Commit a60a2b1e authored by Ursula Braun's avatar Ursula Braun Committed by David S. Miller
Browse files

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: default avatarKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: default avatarUrsula Braun <ubraun@linux.ibm.com>
Reviewed-by: default avatarGuvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: default avatarKarsten Graul <kgraul@linux.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b55353e2

net/smc/af_smc.c

+31 −7
Original line number Diff line number Diff line
@@ -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);

net/smc/smc.h

+2 −0
Original line number Diff line number Diff line
@@ -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*/

net/smc/smc_close.c

+3 −4
Original line number Diff line number Diff line
@@ -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);

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