[net-next,4/7] ixgbe: protect vxlan_get_rx_port in ixgbe_service_task with rtnl_lock

vxlan_get_rx_port requires rtnl_lock to be held.

Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
Cc: Shannon Nelson <shannon.nelson@intel.com>
Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
Cc: Don Skidmore <donald.c.skidmore@intel.com>
Cc: Bruce Allan <bruce.w.allan@intel.com>
Cc: John Ronciak <john.ronciak@intel.com>
Cc: Mitch Williams <mitch.a.williams@intel.com>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
---
 drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 ++
 1 file changed, 2 insertions(+)

On Mon, 2016-04-18 at 21:19 +0200, Hannes Frederic Sowa wrote:
> vxlan_get_rx_port requires rtnl_lock to be held.
> 
> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
> Cc: Shannon Nelson <shannon.nelson@intel.com>
> Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
> Cc: Don Skidmore <donald.c.skidmore@intel.com>
> Cc: Bruce Allan <bruce.w.allan@intel.com>
> Cc: John Ronciak <john.ronciak@intel.com>
> Cc: Mitch Williams <mitch.a.williams@intel.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 2976df77bf14f5..b2f2cf40f06a87 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -7192,10 +7192,12 @@ static void ixgbe_service_task(struct work_struct *work)
>  		return;
>  	}
>  #ifdef CONFIG_IXGBE_VXLAN
> +	rtnl_lock();
>  	if (adapter->flags2 & IXGBE_FLAG2_VXLAN_REREG_NEEDED) {
>  		adapter->flags2 &= ~IXGBE_FLAG2_VXLAN_REREG_NEEDED;
>  		vxlan_get_rx_port(adapter->netdev);
>  	}
> +	rtnl_unlock();
>  #endif /* CONFIG_IXGBE_VXLAN */
>  	ixgbe_reset_subtask(adapter);
>  	ixgbe_phy_interrupt_subtask(adapter);

Although there might be a deadlock with a concurrent
cancel_work_sync(&adapter->service_task);  from ixgbe_remove()

On Fri, Jun 10, 2016 at 2:17 PM, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> On Mon, 2016-04-18 at 21:19 +0200, Hannes Frederic Sowa wrote:
>> vxlan_get_rx_port requires rtnl_lock to be held.
>>
>> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
>> Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
>> Cc: Shannon Nelson <shannon.nelson@intel.com>
>> Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
>> Cc: Don Skidmore <donald.c.skidmore@intel.com>
>> Cc: Bruce Allan <bruce.w.allan@intel.com>
>> Cc: John Ronciak <john.ronciak@intel.com>
>> Cc: Mitch Williams <mitch.a.williams@intel.com>
>> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
>> ---
>>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> index 2976df77bf14f5..b2f2cf40f06a87 100644
>> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
>> @@ -7192,10 +7192,12 @@ static void ixgbe_service_task(struct work_struct *work)
>>               return;
>>       }
>>  #ifdef CONFIG_IXGBE_VXLAN
>> +     rtnl_lock();
>>       if (adapter->flags2 & IXGBE_FLAG2_VXLAN_REREG_NEEDED) {
>>               adapter->flags2 &= ~IXGBE_FLAG2_VXLAN_REREG_NEEDED;
>>               vxlan_get_rx_port(adapter->netdev);
>>       }
>> +     rtnl_unlock();
>>  #endif /* CONFIG_IXGBE_VXLAN */
>>       ixgbe_reset_subtask(adapter);
>>       ixgbe_phy_interrupt_subtask(adapter);
>
> Although there might be a deadlock with a concurrent
> cancel_work_sync(&adapter->service_task);  from ixgbe_remove()

I don't think we are holding the rtnl_lock when that is called.  The
ixgbe_remove function is a PCI function.  The ixgbe_close routine is
the one called with the rtnl_lock held.

- Alex

On Mon, Apr 18, 2016 at 12:19 PM, Hannes Frederic Sowa
<hannes@stressinduktion.org> wrote:
> vxlan_get_rx_port requires rtnl_lock to be held.
>
> Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> Cc: Jesse Brandeburg <jesse.brandeburg@intel.com>
> Cc: Shannon Nelson <shannon.nelson@intel.com>
> Cc: Carolyn Wyborny <carolyn.wyborny@intel.com>
> Cc: Don Skidmore <donald.c.skidmore@intel.com>
> Cc: Bruce Allan <bruce.w.allan@intel.com>
> Cc: John Ronciak <john.ronciak@intel.com>
> Cc: Mitch Williams <mitch.a.williams@intel.com>
> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
> ---
>  drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> index 2976df77bf14f5..b2f2cf40f06a87 100644
> --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c
> @@ -7192,10 +7192,12 @@ static void ixgbe_service_task(struct work_struct *work)
>                 return;
>         }
>  #ifdef CONFIG_IXGBE_VXLAN
> +       rtnl_lock();
>         if (adapter->flags2 & IXGBE_FLAG2_VXLAN_REREG_NEEDED) {
>                 adapter->flags2 &= ~IXGBE_FLAG2_VXLAN_REREG_NEEDED;
>                 vxlan_get_rx_port(adapter->netdev);
>         }
> +       rtnl_unlock();
>  #endif /* CONFIG_IXGBE_VXLAN */
>         ixgbe_reset_subtask(adapter);
>         ixgbe_phy_interrupt_subtask(adapter);
> --
> 2.5.5
>

Would it be possible to only take the lock inside of the conditional
statement?  There isn't really any need to be holding the rtnl_lock to
check the adapter flag.

- Alex