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 <[email protected]> --- drivers/vfio/pci/vfio_pci.c | 23 +++++++++++++++++++++-- 1 file changed, 21 insertions(+), 2 deletions(-) diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index ac37254..41023e4 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); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
