From 48b6190a00425a1bebac9f7ae4b338a1e20f50f3 Mon Sep 17 00:00:00 2001 From: "D. Wythe" Date: Thu, 10 Feb 2022 17:11:36 +0800 Subject: net/smc: Limit SMC visits when handshake workqueue congested This patch intends to provide a mechanism to put constraint on SMC connections visit according to the pressure of SMC handshake process. At present, frequent visits will cause the incoming connections to be backlogged in SMC handshake queue, raise the connections established time. Which is quite unacceptable for those applications who base on short lived connections. There are two ways to implement this mechanism: 1. Put limitation after TCP established. 2. Put limitation before TCP established. In the first way, we need to wait and receive CLC messages that the client will potentially send, and then actively reply with a decline message, in a sense, which is also a sort of SMC handshake, affect the connections established time on its way. In the second way, the only problem is that we need to inject SMC logic into TCP when it is about to reply the incoming SYN, since we already do that, it's seems not a problem anymore. And advantage is obvious, few additional processes are required to complete the constraint. This patch use the second way. After this patch, connections who beyond constraint will not informed any SMC indication, and SMC will not be involved in any of its subsequent processes. Link: https://lore.kernel.org/all/1641301961-59331-1-git-send-email-alibuda@linux.alibaba.com/ Signed-off-by: D. Wythe Signed-off-by: David S. Miller --- include/linux/tcp.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux') diff --git a/include/linux/tcp.h b/include/linux/tcp.h index 78b91bb92f0d..1168302b7927 100644 --- a/include/linux/tcp.h +++ b/include/linux/tcp.h @@ -394,6 +394,7 @@ struct tcp_sock { bool is_mptcp; #endif #if IS_ENABLED(CONFIG_SMC) + bool (*smc_hs_congested)(const struct sock *sk); bool syn_smc; /* SYN includes SMC */ #endif -- cgit v1.3-8-gc7d7 From a6a6fe27bab48f0d09a64b051e7bde432fcae081 Mon Sep 17 00:00:00 2001 From: "D. Wythe" Date: Thu, 10 Feb 2022 17:11:37 +0800 Subject: net/smc: Dynamic control handshake limitation by socket options This patch aims to add dynamic control for SMC handshake limitation for every smc sockets, in production environment, it is possible for the same applications to handle different service types, and may have different opinion on SMC handshake limitation. This patch try socket options to complete it, since we don't have socket option level for SMC yet, which requires us to implement it at the same time. This patch does the following: - add new socket option level: SOL_SMC. - add new SMC socket option: SMC_LIMIT_HS. - provide getter/setter for SMC socket options. Link: https://lore.kernel.org/all/20f504f961e1a803f85d64229ad84260434203bd.1644323503.git.alibuda@linux.alibaba.com/ Signed-off-by: D. Wythe Signed-off-by: David S. Miller --- include/linux/socket.h | 1 + include/uapi/linux/smc.h | 4 +++ net/smc/af_smc.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++- net/smc/smc.h | 1 + 4 files changed, 74 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/socket.h b/include/linux/socket.h index 8ef26d89ef49..6f85f5d957ef 100644 --- a/include/linux/socket.h +++ b/include/linux/socket.h @@ -366,6 +366,7 @@ struct ucred { #define SOL_XDP 283 #define SOL_MPTCP 284 #define SOL_MCTP 285 +#define SOL_SMC 286 /* IPX options */ #define IPX_TYPE 1 diff --git a/include/uapi/linux/smc.h b/include/uapi/linux/smc.h index 6c2874fd2c00..343e7450c3a3 100644 --- a/include/uapi/linux/smc.h +++ b/include/uapi/linux/smc.h @@ -284,4 +284,8 @@ enum { __SMC_NLA_SEID_TABLE_MAX, SMC_NLA_SEID_TABLE_MAX = __SMC_NLA_SEID_TABLE_MAX - 1 }; + +/* SMC socket options */ +#define SMC_LIMIT_HS 1 /* constraint on smc handshake */ + #endif /* _UAPI_LINUX_SMC_H */ diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index a05ffb268c3e..97dcdc0a2107 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -2326,7 +2326,8 @@ static int smc_listen(struct socket *sock, int backlog) inet_csk(smc->clcsock->sk)->icsk_af_ops = &smc->af_ops; - tcp_sk(smc->clcsock->sk)->smc_hs_congested = smc_hs_congested; + if (smc->limit_smc_hs) + tcp_sk(smc->clcsock->sk)->smc_hs_congested = smc_hs_congested; rc = kernel_listen(smc->clcsock, backlog); if (rc) { @@ -2621,6 +2622,67 @@ out: return rc ? rc : rc1; } +static int __smc_getsockopt(struct socket *sock, int level, int optname, + char __user *optval, int __user *optlen) +{ + struct smc_sock *smc; + int val, len; + + smc = smc_sk(sock->sk); + + if (get_user(len, optlen)) + return -EFAULT; + + len = min_t(int, len, sizeof(int)); + + if (len < 0) + return -EINVAL; + + switch (optname) { + case SMC_LIMIT_HS: + val = smc->limit_smc_hs; + break; + default: + return -EOPNOTSUPP; + } + + if (put_user(len, optlen)) + return -EFAULT; + if (copy_to_user(optval, &val, len)) + return -EFAULT; + + return 0; +} + +static int __smc_setsockopt(struct socket *sock, int level, int optname, + sockptr_t optval, unsigned int optlen) +{ + struct sock *sk = sock->sk; + struct smc_sock *smc; + int val, rc; + + smc = smc_sk(sk); + + lock_sock(sk); + switch (optname) { + case SMC_LIMIT_HS: + if (optlen < sizeof(int)) + return -EINVAL; + if (copy_from_sockptr(&val, optval, sizeof(int))) + return -EFAULT; + + smc->limit_smc_hs = !!val; + rc = 0; + break; + default: + rc = -EOPNOTSUPP; + break; + } + release_sock(sk); + + return rc; +} + static int smc_setsockopt(struct socket *sock, int level, int optname, sockptr_t optval, unsigned int optlen) { @@ -2630,6 +2692,8 @@ static int smc_setsockopt(struct socket *sock, int level, int optname, if (level == SOL_TCP && optname == TCP_ULP) return -EOPNOTSUPP; + else if (level == SOL_SMC) + return __smc_setsockopt(sock, level, optname, optval, optlen); smc = smc_sk(sk); @@ -2712,6 +2776,9 @@ static int smc_getsockopt(struct socket *sock, int level, int optname, struct smc_sock *smc; int rc; + if (level == SOL_SMC) + return __smc_getsockopt(sock, level, optname, optval, optlen); + smc = smc_sk(sock->sk); mutex_lock(&smc->clcsock_release_lock); if (!smc->clcsock) { diff --git a/net/smc/smc.h b/net/smc/smc.h index e91e40040d07..7e2693832a1b 100644 --- a/net/smc/smc.h +++ b/net/smc/smc.h @@ -249,6 +249,7 @@ struct smc_sock { /* smc sock container */ struct work_struct smc_listen_work;/* prepare new accept socket */ struct list_head accept_q; /* sockets to be accepted */ spinlock_t accept_q_lock; /* protects accept_q */ + bool limit_smc_hs; /* put constraint on handshake */ bool use_fallback; /* fallback to tcp */ int fallback_rsn; /* reason for fallback */ u32 peer_diagnosis; /* decline reason from peer */ -- cgit v1.3-8-gc7d7