RDS: have sockets get transport module references
Right now there's nothing to stop the various paths that use
rs->rs_transport from racing with rmmod and executing freed transport
code. The simple fix is to have binding to a transport also hold a
reference to the transport's module, removing this class of races.
We already had an unused t_owner field which was set for the modular
transports and which wasn't set for the built-in loop transport.
Signed-off-by: Zach Brown <zach.brown@oracle.com>
diff --git a/net/rds/connection.c b/net/rds/connection.c
index 75a1a37..968b7a7 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -117,6 +117,7 @@
{
struct rds_connection *conn, *parent = NULL;
struct hlist_head *head = rds_conn_bucket(laddr, faddr);
+ struct rds_transport *loop_trans;
unsigned long flags;
int ret;
@@ -163,7 +164,9 @@
* can bind to the destination address then we'd rather the messages
* flow through loopback rather than either transport.
*/
- if (rds_trans_get_preferred(faddr)) {
+ loop_trans = rds_trans_get_preferred(faddr);
+ if (loop_trans) {
+ rds_trans_put(loop_trans);
conn->c_loopback = 1;
if (is_outgoing && trans->t_prefer_loopback) {
/* "outgoing" connection - and the transport
