[PATCH net-next v3 4/4] net/smc: handle sockopt TCP_DEFER_ACCEPT

Ursula Braun
2018-04-26T15:18:23Z

If sockopt TCP_DEFER_ACCEPT is set, the accept is delayed till
data is available.

Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
---
net/smc/af_smc.c | 26 +++++++++++++++++++++++++-
net/smc/smc.h | 4 ++++
net/smc/smc_rx.c | 2 +-
net/smc/smc_rx.h | 1 +
4 files changed, 31 insertions(+), 2 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 9d8b381281e3..20aa4175b9f8 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1044,6 +1044,7 @@ static int smc_accept(struct socket *sock, struct socket *new_sock,

if (lsmc->sk.sk_state != SMC_LISTEN) {
rc = -EINVAL;
+ release_sock(sk);
goto out;
}

@@ -1071,9 +1072,29 @@ static int smc_accept(struct socket *sock, struct socket *new_sock,

if (!rc)
rc = sock_error(nsk);
+ release_sock(sk);
+ if (rc)
+ goto out;
+
+ if (lsmc->sockopt_defer_accept && !(flags & O_NONBLOCK)) {
+ /* wait till data arrives on the socket */
+ timeo = msecs_to_jiffies(lsmc->sockopt_defer_accept *
+ MSEC_PER_SEC);
+ if (smc_sk(nsk)->use_fallback) {
+ struct sock *clcsk = smc_sk(nsk)->clcsock->sk;
+
+ lock_sock(clcsk);
+ if (skb_queue_empty(&clcsk->sk_receive_queue))
+ sk_wait_data(clcsk, &timeo, NULL);
+ release_sock(clcsk);
+ } else if (!atomic_read(&smc_sk(nsk)->conn.bytes_to_rcv)) {
+ lock_sock(nsk);
+ smc_rx_wait_data(smc_sk(nsk), &timeo);
+ release_sock(nsk);
+ }
+ }

out:
- release_sock(sk);
sock_put(sk); /* sock_hold above */
return rc;
}
@@ -1340,6 +1361,9 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
0);
}
break;
+ case TCP_DEFER_ACCEPT:
+ smc->sockopt_defer_accept = val;
+ break;
default:
break;
}
diff --git a/net/smc/smc.h b/net/smc/smc.h
index e4829a2f46ba..2405e889b93d 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -180,6 +180,10 @@ struct smc_sock { /* smc sock container */
struct list_head accept_q; /* sockets to be accepted */
spinlock_t accept_q_lock; /* protects accept_q */
bool use_fallback; /* fallback to tcp */
+ int sockopt_defer_accept;
+ /* sockopt TCP_DEFER_ACCEPT
+ * value
+ */
u8 wait_close_tx_prepared : 1;
/* shutdown wr or close
* started, waiting for unsent
diff --git a/net/smc/smc_rx.c b/net/smc/smc_rx.c
index eff4e0d0bb31..af851d8df1f8 100644
--- a/net/smc/smc_rx.c
+++ b/net/smc/smc_rx.c
@@ -51,7 +51,7 @@ static void smc_rx_data_ready(struct sock *sk)
* 1 if at least 1 byte available in rcvbuf or if socket error/shutdown.
* 0 otherwise (nothing in rcvbuf nor timeout, e.g. interrupted).
*/
-static int smc_rx_wait_data(struct smc_sock *smc, long *timeo)
+int smc_rx_wait_data(struct smc_sock *smc, long *timeo)
{
DEFINE_WAIT_FUNC(wait, woken_wake_function);
struct smc_connection *conn = &smc->conn;
diff --git a/net/smc/smc_rx.h b/net/smc/smc_rx.h
index 3a32b59bf06c..0b75a6b470e6 100644
--- a/net/smc/smc_rx.h
+++ b/net/smc/smc_rx.h
@@ -20,5 +20,6 @@
void smc_rx_init(struct smc_sock *smc);
int smc_rx_recvmsg(struct smc_sock *smc, struct msghdr *msg, size_t len,
int flags);
+int smc_rx_wait_data(struct smc_sock *smc, long *timeo);

#endif /* SMC_RX_H */
--
2.13.5