netdev - Re: [PATCH net v2] igb: re-assign hw address pointer on reset after PCI error

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Message-Id: <58416F5C.20602@linux.vnet.ibm.com>
Date:   Fri, 2 Dec 2016 10:55:56 -0200
From:   "Guilherme G. Piccoli" <gpiccoli@...ux.vnet.ibm.com>
To:     intel-wired-lan@...ts.osuosl.org, jeffrey.t.kirsher@...el.com,
        alexander.duyck@...il.com
Cc:     netdev@...r.kernel.org, todd.fujinaka@...el.com
Subject: Re: [PATCH net v2] igb: re-assign hw address pointer on reset after
 PCI error

On 11/10/2016 04:46 PM, Guilherme G. Piccoli 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, this patch re-assigns the hw_addr value in the slot_reset
> handler.
> 
> Reported-by: Anthony H. Thai <ahthai@...ibm.com>
> Reported-by: Harsha Thyagaraja <hathyaga@...ibm.com>
> Signed-off-by: Guilherme G. Piccoli <gpiccoli@...ux.vnet.ibm.com>
> ---
>  drivers/net/ethernet/intel/igb/igb_main.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c
> index edc9a6a..136ee9e 100644
> --- a/drivers/net/ethernet/intel/igb/igb_main.c
> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -7878,6 +7878,11 @@ static pci_ers_result_t igb_io_slot_reset(struct pci_dev *pdev)
>  		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;
> 

Ping?

Sorry to annoy, any news on this?
Thanks in advance!

Cheers,


Guilherme