From a60a2b1e0af1a7517ba41689b39e9df90ef09041 Mon Sep 17 00:00:00 2001 From: Ursula Braun Date: Thu, 10 Sep 2020 18:48:20 +0200 Subject: net/smc: reduce active tcp_listen workers SMC starts a separate tcp_listen worker for every SMC socket in state SMC_LISTEN, and can accept an incoming connection request only, if this worker is really running and waiting in kernel_accept(). But the number of running workers is limited. This patch reworks the listening SMC code and starts a tcp_listen worker after the SYN-ACK handshake on the internal clc-socket only. Suggested-by: Karsten Graul Signed-off-by: Ursula Braun Reviewed-by: Guvenc Gulce Signed-off-by: Karsten Graul Signed-off-by: David S. Miller --- net/smc/af_smc.c | 38 +++++++++++++++++++++++++++++++------- net/smc/smc.h | 2 ++ net/smc/smc_close.c | 7 +++---- 3 files changed, 36 insertions(+), 11 deletions(-) (limited to 'net') diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index e7649bbc2b87..7212de4da71d 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -940,10 +940,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc) mutex_lock(&lsmc->clcsock_release_lock); if (lsmc->clcsock) - rc = kernel_accept(lsmc->clcsock, &new_clcsock, 0); + rc = kernel_accept(lsmc->clcsock, &new_clcsock, SOCK_NONBLOCK); mutex_unlock(&lsmc->clcsock_release_lock); lock_sock(lsk); - if (rc < 0) + if (rc < 0 && rc != -EAGAIN) lsk->sk_err = -rc; if (rc < 0 || lsk->sk_state == SMC_CLOSED) { new_sk->sk_prot->unhash(new_sk); @@ -956,6 +956,10 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc) goto out; } + /* new clcsock has inherited the smc listen-specific sk_data_ready + * function; switch it back to the original sk_data_ready function + */ + new_clcsock->sk->sk_data_ready = lsmc->clcsk_data_ready; (*new_smc)->clcsock = new_clcsock; out: return rc; @@ -1406,7 +1410,7 @@ static void smc_tcp_listen_work(struct work_struct *work) lock_sock(lsk); while (lsk->sk_state == SMC_LISTEN) { rc = smc_clcsock_accept(lsmc, &new_smc); - if (rc) + if (rc) /* clcsock accept queue empty or error */ goto out; if (!new_smc) continue; @@ -1426,7 +1430,23 @@ static void smc_tcp_listen_work(struct work_struct *work) out: release_sock(lsk); - sock_put(&lsmc->sk); /* sock_hold in smc_listen */ + sock_put(&lsmc->sk); /* sock_hold in smc_clcsock_data_ready() */ +} + +static void smc_clcsock_data_ready(struct sock *listen_clcsock) +{ + struct smc_sock *lsmc; + + lsmc = (struct smc_sock *) + ((uintptr_t)listen_clcsock->sk_user_data & ~SK_USER_DATA_NOCOPY); + if (!lsmc) + return; + lsmc->clcsk_data_ready(listen_clcsock); + if (lsmc->sk.sk_state == SMC_LISTEN) { + sock_hold(&lsmc->sk); /* sock_put in smc_tcp_listen_work() */ + if (!schedule_work(&lsmc->tcp_listen_work)) + sock_put(&lsmc->sk); + } } static int smc_listen(struct socket *sock, int backlog) @@ -1455,15 +1475,19 @@ static int smc_listen(struct socket *sock, int backlog) if (!smc->use_fallback) tcp_sk(smc->clcsock->sk)->syn_smc = 1; + /* save original sk_data_ready function and establish + * smc-specific sk_data_ready function + */ + smc->clcsk_data_ready = smc->clcsock->sk->sk_data_ready; + smc->clcsock->sk->sk_data_ready = smc_clcsock_data_ready; + smc->clcsock->sk->sk_user_data = + (void *)((uintptr_t)smc | SK_USER_DATA_NOCOPY); rc = kernel_listen(smc->clcsock, backlog); if (rc) goto out; sk->sk_max_ack_backlog = backlog; sk->sk_ack_backlog = 0; sk->sk_state = SMC_LISTEN; - sock_hold(sk); /* sock_hold in tcp_listen_worker */ - if (!schedule_work(&smc->tcp_listen_work)) - sock_put(sk); out: release_sock(sk); diff --git a/net/smc/smc.h b/net/smc/smc.h index 6f1c42da7a4c..f38144f83f54 100644 --- a/net/smc/smc.h +++ b/net/smc/smc.h @@ -201,6 +201,8 @@ struct smc_connection { struct smc_sock { /* smc sock container */ struct sock sk; struct socket *clcsock; /* internal tcp socket */ + void (*clcsk_data_ready)(struct sock *sk); + /* original data_ready fct. **/ struct smc_connection conn; /* smc connection */ struct smc_sock *listen_smc; /* listen parent */ struct work_struct connect_work; /* handle non-blocking connect*/ diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c index 0e7409e469c0..10d05a6d34fc 100644 --- a/net/smc/smc_close.c +++ b/net/smc/smc_close.c @@ -208,12 +208,11 @@ again: break; case SMC_LISTEN: sk->sk_state = SMC_CLOSED; + smc->clcsock->sk->sk_data_ready = smc->clcsk_data_ready; + smc->clcsock->sk->sk_user_data = NULL; sk->sk_state_change(sk); /* wake up accept */ - if (smc->clcsock && smc->clcsock->sk) { + if (smc->clcsock && smc->clcsock->sk) rc = kernel_sock_shutdown(smc->clcsock, SHUT_RDWR); - /* wake up kernel_accept of smc_tcp_listen_worker */ - smc->clcsock->sk->sk_data_ready(smc->clcsock->sk); - } smc_close_cleanup_listen(sk); release_sock(sk); flush_work(&smc->tcp_listen_work); -- cgit v1.2.3