vfio-pci: Don't use device_lock around AER interrupt setup
device_lock is much too prone to lockups. For instance if we have a
pending .remove then device_lock is already held. If userspace
attempts to modify AER signaling after that point, a deadlock occurs.
eventfd setup/teardown is already protected in vfio with the igate
mutex. AER is not a high performance interrupt, so we can also use
the same mutex to protect signaling versus setup races.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 6ab71b9..3ffd27f 100644
--- a/drivers/vfio/pci/vfio_pci.c
+++ b/drivers/vfio/pci/vfio_pci.c
@@ -883,9 +883,13 @@
return PCI_ERS_RESULT_DISCONNECT;
}
+ mutex_lock(&vdev->igate);
+
if (vdev->err_trigger)
eventfd_signal(vdev->err_trigger, 1);
+ mutex_unlock(&vdev->igate);
+
vfio_device_put(device);
return PCI_ERS_RESULT_CAN_RECOVER;