a WARN_ON for
- * debuging, but if the group no longer exists, a spurious notify
- * is harmless.
+ * Need to go through a group_lock lookup to get a reference or we
+ * risk racing a group being removed. Ignore spurious notifies.
*/
group = vfio_group_try_get(group);
- if (WARN_ON(!group))
+ if (!group)
return NOTIFY_OK;
switch (action) {
@@ -545,7 +522,13 @@ static int vfio_iommu_group_notifier(struct notifier_block *nb,
vfio_group_nb_add_dev(group, dev);
break;
case IOMMU_GROUP_NOTIFY_DEL_DEVICE:
- vfio_group_nb_del_dev(group, dev);
+ /*
+ * Nothing to do here. If the device is in use, then the
+ * vfio sub-driver should block the remove callback until
+ * it is unused. If the device is unused or attached to a
+ * stub driver, then it should be released and we don't
+ * care that it will be going away.
+ */
break;
case IOMMU_GROUP_NOTIFY_BIND_DRIVER:
pr_debug("%s: Device %s, group %d binding to driver\n",