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PCI/PM: Fix deadlock when unbinding device if parent in D3cold

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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: stable@vger.kernel.org		# v3.6+
CC: Zhang Yanmin <yanmin.zhang@intel.com>
This commit is contained in:
Huang Ying 2012-10-24 14:54:13 +08:00 committed by Bjorn Helgaas
parent 8f0d8163b5
commit 90b5c1d7c4
2 changed files with 16 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/pci/bus.c
View File

@ -320,10 +320,7 @@ void pci_walk_bus(struct pci_bus *top, int (*cb)(struct pci_dev *, void *),
} 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;
}

20
drivers/pci/pcie/aer/aerdrv_core.c
View File

@ -213,6 +213,7 @@ static int report_error_detected(struct pci_dev *dev, void *data)
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 ||
@ -231,12 +232,14 @@ static int report_error_detected(struct pci_dev *dev, void *data)
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;
}
@ -247,14 +250,17 @@ static int report_mmio_enabled(struct pci_dev *dev, void *data)
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;
}
@ -265,14 +271,17 @@ static int report_slot_reset(struct pci_dev *dev, void *data)
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;
}
@ -280,15 +289,18 @@ static int report_resume(struct pci_dev *dev, void *data)
{
const 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;
}