From 3db6e0d172c94bd9953a1347c55ffb64b1d2e74f Mon Sep 17 00:00:00 2001 From: Sowmini Varadhan Date: Thu, 4 Jan 2018 06:53:00 -0800 Subject: 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 Acked-by: Santosh Shilimkar Signed-off-by: David S. Miller --- net/rds/send.c | 37 ++++++++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 5 deletions(-) (limited to 'net/rds/send.c') diff --git a/net/rds/send.c b/net/rds/send.c index f72466c63f0c..d3e32d1f3c7d 100644 --- a/net/rds/send.c +++ b/net/rds/send.c @@ -162,6 +162,12 @@ restart: goto out; } + if (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) { + release_in_xmit(cp); + ret = -ENETUNREACH; /* dont requeue send work */ + goto out; + } + /* * we record the send generation after doing the xmit acquire. * if someone else manages to jump in and do some work, we'll use @@ -437,7 +443,12 @@ over_batch: !list_empty(&cp->cp_send_queue)) && !raced) { if (batch_count < send_batch_count) goto restart; - queue_delayed_work(rds_wq, &cp->cp_send_w, 1); + rcu_read_lock(); + if (test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) + ret = -ENETUNREACH; + else + queue_delayed_work(rds_wq, &cp->cp_send_w, 1); + rcu_read_unlock(); } else if (raced) { rds_stats_inc(s_send_lock_queue_raced); } @@ -1151,6 +1162,11 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len) else cpath = &conn->c_path[0]; + if (test_bit(RDS_DESTROY_PENDING, &cpath->cp_flags)) { + ret = -EAGAIN; + goto out; + } + rds_conn_path_connect_if_down(cpath); ret = rds_cong_wait(conn->c_fcong, dport, nonblock, rs); @@ -1190,9 +1206,17 @@ int rds_sendmsg(struct socket *sock, struct msghdr *msg, size_t payload_len) rds_stats_inc(s_send_queued); ret = rds_send_xmit(cpath); - if (ret == -ENOMEM || ret == -EAGAIN) - queue_delayed_work(rds_wq, &cpath->cp_send_w, 1); - + if (ret == -ENOMEM || ret == -EAGAIN) { + ret = 0; + rcu_read_lock(); + if (test_bit(RDS_DESTROY_PENDING, &cpath->cp_flags)) + ret = -ENETUNREACH; + else + queue_delayed_work(rds_wq, &cpath->cp_send_w, 1); + rcu_read_unlock(); + } + if (ret) + goto out; rds_message_put(rm); return payload_len; @@ -1270,7 +1294,10 @@ rds_send_probe(struct rds_conn_path *cp, __be16 sport, rds_stats_inc(s_send_pong); /* schedule the send work on rds_wq */ - queue_delayed_work(rds_wq, &cp->cp_send_w, 1); + rcu_read_lock(); + if (!test_bit(RDS_DESTROY_PENDING, &cp->cp_flags)) + queue_delayed_work(rds_wq, &cp->cp_send_w, 1); + rcu_read_unlock(); rds_message_put(rm); return 0; -- cgit v1.2.3