rds: cancel send/recv work before queuing connection shutdown

We could end up executing rds_conn_shutdown before the rds_recv_worker
thread, then rds_conn_shutdown -> rds_tcp_conn_shutdown can do a
sock_release and set sock->sk to null, which may interleave in bad
ways with rds_recv_worker, e.g., it could result in:

"BUG: unable to handle kernel NULL pointer dereference at 0000000000000078"
    [ffff881769f6fd70] release_sock at ffffffff815f337b
    [ffff881769f6fd90] rds_tcp_recv at ffffffffa043c888 [rds_tcp]
    [ffff881769f6fdb0] rds_recv_worker at ffffffffa04a4810 [rds]
    [ffff881769f6fde0] process_one_work at ffffffff810a14c1
    [ffff881769f6fe40] worker_thread at ffffffff810a1940
    [ffff881769f6fec0] kthread at ffffffff810a6b1e

Also, do not enqueue any new shutdown workq items when the connection is
shutting down (this may happen for rds-tcp in softirq mode, if a FIN
or CLOSE is received while the modules is in the middle of an unload)

Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/net/rds/tcp_connect.c b/net/rds/tcp_connect.c
index cbe08a1fa4c7..46f74dad0e16 100644
--- a/net/rds/tcp_connect.c
+++ b/net/rds/tcp_connect.c
@@ -69,14 +69,14 @@ void rds_tcp_state_change(struct sock *sk)
                 if (!IS_CANONICAL(cp->cp_conn->c_laddr, cp->cp_conn->c_faddr) &&
                     rds_conn_path_transition(cp, RDS_CONN_CONNECTING,
                                              RDS_CONN_ERROR)) {
-                        rds_conn_path_drop(cp);
+                        rds_conn_path_drop(cp, false);
                 } else {
                         rds_connect_path_complete(cp, RDS_CONN_CONNECTING);
                 }
                 break;
         case TCP_CLOSE_WAIT:
         case TCP_CLOSE:
-                rds_conn_path_drop(cp);
+                rds_conn_path_drop(cp, false);
         default:
                 break;
         }