Re: Expose bond_xmit_hash function

From: Maor Gottlieb <maorg@mellanox.com>
To: Jiri Pirko <jiri@resnulli.us>
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 13:04:49 +0000	[thread overview]
Message-ID: <80ad03a2-9926-bf75-d79c-be554c4afaaf@mellanox.com> (raw)
In-Reply-To: <20200115094513.GS2131@nanopsycho>

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

>
> 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?