Re: [PATCH net-next] net/smc: use new helper to get the netdev associated to an ibdev

[Wenjia Zhang <wenjia@linux.ibm.com>]

On 24.10.24 13:06, Wen Gu wrote:
> 
> 
> On 2024/10/24 18:00, Wenjia Zhang wrote:
>>
>>
>> On 24.10.24 07:44, Wen Gu wrote:
>>> Patch [1] provides common interfaces to store and get net devices
>>> associated to an IB device port and removes the ops->get_netdev()
>>> callback of mlx5 driver. So use the new interface in smc.
>>>
>>> [1]: 8d159eb2117b ("RDMA/mlx5: Use IB set_netdev and get_netdev 
>>> functions")
>>>
>>> Reported-by: D. Wythe <alibuda@linux.alibaba.com>
>>> Signed-off-by: Wen Gu <guwen@linux.alibaba.com>
>>> ---
>> [...]
>>
>> We detected the problem as well, and I already sent a patch with the 
>> same code change in our team internally these. Because some agreement 
>> issues on the commit message, it is still not sent out externally. Now 
>> we (our team) have almost an agreement, I'd like to attach it here. 
>> Please have a look if it is also for you to use:
>>
>> "
>> [PATCH net] net/smc: Fix lookup of netdev by using ib_device_get_netdev()
>>
>> Since/Although commit c2261dd76b54 ("RDMA/device: Add 
>> ib_device_set_netdev() as an alternative to get_netdev") introduced an 
>> API ib_device_get_netdev, the SMC-R variant of the SMC protocol 
>> continued to use the old API ib_device_ops.get_netdev() to lookup 
>> netdev. As commit 8d159eb2117b ("RDMA/mlx5: Use IB set_netdev and 
>> get_netdev functions") removed the get_netdev callback from 
>> mlx5_ib_dev_common_roce_ops, calling ib_device_ops.get_netdev didn't 
>> work any more at least by using a mlx5 device driver. Thus, using 
>> ib_device_set_netdev() now became mandatory.
>>
>> Replace ib_device_ops.get_netdev() with ib_device_get_netdev().
>>
>> Fixes: 54903572c23c ("net/smc: allow pnetid-less configuration")
>> Fixes: 8d159eb2117b ("RDMA/mlx5: Use IB set_netdev and get_netdev 
>> functions")
>> "
>> My main points are:
>> - This patch should go to net, not net-next. Because it can result in 
>> malfunction. e.g. if the RoCE devices are used as both handshake 
>> device and RDMA device without any PNET_ID, it would be failed to find 
>> SMC-R device, then fallback.
>> - We need the both fixes, which would help us for the backport
>>
>>
>> Thanks,
>> Wenjia
> 
> Hi, Wenjia. I see. Since you're ready to post a patch, and this one has 
> some problems,
> I think you can supersede this one with yours. It is totally OK for me.
> 
> Thanks!
> Wen Gu
> 
Thank you, Wen!
I'll send some fixes this days.

Thanks,
Wenjia