net/smc: Add connection counters for links

Add connection counters to the structure of the link.
Increase/decrease the counters as needed in the corresponding
routines.
Signed-off-by: Guvenc Gulce <guvenc@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/smc/smc_core.c

@@ -139,6 +139,7 @@ static int smcr_lgr_conn_assign_link(struct smc_connection *conn, bool first)
 	}
 	if (!conn->lnk)
 		return SMC_CLC_DECL_NOACTLINK;
+	atomic_inc(&conn->lnk->conn_cnt);
 	return 0;
 }
 
@@ -180,6 +181,8 @@ static void __smc_lgr_unregister_conn(struct smc_connection *conn)
 	struct smc_link_group *lgr = conn->lgr;
 
 	rb_erase(&conn->alert_node, &lgr->conns_all);
+	if (conn->lnk)
+		atomic_dec(&conn->lnk->conn_cnt);
 	lgr->conns_num--;
 	conn->alert_token_local = 0;
 	sock_put(&smc->sk); /* sock_hold in smc_lgr_register_conn() */
@@ -314,6 +317,7 @@ int smcr_link_init(struct smc_link_group *lgr, struct smc_link *lnk,
 	lnk->smcibdev = ini->ib_dev;
 	lnk->ibport = ini->ib_port;
 	lnk->path_mtu = ini->ib_dev->pattr[ini->ib_port - 1].active_mtu;
+	atomic_set(&lnk->conn_cnt, 0);
 	smc_llc_link_set_uid(lnk);
 	INIT_WORK(&lnk->link_down_wrk, smc_link_down_work);
 	if (!ini->ib_dev->initialized) {
@@ -526,6 +530,14 @@ static int smc_switch_cursor(struct smc_sock *smc, struct smc_cdc_tx_pend *pend,
 	return rc;
 }
 
+static void smc_switch_link_and_count(struct smc_connection *conn,
+				      struct smc_link *to_lnk)
+{
+	atomic_dec(&conn->lnk->conn_cnt);
+	conn->lnk = to_lnk;
+	atomic_inc(&conn->lnk->conn_cnt);
+}
+
 struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
 				  struct smc_link *from_lnk, bool is_dev_err)
 {
@@ -574,7 +586,7 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
 		    smc->sk.sk_state == SMC_PEERABORTWAIT ||
 		    smc->sk.sk_state == SMC_PROCESSABORT) {
 			spin_lock_bh(&conn->send_lock);
-			conn->lnk = to_lnk;
+			smc_switch_link_and_count(conn, to_lnk);
 			spin_unlock_bh(&conn->send_lock);
 			continue;
 		}
@@ -588,7 +600,7 @@ struct smc_link *smc_switch_conns(struct smc_link_group *lgr,
 		}
 		/* avoid race with smcr_tx_sndbuf_nonempty() */
 		spin_lock_bh(&conn->send_lock);
-		conn->lnk = to_lnk;
+		smc_switch_link_and_count(conn, to_lnk);
 		rc = smc_switch_cursor(smc, pend, wr_buf);
 		spin_unlock_bh(&conn->send_lock);
 		sock_put(&smc->sk);

net/smc/smc_core.h

@@ -129,6 +129,7 @@ struct smc_link {
 	struct delayed_work	llc_testlink_wrk; /* testlink worker */
 	struct completion	llc_testlink_resp; /* wait for rx of testlink */
 	int			llc_testlink_time; /* testlink interval */
+	atomic_t		conn_cnt; /* connections on this link */
 };
 
 /* For now we just allow one parallel link per link group. The SMC protocol