On Wed, Oct 24, 2012 at 12:54 AM, Huang Ying <ying.huang@xxxxxxxxx> wrote: > 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) <--- dead lock here > > > If we do not do device_lock in pci_walk_bus, we can avoid dead lock. > 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 dead lock as follow: > > - 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. Is there a problem report or bugzilla for this issue? > Signed-off-by: Huang Ying <ying.huang@xxxxxxxxx> > Cc: Zhang Yanmin <yanmin.zhang@xxxxxxxxx> Should this go to stable as well? The D3cold support appeared in v3.6, so my guess is that this fix could go to v3.6.x. > --- > 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 > @@ -320,10 +320,7 @@ 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 > @@ -213,6 +213,7 @@ 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 || > @@ -231,12 +232,14 @@ 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; > } > > @@ -247,14 +250,17 @@ 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; > } > > @@ -265,14 +271,17 @@ 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; > } > > @@ -280,15 +289,18 @@ static int report_resume(struct pci_dev > { > 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; > } > -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
