Re: [PATCH v6 0/8] Fix the problem that rxe can not work in net namespace

[Bob Pearson <rpearsonhpe@gmail.com>]

On 6/23/23 04:57, Zhu Yanjun wrote:
> From: Zhu Yanjun <yanjun.zhu@linux.dev>
> 
> When run "ip link add" command to add a rxe rdma link in a net
> namespace, normally this rxe rdma link can not work in a net
> name space.
> 
> The root cause is that a sock listening on udp port 4791 is created
> in init_net when the rdma_rxe module is loaded into kernel. That is,
> the sock listening on udp port 4791 is created in init_net. Other net
> namespace is difficult to use this sock.
> 
> The following commits will solve this problem.
> 
> In the first commit, move the creating sock listening on udp port 4791
> from module_init function to rdma link creating functions. That is,
> after the module rdma_rxe is loaded, the sock will not be created.
> When run "rdma link add ..." command, the sock will be created. So
> when creating a rdma link in the net namespace, the sock will be
> created in this net namespace.
> 
> In the second commit, the functions udp4_lib_lookup and udp6_lib_lookup
> will check the sock exists in the net namespace or not. If yes, rdma
> link will increase the reference count of this sock, then continue other
> jobs instead of creating a new sock to listen on udp port 4791. Since the
> network notifier is global, when the module rdma_rxe is loaded, this
> notifier will be registered.
> 
> After the rdma link is created, the command "rdma link del" is to
> delete rdma link at the same time the sock is checked. If the reference
> count of this sock is greater than the sock reference count needed by
> udp tunnel, the sock reference count is decreased by one. If equal, it
> indicates that this rdma link is the last one. As such, the udp tunnel
> is shut down and the sock is closed. The above work should be
> implemented in linkdel function. But currently no dellink function in
> rxe. So the 3rd commit addes dellink function pointer. And the 4th
> commit implements the dellink function in rxe.
> 
> To now, it is not necessary to keep a global variable to store the sock
> listening udp port 4791. This global variable can be replaced by the
> functions udp4_lib_lookup and udp6_lib_lookup totally. Because the
> function udp6_lib_lookup is in the fast path, a member variable l_sk6
> is added to store the sock. If l_sk6 is NULL, udp6_lib_lookup is called
> to lookup the sock, then the sock is stored in l_sk6, in the future,it
> can be used directly.
> 
> All the above work has been done in init_net. And it can also work in
> the net namespace. So the init_net is replaced by the individual net
> namespace. This is what the 6th commit does. Because rxe device is
> dependent on the net device and the sock listening on udp port 4791,
> every rxe device is in exclusive mode in the individual net namespace.
> Other rdma netns operations will be considerred in the future.
> 
> In the 7th commit, the register_pernet_subsys/unregister_pernet_subsys
> functions are added. When a new net namespace is created, the init
> function will initialize the sk4 and sk6 socks. Then the 2 socks will
> be released when the net namespace is destroyed. The functions
> rxe_ns_pernet_sk4/rxe_ns_pernet_set_sk4 will get and set sk4 in the net
> namespace. The functions rxe_ns_pernet_sk6/rxe_ns_pernet_set_sk6 will
> handle sk6. Then sk4 and sk6 are used in the previous commits.
> 
> As the sk4 and sk6 in pernet namespace can be accessed, it is not
> necessary to add a new l_sk6. As such, in the 8th commit, the l_sk6 is
> replaced with the sk6 in pernet namespace.
> 
> Test steps:
> 1) Suppose that 2 NICs are in 2 different net namespaces.
> 
>   # ip netns exec net0 ip link
>   3: eno2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP
>      link/ether 00:1e:67:a0:22:3f brd ff:ff:ff:ff:ff:ff
>      altname enp5s0
> 
>   # ip netns exec net1 ip link
>   4: eno3: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel
>      link/ether f8:e4:3b:3b:e4:10 brd ff:ff:ff:ff:ff:ff
> 
> 2) Add rdma link in the different net namespace
>     net0:
>     # ip netns exec net0 rdma link add rxe0 type rxe netdev eno2
> 
>     net1:
>     # ip netns exec net1 rdma link add rxe1 type rxe netdev eno3
> 
> 3) Run rping test.
>     net0
>     # ip netns exec net0 rping -s -a 192.168.2.1 -C 1&
>     [1] 1737
>     # ip netns exec net1 rping -c -a 192.168.2.1 -d -v -C 1
>     verbose
>     count 1
>     ...
>     ping data: rdma-ping-0: ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqr
>     ...
> 
> 4) Remove the rdma links from the net namespaces.
>     net0:
>     # ip netns exec net0 ss -lu
>     State     Recv-Q    Send-Q    Local Address:Port    Peer Address:Port    Process
>     UNCONN    0         0         0.0.0.0:4791          0.0.0.0:*
>     UNCONN    0         0         [::]:4791             [::]:*
> 
>     # ip netns exec net0 rdma link del rxe0
> 
>     # ip netns exec net0 ss -lu
>     State     Recv-Q    Send-Q    Local Address:Port    Peer Address:Port    Process
> 
>     net1:
>     # ip netns exec net0 ss -lu
>     State     Recv-Q    Send-Q    Local Address:Port    Peer Address:Port    Process
>     UNCONN    0         0         0.0.0.0:4791          0.0.0.0:*
>     UNCONN    0         0         [::]:4791             [::]:*
> 
>     # ip netns exec net1 rdma link del rxe1
> 
>     # ip netns exec net0 ss -lu
>     State     Recv-Q    Send-Q    Local Address:Port    Peer Address:Port    Process
> 
> V5->V6: Fix resource leak problem when rxe_net_init fails. And fix some
> 	style problems.
> 
> V4->V5: Rebase the commits to V6.4-rc1
> 
> V3->V4: Rebase the commits to rdma-next;
> 
> V2->V3: 1) Add "rdma link del" example in the cover letter, and use "ss -lu" to
>            verify rdma link is removed.
>         2) Add register_pernet_subsys/unregister_pernet_subsys net namespace
>         3) Replace l_sk6 with sk6 of pernet_name_space
> 
> V1->V2: Add the explicit initialization of sk6.
> 
> Zhu Yanjun (8):
>   RDMA/rxe: Creating listening sock in newlink function
>   RDMA/rxe: Support more rdma links in init_net
>   RDMA/nldev: Add dellink function pointer
>   RDMA/rxe: Implement dellink in rxe
>   RDMA/rxe: Replace global variable with sock lookup functions
>   RDMA/rxe: add the support of net namespace
>   RDMA/rxe: Add the support of net namespace notifier
>   RDMA/rxe: Replace l_sk6 with sk6 in net namespace
> 
>  drivers/infiniband/core/nldev.c     |   6 ++
>  drivers/infiniband/sw/rxe/Makefile  |   3 +-
>  drivers/infiniband/sw/rxe/rxe.c     |  35 +++++++-
>  drivers/infiniband/sw/rxe/rxe_net.c | 119 ++++++++++++++++++------
>  drivers/infiniband/sw/rxe/rxe_net.h |   9 +-
>  drivers/infiniband/sw/rxe/rxe_ns.c  | 134 ++++++++++++++++++++++++++++
>  drivers/infiniband/sw/rxe/rxe_ns.h  |  17 ++++
>  include/rdma/rdma_netlink.h         |   2 +
>  8 files changed, 285 insertions(+), 40 deletions(-)
>  create mode 100644 drivers/infiniband/sw/rxe/rxe_ns.c
>  create mode 100644 drivers/infiniband/sw/rxe/rxe_ns.h
> 

I am OOO until Monday evening. I will try it then.

Bob