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Re: [PATCH V2 net 06/20] net/ena: fix NULL dereference when removing the driver after device reset faild

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On Sun, Dec 04, 2016 at 03:19:24PM +0200, Netanel Belgazal wrote:
> If for some reason the device stop responding and the device reset failed
> to recover the device, the mmio register read datastructure will not be
> reinitialized.

If for some reason the device stops responding, and the device reset
fails to recover the device, the MMIO register read data structure
will not be reinitialized.

> On driver removal, the driver will also tries to reset the device
> but this time the mmio data structure will be NULL.

On driver removal, the driver will also try to reset the device, but
this time the MMIO data structure will be NULL.

> To solve this issue perform the device reset in the remove function only if
> the device is runnig.

To solve this issue, perform the device reset in the remove function
only if the device is running.

Do you have an example of the NULL pointer dereference that you can
paste in? It can be helpful for those searching for a fix for a bug
they've experienced.

--msw

> Signed-off-by: Netanel Belgazal <netanel@annapurnalabs.com>
> ---
>  drivers/net/ethernet/amazon/ena/ena_netdev.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> index 224302c..ad5f78f 100644
> --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
> +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> @@ -2516,6 +2516,8 @@ static void ena_fw_reset_device(struct work_struct *work)
>  err:
>  	rtnl_unlock();
>  
> +	clear_bit(ENA_FLAG_DEVICE_RUNNING, &adapter->flags);
> +
>  	dev_err(&pdev->dev,
>  		"Reset attempt failed. Can not reset the device\n");
>  }
> @@ -3126,7 +3128,9 @@ static void ena_remove(struct pci_dev *pdev)
>  
>  	cancel_work_sync(&adapter->resume_io_task);
>  
> -	ena_com_dev_reset(ena_dev);
> +	/* Reset the device only if the device is running. */
> +	if (test_bit(ENA_FLAG_DEVICE_RUNNING, &adapter->flags))
> +		ena_com_dev_reset(ena_dev);
>  
>  	ena_free_mgmnt_irq(adapter);
>  

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[PATCH V2 net 00/20] Increase ENA driver version to 1.1.2 Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 05/20] net/ena: fix RSS default hash configuration Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 05/20] net/ena: fix RSS default hash configuration Matt Wilson <msw@amzn.com> - 2016-12-05 05:30 +0100
      Re: [PATCH V2 net 05/20] net/ena: fix RSS default hash configuration Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:40 +0100
  [PATCH V2 net 13/20] net/ena: change driver's default timeouts Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 13/20] net/ena: change driver's default timeouts Matt Wilson <msw@amzn.com> - 2016-12-05 05:40 +0100
      Re: [PATCH V2 net 13/20] net/ena: change driver's default timeouts Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:30 +0100
  [PATCH V2 net 08/20] net/ena: add hardware hints capability to the driver Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 08/20] net/ena: add hardware hints capability to  the driver Matt Wilson <msw@amzn.com> - 2016-12-05 05:40 +0100
      Re: [PATCH V2 net 08/20] net/ena: add hardware hints capability to  the driver Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:40 +0100
  [PATCH V2 net 17/20] net/ena: add IPv6 extended protocols to ena_admin_flow_hash_proto Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 09/20] net/ena: fix potential access to freed memory during device reset Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 07/20] net/ena: refactor ena_get_stats64 to be atomic context safe Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 07/20] net/ena: refactor ena_get_stats64 to be  atomic context safe Matt Wilson <msw@amzn.com> - 2016-12-05 05:30 +0100
      Re: [PATCH V2 net 07/20] net/ena: refactor ena_get_stats64 to be  atomic context safe Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:40 +0100
  [PATCH V2 net 12/20] net/ena: reduce the severity of ena printouts Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 16/20] net/ena: use napi_schedule_irqoff when possible Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 11/20] net/ena: use READ_ONCE to access completion descriptors Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 06/20] net/ena: fix NULL dereference when removing the driver after device reset faild Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 06/20] net/ena: fix NULL dereference when removing  the driver after device reset faild Matt Wilson <msw@amzn.com> - 2016-12-05 05:40 +0100
      Re: [PATCH V2 net 06/20] net/ena: fix NULL dereference when removing  the driver after device reset faild Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:40 +0100
  [PATCH V2 net 14/20] net/ena: change condition for host attribute configuration Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 04/20] net/ena: fix ethtool RSS flow configuration Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 04/20] net/ena: fix ethtool RSS flow configuration Matt Wilson <msw@amzn.com> - 2016-12-05 05:20 +0100
      Re: [PATCH V2 net 04/20] net/ena: fix ethtool RSS flow configuration Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:30 +0100
  [PATCH V2 net 02/20] net/ena: fix error handling when probe fails Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 02/20] net/ena: fix error handling when probe fails Matt Wilson <msw@amzn.com> - 2016-12-05 05:20 +0100
      Re: [PATCH V2 net 02/20] net/ena: fix error handling when probe fails Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:30 +0100
  [PATCH V2 net 10/20] net/ena: remove redundant logic in napi callback for busy poll mode Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 10/20] net/ena: remove redundant logic in napi  callback for busy poll mode Eric Dumazet <eric.dumazet@gmail.com> - 2016-12-05 07:00 +0100
      Re: [PATCH V2 net 10/20] net/ena: remove redundant logic in napi  callback for busy poll mode Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:30 +0100
        Re: [PATCH V2 net 10/20] net/ena: remove redundant logic in napi  callback for busy poll mode Eric Dumazet <eric.dumazet@gmail.com> - 2016-12-05 20:00 +0100
  [PATCH V2 net 15/20] net/ena: change sizeof() argument to be the type pointer Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 01/20] net/ena: remove ntuple filter support from device feature list Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 01/20] net/ena: remove ntuple filter support from  device feature list Matt Wilson <msw@amzn.com> - 2016-12-05 05:10 +0100
  [PATCH V2 net 19/20] net/ena: restructure skb allocation Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
  [PATCH V2 net 03/20] net/ena: fix queues number calculation Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-04 14:30 +0100
    Re: [PATCH V2 net 03/20] net/ena: fix queues number calculation Matt Wilson <msw@amzn.com> - 2016-12-05 05:20 +0100
      Re: [PATCH V2 net 03/20] net/ena: fix queues number calculation Netanel Belgazal <netanel@annapurnalabs.com> - 2016-12-05 19:30 +0100
  Re: [PATCH V2 net 00/20] Increase ENA driver version to 1.1.2 David Miller <davem@davemloft.net> - 2016-12-05 03:50 +0100
    Re: [PATCH V2 net 00/20] Increase ENA driver version to 1.1.2 Matt Wilson <msw@amzn.com> - 2016-12-05 04:40 +0100

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