net/smc: assign link to a new connection

For new connections, assign a link from the link group, using some
simple load balancing.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Reviewed-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 8f630b7..9c19b9a 100644 (file)
--- a/net/smc/smc_core.c
+++ b/net/smc/smc_core.c
@@ -121,16 +121,59 @@ static void smc_lgr_add_alert_token(struct smc_connection *conn)
        rb_insert_color(&conn->alert_node, &conn->lgr->conns_all);
 }
 
+/* assign an SMC-R link to the connection */
+static int smcr_lgr_conn_assign_link(struct smc_connection *conn, bool first)
+{
+       enum smc_link_state expected = first ? SMC_LNK_ACTIVATING :
+                                      SMC_LNK_ACTIVE;
+       int i, j;
+
+       /* do link balancing */
+       for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
+               struct smc_link *lnk = &conn->lgr->lnk[i];
+
+               if (lnk->state != expected)
+                       continue;
+               if (conn->lgr->role == SMC_CLNT) {
+                       conn->lnk = lnk; /* temporary, SMC server assigns link*/
+                       break;
+               }
+               if (conn->lgr->conns_num % 2) {
+                       for (j = i + 1; j < SMC_LINKS_PER_LGR_MAX; j++) {
+                               struct smc_link *lnk2;
+
+                               lnk2 = &conn->lgr->lnk[j];
+                               if (lnk2->state == expected) {
+                                       conn->lnk = lnk2;
+                                       break;
+                               }
+                       }
+               }
+               if (!conn->lnk)
+                       conn->lnk = lnk;
+               break;
+       }
+       if (!conn->lnk)
+               return SMC_CLC_DECL_NOACTLINK;
+       return 0;
+}
+
 /* Register connection in link group by assigning an alert token
  * registered in a search tree.
  * Requires @conns_lock
  * Note that '0' is a reserved value and not assigned.
  */
-static int smc_lgr_register_conn(struct smc_connection *conn)
+static int smc_lgr_register_conn(struct smc_connection *conn, bool first)
 {
        struct smc_sock *smc = container_of(conn, struct smc_sock, conn);
        static atomic_t nexttoken = ATOMIC_INIT(0);
+       int rc;
 
+       if (!conn->lgr->is_smcd) {
+               rc = smcr_lgr_conn_assign_link(conn, first);
+               if (rc)
+                       return rc;
+       }
        /* find a new alert_token_local value not yet used by some connection
         * in this link group
         */
@@ -141,22 +184,6 @@ static int smc_lgr_register_conn(struct smc_connection *conn)
                        conn->alert_token_local = 0;
        }
        smc_lgr_add_alert_token(conn);
-
-       /* assign the new connection to a link */
-       if (!conn->lgr->is_smcd) {
-               struct smc_link *lnk;
-               int i;
-
-               /* tbd - link balancing */
-               for (i = 0; i < SMC_LINKS_PER_LGR_MAX; i++) {
-                       lnk = &conn->lgr->lnk[i];
-                       if (lnk->state == SMC_LNK_ACTIVATING ||
-                           lnk->state == SMC_LNK_ACTIVE)
-                               conn->lnk = lnk;
-               }
-               if (!conn->lnk)
-                       return SMC_CLC_DECL_NOACTLINK;
-       }
        conn->lgr->conns_num++;
        return 0;
 }
@@ -1285,7 +1312,7 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini)
                        /* link group found */
                        ini->cln_first_contact = SMC_REUSE_CONTACT;
                        conn->lgr = lgr;
-                       rc = smc_lgr_register_conn(conn); /* add conn to lgr */
+                       rc = smc_lgr_register_conn(conn, false);
                        write_unlock_bh(&lgr->conns_lock);
                        if (!rc && delayed_work_pending(&lgr->free_work))
                                cancel_delayed_work(&lgr->free_work);
@@ -1313,7 +1340,7 @@ create:
                        goto out;
                lgr = conn->lgr;
                write_lock_bh(&lgr->conns_lock);
-               rc = smc_lgr_register_conn(conn); /* add smc conn to lgr */
+               rc = smc_lgr_register_conn(conn, true);
                write_unlock_bh(&lgr->conns_lock);
                if (rc)
                        goto out;