netdev - Re: Expose bond_xmit

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Date:   Wed, 15 Jan 2020 15:15:35 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     Maor Gottlieb <maorg@...lanox.com>
Cc:     "j.vosburgh@...il.com" <j.vosburgh@...il.com>,
        "vfalico@...il.com" <vfalico@...il.com>,
        "andy@...yhouse.net" <andy@...yhouse.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Saeed Mahameed <saeedm@...lanox.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Leon Romanovsky <leonro@...lanox.com>,
        Jiri Pirko <jiri@...lanox.com>,
        Alex Rosenbaum <alexr@...lanox.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        Mark Zhang <markz@...lanox.com>,
        Parav Pandit <parav@...lanox.com>
Subject: Re: Expose bond_xmit_hash function

Wed, Jan 15, 2020 at 02:04:49PM CET, maorg@...lanox.com wrote:
>
>On 1/15/2020 11:45 AM, Jiri Pirko wrote:
>> Wed, Jan 15, 2020 at 09:01:43AM CET, maorg@...lanox.com wrote:
>>> RDMA over Converged Ethernet (RoCE) is a standard protocol which enables
>>> RDMA’s efficient data transfer over Ethernet networks allowing transport
>>> offload with hardware RDMA engine implementation.
>>> The RoCE v2 protocol exists on top of either the UDP/IPv4 or the
>>> UDP/IPv6 protocol:
>>>
>>> --------------------------------------------------------------
>>> | L2 | L3 | UDP |IB BTH | Payload| ICRC | FCS |
>>> --------------------------------------------------------------
>>>
>>> When a bond LAG netdev is in use, we would like to have the same hash
>>> result for RoCE packets as any other UDP packets, for this purpose we
>>> need to expose the bond_xmit_hash function to external modules.
>>> If no objection, I will push a patch that export this symbol.
>> I don't think it is good idea to do it. It is an internal bond function.
>> it even accepts "struct bonding *bond". Do you plan to push netdev
>> struct as an arg instead? What about team? What about OVS bonding?
>
>No, I am planning to pass the bond struct as an arg. Currently, team 

Hmm, that would be ofcourse wrong, as it is internal bonding driver
structure.


>bonding is not supported in RoCE LAG and I don't see how OVS is related.

Should work for all. OVS is related in a sense that you can do bonding
there too.


>
>>
>> Also, you don't really need a hash, you need a slave that is going to be
>> used for a packet xmit.
>>
>> I think this could work in a generic way:
>>
>> struct net_device *master_xmit_slave_get(struct net_device *master_dev,
>> 					 struct sk_buff *skb);
>
>The suggestion is to put this function in the bond driver and call it 
>instead of bond_xmit_hash? is it still necessary if I have the bond pointer?

No. This should be in a generic code. No direct calls down to bonding
driver please. Or do you want to load bonding module every time your
module loads?

I thinks this can be implemented with ndo with "master_xmit_slave_get()"
as a wrapper. Masters that support this would just implement the ndo.

>