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>

1 files changed, 2 insertions, 3 deletions

diff --git a/net/rds/send.c b/net/rds/send.c
index ad2e46947c8a..1a2ef24fbc94 100644
--- 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));
         }