rds: use RCU to synchronize work-enqueue with connection teardown
rds_sendmsg() can enqueue work on cp_send_w from process context, but
it should not enqueue this work if connection teardown has commenced
(else we risk enquing work after rds_conn_path_destroy() has assumed that
all work has been cancelled/flushed).
Similarly some other functions like rds_cong_queue_updates
and rds_tcp_data_ready are called in softirq context, and may end
up enqueuing work on rds_wq after rds_conn_path_destroy() has assumed
that all workqs are quiesced.
Check the RDS_DESTROY_PENDING bit and use rcu synchronization to avoid
all these races.
Signed-off-by: Sowmini Varadhan <sowmini.varadhan@oracle.com>
Acked-by: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/rds/connection.c b/net/rds/connection.c
index 1eed197e..b10c0ef 100644
--- a/net/rds/connection.c
+++ b/net/rds/connection.c
@@ -366,8 +366,6 @@ void rds_conn_shutdown(struct rds_conn_path *cp)
* to the conn hash, so we never trigger a reconnect on this
* conn - the reconnect is always triggered by the active peer. */
cancel_delayed_work_sync(&cp->cp_conn_w);
- if (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
- return;
rcu_read_lock();
if (!hlist_unhashed(&conn->c_hash_node)) {
rcu_read_unlock();
@@ -390,6 +388,7 @@ static void rds_conn_path_destroy(struct rds_conn_path *cp)
return;
/* make sure lingering queued work won't try to ref the conn */
+ synchronize_rcu();
cancel_delayed_work_sync(&cp->cp_send_w);
cancel_delayed_work_sync(&cp->cp_recv_w);
@@ -407,6 +406,11 @@ static void rds_conn_path_destroy(struct rds_conn_path *cp)
if (cp->cp_xmit_rm)
rds_message_put(cp->cp_xmit_rm);
+ WARN_ON(delayed_work_pending(&cp->cp_send_w));
+ WARN_ON(delayed_work_pending(&cp->cp_recv_w));
+ WARN_ON(delayed_work_pending(&cp->cp_conn_w));
+ WARN_ON(work_pending(&cp->cp_down_w));
+
cp->cp_conn->c_trans->conn_free(cp->cp_transport_data);
}
@@ -686,10 +690,13 @@ void rds_conn_path_drop(struct rds_conn_path *cp, bool destroy)
{
atomic_set(&cp->cp_state, RDS_CONN_ERROR);
- if (!destroy && test_bit(RDS_DESTROY_PENDING, &cp->cp_flags))
+ rcu_read_lock();
+ if (!destroy && test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) {
+ rcu_read_unlock();
return;
-
+ }
queue_work(rds_wq, &cp->cp_down_w);
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(rds_conn_path_drop);
@@ -706,9 +713,15 @@ EXPORT_SYMBOL_GPL(rds_conn_drop);
*/
void rds_conn_path_connect_if_down(struct rds_conn_path *cp)
{
+ rcu_read_lock();
+ if (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) {
+ rcu_read_unlock();
+ return;
+ }
if (rds_conn_path_state(cp) == RDS_CONN_DOWN &&
!test_and_set_bit(RDS_RECONNECT_PENDING, &cp->cp_flags))
queue_delayed_work(rds_wq, &cp->cp_conn_w, 0);
+ rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(rds_conn_path_connect_if_down);