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authorBjorn Helgaas <bhelgaas@google.com>2014-01-15 17:53:35 (GMT)
committerBjorn Helgaas <bhelgaas@google.com>2014-01-15 17:53:35 (GMT)
commit6e2d98dc1af49a6736cd9c54e2e44b5d5234d242 (patch)
treef17178aad8cc3e721c8da14ad439379a03a488ef /drivers
parent40304618468cae5259f77c15511e4feb7bfb624b (diff)
parent890ed578df82f5b7b5a874f9f2fa4f117305df5f (diff)
downloadlinux-6e2d98dc1af49a6736cd9c54e2e44b5d5234d242.tar.xz
Merge branch 'pci/reset' into next
* pci/reset: vfio-pci: Use pci "try" reset interface PCI: Add pci_try_reset_function(), pci_try_reset_slot(), pci_try_reset_bus()
Diffstat (limited to 'drivers')
-rw-r--r--drivers/pci/pci.c155
-rw-r--r--drivers/vfio/pci/vfio_pci.c29
2 files changed, 164 insertions, 20 deletions
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 95c97be..b6d4afa 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -3250,6 +3250,18 @@ static void pci_dev_lock(struct pci_dev *dev)
device_lock(&dev->dev);
}
+/* Return 1 on successful lock, 0 on contention */
+static int pci_dev_trylock(struct pci_dev *dev)
+{
+ if (pci_cfg_access_trylock(dev)) {
+ if (device_trylock(&dev->dev))
+ return 1;
+ pci_cfg_access_unlock(dev);
+ }
+
+ return 0;
+}
+
static void pci_dev_unlock(struct pci_dev *dev)
{
device_unlock(&dev->dev);
@@ -3393,6 +3405,34 @@ int pci_reset_function(struct pci_dev *dev)
}
EXPORT_SYMBOL_GPL(pci_reset_function);
+/**
+ * pci_try_reset_function - quiesce and reset a PCI device function
+ * @dev: PCI device to reset
+ *
+ * Same as above, except return -EAGAIN if unable to lock device.
+ */
+int pci_try_reset_function(struct pci_dev *dev)
+{
+ int rc;
+
+ rc = pci_dev_reset(dev, 1);
+ if (rc)
+ return rc;
+
+ pci_dev_save_and_disable(dev);
+
+ if (pci_dev_trylock(dev)) {
+ rc = __pci_dev_reset(dev, 0);
+ pci_dev_unlock(dev);
+ } else
+ rc = -EAGAIN;
+
+ pci_dev_restore(dev);
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(pci_try_reset_function);
+
/* Lock devices from the top of the tree down */
static void pci_bus_lock(struct pci_bus *bus)
{
@@ -3417,6 +3457,32 @@ static void pci_bus_unlock(struct pci_bus *bus)
}
}
+/* Return 1 on successful lock, 0 on contention */
+static int pci_bus_trylock(struct pci_bus *bus)
+{
+ struct pci_dev *dev;
+
+ list_for_each_entry(dev, &bus->devices, bus_list) {
+ if (!pci_dev_trylock(dev))
+ goto unlock;
+ if (dev->subordinate) {
+ if (!pci_bus_trylock(dev->subordinate)) {
+ pci_dev_unlock(dev);
+ goto unlock;
+ }
+ }
+ }
+ return 1;
+
+unlock:
+ list_for_each_entry_continue_reverse(dev, &bus->devices, bus_list) {
+ if (dev->subordinate)
+ pci_bus_unlock(dev->subordinate);
+ pci_dev_unlock(dev);
+ }
+ return 0;
+}
+
/* Lock devices from the top of the tree down */
static void pci_slot_lock(struct pci_slot *slot)
{
@@ -3445,6 +3511,37 @@ static void pci_slot_unlock(struct pci_slot *slot)
}
}
+/* Return 1 on successful lock, 0 on contention */
+static int pci_slot_trylock(struct pci_slot *slot)
+{
+ struct pci_dev *dev;
+
+ list_for_each_entry(dev, &slot->bus->devices, bus_list) {
+ if (!dev->slot || dev->slot != slot)
+ continue;
+ if (!pci_dev_trylock(dev))
+ goto unlock;
+ if (dev->subordinate) {
+ if (!pci_bus_trylock(dev->subordinate)) {
+ pci_dev_unlock(dev);
+ goto unlock;
+ }
+ }
+ }
+ return 1;
+
+unlock:
+ list_for_each_entry_continue_reverse(dev,
+ &slot->bus->devices, bus_list) {
+ if (!dev->slot || dev->slot != slot)
+ continue;
+ if (dev->subordinate)
+ pci_bus_unlock(dev->subordinate);
+ pci_dev_unlock(dev);
+ }
+ return 0;
+}
+
/* Save and disable devices from the top of the tree down */
static void pci_bus_save_and_disable(struct pci_bus *bus)
{
@@ -3568,6 +3665,35 @@ int pci_reset_slot(struct pci_slot *slot)
}
EXPORT_SYMBOL_GPL(pci_reset_slot);
+/**
+ * pci_try_reset_slot - Try to reset a PCI slot
+ * @slot: PCI slot to reset
+ *
+ * Same as above except return -EAGAIN if the slot cannot be locked
+ */
+int pci_try_reset_slot(struct pci_slot *slot)
+{
+ int rc;
+
+ rc = pci_slot_reset(slot, 1);
+ if (rc)
+ return rc;
+
+ pci_slot_save_and_disable(slot);
+
+ if (pci_slot_trylock(slot)) {
+ might_sleep();
+ rc = pci_reset_hotplug_slot(slot->hotplug, 0);
+ pci_slot_unlock(slot);
+ } else
+ rc = -EAGAIN;
+
+ pci_slot_restore(slot);
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(pci_try_reset_slot);
+
static int pci_bus_reset(struct pci_bus *bus, int probe)
{
if (!bus->self)
@@ -3627,6 +3753,35 @@ int pci_reset_bus(struct pci_bus *bus)
EXPORT_SYMBOL_GPL(pci_reset_bus);
/**
+ * pci_try_reset_bus - Try to reset a PCI bus
+ * @bus: top level PCI bus to reset
+ *
+ * Same as above except return -EAGAIN if the bus cannot be locked
+ */
+int pci_try_reset_bus(struct pci_bus *bus)
+{
+ int rc;
+
+ rc = pci_bus_reset(bus, 1);
+ if (rc)
+ return rc;
+
+ pci_bus_save_and_disable(bus);
+
+ if (pci_bus_trylock(bus)) {
+ might_sleep();
+ pci_reset_bridge_secondary_bus(bus->self);
+ pci_bus_unlock(bus);
+ } else
+ rc = -EAGAIN;
+
+ pci_bus_restore(bus);
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(pci_try_reset_bus);
+
+/**
* pcix_get_max_mmrbc - get PCI-X maximum designed memory read byte count
* @dev: PCI device to query
*
diff --git a/drivers/vfio/pci/vfio_pci.c b/drivers/vfio/pci/vfio_pci.c
index 6ab71b9..2319d20 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--)