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Message-ID: <2cb8660b-d582-4cef-9c44-80fd6f5c1d6c@linux.dev>
Date: Mon, 30 Sep 2024 18:46:57 +0800
From: Zhu Yanjun <yanjun.zhu@...ux.dev>
To: "D. Wythe" <alibuda@...ux.alibaba.com>, kgraul@...ux.ibm.com,
wenjia@...ux.ibm.com, jaka@...ux.ibm.com, wintera@...ux.ibm.com,
guwen@...ux.alibaba.com
Cc: kuba@...nel.org, davem@...emloft.net, netdev@...r.kernel.org,
linux-s390@...r.kernel.org, linux-rdma@...r.kernel.org,
tonylu@...ux.alibaba.com, pabeni@...hat.com, edumazet@...gle.com,
bpf@...r.kernel.org
Subject: Re: [RFC PATCH net-next v2] net/smc: Introduce a hook to modify
syn_smc at runtime
在 2024/9/30 15:15, D. Wythe 写道:
>
>
> On 9/29/24 7:56 PM, Zhu Yanjun wrote:
>> 在 2024/9/27 11:42, D. Wythe 写道:
>>> From: "D. Wythe" <alibuda@...ux.alibaba.com>
>>>
>>> The introduction of IPPROTO_SMC enables eBPF programs to determine
>>> whether to use SMC based on the context of socket creation, such as
>>> network namespaces, PID and comm name, etc.
>>>
>>> As a subsequent enhancement, this patch introduces a new hook for eBPF
>>> programs that allows decisions on whether to use SMC or not at runtime,
>>> including but not limited to local/remote IP address or ports. In
>>> simpler words, this feature allows modifications to syn_smc through eBPF
>>> programs before the TCP three-way handshake got established.
>>>
>>> Thanks to kfunc for making it easier for us to implement this feature in
>>> SMC.
>>>
>>> Signed-off-by: D. Wythe <alibuda@...ux.alibaba.com>
>>>
>>> ---
>>> v1 -> v2:
>>> 1. Fix wrong use of ireq->smc_ok, should be rx_opt->smc_ok.
>>> 2. Fix compile error when CONFIG_IPV6 or CONFIG_BPF_SYSCALL was not set.
>>>
>>> ---
>>> include/linux/tcp.h | 4 ++-
>>> net/ipv4/tcp_input.c | 4 +--
>>> net/smc/af_smc.c | 75 +++++++++++++++++++++++++++++++++++++++++
>>> +++++------
>>> 3 files changed, 72 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/include/linux/tcp.h b/include/linux/tcp.h
>>> index 6a5e08b..d028d76 100644
>>> --- a/include/linux/tcp.h
>>> +++ b/include/linux/tcp.h
>>> @@ -478,7 +478,9 @@ struct tcp_sock {
>>> #endif
>>> #if IS_ENABLED(CONFIG_SMC)
>>> bool syn_smc; /* SYN includes SMC */
>>> - bool (*smc_hs_congested)(const struct sock *sk);
>>> + void (*smc_openreq_init)(struct request_sock *req,
>>> + const struct tcp_options_received *rx_opt,
>>> + struct sk_buff *skb, const struct sock *sk);
>>> #endif
>>> #if defined(CONFIG_TCP_MD5SIG) || defined(CONFIG_TCP_AO)
>>> diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
>>> index 9f314df..99f34f5 100644
>>> --- a/net/ipv4/tcp_input.c
>>> +++ b/net/ipv4/tcp_input.c
>>> @@ -7036,8 +7036,8 @@ static void tcp_openreq_init(struct
>>> request_sock *req,
>>> ireq->ir_num = ntohs(tcp_hdr(skb)->dest);
>>> ireq->ir_mark = inet_request_mark(sk, skb);
>>> #if IS_ENABLED(CONFIG_SMC)
>>> - ireq->smc_ok = rx_opt->smc_ok && !(tcp_sk(sk)->smc_hs_congested &&
>>> - tcp_sk(sk)->smc_hs_congested(sk));
>>> + if (rx_opt->smc_ok && tcp_sk(sk)->smc_openreq_init)
>>> + tcp_sk(sk)->smc_openreq_init(req, rx_opt, skb, sk);
>>> #endif
>>> }
>>> diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
>>> index 0316217..fdac7e2b 100644
>>> --- a/net/smc/af_smc.c
>>> +++ b/net/smc/af_smc.c
>>> @@ -70,6 +70,15 @@
>>> static void smc_tcp_listen_work(struct work_struct *);
>>> static void smc_connect_work(struct work_struct *);
>>> +__bpf_hook_start();
>>> +
>>> +__weak noinline int select_syn_smc(const struct sock *sk, struct
>>> sockaddr *peer)
>>> +{
>>> + return 1;
>>> +}
>>> +
>>> +__bpf_hook_end();
>>> +
>>> int smc_nl_dump_hs_limitation(struct sk_buff *skb, struct
>>> netlink_callback *cb)
>>> {
>>> struct smc_nl_dmp_ctx *cb_ctx = smc_nl_dmp_ctx(cb);
>>> @@ -156,19 +165,43 @@ static struct sock *smc_tcp_syn_recv_sock(const
>>> struct sock *sk,
>>> return NULL;
>>> }
>>> -static bool smc_hs_congested(const struct sock *sk)
>>> +static void smc_openreq_init(struct request_sock *req,
>>> + const struct tcp_options_received *rx_opt,
>>> + struct sk_buff *skb, const struct sock *sk)
>>> {
>>> + struct inet_request_sock *ireq = inet_rsk(req);
>>> + struct sockaddr_storage rmt_sockaddr = {0};
>>
>> A trivial problem.
