Re: [PATCH net-next v2] net/smc: use the correct ndev to find pnetid by pnetid table

Wenjia Zhang
2025-03-11T14:36:17Z

On 11.03.25 09:59, Paolo Abeni wrote:
> On 3/4/25 1:43 PM, Guangguan Wang wrote:
>> When using smc_pnet in SMC, it will only search the pnetid in the
>> base_ndev of the netdev hierarchy(both HW PNETID and User-defined
>> sw pnetid). This may not work for some scenarios when using SMC in
>> container on cloud environment.
>> In container, there have choices of different container network,
>> such as directly using host network, virtual network IPVLAN, veth,
>> etc. Different choices of container network have different netdev
>> hierarchy. Examples of netdev hierarchy show below. (eth0 and eth1
>> in host below is the netdev directly related to the physical device).
>> _______________________________
>> | _________________ |
>> | |POD | |
>> | | | |
>> | | eth0_________ | |
>> | |____| |__| |
>> | | | |
>> | | | |
>> | eth1|base_ndev| eth0_______ |
>> | | | | RDMA ||
>> | host |_________| |_______||
>> ---------------------------------
>> netdev hierarchy if directly using host network
>> ________________________________
>> | _________________ |
>> | |POD __________ | |
>> | | |upper_ndev| | |
>> | |eth0|__________| | |
>> | |_______|_________| |
>> | |lower netdev |
>> | __|______ |
>> | eth1| | eth0_______ |
>> | |base_ndev| | RDMA ||
>> | host |_________| |_______||
>> ---------------------------------
>> netdev hierarchy if using IPVLAN
>> _______________________________
>> | _____________________ |
>> | |POD _________ | |
>> | | |base_ndev|| |
>> | |eth0(veth)|_________|| |
>> | |____________|________| |
>> | |pairs |
>> | _______|_ |
>> | | | eth0_______ |
>> | veth|base_ndev| | RDMA ||
>> | |_________| |_______||
>> | _________ |
>> | eth1|base_ndev| |
>> | host |_________| |
>> ---------------------------------
>> netdev hierarchy if using veth
>> Due to some reasons, the eth1 in host is not RDMA attached netdevice,
>> pnetid is needed to map the eth1(in host) with RDMA device so that POD
>> can do SMC-R. Because the eth1(in host) is managed by CNI plugin(such
>> as Terway, network management plugin in container environment), and in
>> cloud environment the eth(in host) can dynamically be inserted by CNI
>> when POD create and dynamically be removed by CNI when POD destroy and
>> no POD related to the eth(in host) anymore. It is hard to config the
>> pnetid to the eth1(in host). But it is easy to config the pnetid to the
>> netdevice which can be seen in POD. When do SMC-R, both the container
>> directly using host network and the container using veth network can
>> successfully match the RDMA device, because the configured pnetid netdev
>> is a base_ndev. But the container using IPVLAN can not successfully
>> match the RDMA device and 0x03030000 fallback happens, because the
>> configured pnetid netdev is not a base_ndev. Additionally, if config
>> pnetid to the eth1(in host) also can not work for matching RDMA device
>> when using veth network and doing SMC-R in POD.
>>
>> To resolve the problems list above, this patch extends to search user
>> -defined sw pnetid in the clc handshake ndev when no pnetid can be found
>> in the base_ndev, and the base_ndev take precedence over ndev for backward
>> compatibility. This patch also can unify the pnetid setup of different
>> network choices list above in container(Config user-defined sw pnetid in
>> the netdevice can be seen in POD).
>>
>> Signed-off-by: Guangguan Wang <guangguan.wang@linux.alibaba.com>
>> ---
>> net/smc/smc_pnet.c | 8 +++++---
>> 1 file changed, 5 insertions(+), 3 deletions(-)
>>
>> diff --git a/net/smc/smc_pnet.c b/net/smc/smc_pnet.c
>> index 716808f374a8..b391c2ef463f 100644
>> --- a/net/smc/smc_pnet.c
>> +++ b/net/smc/smc_pnet.c
>> @@ -1079,14 +1079,16 @@ static void smc_pnet_find_roce_by_pnetid(struct net_device *ndev,
>> struct smc_init_info *ini)
>> {
>> u8 ndev_pnetid[SMC_MAX_PNETID_LEN];
>> + struct net_device *base_ndev;
>> struct net *net;
>>
>> - ndev = pnet_find_base_ndev(ndev);
>> + base_ndev = pnet_find_base_ndev(ndev);
>> net = dev_net(ndev);
>> - if (smc_pnetid_by_dev_port(ndev->dev.parent, ndev->dev_port,
>> + if (smc_pnetid_by_dev_port(base_ndev->dev.parent, base_ndev->dev_port,
>> ndev_pnetid) &&
>> + smc_pnet_find_ndev_pnetid_by_table(base_ndev, ndev_pnetid) &&
>> smc_pnet_find_ndev_pnetid_by_table(ndev, ndev_pnetid)) {
>> - smc_pnet_find_rdma_dev(ndev, ini);
>> + smc_pnet_find_rdma_dev(base_ndev, ini);
>> return; /* pnetid could not be determined */
>> }
>> _smc_pnet_find_roce_by_pnetid(ndev_pnetid, ini, NULL, net);
>
> I understand Wenjia opposed to this solution as it may create invalid
> topologies ?!?
>
> https://lore.kernel.org/netdev/08cd6e15-3f8c-47a0-8490-103d59abf910@linux.ibm.com/#t
>
> Wenjia, could you please confirm?
>
> Thanks,
>
> Paolo
>

Hi Paolo,

Thanks for asking! I really appreciate it.

I was initially opposed, but after discussing with Halil, I agreed that
my concerns might be not necessary. Halil and I reached an agreement
that he responded to the emails (v1) to ask for the version as he
already did, and we will double-check version 2 to ensure it works
correctly.

In any case, I still need to review it carefully and will provide my
answer as soon as possible.

Thanks,
Wenjia