Re: [PATCH net-next v9 2/4] net: Introduce generic failover module

["Samudrala, Sridhar" <sridhar.samudrala@intel.com>]

On 4/28/2018 2:06 AM, Jiri Pirko wrote:
> Fri, Apr 27, 2018 at 07:06:58PM CEST, sridhar.samudrala@intel.com wrote:
>> This provides a generic interface for paravirtual drivers to listen
>> for netdev register/unregister/link change events from pci ethernet
>> devices with the same MAC and takeover their datapath. The notifier and
>> event handling code is based on the existing netvsc implementation.
>>
>> It exposes 2 sets of interfaces to the paravirtual drivers.
>> 1. For paravirtual drivers like virtio_net that use 3 netdev model, the
>>    the failover module provides interfaces to create/destroy additional
>>    master netdev and all the slave events are managed internally.
>>         net_failover_create()
>>         net_failover_destroy()
>>    A failover netdev is created that acts a master device and controls 2
>>    slave devices. The original virtio_net netdev is registered as 'standby'
>>    netdev and a passthru/vf device with the same MAC gets registered as
>>    'primary' netdev. Both 'standby' and 'primary' netdevs are associated
>>    with the same 'pci' device.  The user accesses the network interface via
>>    'failover' netdev. The 'failover' netdev chooses 'primary' netdev as
>>    default for transmits when it is available with link up and running.
>> 2. For existing netvsc driver that uses 2 netdev model, no master netdev
>>    is created. The paravirtual driver registers each instance of netvsc
>>    as a 'failover' netdev  along with a set of ops to manage the slave
>>    events. There is no 'standby' netdev in this model. A passthru/vf device
>>    with the same MAC gets registered as 'primary' netdev.
>>         net_failover_register()
>>         net_failover_unregister()
>>
> First of all, I like this v9 very much. Nice progress!
> Couple of notes inlined.

Thanks for the detailed reviews and all your suggestions for improvements
agree with all your comments. will address them in v10.