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>

1 files changed, 2 insertions, 0 deletions

diff --git a/net/rds/af_rds.c b/net/rds/af_rds.c
index 57ef0ec4f03d..8e3886d353b5 100644
--- a/net/rds/af_rds.c
+++ b/net/rds/af_rds.c
@@ -90,6 +90,8 @@ static int rds_release(struct socket *sock)
         rds_sock_count--;
         spin_unlock_irqrestore(&rds_sock_lock, flags);
 
+        rds_trans_put(rs->rs_transport);
+
         sock->sk = NULL;
         sock_put(sk);
 out: