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 <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Reviewed-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index e7649bb..7212de4 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);
