RDS: Fix locking in rds_send_drop_to()

It seems rds_send_drop_to() called
__rds_rdma_send_complete(rs, rm, RDS_RDMA_CANCELED)
with only rds_sock lock, but not rds_message lock. It raced with
other threads that is attempting to modify the rds_message as well,
such as from within rds_rdma_send_complete().

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, 7 insertions, 6 deletions

diff --git a/net/rds/send.c b/net/rds/send.c
index 1a2ef24fbc94..192a480076d0 100644
--- a/net/rds/send.c
+++ b/net/rds/send.c
@@ -632,9 +632,6 @@ void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
                 list_move(&rm->m_sock_item, &list);
                 rds_send_sndbuf_remove(rs, rm);
                 clear_bit(RDS_MSG_ON_SOCK, &rm->m_flags);
-
-                /* If this is a RDMA operation, notify the app. */
-                __rds_rdma_send_complete(rs, rm, RDS_RDMA_CANCELED);
         }
 
         /* order flag updates with the rs lock */
@@ -643,9 +640,6 @@ void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
 
         spin_unlock_irqrestore(&rs->rs_lock, flags);
 
-        if (wake)
-                rds_wake_sk_sleep(rs);
-
         conn = NULL;
 
         /* now remove the messages from the conn list as needed */
@@ -653,6 +647,10 @@ void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
                 /* We do this here rather than in the loop above, so that
                  * we don't have to nest m_rs_lock under rs->rs_lock */
                 spin_lock_irqsave(&rm->m_rs_lock, flags2);
+                /* If this is a RDMA operation, notify the app. */
+                spin_lock(&rs->rs_lock);
+                __rds_rdma_send_complete(rs, rm, RDS_RDMA_CANCELED);
+                spin_unlock(&rs->rs_lock);
                 rm->m_rs = NULL;
                 spin_unlock_irqrestore(&rm->m_rs_lock, flags2);
 
@@ -681,6 +679,9 @@ void rds_send_drop_to(struct rds_sock *rs, struct sockaddr_in *dest)
         if (conn)
                 spin_unlock_irqrestore(&conn->c_lock, flags);
 
+        if (wake)
+                rds_wake_sk_sleep(rs);
+
         while (!list_empty(&list)) {
                 rm = list_entry(list.next, struct rds_message, m_sock_item);
                 list_del_init(&rm->m_sock_item);