Re: Expose bond_xmit_hash function

From: Jiri Pirko <jiri@resnulli.us>
To: Maor Gottlieb <maorg@mellanox.com>
Cc: "j.vosburgh@gmail.com" <j.vosburgh@gmail.com>,
	"vfalico@gmail.com" <vfalico@gmail.com>,
	"andy@greyhouse.net" <andy@greyhouse.net>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Saeed Mahameed <saeedm@mellanox.com>,
	Jason Gunthorpe <jgg@mellanox.com>,
	Leon Romanovsky <leonro@mellanox.com>,
	Jiri Pirko <jiri@mellanox.com>,
	Alex Rosenbaum <alexr@mellanox.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
	Mark Zhang <markz@mellanox.com>,
	Parav Pandit <parav@mellanox.com>
Subject: Re: Expose bond_xmit_hash function
Date: Wed, 15 Jan 2020 15:15:35 +0100	[thread overview]
Message-ID: <20200115141535.GT2131@nanopsycho> (raw)
In-Reply-To: <80ad03a2-9926-bf75-d79c-be554c4afaaf@mellanox.com>

Wed, Jan 15, 2020 at 02:04:49PM CET, maorg@mellanox.com wrote:
>
>On 1/15/2020 11:45 AM, Jiri Pirko wrote:
>> Wed, Jan 15, 2020 at 09:01:43AM CET, maorg@mellanox.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.

>