[PATCH net-next 07/12] net/smc: assign link to a new connection

Karsten Graul
2020-05-04T12:19:15Z

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>
---
net/smc/smc_core.c | 65 ++++++++++++++++++++++++++++++++--------------
1 file changed, 46 insertions(+), 19 deletions(-)

diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
index 8f630b76c5a4..9c19b9aa3719 100644
--- 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 @@ int smc_conn_create(struct smc_sock *smc, struct smc_init_info *ini)
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;
--
2.17.1