[PATCH net-next] rds: transport module should be auto loaded when transport is set

[rao . shoaib]

From: Rao Shoaib <rao.sho...@oracle.com>

This enhancement auto loads transport module when the transport
is set via SO_RDS_TRANSPORT socket option.

Orabug: 31032127

Reviewed-by: Ka-Cheong Poon <ka-cheong.p...@oracle.com>
Reviewed-by: Håkon Bugge <haakon.bu...@oracle.com>
Signed-off-by: Rao Shoaib <rao.sho...@oracle.com>
Signed-off-by: Somasundaram Krishnasamy <somasundaram.krishnas...@oracle.com>
---
 include/uapi/linux/rds.h |  2 +-
 net/rds/transport.c      | 26 +++++++++++++++++---------
 2 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/include/uapi/linux/rds.h b/include/uapi/linux/rds.h
index cba368e55863..7273c681e6c1 100644
--- a/include/uapi/linux/rds.h
+++ b/include/uapi/linux/rds.h
@@ -64,7 +64,7 @@
 
 /* supported values for SO_RDS_TRANSPORT */
 #define        RDS_TRANS_IB    0
-#define        RDS_TRANS_IWARP 1
+#define        RDS_TRANS_GAP   1
 #define        RDS_TRANS_TCP   2
 #define RDS_TRANS_COUNT        3
 #define        RDS_TRANS_NONE  (~0)
diff --git a/net/rds/transport.c b/net/rds/transport.c
index 46f709a4b577..f8001ec80867 100644
--- a/net/rds/transport.c
+++ b/net/rds/transport.c
@@ -38,6 +38,12 @@
 #include "rds.h"
 #include "loop.h"
 
+static char * const rds_trans_modules[] = {
+       [RDS_TRANS_IB] = "rds_rdma",
+       [RDS_TRANS_GAP] = NULL,
+       [RDS_TRANS_TCP] = "rds_tcp",
+};
+
 static struct rds_transport *transports[RDS_TRANS_COUNT];
 static DECLARE_RWSEM(rds_trans_sem);
 
@@ -110,18 +116,20 @@ struct rds_transport *rds_trans_get(int t_type)
 {
        struct rds_transport *ret = NULL;
        struct rds_transport *trans;
-       unsigned int i;
 
        down_read(&rds_trans_sem);
-       for (i = 0; i < RDS_TRANS_COUNT; i++) {
-               trans = transports[i];
-
-               if (trans && trans->t_type == t_type &&
-                   (!trans->t_owner || try_module_get(trans->t_owner))) {
-                       ret = trans;
-                       break;
-               }
+       trans = transports[t_type];
+       if (!trans) {
+               up_read(&rds_trans_sem);
+               if (rds_trans_modules[t_type])
+                       request_module(rds_trans_modules[t_type]);
+               down_read(&rds_trans_sem);
+               trans = transports[t_type];
        }
+       if (trans && trans->t_type == t_type &&
+           (!trans->t_owner || try_module_get(trans->t_owner)))
+               ret = trans;
+
        up_read(&rds_trans_sem);
 
        return ret;
-- 
2.16.6