Commit b8ded9de authored by Karsten Graul's avatar Karsten Graul Committed by David S. Miller
Browse files

net/smc: pre-fetch send buffer outside of send_lock 



Pre-fetch send buffer for the CDC validation message before entering the
send_lock. Without that the send call might fail with -EBUSY because
there are no free buffers and waiting for buffers is not possible under
send_lock.

Signed-off-by: default avatarKarsten Graul <kgraul@linux.ibm.com>
Reviewed-by: default avatarUrsula Braun <ubraun@linux.ibm.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent b86a3722

net/smc/smc_cdc.c

+3 −7
Original line number Diff line number Diff line
@@ -116,19 +116,15 @@ int smc_cdc_msg_send(struct smc_connection *conn, 
}



/* send a validation msg indicating the move of a conn to an other QP link */

int smcr_cdc_msg_send_validation(struct smc_connection *conn)

int smcr_cdc_msg_send_validation(struct smc_connection *conn,

				 struct smc_cdc_tx_pend *pend,

				 struct smc_wr_buf *wr_buf)

{

	struct smc_host_cdc_msg *local = &conn->local_tx_ctrl;

	struct smc_link *link = conn->lnk;

	struct smc_cdc_tx_pend *pend;

	struct smc_wr_buf *wr_buf;

	struct smc_cdc_msg *peer;

	int rc;



	rc = smc_cdc_get_free_slot(conn, link, &wr_buf, NULL, &pend);

	if (rc)

		return rc;



	peer = (struct smc_cdc_msg *)wr_buf;

	peer->common.type = local->common.type;

	peer->len = local->len;

net/smc/smc_cdc.h

+3 −1
Original line number Diff line number Diff line
@@ -296,7 +296,9 @@ int smc_cdc_msg_send(struct smc_connection *conn, struct smc_wr_buf *wr_buf, 
		     struct smc_cdc_tx_pend *pend);

int smc_cdc_get_slot_and_msg_send(struct smc_connection *conn);

int smcd_cdc_msg_send(struct smc_connection *conn);

int smcr_cdc_msg_send_validation(struct smc_connection *conn);

int smcr_cdc_msg_send_validation(struct smc_connection *conn,

				 struct smc_cdc_tx_pend *pend,

				 struct smc_wr_buf *wr_buf);

int smc_cdc_init(void) __init;

void smcd_cdc_rx_init(struct smc_connection *conn);

net/smc/smc_core.c

+15 −3
Original line number Diff line number Diff line
@@ -483,7 +483,8 @@ static int smc_write_space(struct smc_connection *conn) 
	return space;

}



static int smc_switch_cursor(struct smc_sock *smc)

static int smc_switch_cursor(struct smc_sock *smc, struct smc_cdc_tx_pend *pend,

			     struct smc_wr_buf *wr_buf)

{

	struct smc_connection *conn = &smc->conn;

	union smc_host_cursor cons, fin;
@@ -520,11 +521,14 @@ static int smc_switch_cursor(struct smc_sock *smc) 


	if (smc->sk.sk_state != SMC_INIT &&

	    smc->sk.sk_state != SMC_CLOSED) {

		rc = smcr_cdc_msg_send_validation(conn);

		rc = smcr_cdc_msg_send_validation(conn, pend, wr_buf);

		if (!rc) {

			schedule_delayed_work(&conn->tx_work, 0);

			smc->sk.sk_data_ready(&smc->sk);

		}

	} else {

		smc_wr_tx_put_slot(conn->lnk,

				   (struct smc_wr_tx_pend_priv *)pend);

	}

	return rc;

}
@@ -533,7 +537,9 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr, 
				  struct smc_link *from_lnk, bool is_dev_err)

{

	struct smc_link *to_lnk = NULL;

	struct smc_cdc_tx_pend *pend;

	struct smc_connection *conn;

	struct smc_wr_buf *wr_buf;

	struct smc_sock *smc;

	struct rb_node *node;

	int i, rc = 0;
@@ -582,10 +588,16 @@ again: 
		}

		sock_hold(&smc->sk);

		read_unlock_bh(&lgr->conns_lock);

		/* pre-fetch buffer outside of send_lock, might sleep */

		rc = smc_cdc_get_free_slot(conn, to_lnk, &wr_buf, NULL, &pend);

		if (rc) {

			smcr_link_down_cond_sched(to_lnk);

			return NULL;

		}

		/* avoid race with smcr_tx_sndbuf_nonempty() */

		spin_lock_bh(&conn->send_lock);

		conn->lnk = to_lnk;

		rc = smc_switch_cursor(smc);

		rc = smc_switch_cursor(smc, pend, wr_buf);

		spin_unlock_bh(&conn->send_lock);

		sock_put(&smc->sk);

		if (rc) {

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