From 918b4053184c0ca22236e70e299c5343eea35304 Mon Sep 17 00:00:00 2001 From: Vijay Mohan Pandarathil Date: Sat, 17 Nov 2012 11:47:18 +0000 Subject: [PATCH] PCI/AER: Report success only when every device has AER-aware driver 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(s)in an unrecovered state if the driver for the device or for any device in the subtree 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. [bhelgaas: changelog] Signed-off-by: Vijay Mohan Pandarathil Signed-off-by: Bjorn Helgaas Reviewed-by: Linas Vepstas Reviewed-by: Myron Stowe --- drivers/pci/pcie/aer/aerdrv.h | 5 ++++- drivers/pci/pcie/aer/aerdrv_core.c | 21 ++++++++++++++++++--- include/linux/pci.h | 3 +++ 3 files changed, 25 insertions(+), 4 deletions(-) diff --git a/drivers/pci/pcie/aer/aerdrv.h b/drivers/pci/pcie/aer/aerdrv.h index 94a7598eb262..22f840f4dda1 100644 --- a/drivers/pci/pcie/aer/aerdrv.h +++ b/drivers/pci/pcie/aer/aerdrv.h @@ -87,6 +87,9 @@ struct aer_broadcast_data { static inline pci_ers_result_t merge_result(enum pci_ers_result orig, enum pci_ers_result new) { + if (new == PCI_ERS_RESULT_NO_AER_DRIVER) + return PCI_ERS_RESULT_NO_AER_DRIVER; + if (new == PCI_ERS_RESULT_NONE) return orig; @@ -97,7 +100,7 @@ static inline pci_ers_result_t merge_result(enum pci_ers_result orig, break; case PCI_ERS_RESULT_DISCONNECT: if (new == PCI_ERS_RESULT_NEED_RESET) - orig = new; + orig = PCI_ERS_RESULT_NEED_RESET; break; default: break; diff --git a/drivers/pci/pcie/aer/aerdrv_core.c b/drivers/pci/pcie/aer/aerdrv_core.c index 06bad96af415..eb2f19a9c3cd 100644 --- a/drivers/pci/pcie/aer/aerdrv_core.c +++ b/drivers/pci/pcie/aer/aerdrv_core.c @@ -231,11 +231,26 @@ static int report_error_detected(struct pci_dev *dev, void *data) dev->driver ? "no AER-aware driver" : "no driver"); } - return 0; + + /* + * If there's any device in the subtree that does not + * have an error_detected callback, returning + * PCI_ERS_RESULT_NO_AER_DRIVER prevents calling of + * the subsequent mmio_enabled/slot_reset/resume + * callbacks of "any" device in the subtree. All the + * devices in the subtree are left in the error state + * without recovery. + */ + + if (!(dev->hdr_type & PCI_HEADER_TYPE_BRIDGE)) + vote = PCI_ERS_RESULT_NO_AER_DRIVER; + else + vote = PCI_ERS_RESULT_NONE; + } 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; } diff --git a/include/linux/pci.h b/include/linux/pci.h index ee2179546c63..fb7e8699673d 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -538,6 +538,9 @@ enum pci_ers_result { /* Device driver is fully recovered and operational */ PCI_ERS_RESULT_RECOVERED = (__force pci_ers_result_t) 5, + + /* No AER capabilities registered for the driver */ + PCI_ERS_RESULT_NO_AER_DRIVER = (__force pci_ers_result_t) 6, }; /* PCI bus error event callbacks */ -- 2.20.1