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authorAlex Williamson <alex.williamson@redhat.com>2017-07-26 14:33:15 -0600
committerAlex Williamson <alex.williamson@redhat.com>2017-07-26 14:33:15 -0600
commit9f47803503247c9ec414072c0724073a1c8c3433 (patch)
treed0fb9cdb6f4864c8890b68b550564d98a74e224b /drivers/vfio
parentbb67b496c338e15813f075f482067da930f52e39 (diff)
downloadlinux-9f47803503247c9ec414072c0724073a1c8c3433.tar.bz2
vfio/pci: Use pci_try_reset_function() on initial open
Device lock bites again; if a device .remove() callback races a user calling ioctl(VFIO_GROUP_GET_DEVICE_FD), the unbind request will hold the device lock, but the user ioctl may have already taken a vfio_device reference. In the case of a PCI device, the initial open will attempt to reset the device, which again attempts to get the device lock, resulting in deadlock. Use the trylock PCI reset interface and return error on the open path if reset fails due to lock contention. Link: https://lkml.org/lkml/2017/7/25/381 Reported-by: Wen Congyang <wencongyang2@huawei.com> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio')
-rw-r--r--drivers/vfio/pci/vfio_pci.c9
1 files changed, 8 insertions, 1 deletions
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 063c1ce6fa42..f041b1a6cf66 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -226,7 +226,14 @@ static int vfio_pci_enable(struct vfio_pci_device *vdev)
if (ret)
return ret;
- vdev->reset_works = (pci_reset_function(pdev) == 0);
+ /* If reset fails because of the device lock, fail this path entirely */
+ ret = pci_try_reset_function(pdev);
+ if (ret == -EAGAIN) {
+ pci_disable_device(pdev);
+ return ret;
+ }
+
+ vdev->reset_works = !ret;
pci_save_state(pdev);
vdev->pci_saved_state = pci_store_saved_state(pdev);
if (!vdev->pci_saved_state)