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Subject[PATCH 4.4 08/50] igb: re-assign hw address pointer on reset after PCI error
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4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Guilherme G Piccoli <gpiccoli@linux.vnet.ibm.com>


[ Upstream commit 69b97cf6dbce7403845a28bbc75d57f5be7b12ac ]

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, this patch re-assigns the hw_addr value in the slot_reset
handler.

Reported-by: Anthony H Thai <ahthai@us.ibm.com>
Reported-by: Harsha Thyagaraja <hathyaga@in.ibm.com>
Signed-off-by: Guilherme G Piccoli <gpiccoli@linux.vnet.ibm.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/intel/igb/igb_main.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/drivers/net/ethernet/intel/igb/igb_main.c
+++ b/drivers/net/ethernet/intel/igb/igb_main.c
@@ -7658,6 +7658,11 @@ static pci_ers_result_t igb_io_slot_rese
pci_enable_wake(pdev, PCI_D3hot, 0);
pci_enable_wake(pdev, PCI_D3cold, 0);

+ /* In case of PCI error, adapter lose its HW address
+ * so we should re-assign it here.
+ */
+ hw->hw_addr = adapter->io_addr;
+
igb_reset(adapter);
wr32(E1000_WUS, ~0);
result = PCI_ERS_RESULT_RECOVERED;

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