[+cc Lance, Huang, Hidetoshi, Andrew, Zhang] On Sat, Nov 10, 2012 at 07:41:04AM +0000, Pandarathil, Vijaymohan R wrote: > When an error is detected on a PCIe device which does not have an > AER-aware driver, prevent AER infrastructure from reporting > successful error recovery. > > This is because the report_error_detected() function that gets > called in the first phase of recovery process allows forward > progress even when the driver for the device does not have AER > capabilities. It seems that all callbacks (in pci_error_handlers > structure) registered by drivers that gets called during error > recovery are not mandatory. So the intention of the infrastructure > design seems to be to allow forward progress even when a specific > callback has not been registered by a driver. However, if error > handler structure itself has not been registered, it doesn't make > sense to allow forward progress. > > As a result of the current design, in the case of a single device > having an AER-unaware driver or in the case of any function in a > multi-function card having an AER-unaware driver, a successful > recovery is reported. > > Typical scenario this happens is when a PCI device is detached > from a KVM host and the pci-stub driver on the host claims the > device. The pci-stub driver does not have error handling capabilities > but the AER infrastructure still reports that the device recovered > successfully. > > The changes proposed here leaves the device in an unrecovered state > if the driver for the device or for any function in a multi-function > card does not have error handler structure registered. This reflects > the true state of the device and prevents any partial recovery (or no > recovery at all) reported as successful. > > Please also see comments from Linas Vepstas at the following link > http://www.spinics.net/lists/linux-pci/msg18572.html > > Reviewed-by: Linas Vepstas <linasvepstas <at> gmail.com> > Reviewed-by: Myron Stowe <mstowe <at> redhat.com> > Signed-off-by: Vijay Mohan Pandarathil <vijaymohan.pandarathil <at> hp.com> > > --- > > drivers/pci/pcie/aer/aerdrv_core.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c > index 06bad96..030b229 100644 > --- a/drivers/pci/pcie/aer/aerdrv_core.c > +++ b/drivers/pci/pcie/aer/aerdrv_core.c > @@ -215,6 +215,12 @@ static int report_error_detected(struct pci_dev *dev, void *data) > > dev->error_state = result_data->state; > > + if ((!dev->driver || !dev->driver->err_handler) && > + !(dev->hdr_type & PCI_HEADER_TYPE_BRIDGE)) { > + dev_info(&dev->dev, "AER: Error detected but no driver has claimed this device or the driver is AER-unaware\n"); > + result_data->result = PCI_ERS_RESULT_NONE; > + return 1; This doesn't seem right because returning 1 here causes pci_walk_bus() to terminate, which means we won't set dev->error_state or notify drivers for any devices we haven't visited yet. > + } > if (!dev->driver || > !dev->driver->err_handler || > !dev->driver->err_handler->error_detected) { If none of the drivers in the affected hierarchy supports error handling, I think the call tree looks like this: do_recovery # uncorrectable only broadcast_error_message(dev, ..., report_error_detected) result_data.result = CAN_RECOVER pci_walk_bus(..., report_error_detected) report_error_detected # (each dev in subtree) return 0 # no change to result return result_data.result broadcast_error_message(dev, ..., report_mmio_enabled) result_data.result = PCI_ERS_RESULT_RECOVERED pci_walk_bus(..., report_mmio_enabled) report_mmio_enabled # (each dev in subtree) return 0 # no change to result dev_info("recovery successful") Specifically, there are no error_handler functions, so we never change result_data.result, and the default is that we treat the error as "recovered successfully." That seems broken. An uncorrectable error is by definition recoverable only by device-specific software, i.e., the driver. We didn't call any drivers, so we can't have recovered anything. What do you think of the following alternative? I don't know why you checked for bridge devices in your patch, so I don't know whether that's important here or not. diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c index 06bad96..a109c68 100644 --- a/drivers/pci/pcie/aer/aerdrv_core.c +++ b/drivers/pci/pcie/aer/aerdrv_core.c @@ -231,11 +231,11 @@ static int report_error_detected(struct pci_dev *dev, void *data) dev->driver ? "no AER-aware driver" : "no driver"); } - return 0; + vote = PCI_ERS_RESULT_DISCONNECT; + } else { + err_handler = dev->driver->err_handler; + vote = err_handler->error_detected(dev, result_data->state); } - - err_handler = dev->driver->err_handler; - vote = err_handler->error_detected(dev, result_data->state); result_data->result = merge_result(result_data->result, vote); 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
