linux-kernel - Re: [PATCH net-next] net/smc: add support for netdevice in containers.

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Message-ID: <afea5e9952a8a23a28748539cc65b508d1a0f68b.camel@linux.ibm.com>
Date:   Fri, 13 Oct 2023 10:04:38 +0200
From:   Niklas Schnelle <schnelle@...ux.ibm.com>
To:     dust.li@...ux.alibaba.com,
        Albert Huang <huangjie.albert@...edance.com>,
        Karsten Graul <kgraul@...ux.ibm.com>,
        Wenjia Zhang <wenjia@...ux.ibm.com>,
        Jan Karcher <jaka@...ux.ibm.com>
Cc:     "D. Wythe" <alibuda@...ux.alibaba.com>,
        Tony Lu <tonylu@...ux.alibaba.com>,
        Wen Gu <guwen@...ux.alibaba.com>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, linux-s390@...r.kernel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next] net/smc: add support for netdevice in
 containers.

On Thu, 2023-10-12 at 20:17 +0800, Dust Li wrote:
> On Wed, Oct 11, 2023 at 10:48:16PM +0800, Dust Li wrote:
> > On Thu, Sep 28, 2023 at 05:04:21PM +0200, Niklas Schnelle wrote:
> > > On Mon, 2023-09-25 at 10:35 +0800, Albert Huang wrote:
> > > > If the netdevice is within a container and communicates externally
> > > > through network technologies like VXLAN, we won't be able to find
> > > > routing information in the init_net namespace. To address this issue,
> > > > we need to add a struct net parameter to the smc_ib_find_route function.
> > > > This allow us to locate the routing information within the corresponding
> > > > net namespace, ensuring the correct completion of the SMC CLC interaction.
> > > > 
> > > > Signed-off-by: Albert Huang <huangjie.albert@...edance.com>
> > > > ---
> > > >  net/smc/af_smc.c | 3 ++-
> > > >  net/smc/smc_ib.c | 7 ++++---
> > > >  net/smc/smc_ib.h | 2 +-
> > > >  3 files changed, 7 insertions(+), 5 deletions(-)
> > > > 
> > > 
> > > I'm trying to test this patch on s390x but I'm running into the same
> > > issue I ran into with the original SMC namespace
> > > support:https://lore.kernel.org/netdev/8701fa4557026983a9ec687cfdd7ac5b3b85fd39.camel@linux.ibm.com/
> > > 
> > > Just like back then I'm using a server and a client network namespace
> > > on the same system with two ConnectX-4 VFs from the same card and port.
> > > Both TCP/IP traffic as well as user-space RDMA via "qperf … rc_bw" and
> > > `qperf … rc_lat` work between namespaces and definitely go via the
> > > card.
> > > 
> > > I did use "rdma system set netns exclusive" then moved the RDMA devices
> > > into the namespaces with "rdma dev set <rdma_dev> netns <namespace>". I
> > > also verified with "ip netns exec <namespace> rdma dev"
> > > that the RDMA devices are in the network namespace and as seen by the
> > > qperf runs normal RDMA does work.
> > > 
> > > For reference the smc_chck tool gives me the following output:
> > > 
> > > Server started on port 37373
> > > [DEBUG] Interfaces to check: eno4378
> > > Test with target IP 10.10.93.12 and port 37373
> > >  Live test (SMC-D and SMC-R)
> > > [DEBUG] Running client: smc_run /tmp/echo-clt.x0q8iO 10.10.93.12 -p
> > > 37373
> > > [DEBUG] Client result: TCP 0x05000000/0x03030000
> > >     Failed  (TCP fallback), reasons:
> > >          Client:        0x05000000   Peer declined during handshake
> > >          Server:        0x03030000   No SMC devices found (R and D)
> > > 
> > > I also checked that SMC is generally working, once I add an ISM device
> > > I do get SMC-D between the namespaces. Any ideas what could break SMC-R
> > > here?
> > 
> > I missed the email :(
> > 
> > Are you running SMC-Rv2 or v1 ?
> 
> Hi Niklas,
> 
> I tried your test today, and I encounter the same issue.
> But I found it's because my 2 VFs are in difference subnets,
> SMC-Rv2 work fine, SMC-Rv1 won't work, which is expected.
> When I set the 2 VFs in the same subnet, SMC-Rv1 also works.
> 
> So I'm not sure it's the same for you. Can you check it out ?
> 
> BTW, the fallback reason(SMC_CLC_DECL_NOSMCDEV) in this case
> is really not friendly, it's better to return SMC_CLC_DECL_DIFFPREFIX.
> 
> Best regards,
> Dust

I think you are right. I did use two consecutive private IPs but I had
set the subnet mask to /32. Setting that to /16 the SMC-R connection is
established. I'll work with Wenjia and Jan on why my system is
defaulting to SMC-Rv1 I would have hoped to get SMC-Rv2.

Thanks for your insights!
Niklas