From: Alex Williamson alex.williamson@redhat.com
[ Upstream commit ddefc033eecf23f1e8b81d0663c5db965adf5516 ]
The commit referenced below introduced device locking around save and restore of state for each device during a PCI bus "try" reset, making it decidely non-"try" and prone to deadlock in the event that a device is already locked. Restore __pci_reset_bus() and __pci_reset_slot() to their advertised locking semantics by pushing the save and restore functions into the branch where the entire tree is already locked. Extend the helper function names with "_locked" and update the comment to reflect this calling requirement.
Fixes: b014e96d1abb ("PCI: Protect pci_error_handlers->reset_notify() usage with device_lock()") Signed-off-by: Alex Williamson alex.williamson@redhat.com Signed-off-by: Bjorn Helgaas bhelgaas@google.com Reviewed-by: Sinan Kaya okaya@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pci/pci.c | 54 +++++++++++++++++++++++------------------------ 1 file changed, 26 insertions(+), 28 deletions(-)
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index c9f51fc24563..57a87a001b4f 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5039,39 +5039,42 @@ static int pci_slot_trylock(struct pci_slot *slot) return 0; }
-/* Save and disable devices from the top of the tree down */ -static void pci_bus_save_and_disable(struct pci_bus *bus) +/* + * Save and disable devices from the top of the tree down while holding + * the @dev mutex lock for the entire tree. + */ +static void pci_bus_save_and_disable_locked(struct pci_bus *bus) { struct pci_dev *dev;
list_for_each_entry(dev, &bus->devices, bus_list) { - pci_dev_lock(dev); pci_dev_save_and_disable(dev); - pci_dev_unlock(dev); if (dev->subordinate) - pci_bus_save_and_disable(dev->subordinate); + pci_bus_save_and_disable_locked(dev->subordinate); } }
/* - * Restore devices from top of the tree down - parent bridges need to be - * restored before we can get to subordinate devices. + * Restore devices from top of the tree down while holding @dev mutex lock + * for the entire tree. Parent bridges need to be restored before we can + * get to subordinate devices. */ -static void pci_bus_restore(struct pci_bus *bus) +static void pci_bus_restore_locked(struct pci_bus *bus) { struct pci_dev *dev;
list_for_each_entry(dev, &bus->devices, bus_list) { - pci_dev_lock(dev); pci_dev_restore(dev); - pci_dev_unlock(dev); if (dev->subordinate) - pci_bus_restore(dev->subordinate); + pci_bus_restore_locked(dev->subordinate); } }
-/* Save and disable devices from the top of the tree down */ -static void pci_slot_save_and_disable(struct pci_slot *slot) +/* + * Save and disable devices from the top of the tree down while holding + * the @dev mutex lock for the entire tree. + */ +static void pci_slot_save_and_disable_locked(struct pci_slot *slot) { struct pci_dev *dev;
@@ -5080,26 +5083,25 @@ static void pci_slot_save_and_disable(struct pci_slot *slot) continue; pci_dev_save_and_disable(dev); if (dev->subordinate) - pci_bus_save_and_disable(dev->subordinate); + pci_bus_save_and_disable_locked(dev->subordinate); } }
/* - * Restore devices from top of the tree down - parent bridges need to be - * restored before we can get to subordinate devices. + * Restore devices from top of the tree down while holding @dev mutex lock + * for the entire tree. Parent bridges need to be restored before we can + * get to subordinate devices. */ -static void pci_slot_restore(struct pci_slot *slot) +static void pci_slot_restore_locked(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; - pci_dev_lock(dev); pci_dev_restore(dev); - pci_dev_unlock(dev); if (dev->subordinate) - pci_bus_restore(dev->subordinate); + pci_bus_restore_locked(dev->subordinate); } }
@@ -5158,17 +5160,15 @@ static int __pci_reset_slot(struct pci_slot *slot) if (rc) return rc;
- pci_slot_save_and_disable(slot); - if (pci_slot_trylock(slot)) { + pci_slot_save_and_disable_locked(slot); might_sleep(); rc = pci_reset_hotplug_slot(slot->hotplug, 0); + pci_slot_restore_locked(slot); pci_slot_unlock(slot); } else rc = -EAGAIN;
- pci_slot_restore(slot); - return rc; }
@@ -5254,17 +5254,15 @@ static int __pci_reset_bus(struct pci_bus *bus) if (rc) return rc;
- pci_bus_save_and_disable(bus); - if (pci_bus_trylock(bus)) { + pci_bus_save_and_disable_locked(bus); might_sleep(); rc = pci_bridge_secondary_bus_reset(bus->self); + pci_bus_restore_locked(bus); pci_bus_unlock(bus); } else rc = -EAGAIN;
- pci_bus_restore(bus); - return rc; }