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()

1 files changed, 155 insertions, 0 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 95c97bec8018..b6d4afa8ba40 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
  *