From 24ac3a08e65845a098140ff270229dec4a897404 Mon Sep 17 00:00:00 2001 From: Ursula Braun Date: Wed, 27 Jun 2018 17:59:50 +0200 Subject: [PATCH] net/smc: rebuild nonblocking connect The recent poll change may lead to stalls for non-blocking connecting SMC sockets, since sock_poll_wait is no longer performed on the internal CLC socket, but on the outer SMC socket. kernel_connect() on the internal CLC socket returns with -EINPROGRESS, but the wake up logic does not work in all cases. If the internal CLC socket is still in state TCP_SYN_SENT when polled, sock_poll_wait() from sock_poll() does not sleep. It is supposed to sleep till the state of the internal CLC socket switches to TCP_ESTABLISHED. This problem triggered a redesign of the SMC nonblocking connect logic. This patch introduces a connect worker covering all connect steps followed by a wake up of socket waiters. It allows to get rid of all delays and locks in smc_poll(). Fixes: c0129a061442 ("smc: convert to ->poll_mask") Signed-off-by: Ursula Braun Signed-off-by: David S. Miller --- net/smc/af_smc.c | 91 +++++++++++++++++++++++++++++++++--------------- net/smc/smc.h | 8 +++++ 2 files changed, 71 insertions(+), 28 deletions(-) diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c index da7f02edcd37..4d1d4ddb2f49 100644 --- a/net/smc/af_smc.c +++ b/net/smc/af_smc.c @@ -45,6 +45,7 @@ static DEFINE_MUTEX(smc_create_lgr_pending); /* serialize link group */ static void smc_tcp_listen_work(struct work_struct *); +static void smc_connect_work(struct work_struct *); static void smc_set_keepalive(struct sock *sk, int val) { @@ -122,6 +123,12 @@ static int smc_release(struct socket *sock) goto out; smc = smc_sk(sk); + + /* cleanup for a dangling non-blocking connect */ + flush_work(&smc->connect_work); + kfree(smc->connect_info); + smc->connect_info = NULL; + if (sk->sk_state == SMC_LISTEN) /* smc_close_non_accepted() is called and acquires * sock lock for child sockets again @@ -186,6 +193,7 @@ static struct sock *smc_sock_alloc(struct net *net, struct socket *sock, sk->sk_protocol = protocol; smc = smc_sk(sk); INIT_WORK(&smc->tcp_listen_work, smc_tcp_listen_work); + INIT_WORK(&smc->connect_work, smc_connect_work); INIT_DELAYED_WORK(&smc->conn.tx_work, smc_tx_work); INIT_LIST_HEAD(&smc->accept_q); spin_lock_init(&smc->accept_q_lock); @@ -576,6 +584,35 @@ static int __smc_connect(struct smc_sock *smc) return 0; } +static void smc_connect_work(struct work_struct *work) +{ + struct smc_sock *smc = container_of(work, struct smc_sock, + connect_work); + int rc; + + lock_sock(&smc->sk); + rc = kernel_connect(smc->clcsock, &smc->connect_info->addr, + smc->connect_info->alen, smc->connect_info->flags); + if (smc->clcsock->sk->sk_err) { + smc->sk.sk_err = smc->clcsock->sk->sk_err; + goto out; + } + if (rc < 0) { + smc->sk.sk_err = -rc; + goto out; + } + + rc = __smc_connect(smc); + if (rc < 0) + smc->sk.sk_err = -rc; + +out: + smc->sk.sk_state_change(&smc->sk); + kfree(smc->connect_info); + smc->connect_info = NULL; + release_sock(&smc->sk); +} + static int smc_connect(struct socket *sock, struct sockaddr *addr, int alen, int flags) { @@ -605,15 +642,32 @@ static int smc_connect(struct socket *sock, struct sockaddr *addr, smc_copy_sock_settings_to_clc(smc); tcp_sk(smc->clcsock->sk)->syn_smc = 1; - rc = kernel_connect(smc->clcsock, addr, alen, flags); - if (rc) - goto out; + if (flags & O_NONBLOCK) { + if (smc->connect_info) { + rc = -EALREADY; + goto out; + } + smc->connect_info = kzalloc(alen + 2 * sizeof(int), GFP_KERNEL); + if (!smc->connect_info) { + rc = -ENOMEM; + goto out; + } + smc->connect_info->alen = alen; + smc->connect_info->flags = flags ^ O_NONBLOCK; + memcpy(&smc->connect_info->addr, addr, alen); + schedule_work(&smc->connect_work); + rc = -EINPROGRESS; + } else { + rc = kernel_connect(smc->clcsock, addr, alen, flags); + if (rc) + goto out; - rc = __smc_connect(smc); - if (rc < 0) - goto out; - else - rc = 0; /* success cases including fallback */ + rc = __smc_connect(smc); + if (rc < 0) + goto out; + else + rc = 0; /* success cases including fallback */ + } out: release_sock(sk); @@ -1278,34 +1332,17 @@ static __poll_t smc_poll_mask(struct socket *sock, __poll_t events) struct sock *sk = sock->sk; __poll_t mask = 0; struct smc_sock *smc; - int rc; if (!sk) return EPOLLNVAL; smc = smc_sk(sock->sk); - sock_hold(sk); - lock_sock(sk); if ((sk->sk_state == SMC_INIT) || smc->use_fallback) { /* delegate to CLC child sock */ - release_sock(sk); mask = smc->clcsock->ops->poll_mask(smc->clcsock, events); - lock_sock(sk); sk->sk_err = smc->clcsock->sk->sk_err; - if (sk->sk_err) { + if (sk->sk_err) mask |= EPOLLERR; - } else { - /* if non-blocking connect finished ... */ - if (sk->sk_state == SMC_INIT && - mask & EPOLLOUT && - smc->clcsock->sk->sk_state != TCP_CLOSE) { - rc = __smc_connect(smc); - if (rc < 0) - mask |= EPOLLERR; - /* success cases including fallback */ - mask |= EPOLLOUT | EPOLLWRNORM; - } - } } else { if (sk->sk_err) mask |= EPOLLERR; @@ -1334,8 +1371,6 @@ static __poll_t smc_poll_mask(struct socket *sock, __poll_t events) mask |= EPOLLPRI; } - release_sock(sk); - sock_put(sk); return mask; } diff --git a/net/smc/smc.h b/net/smc/smc.h index 51ae1f10d81a..d7ca26570482 100644 --- a/net/smc/smc.h +++ b/net/smc/smc.h @@ -187,11 +187,19 @@ struct smc_connection { struct work_struct close_work; /* peer sent some closing */ }; +struct smc_connect_info { + int flags; + int alen; + struct sockaddr addr; +}; + struct smc_sock { /* smc sock container */ struct sock sk; struct socket *clcsock; /* internal tcp socket */ struct smc_connection conn; /* smc connection */ struct smc_sock *listen_smc; /* listen parent */ + struct smc_connect_info *connect_info; /* connect address & flags */ + struct work_struct connect_work; /* handle non-blocking connect*/ struct work_struct tcp_listen_work;/* handle tcp socket accepts */ struct work_struct smc_listen_work;/* prepare new accept socket */ struct list_head accept_q; /* sockets to be accepted */