ACK: [SRU][XBCD][PATCH] UBUNTU: SAUCE: net: ena: fix crash during ena_remove()

[Colin Ian King]

On 08/11/2018 18:37, Kamal Mostafa wrote:
> From: Arthur Kiyanovski <akiyano at amazon.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1802341
> 
> In ena_remove() we have the following stack call:
> ena_remove()
>   unregister_netdev()
>   ena_destroy_device()
>     netif_carrier_off()
> 
> Calling netif_carrier_off() causes linkwatch to try to handle the
> link change event on the already unregistered netdev, which leads
> to a read from an unreadable memory address.
> 
> This patch switches the order of the two functions, so that
> netif_carrier_off() is called on a regiestered netdev.
> 
> To accomplish this fix we also had to:
> 1. Remove the set bit ENA_FLAG_TRIGGER_RESET
> 2. Add a sanitiy check in ena_close()
> both to prevent double device reset (when calling unregister_netdev()
> ena_close is called, but the device was already deleted in
> ena_destroy_device()).
> 3. Set the admin_queue running state to false to avoid using it after
> device was reset (for example when calling ena_destroy_all_io_queues()
> right after ena_com_dev_reset() in ena_down)
> 
> Finally, driver version is also updated.
> 
> Change-Id: I3cc1aafe9cb3701a6eaee44e00add0e175c93148
> 
> Signed-off-by: Arthur Kiyanovski <akiyano at amazon.com>
> Signed-off-by: Kamal Mostafa <kamal at canonical.com>
> ---
>  drivers/net/ethernet/amazon/ena/ena_netdev.c | 21 ++++++++++-----------
>  drivers/net/ethernet/amazon/ena/ena_netdev.h |  2 +-
>  2 files changed, 11 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.c b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> index 7739cca..08a05f3 100644
> --- a/drivers/net/ethernet/amazon/ena/ena_netdev.c
> +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.c
> @@ -1849,6 +1849,8 @@ static void ena_down(struct ena_adapter *adapter)
>  		rc = ena_com_dev_reset(adapter->ena_dev, adapter->reset_reason);
>  		if (rc)
>  			dev_err(&adapter->pdev->dev, "Device reset failed\n");
> +		/* stop submitting admin commands on a device that was reset */
> +		ena_com_set_admin_running_state(adapter->ena_dev, false);
>  	}
>  
>  	ena_destroy_all_io_queues(adapter);
> @@ -1915,6 +1917,9 @@ static int ena_close(struct net_device *netdev)
>  
>  	netif_dbg(adapter, ifdown, netdev, "%s\n", __func__);
>  
> +	if (!test_bit(ENA_FLAG_DEVICE_RUNNING, &adapter->flags))
> +		return 0;
> +
>  	if (test_bit(ENA_FLAG_DEV_UP, &adapter->flags))
>  		ena_down(adapter);
>  
> @@ -2613,9 +2618,7 @@ static void ena_destroy_device(struct ena_adapter *adapter, bool graceful)
>  		ena_down(adapter);
>  
>  	/* Stop the device from sending AENQ events (in case reset flag is set
> -	 *  and device is up, ena_close already reset the device
> -	 * In case the reset flag is set and the device is up, ena_down()
> -	 * already perform the reset, so it can be skipped.
> +	 *  and device is up, ena_down() already reset the device.
>  	 */
>  	if (!(test_bit(ENA_FLAG_TRIGGER_RESET, &adapter->flags) && dev_up))
>  		ena_com_dev_reset(adapter->ena_dev, adapter->reset_reason);
> @@ -3452,6 +3455,8 @@ static int ena_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
>  	ena_com_rss_destroy(ena_dev);
>  err_free_msix:
>  	ena_com_dev_reset(ena_dev, ENA_REGS_RESET_INIT_ERR);
> +	/* stop submitting admin commands on a device that was reset */
> +	ena_com_set_admin_running_state(ena_dev, false);
>  	ena_free_mgmnt_irq(adapter);
>  	ena_disable_msix(adapter);
>  err_worker_destroy:
> @@ -3524,18 +3529,12 @@ static void ena_remove(struct pci_dev *pdev)
>  
>  	cancel_work_sync(&adapter->reset_task);
>  
> -	unregister_netdev(netdev);
> -
> -	/* If the device is running then we want to make sure the device will be
> -	 * reset to make sure no more events will be issued by the device.
> -	 */
> -	if (test_bit(ENA_FLAG_DEVICE_RUNNING, &adapter->flags))
> -		set_bit(ENA_FLAG_TRIGGER_RESET, &adapter->flags);
> -
>  	rtnl_lock();
>  	ena_destroy_device(adapter, true);
>  	rtnl_unlock();
>  
> +	unregister_netdev(netdev);
> +
>  	free_netdev(netdev);
>  
>  	ena_com_rss_destroy(ena_dev);
> diff --git a/drivers/net/ethernet/amazon/ena/ena_netdev.h b/drivers/net/ethernet/amazon/ena/ena_netdev.h
> index 5218736..dc8b617 100644
> --- a/drivers/net/ethernet/amazon/ena/ena_netdev.h
> +++ b/drivers/net/ethernet/amazon/ena/ena_netdev.h
> @@ -45,7 +45,7 @@
>  
>  #define DRV_MODULE_VER_MAJOR	2
>  #define DRV_MODULE_VER_MINOR	0
> -#define DRV_MODULE_VER_SUBMINOR 1
> +#define DRV_MODULE_VER_SUBMINOR 2
>  
>  #define DRV_MODULE_NAME		"ena"
>  #ifndef DRV_MODULE_VERSION
> 

Acked-by: Colin Ian King <colin.king at canonical.com>