>>
>> The following should be better?
>>
>> struct sockaddr_storage rmt_sockaddr = {};
>>
>> I think, we have discussed this problem in RDMA maillist for several
>> times.
>>
>> Zhu Yanjun
>
>
> This is truly new information to me. Can you provide me with some
> discussion links?
> Thanks.
It is a trivial problem. This is the link
https://www.spinics.net/lists/linux-rdma/msg119815.html
Zhu Yanjun
>
> D. Wythe
>
>
>>
>>> const struct smc_sock *smc;
>>> smc = smc_clcsock_user_data(sk);
>>> if (!smc)
>>> - return true;
>>> + return;
>>> - if (workqueue_congested(WORK_CPU_UNBOUND, smc_hs_wq))
>>> - return true;
>>> + if (smc->limit_smc_hs && workqueue_congested(WORK_CPU_UNBOUND,
>>> smc_hs_wq))
>>> + goto out_no_smc;
>>> - return false;
>>> + rmt_sockaddr.ss_family = sk->sk_family;
>>> +
>>> + if (rmt_sockaddr.ss_family == AF_INET) {
>>> + struct sockaddr_in *rmt4_sockaddr = (struct sockaddr_in
>>> *)&rmt_sockaddr;
>>> +
>>> + rmt4_sockaddr->sin_addr.s_addr = ireq->ir_rmt_addr;
>>> + rmt4_sockaddr->sin_port = ireq->ir_rmt_port;
>>> +#if IS_ENABLED(CONFIG_IPV6)
>>> + } else {
>>> + struct sockaddr_in6 *rmt6_sockaddr = (struct sockaddr_in6
>>> *)&rmt_sockaddr;
>>> +
>>> + rmt6_sockaddr->sin6_addr = ireq->ir_v6_rmt_addr;
>>> + rmt6_sockaddr->sin6_port = ireq->ir_rmt_port;
>>> +#endif /* CONFIG_IPV6 */
>>> + }
>>> +
>>> + ireq->smc_ok = select_syn_smc(sk, (struct sockaddr
>>> *)&rmt_sockaddr);
>>> + return;
>>> +out_no_smc:
>>> + ireq->smc_ok = 0;
>>> + return;
>>> }
>>> struct smc_hashinfo smc_v4_hashinfo = {
>>> @@ -1671,7 +1704,7 @@ int smc_connect(struct socket *sock, struct
>>> sockaddr *addr,
>>> }
>>> smc_copy_sock_settings_to_clc(smc);
>>> - tcp_sk(smc->clcsock->sk)->syn_smc = 1;
>>> + tcp_sk(smc->clcsock->sk)->syn_smc = select_syn_smc(sk, addr);
>>> if (smc->connect_nonblock) {
>>> rc = -EALREADY;
>>> goto out;
>>> @@ -2650,8 +2683,7 @@ int smc_listen(struct socket *sock, int backlog)
>>> inet_csk(smc->clcsock->sk)->icsk_af_ops = &smc->af_ops;
>>> - if (smc->limit_smc_hs)
>>> - tcp_sk(smc->clcsock->sk)->smc_hs_congested = smc_hs_congested;
>>> + tcp_sk(smc->clcsock->sk)->smc_openreq_init = smc_openreq_init;
>>> rc = kernel_listen(smc->clcsock, backlog);
>>> if (rc) {
>>> @@ -3475,6 +3507,24 @@ static void __net_exit
>>> smc_net_stat_exit(struct net *net)
>>> .exit = smc_net_stat_exit,
>>> };
>>> +#if IS_ENABLED(CONFIG_BPF_SYSCALL)
>>> +BTF_SET8_START(bpf_smc_fmodret_ids)
>>> +BTF_ID_FLAGS(func, select_syn_smc)
>>> +BTF_SET8_END(bpf_smc_fmodret_ids)
>>> +
>>> +static const struct btf_kfunc_id_set bpf_smc_fmodret_set = {
>>> + .owner = THIS_MODULE,
>>> + .set = &bpf_smc_fmodret_ids,
>>> +};
>>> +
>>> +static int bpf_smc_kfunc_init(void)
>>> +{
>>> + return register_btf_fmodret_id_set(&bpf_smc_fmodret_set);
>>> +}
>>> +#else
>>> +static inline int bpf_smc_kfunc_init(void) { return 0; }
>>> +#endif /* CONFIG_BPF_SYSCALL */
>>> +
>>> static int __init smc_init(void)
>>> {
>>> int rc;
>>> @@ -3574,8 +3624,17 @@ static int __init smc_init(void)
>>> pr_err("%s: smc_inet_init fails with %d\n", __func__, rc);
>>> goto out_ulp;
>>> }
>>> +
>>> + rc = bpf_smc_kfunc_init();
>>> + if (rc) {
>>> + pr_err("%s: bpf_smc_kfunc_init fails with %d\n", __func__, rc);
>>> + goto out_inet;
>>> + }
>>> +
>>> static_branch_enable(&tcp_have_smc);
>>> return 0;
>>> +out_inet:
>>> + smc_inet_exit();
>>> out_ulp:
>>> tcp_unregister_ulp(&smc_ulp_ops);
>>> out_lo:
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