RDS: Fix send locking issue

Fix a deadlock between rds_rdma_send_complete() and
rds_send_remove_from_sock() when rds socket lock and
rds message lock are acquired out-of-order.

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

diff --git a/net/rds/send.c b/net/rds/send.c
index ad2e469..1a2ef24 100644 (file)
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -533,14 +533,13 @@ void rds_send_remove_from_sock(struct list_head *messages, int status)
 
                if (rs != rm->m_rs) {
                        if (rs) {
-                               spin_unlock(&rs->rs_lock);
                                rds_wake_sk_sleep(rs);
                                sock_put(rds_rs_to_sk(rs));
                        }
                        rs = rm->m_rs;
-                       spin_lock(&rs->rs_lock);
                        sock_hold(rds_rs_to_sk(rs));
                }
+               spin_lock(&rs->rs_lock);
 
                if (test_and_clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags)) {
                        struct rds_rdma_op *ro = rm->m_rdma_op;
@@ -560,6 +559,7 @@ void rds_send_remove_from_sock(struct list_head *messages, int status)
                        rds_message_put(rm);
                        rm->m_rs = NULL;
                }
+               spin_unlock(&rs->rs_lock);
 
 unlock_and_drop:
                spin_unlock(&rm->m_rs_lock);
@@ -567,7 +567,6 @@ unlock_and_drop:
        }
 
        if (rs) {
-               spin_unlock(&rs->rs_lock);
                rds_wake_sk_sleep(rs);
                sock_put(rds_rs_to_sk(rs));
        }