diff options
| author | Alex Williamson <alex.williamson@redhat.com> | 2013-06-10 16:40:57 -0600 |
|---|---|---|
| committer | Alex Williamson <alex.williamson@redhat.com> | 2013-07-24 16:36:41 -0600 |
| commit | d24cdbfd28b7e0ffecb1e281d73e73c03a57f734 (patch) | |
| tree | 5121604d0025974356f09bb0027e018f1be05e03 /drivers/vfio | |
| parent | c64019302bbb0b445484d870e674ab34a19a18a1 (diff) | |
| download | linux-rt-d24cdbfd28b7e0ffecb1e281d73e73c03a57f734.tar.gz | |
vfio-pci: Avoid deadlock on remove
If an attempt is made to unbind a device from vfio-pci while that
device is in use, the request is blocked until the device becomes
unused. Unfortunately, that unbind path still grabs the device_lock,
which certain things like __pci_reset_function() also want to take.
This means we need to try to acquire the locks ourselves and use the
pre-locked version, __pci_reset_function_locked().
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Diffstat (limited to 'drivers/vfio')
| -rw-r--r-- | drivers/vfio/pci/vfio_pci.c | 23 |
1 files changed, 21 insertions, 2 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); } |