On Mon, Oct 31, 2016 at 1:12 PM, Guilherme G. Piccoli <gpicc...@linux.vnet.ibm.com> wrote: > Whenever the igb driver detects the result of a read operation returns > a value composed only by F's (like 0xFFFFFFFF), it will detach the > net_device, clear the hw_addr pointer and warn to the user that adapter's > link is lost - those steps happen on igb_rd32(). > > In case a PCI error happens on Power architecture, there's a recovery > mechanism called EEH, that will reset the PCI slot and call driver's > handlers to reset the adapter and network functionality as well. > > We observed that once hw_addr is NULL after the error is detected on > igb_rd32(), it's never assigned back, so in the process of resetting > the network functionality we got a NULL pointer dereference in both > igb_configure_tx_ring() and igb_configure_rx_ring(). In order to avoid > such bug, we re-assign the hw_addr value in the beginning of the > function igb_reset(), in case the hw_addr is NULL when we reach that > path. > > Reported-by: Anthony H. Thai <aht...@us.ibm.com> > Reported-by: Harsha Thyagaraja <hathy...@in.ibm.com> > Signed-off-by: Guilherme G. Piccoli <gpicc...@linux.vnet.ibm.com> > --- > drivers/net/ethernet/intel/igb/igb_main.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/drivers/net/ethernet/intel/igb/igb_main.c > b/drivers/net/ethernet/intel/igb/igb_main.c > index edc9a6a..c19119c 100644 > --- a/drivers/net/ethernet/intel/igb/igb_main.c > +++ b/drivers/net/ethernet/intel/igb/igb_main.c > @@ -1873,6 +1873,13 @@ void igb_reset(struct igb_adapter *adapter) > struct e1000_fc_info *fc = &hw->fc; > u32 pba, hwm; > > + /* In case of PCI error, adapter might have lost its HW > + * address; if we reached this point after an error scenario, > + * we should re-assign the hw_addr based on the saved io_addr. > + */ > + if (!hw->hw_addr) > + hw->hw_addr = adapter->io_addr; > + > /* Repartition Pba for greater than 9k mtu > * To take effect CTRL.RST is required. > */
It seems like this would have the potential to get noisy pretty quickly since every reset would retrigger this. It might make more sense to move this line into igb_io_slot_reset and igb_resume where the device would have gone through a reset of some sort and then had the state of the device restored and the device memory access was re-enabled via pci_enable_device_mem. Also there is no point in really doing the "if" since you should always be okay to overwrite hw->hw_addr with adapter->io_addr. Thanks. - Alex
