+++ /dev/null
-From 90b5c1d7c45eeb622302680ff96ed30c1a2b6f0e Mon Sep 17 00:00:00 2001
-From: Huang Ying <ying.huang@intel.com>
-Date: Wed, 24 Oct 2012 14:54:13 +0800
-Subject: PCI/PM: Fix deadlock when unbinding device if parent in D3cold
-
-From: Huang Ying <ying.huang@intel.com>
-
-commit 90b5c1d7c45eeb622302680ff96ed30c1a2b6f0e upstream.
-
-If a PCI device and its parents are put into D3cold, unbinding the
-device will trigger deadlock as follow:
-
-- driver_unbind
- - device_release_driver
- - device_lock(dev) <--- previous lock here
- - __device_release_driver
- - pm_runtime_get_sync
- ...
- - rpm_resume(dev)
- - rpm_resume(dev->parent)
- ...
- - pci_pm_runtime_resume
- ...
- - pci_set_power_state
- - __pci_start_power_transition
- - pci_wakeup_bus(dev->parent->subordinate)
- - pci_walk_bus
- - device_lock(dev) <--- deadlock here
-
-
-If we do not do device_lock in pci_walk_bus, we can avoid deadlock.
-Device_lock in pci_walk_bus is introduced in commit:
-d71374dafbba7ec3f67371d3b7e9f6310a588808, corresponding email thread
-is: https://lkml.org/lkml/2006/5/26/38. The patch author Zhang Yanmin
-said device_lock is added to pci_walk_bus because:
-
- Some error handling functions call pci_walk_bus. For example, PCIe
- aer. Here we lock the device, so the driver wouldn't detach from the
- device, as the cb might call driver's callback function.
-
-So I fixed the deadlock as follows:
-
-- remove device_lock from pci_walk_bus
-- add device_lock into callback if callback will call driver's callback
-
-I checked pci_walk_bus users one by one, and found only PCIe aer needs
-device lock.
-
-Signed-off-by: Huang Ying <ying.huang@intel.com>
-Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
-Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
-CC: Zhang Yanmin <yanmin.zhang@intel.com>
-Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-
----
- drivers/pci/bus.c | 3 ---
- drivers/pci/pcie/aer/aerdrv_core.c | 20 ++++++++++++++++----
- 2 files changed, 16 insertions(+), 7 deletions(-)
-
---- a/drivers/pci/bus.c
-+++ b/drivers/pci/bus.c
-@@ -316,10 +316,7 @@ void pci_walk_bus(struct pci_bus *top, i
- } else
- next = dev->bus_list.next;
-
-- /* Run device routines with the device locked */
-- device_lock(&dev->dev);
- retval = cb(dev, userdata);
-- device_unlock(&dev->dev);
- if (retval)
- break;
- }
---- a/drivers/pci/pcie/aer/aerdrv_core.c
-+++ b/drivers/pci/pcie/aer/aerdrv_core.c
-@@ -244,6 +244,7 @@ static int report_error_detected(struct
- struct aer_broadcast_data *result_data;
- result_data = (struct aer_broadcast_data *) data;
-
-+ device_lock(&dev->dev);
- dev->error_state = result_data->state;
-
- if (!dev->driver ||
-@@ -262,12 +263,14 @@ static int report_error_detected(struct
- dev->driver ?
- "no AER-aware driver" : "no driver");
- }
-- return 0;
-+ goto out;
- }
-
- err_handler = dev->driver->err_handler;
- vote = err_handler->error_detected(dev, result_data->state);
- result_data->result = merge_result(result_data->result, vote);
-+out:
-+ device_unlock(&dev->dev);
- return 0;
- }
-
-@@ -278,14 +281,17 @@ static int report_mmio_enabled(struct pc
- struct aer_broadcast_data *result_data;
- result_data = (struct aer_broadcast_data *) data;
-
-+ device_lock(&dev->dev);
- if (!dev->driver ||
- !dev->driver->err_handler ||
- !dev->driver->err_handler->mmio_enabled)
-- return 0;
-+ goto out;
-
- err_handler = dev->driver->err_handler;
- vote = err_handler->mmio_enabled(dev);
- result_data->result = merge_result(result_data->result, vote);
-+out:
-+ device_unlock(&dev->dev);
- return 0;
- }
-
-@@ -296,14 +302,17 @@ static int report_slot_reset(struct pci_
- struct aer_broadcast_data *result_data;
- result_data = (struct aer_broadcast_data *) data;
-
-+ device_lock(&dev->dev);
- if (!dev->driver ||
- !dev->driver->err_handler ||
- !dev->driver->err_handler->slot_reset)
-- return 0;
-+ goto out;
-
- err_handler = dev->driver->err_handler;
- vote = err_handler->slot_reset(dev);
- result_data->result = merge_result(result_data->result, vote);
-+out:
-+ device_unlock(&dev->dev);
- return 0;
- }
-
-@@ -311,15 +320,18 @@ static int report_resume(struct pci_dev
- {
- struct pci_error_handlers *err_handler;
-
-+ device_lock(&dev->dev);
- dev->error_state = pci_channel_io_normal;
-
- if (!dev->driver ||
- !dev->driver->err_handler ||
- !dev->driver->err_handler->resume)
-- return 0;
-+ goto out;
-
- err_handler = dev->driver->err_handler;
- err_handler->resume(dev);
-+out:
-+ device_unlock(&dev->dev);
- return 0;
- }
-