RDS: Track transports via an array, not a list

Now that transports can be loaded in arbitrary order,
it is important for rds_trans_get_preferred() to look
for them in a particular order, instead of walking the list
until it finds a transport that works for a given address.
Now, each transport registers for a specific transport slot,
and these are ordered so that preferred transports come first,
and then if they are not loaded, other transports are queried.

Signed-off-by: Andy Grover <andy.grover@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 19 insertions, 10 deletions

diff --git a/net/rds/transport.c b/net/rds/transport.c
index 56a530996a4a..7e1067901353 100644
--- a/net/rds/transport.c
+++ b/net/rds/transport.c
@@ -37,7 +37,7 @@
 #include "rds.h"
 #include "loop.h"
 
-static LIST_HEAD(rds_transports);
+static struct rds_transport *transports[RDS_TRANS_COUNT];
 static DECLARE_RWSEM(rds_trans_sem);
 
 int rds_trans_register(struct rds_transport *trans)
@@ -46,8 +46,13 @@ int rds_trans_register(struct rds_transport *trans)
 
         down_write(&rds_trans_sem);
 
-        list_add_tail(&trans->t_item, &rds_transports);
-        printk(KERN_INFO "Registered RDS/%s transport\n", trans->t_name);
+        if (transports[trans->t_type])
+                printk(KERN_ERR "RDS Transport type %d already registered\n",
+                        trans->t_type);
+        else {
+                transports[trans->t_type] = trans;
+                printk(KERN_INFO "Registered RDS/%s transport\n", trans->t_name);
+        }
 
         up_write(&rds_trans_sem);
 
@@ -59,7 +64,7 @@ void rds_trans_unregister(struct rds_transport *trans)
 {
         down_write(&rds_trans_sem);
 
-        list_del_init(&trans->t_item);
+        transports[trans->t_type] = NULL;
         printk(KERN_INFO "Unregistered RDS/%s transport\n", trans->t_name);
 
         up_write(&rds_trans_sem);
@@ -68,16 +73,17 @@ EXPORT_SYMBOL_GPL(rds_trans_unregister);
 
 struct rds_transport *rds_trans_get_preferred(__be32 addr)
 {
-        struct rds_transport *trans;
         struct rds_transport *ret = NULL;
+        int i;
 
         if (IN_LOOPBACK(ntohl(addr)))
                 return &rds_loop_transport;
 
         down_read(&rds_trans_sem);
-        list_for_each_entry(trans, &rds_transports, t_item) {
-                if (trans->laddr_check(addr) == 0) {
-                        ret = trans;
+        for (i = 0; i < RDS_TRANS_COUNT; i++)
+        {
+                if (transports[i] && (transports[i]->laddr_check(addr) == 0)) {
+                        ret = transports[i];
                         break;
                 }
         }
@@ -99,12 +105,15 @@ unsigned int rds_trans_stats_info_copy(struct rds_info_iterator *iter,
         struct rds_transport *trans;
         unsigned int total = 0;
         unsigned int part;
+        int i;
 
         rds_info_iter_unmap(iter);
         down_read(&rds_trans_sem);
 
-        list_for_each_entry(trans, &rds_transports, t_item) {
-                if (trans->stats_info_copy == NULL)
+        for (i = 0; i < RDS_TRANS_COUNT; i++)
+        {
+                trans = transports[i];
+                if (!trans || !trans->stats_info_copy)
                         continue;
 
                 part = trans->stats_info_copy(iter, avail);