netdev - Re: [PATCHv2 0/6] Fix the problem that rxe can not work in net

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Date:   Wed, 19 Oct 2022 22:56:45 +0800
From:   Yanjun Zhu <yanjun.zhu@...ux.dev>
To:     yanjun.zhu@...ux.dev, jgg@...pe.ca, leon@...nel.org,
        zyjzyj2000@...il.com, linux-rdma@...r.kernel.org,
        netdev@...r.kernel.org, davem@...emloft.net
Cc:     Zhu Yanjun <yanjun.zhu@...el.com>
Subject: Re: [PATCHv2 0/6] Fix the problem that rxe can not work in net

在 2022/10/6 16:59, yanjun.zhu@...ux.dev 写道:
> From: Zhu Yanjun <yanjun.zhu@...el.com>
> 
> 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.
> 
> 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 rdma link del rxe0
>     net1:
>     ip netns exec net1 rdma link del rxe1
> 
> ---
> V1->V2: Add the explicit initialization of sk6.
> ---
> Zhu Yanjun (6):
>    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

Gently ping

Zhu Yanjun

> 
>   drivers/infiniband/core/nldev.c       |   6 ++
>   drivers/infiniband/sw/rxe/rxe.c       |  26 +++++-
>   drivers/infiniband/sw/rxe/rxe_net.c   | 129 ++++++++++++++++++++------
>   drivers/infiniband/sw/rxe/rxe_net.h   |   9 +-
>   drivers/infiniband/sw/rxe/rxe_verbs.h |   1 +
>   include/rdma/rdma_netlink.h           |   2 +
>   6 files changed, 134 insertions(+), 39 deletions(-)
>