diff options
| author | Alex Williamson <alex.williamson@redhat.com> | 2014-01-14 20:45:09 -0700 |
|---|---|---|
| committer | Bjorn Helgaas <bhelgaas@google.com> | 2014-01-15 10:43:17 -0700 |
| commit | 890ed578df82f5b7b5a874f9f2fa4f117305df5f (patch) | |
| tree | 8105161071fa46a98feea8253f407adb71f1e242 /drivers/vfio | |
| parent | 61cf16d8bd38c3dc52033ea75d5b1f8368514a17 (diff) | |
| download | linux-890ed578df82f5b7b5a874f9f2fa4f117305df5f.tar.gz | |
vfio-pci: Use pci "try" reset interface
PCI resets will attempt to take the device_lock for any device to be reset. This is a problem if that lock is already held, for instance in the device remove path. It's not sufficient to simply kill the user process or skip the reset if called after .remove as a race could result in the same deadlock. Instead, we handle all resets as "best effort" using the PCI "try" reset interfaces. This prevents the user from being able to induce a deadlock by triggering a reset. Signed-off-by: Alex Williamson <alex.williamson@redhat.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Diffstat (limited to 'drivers/vfio')
| -rw-r--r-- | drivers/vfio/pci/vfio_pci.c | 29 |
1 files changed, 9 insertions, 20 deletions
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c index 6ab71b9fcf8d..2319d206f630 100644 --- a/drivers/vfio/pci/vfio_pci.c +++ b/drivers/vfio/pci/vfio_pci.c @@ -139,25 +139,14 @@ static void vfio_pci_disable(struct vfio_pci_device *vdev) pci_write_config_word(pdev, PCI_COMMAND, PCI_COMMAND_INTX_DISABLE); /* - * 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. + * Try to reset the device. The success of this is dependent on + * being able to lock the device, which is not always possible. */ 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)); + int ret = pci_try_reset_function(pdev); + if (ret) + pr_warn("%s: Failed to reset device %s (%d)\n", + __func__, dev_name(&pdev->dev), ret); } pci_restore_state(pdev); @@ -514,7 +503,7 @@ static long vfio_pci_ioctl(void *device_data, } else if (cmd == VFIO_DEVICE_RESET) { return vdev->reset_works ? - pci_reset_function(vdev->pdev) : -EINVAL; + pci_try_reset_function(vdev->pdev) : -EINVAL; } else if (cmd == VFIO_DEVICE_GET_PCI_HOT_RESET_INFO) { struct vfio_pci_hot_reset_info hdr; @@ -684,8 +673,8 @@ reset_info_exit: &info, slot); if (!ret) /* User has access, do the reset */ - ret = slot ? pci_reset_slot(vdev->pdev->slot) : - pci_reset_bus(vdev->pdev->bus); + ret = slot ? pci_try_reset_slot(vdev->pdev->slot) : + pci_try_reset_bus(vdev->pdev->bus); hot_reset_release: for (i--; i >= 0; i--) |