rds: don't let RDS shutdown a connection while senders are present

This is the first in a long line of patches that tries to fix races
between RDS connection shutdown and RDS traffic.

Here we are maintaining a count of active senders to make sure
the connection doesn't go away while they are using it.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/net/rds/connection.c b/net/rds/connection.c
index 7e4e9dfdbc0b..9c249f394f29 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -148,6 +148,7 @@ static struct rds_connection *__rds_conn_create(__be32 laddr, __be32 faddr,
 
         spin_lock_init(&conn->c_send_lock);
         atomic_set(&conn->c_send_generation, 1);
+        atomic_set(&conn->c_senders, 0);
         INIT_LIST_HEAD(&conn->c_send_queue);
         INIT_LIST_HEAD(&conn->c_retrans);
 
@@ -276,6 +277,12 @@ void rds_conn_shutdown(struct rds_connection *conn)
                 spin_lock_irq(&conn->c_send_lock);
                 spin_unlock_irq(&conn->c_send_lock);
 
+                while(atomic_read(&conn->c_senders)) {
+                        schedule_timeout(1);
+                        spin_lock_irq(&conn->c_send_lock);
+                        spin_unlock_irq(&conn->c_send_lock);
+                }
+
                 conn->c_trans->conn_shutdown(conn);
                 rds_conn_reset(conn);