[PATCH net-next v3 3/4] net/smc: sockopts TCP_NODELAY and TCP_CORK

Ursula Braun
2018-04-26T15:18:22Z

Setting sockopt TCP_NODELAY or resetting sockopt TCP_CORK
triggers data transfer.

For a corked SMC socket RDMA writes are deferred, if there is
still sufficient send buffer space available.

Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
---
net/smc/af_smc.c | 20 +++++++++++++++++++-
net/smc/smc_tx.c | 24 +++++++++++++++++++++---
2 files changed, 40 insertions(+), 4 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index d274be7265ea..9d8b381281e3 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1291,7 +1291,7 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
{
struct sock *sk = sock->sk;
struct smc_sock *smc;
- int rc;
+ int val, rc;

smc = smc_sk(sk);

@@ -1307,6 +1307,10 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
if (rc)
return rc;

+ if (optlen < sizeof(int))
+ return rc;
+ get_user(val, (int __user *)optval);
+
lock_sock(sk);
switch (optname) {
case TCP_ULP:
@@ -1322,6 +1326,20 @@ static int smc_setsockopt(struct socket *sock, int level, int optname,
rc = -EINVAL;
}
break;
+ case TCP_NODELAY:
+ if (sk->sk_state != SMC_INIT && sk->sk_state != SMC_LISTEN) {
+ if (val)
+ mod_delayed_work(system_wq, &smc->conn.tx_work,
+ 0);
+ }
+ break;
+ case TCP_CORK:
+ if (sk->sk_state != SMC_INIT && sk->sk_state != SMC_LISTEN) {
+ if (!val)
+ mod_delayed_work(system_wq, &smc->conn.tx_work,
+ 0);
+ }
+ break;
default:
break;
}
diff --git a/net/smc/smc_tx.c b/net/smc/smc_tx.c
index 72f004c9c9b1..58dfe0bd9d60 100644
--- a/net/smc/smc_tx.c
+++ b/net/smc/smc_tx.c
@@ -19,6 +19,7 @@
#include <linux/sched/signal.h>

#include <net/sock.h>
+#include <net/tcp.h>

#include "smc.h"
#include "smc_wr.h"
@@ -26,6 +27,7 @@
#include "smc_tx.h"

#define SMC_TX_WORK_DELAY HZ
+#define SMC_TX_CORK_DELAY (HZ >> 2) /* 250 ms */

/***************************** sndbuf producer *******************************/

@@ -115,6 +117,13 @@ static int smc_tx_wait_memory(struct smc_sock *smc, int flags)
return rc;
}

+static bool smc_tx_is_corked(struct smc_sock *smc)
+{
+ struct tcp_sock *tp = tcp_sk(smc->clcsock->sk);
+
+ return (tp->nonagle & TCP_NAGLE_CORK) ? true : false;
+}
+
/* sndbuf producer: main API called by socket layer.
* called under sock lock.
*/
@@ -209,7 +218,16 @@ int smc_tx_sendmsg(struct smc_sock *smc, struct msghdr *msg, size_t len)
/* since we just produced more new data into sndbuf,
* trigger sndbuf consumer: RDMA write into peer RMBE and CDC
*/
- smc_tx_sndbuf_nonempty(conn);
+ if ((msg->msg_flags & MSG_MORE || smc_tx_is_corked(smc)) &&
+ (atomic_read(&conn->sndbuf_space) >
+ (conn->sndbuf_size >> 1)))
+ /* for a corked socket defer the RDMA writes if there
+ * is still sufficient sndbuf_space available
+ */
+ schedule_delayed_work(&conn->tx_work,
+ SMC_TX_CORK_DELAY);
+ else
+ smc_tx_sndbuf_nonempty(conn);
} /* while (msg_data_left(msg)) */

return send_done;
@@ -409,8 +427,8 @@ int smc_tx_sndbuf_nonempty(struct smc_connection *conn)
}
rc = 0;
if (conn->alert_token_local) /* connection healthy */
- schedule_delayed_work(&conn->tx_work,
- SMC_TX_WORK_DELAY);
+ mod_delayed_work(system_wq, &conn->tx_work,
+ SMC_TX_WORK_DELAY);
}
goto out_unlock;
}
--
2.13.5